The purpose of this study was to establish a high-performance liquid chromatography (HPLC) method for the simultaneous determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, a...The purpose of this study was to establish a high-performance liquid chromatography (HPLC) method for the simultaneous determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid in Danhong injection. The chromatographic method employed was as follows: the column was a Welch Ultimate XB-C18 column (250 mm × 4.6 mm, 10 μm), the mobile phase was a gradient elution of 0.4% formic acid aqueous solution (A) and acetonitrile (B), the detection wavelengths were 280 nm for sodium danshensu, protocatechuic aldehyde, and salvianolic acid B and 326 nm for 4-coumaric acid and rosmarinic acid, the sample volume was 10 μL, the flow rate was 1.0 mL/min, and the column temperature was 35°C. This method can realize the separation and determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid within 50 minutes. The linear relationships of the five peak areas and their concentrations are good (R<sup>2</sup>> 0.9997). The precision RSD values are all less than 1.0%. The reproducibility RSD values are all less than 1.3%. The stability RSD values are all less than 2.2%. The recovery values ranged from 92.4% to 99.4%. This method is simple, accurate, and reproducible. It can be used for the determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid in Danhong injection.展开更多
A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as ...A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as the reversed dispersive sorbent.It was analyzed after purification by highperformance liquid chromatography,the extraction time and the properties of the nanocomposite were optimized.Under optimized conditions,present method has linear response over concentration range of 0.5–50 ng/mL in pork samples with a satisfactory detection limit close to 0.1 ng/mL.The precisions of the current method(coefficient of variation)are lower than 5%,while recoveries are more than 98.3%.The nanocomposite exhibited high adsorptivity,long-term storage stability,satisfactory anti-interfering activity and high selectivity toward2-agonists compared with those of rGO and CNTs.展开更多
The modification of high-performance liquid chromatography parameters leads to a more effective oligonucleotide-A purification process. Using various experimental parameters such as buffer, concentration, and pH, a me...The modification of high-performance liquid chromatography parameters leads to a more effective oligonucleotide-A purification process. Using various experimental parameters such as buffer, concentration, and pH, a method for optimizing the purification of an oligonucleotide-A on a reverse-phase C18 column was created. To purify oligonucleotide-A, High-Performance Liquid Chromatography (HPLC), Ultraviolet-Visible Spectrophotometry (UV-Vis), Liquid Chromatography-Mass Spectrometry (LC-MS), and lyophilization were used. Chromatographic data were collected with a semi-prep HPLC system, quantified with the UV-Vis technique, and validated with the LC-MS method. The most optimized parameters found to obtain the purity of 93.0% are 40 mM triethylammonium bicarbonate (TEAB) buffer with pH 7, which is approximately 6.0% higher than the reported method of which the purity is 87.0%. However, the yield under these conditions was reduced by about 5%. The worst possible optimized settings that resulted in the lowest purity (84.0%) and yield (69.0%) are 10 mM ammonium acetate (NH<sub>4</sub>CH<sub>3</sub>CO<sub>2</sub>) with pH 7.展开更多
Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydroge...Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydrogen phosphate at 0.067 mol/L(mixed with triethylamine;pH value was adjusted to 6.5).The chromatographic column was Kromasil C18(250 mm × 4.6 mm;5.0μm)and the relative standard deviation(RSD)of the drug content level was 1.25%.The injection volume was set to 20μL,the detection wavelength was set to 210 nm,the external standard method was used to complete the quantitative work,and the theoretical plate number should be more than 1000 according to the drug peak calculation.The effect of HPLC on the determmation of azithromycin was analyzed.Results:The concentration of azithromycin was 1.40-3.40 mg/mL,and the linear relationship was good.RSD of the drug content level was 1.25%.The representative test product had strong stability within 8.0 hours and the method had good repeatability.According to the recovery experiment method,the recovery rates of three standard samples from low to high were 99.87%,100.15%,and 100.62%.The average recovery rate was 100.21%.RSD value was 0.39%.It means that the recovery rate of HPLC is good.Conclusion:In the determination of azithromycin,the use of HPLC to complete the work was of high sensitivity,simple,and fast.The method had good repeatability in the determination of drug components which is worthy of further promotion.展开更多
The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time...The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.展开更多
AIM:To perform plasma free amino acid(PFAA)profiling of esophageal squamous cell carcinoma(ESCC)patients at different pathological stages and healthy subjects.METHODS:Plasma samples from ESCC patients(n=51)and healthy...AIM:To perform plasma free amino acid(PFAA)profiling of esophageal squamous cell carcinoma(ESCC)patients at different pathological stages and healthy subjects.METHODS:Plasma samples from ESCC patients(n=51)and healthy control adults(n=60)were analyzed by high-performance liquid chromatography(HPLC).The ESCC patients included moderate/poorly-differentiation(n=24),lymph node metastasis(n=17)and clinical stage>Ib2(n=36).Partial least squares discriminant analysis was performed to demonstrate that the PFAA metabolic patterns enabled discrimination between ESCC patients and controls,and the Student t test was applied to assess significant differences in PFAA concentrations between the two groups.RESULTS:There were significant differences in the PFAA profiles between controls and ESCC patients.Compared with healthy controls,the levels of Asp,Glu,Gly,His,Thr,Tau,Ala,Met,Ile,Leu,and Phe were decreased in ESCC patients,but Cys was increased.There exists a strong correlation between PFAA profiles and clinicopathological characteristics in ESCC patients.The levels of many PFAAs(i.e.,Glu,Asp,Ser,Gly,Tau,Ala,Tyr,Val,Ile,and Leu)were related to pathological grading,lymph node metastasis,and ESCC clinical stage.Very good discrimination between ESCC patients and control subjects was achieved by multivariate modeling of plasma profiles.CONCLUSION:HPLC-based plasma profiling analysis was shown to be an effective approach to differentiate between ESCC patients and controls.PFAA profiles may have potential value for screening or diagnosing ESCC.展开更多
A simple, accurate and sensitive high-performance liquid chromatography(HPLC) method was developed,validated and applied to the determination of either theophylline or paracetamol in milk-based samples. The method all...A simple, accurate and sensitive high-performance liquid chromatography(HPLC) method was developed,validated and applied to the determination of either theophylline or paracetamol in milk-based samples. The method allowed drug quantification in fresh and powdered milk with a relatively short run time of analysis and it was also successfully applied to the quantification of the drugs in solid dosage forms intended for pediatric use. Moreover, the main significant advantages over other published works are the simplicity of the sample preparation, reduced assay time and sample loss. The method meets the International Conference on Harmonization guideline for analytical methods validation regarding specificity, linearity, accuracy, precision,specificity and robustness as required by health authorities and applied by industry while designing and marketing new drug products. The technique encompasses the separation of the analytes with a reverse phase C_(18) column under isocratic conditions and UV detection at 272 nm and 243 nm, respectively, for theophylline and paracetamol. The lower limit of quantification for both drugs was determined as 0.2 μg/m L and the between-batch accuracy was 99.7%. This HPLC method allows quantification of theophylline and paracetamol in milk matrices and it can be applied in the design, development and production of milk-based pediatric dosage forms.展开更多
A new reversed-phase high performance liquid chromatography method was developed to quantitate the activity of xanthine oxidase involved in milk fat globule membrane with xanthine as the substrate and the separation o...A new reversed-phase high performance liquid chromatography method was developed to quantitate the activity of xanthine oxidase involved in milk fat globule membrane with xanthine as the substrate and the separation of product (uric acid). The increment of uric acid in the reaction system was used to calculate the total activity of XO. The optimized assay conditions, linearity of detection, recovery of uric acid and chromatogram were developed in text, indicating this method is simple, rapid and efficient. It is an alternative potential method for the determination of the activity of XO in milk.展开更多
To investigate the pharmacokinetics of felodipine in the plasma of healthy Chinese volunteers, 30 healthy volunteers received a single oral dose of 5 mg of extended release felodipine tablets. The felodipine was extra...To investigate the pharmacokinetics of felodipine in the plasma of healthy Chinese volunteers, 30 healthy volunteers received a single oral dose of 5 mg of extended release felodipine tablets. The felodipine was extracted from the matrix with a liquid-liquid extract procedure and analyzed by high-performance liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring(MRM) mode using an electrospray ion source with positive ion detection. The method was validated over a felodipine concentration range of 0.05—10.00 ng/mL in human plasma. Its main pharmacokinetic parameters values were: ρ_ max =(1.67±0.84) ng/mL, occurring at (3.93±2.49) h; the plasma elimination half-life: (23.08±9.48) h and the area under the plasma concentration versus time curve: (29.94±14.39) ng·h/mL. The validation results demonstrated that this method showed a satisfactory precision and accuracy across the calibration range. The procedure involved minimal drug administration, sample preparation, and a 2.5-min chromatographic run time. It was well suited to clinical studies of the drug involving large numbers of samples.展开更多
Chromatography fingerprint (CFP) of 10 samples of hongqi were studied. 23 common peaks were analyzed, their average similarity was 97.29%. CFP were positioned with main index composition such as formononetin, calycosi...Chromatography fingerprint (CFP) of 10 samples of hongqi were studied. 23 common peaks were analyzed, their average similarity was 97.29%. CFP were positioned with main index composition such as formononetin, calycosin and then the contents of index composition were determined. The character and exclusive of CFP of 10 samples of hongqi were clear. CFP and content determination of index composition of hongqi could be used to evaluate the quality of hongqi comprehensively.展开更多
A simple method has been proposed for the determination of clozapine (CLZ) and chlorpromazine (CPZ) in human urine by dispersive liquid-liquid microextraction (DLLME) in combination with high-performance liquid chroma...A simple method has been proposed for the determination of clozapine (CLZ) and chlorpromazine (CPZ) in human urine by dispersive liquid-liquid microextraction (DLLME) in combination with high-performance liquid chromatography-ultraviolet detector (HPLC-UV). All important variables influencing the extraction efficiency, such as pH, types of the extraction solvent and the disperser solvent and their volume, ionic strength and centrifugation time were investigated and optimized. Under the optimal conditions, the limit of detection (LODs) and quantification (LOQs) of the method were 13 and 39 ng/mL for CLZ, and 2 and 6 ng/mL for CPZ, respectively. The relative standard deviations (RSDs) of the targets were less than 5.1% (C=0.100 μg/mL, n=9). Good linear behaviors over the tested concentration ranges were obtained with the values of R2>0.999 for the targets. The absolute extraction efficiencies of CLZ and CPZ from the spiked blank urine samples were 98.3% and 97.8%, respectively. The applicability of the technique was validated by analyzing urine samples and the mean recoveries for spiked urine samples ranged from 93.3% to 105.0%. The method was successfully applied for the determination of CLZ and CPZ in real human urine.展开更多
A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS) method was developed for the analysis of tetracycline antibiotics, including tetracycline (TC), oxytetrac...A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS) method was developed for the analysis of tetracycline antibiotics, including tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and their 4-epimers (4-epiTCs) in agricultural soil fertilized with swine manure. Soil samples were extracted and cleaned-up with 10 mL EDTA-McIlvaine buffer solution (pH 4.0), then cleaned-up and pre-concentrated using the Oasis MAX cartridge and then eluted with 1 mL solution by mixing formic acid, methanol and water at a ratio of 2:15:83 (v/v/v). The purified samples were separated by an ACQUITY UPLC BEH C18 column using acetonitrile and water containing 0.1% formic acid mobile phase and detected by a single quadrupole MS. The limits of detection for the soil extraction method (LODsoil) ranged from 0.6-2.5 μg kg-1 with recoveries from 23.3-159.2%. Finally, the method was applied to an agricultural field in an area with intensive pig-fattening farming. Tetracyclines were detected in soil from 2.8 to 42.4 μg kg-1 soil. These results demonstrate that soil from swine farms can become severely contaminated with tetracycline antibiotics and their metabolites.展开更多
Creatinine, uric acid, hypoxanthine and xanthine are important diagnostic biomarkers in human urine for gouty arthritis or renal disease diacrisis. A simple method for simultaneous determination of these biomarkers in...Creatinine, uric acid, hypoxanthine and xanthine are important diagnostic biomarkers in human urine for gouty arthritis or renal disease diacrisis. A simple method for simultaneous determination of these biomarkers in urine based on reversed-phase high-performance liquid chromatography(RPHPLC) with ultraviolet(UV) detector was proposed. After pretreatment by dilution, centrifugation and filtration, the biomarkers in urine samples were separated by ODS-BP column by elution with methanol/50 mM NaH2PO4 buffer solution at pH 5.26(5:95). Good linearity between peak areas and concentrations of standards was obtained for the biomarkers with correlation coefficients in the range of 0.9957–0.9993.The proposed analytical method has satisfactory repeatability(the recovery of data in a range of creatinine, uric acid, hypoxanthine and xanthine was 93.49–97.90%, 95.38–96.45%, 112.46–115.78% and90.82–97.13% with standard deviation of o5%, respectively) and the limits of detection(LODs, S/NZ3)for creatinine, uric acid, hypoxanthine, and xanthine were 0.010, 0.025, 0.050 and 0.025 mg/L,respectively. The established method was proved to be simple, accurate, sensitive and reliable for the quantitation of gouty arthritis' biomarkers in human urine samples. The ratio of creatinine to uric acid was found to be a possible factor for assessment of gouty arthritis.展开更多
AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with...AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with moxonidine in a high intraocular pressure(IOP)model.METHODS:The eyes of albino rabbits were administered topically and ipsilaterally with 0.2%moxonidine.A RPHPLC method was employed for the identification and quantification of moxonidine between 2 and 480 min,which presented in the aqueous humor and iris-ciliary body.Flash electroretinography(F-ERG)amplitude and superoxide dismutase(SOD)level were measured between day 1 and day 15 after topical administration with moxonidine in a rabbit model of high IOP.Histological and ultrastructural observation underwent to analyze the changes of retinal morphology,the inner retinal layers(IRL)thickness,and retinal ganglion cell(RGC)counting.RESULTS:Moxonidine was detectable between 2 and 480 min after administration,and the peak concentration developed both in the two tissues at 30 min,0.51μg/m Lin aqueous humor and 1.03μg/g in iris-ciliary body.In comparison to control,F-ERG b-wave amplitude in moxonidine eyes were significantly differences between day 3 and day 15(P<0.01)in the high IOP model;SOD levels were significantly higher at all time-points(P<0.01)with a maximum level of 20.29 U/mgprot at day 15;and RGCs were significantly higher(P<0.05).CONCLUSION:Moxonidine is a viable neuroprotective agent with application to high IOP model.All layers of retina,including RGC layer,retinal nerve fiber layer and INL,are more preserved after moxonidine administration.SOD plays a neuroprotective role in ocular hypertension-mediated RGC death.展开更多
5-Fluorouracil (5-FU) has a broad spectrum of anti-tumor activity, widely applied to the treatment of cancers. However, it is necessary to determine the plasma concentration of 5-FU in clinical practice due to its nar...5-Fluorouracil (5-FU) has a broad spectrum of anti-tumor activity, widely applied to the treatment of cancers. However, it is necessary to determine the plasma concentration of 5-FU in clinical practice due to its narrow therapeutic index. Therefore, a simple, economic and sensitive high-performance liquid chromatography (HPLC) method was developed and validated for the determination of 5-FU in human plasma. Ethyl acetate was chosen as extraction reagent. Chromatographic separation was performed on a Diamonsil C18 column (250 mm × 4.6 mm i.d., 5 μm) with the mobile phase consisting of methanol and 20 mmol/L ammonium formate using a linear gradient elution at a flow rate of 0.8 mL/min. 5-FU and 5-bromouracil (5-BU) were detected by UV detector at 265 nm. The calibration curve was linear over the concentration range of 5—500 ng/mL and the correlation coefficient was not less than 0.992 6 for all calibration curves. The intra- and inter-day precisions were less than 10.5% and 4.3%, respectively, and the accuracy was within ±3.7%. The recovery at all concentration levels was 80.1±8.6%. 5-FU was stable under possible conditions of storing and handling. This method is proved applicable to therapeutic drug monitoring and pharmacokinetic studies of 5-FU in human.展开更多
The recent paper by I. Brondz (2018), “One-Step Procedure for Direct Purification of Pediocin-Like Bacteriocins and Cationic Antimicrobial Peptides from Complex Culture Medium on an Analytical, Semipreparative, and P...The recent paper by I. Brondz (2018), “One-Step Procedure for Direct Purification of Pediocin-Like Bacteriocins and Cationic Antimicrobial Peptides from Complex Culture Medium on an Analytical, Semipreparative, and Preparative Scale. A New Type of Liquid Chromatography—Colloidal High-Performance Liquid Chromatography (CHPLC)” (International Journal of Analytical Mass Spectrometry and Chromatography, 6, 41-49, https://doi.org/10.4236/ijamsc.2018.63004), described a new type of CHPLC. This technique allows colloidal liquids and suspensions to be chromatographed directly despite the presence in the liquids of material such as bacteria, fungi, and other soft and hard particles. The significance of this development lies in enabling the single-step cleanup and concentration of the target substance from a complex mixture of soluble molecules in the presence of insoluble particles by high performance liquid chromatography (HPLC). The technique also allows the use of viscose liquids (as described in Brondz (2018) that are not suitable for analysis by conventional HPLC. In the previous paper, emphasis was placed on describing the applications of the techniques for the preparation of target substances such as small peptides, bacteriocins, bacitracin, and lysosome. Normally, the industrial preparation of these substances requires multistep procedures, which are time- and labor-consuming, and typically results in significant loss of target material and specific activity. In the present paper, the application of CHPLC for the isolation of alkaloids from crude raw material such as opium cake is demonstrated. In the opium cake, large amounts of hard vegetable particles and even sand corns are present together with the target alkaloids. Despite this, isolation by CHPLC of the desired compound was achieved in a single step by using a water/ethanol-based liquid. Isolation of alkaloids from such raw material normally requires a multistep procedure that includes the preparation of insoluble tartrate or picrate complex and this process includes dissolving the substance in flammable organic liquid. The isolation described here was performed in a single step by using the water/ethanol-based liquid.展开更多
The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concent...The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.展开更多
Cation-exchange high-performance liquid chromatography(CE-HPLC) is a widely used laboratory test to detect variant hemoglobins as well as quantify hemoglobins F and A2 for the diagnosis of thalassemia syndromes. It...Cation-exchange high-performance liquid chromatography(CE-HPLC) is a widely used laboratory test to detect variant hemoglobins as well as quantify hemoglobins F and A2 for the diagnosis of thalassemia syndromes. It's versatility, speed, reproducibility and convenience have made CE-HPLC the method of choice to initially screen for hemoglobin disorders. Despite its popularity, several methodological aspects of the technology remain obscure to pathologists and this may have consequences in specific situations. This paper discusses the basic principles of the technique, the initial quality control steps and the interpretation of various controls and variables that are available on the instrument output. Subsequent sections are devoted to methodological considerations that arise during reporting of cases. For instance, common problems of misidentified peaks, totals crossing 100%, causes of total area being above or below acceptable limits and the importance of pre-integration region peaks are dealt with. Ultimately, CE-HPLC remains an investigation, the reporting of which combines in-depth knowledge of the biological basics with more than a working knowledge of the technological aspects of the technique.展开更多
Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and conveni...Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and convenient assay for screening antimicrotubule compounds in which in vitro microdialysis/high-performance liquid chromatography (HPLC) is used to monitor the binding of the compounds extracted from TCM Taxus cuspidata Siebold & Zucc(Taxus) to microtubules is reported. It was observed that the extract of Taxus contains at least five compounds which have affinity interaction with microtubules by biological fingerprinting analysis,and they were identified as the taxoids of taxol,baccatin Ⅲ,10-deacetylbaccatin Ⅲ(10-DAB),cephalomannine and 7-epi-10-deacetyltaxol (7-epi-10-DAT) based on the comparison of their high-performance liquid chromatographic/mass spectrometric and UV spectra with those of the standard samples,both assembly-promoting and disassembly-inhibiting characteristics of those compounds were evaluated. It was observed that baccatin Ⅲ and 10-DAB bound to microtubules and the binding degrees were influenced by GTP. Competitive binding behavior of taxol with other four taxoids to microtubules was also investigated.展开更多
The applicability of hollow fiber liquid-phase microextraction (HF-LPME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was evaluated for the extraction and determination of tamox...The applicability of hollow fiber liquid-phase microextraction (HF-LPME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was evaluated for the extraction and determination of tamoxifen (TAM) in biological fluids including human urine and plasma. The drug was extracted from a 15 mL aqueous sample (source phase;SP) into an organic phase impregnated in the pores of the hollow fiber (membrane phase;MP) followed by the back-extraction into a second aqueous solution (receiving phase;RP) located in the lumen of the hollow fiber. The effects of several factors such as the nature of organic solvent, compositions of SP and RP solutions, extraction time, ionic strength and stirring rate on the extraction efficiency were examined and optimized. An enrichment factor of 360 along with substantial sample clean up was obtained under the optimized conditions. The calibration curve showed linearity in the range of 1 - 500 ng?mL–1 and the limit of detection was found to be 0.5 ng?mL–1 in aqueous medium. A reasonable relative recovery (≥89%) and satisfactory intra-assay (3.7% - 4.2%, n = 3) and inter-assay (7.5% - 7.8%, n = 3) precision illustrated good performance of the analytical procedure in spiked human urine and plasma samples.展开更多
文摘The purpose of this study was to establish a high-performance liquid chromatography (HPLC) method for the simultaneous determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid in Danhong injection. The chromatographic method employed was as follows: the column was a Welch Ultimate XB-C18 column (250 mm × 4.6 mm, 10 μm), the mobile phase was a gradient elution of 0.4% formic acid aqueous solution (A) and acetonitrile (B), the detection wavelengths were 280 nm for sodium danshensu, protocatechuic aldehyde, and salvianolic acid B and 326 nm for 4-coumaric acid and rosmarinic acid, the sample volume was 10 μL, the flow rate was 1.0 mL/min, and the column temperature was 35°C. This method can realize the separation and determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid within 50 minutes. The linear relationships of the five peak areas and their concentrations are good (R<sup>2</sup>> 0.9997). The precision RSD values are all less than 1.0%. The reproducibility RSD values are all less than 1.3%. The stability RSD values are all less than 2.2%. The recovery values ranged from 92.4% to 99.4%. This method is simple, accurate, and reproducible. It can be used for the determination of sodium danshensu, protocatechuic aldehyde, rosmarinic acid, salvianolic acid B, and 4-coumaric acid in Danhong injection.
基金This study was financially supported by the Program of Technology Gansu Province(1309RTSA025,1009FTGA018,1306TTPA036).
文摘A reliable and inexpensive pretreatment procedure in the determination ofβ2-agonists in pork was developped.The procedure used a nanocomposite of multiwalled carbon nanotubes(CNTs)functionalized with graphene(rGO)as the reversed dispersive sorbent.It was analyzed after purification by highperformance liquid chromatography,the extraction time and the properties of the nanocomposite were optimized.Under optimized conditions,present method has linear response over concentration range of 0.5–50 ng/mL in pork samples with a satisfactory detection limit close to 0.1 ng/mL.The precisions of the current method(coefficient of variation)are lower than 5%,while recoveries are more than 98.3%.The nanocomposite exhibited high adsorptivity,long-term storage stability,satisfactory anti-interfering activity and high selectivity toward2-agonists compared with those of rGO and CNTs.
文摘The modification of high-performance liquid chromatography parameters leads to a more effective oligonucleotide-A purification process. Using various experimental parameters such as buffer, concentration, and pH, a method for optimizing the purification of an oligonucleotide-A on a reverse-phase C18 column was created. To purify oligonucleotide-A, High-Performance Liquid Chromatography (HPLC), Ultraviolet-Visible Spectrophotometry (UV-Vis), Liquid Chromatography-Mass Spectrometry (LC-MS), and lyophilization were used. Chromatographic data were collected with a semi-prep HPLC system, quantified with the UV-Vis technique, and validated with the LC-MS method. The most optimized parameters found to obtain the purity of 93.0% are 40 mM triethylammonium bicarbonate (TEAB) buffer with pH 7, which is approximately 6.0% higher than the reported method of which the purity is 87.0%. However, the yield under these conditions was reduced by about 5%. The worst possible optimized settings that resulted in the lowest purity (84.0%) and yield (69.0%) are 10 mM ammonium acetate (NH<sub>4</sub>CH<sub>3</sub>CO<sub>2</sub>) with pH 7.
文摘Objective:To analyze the effect of high-performance liquid chromatography(HPLC)for the determination of azithromycin and to provide references for related research work.Methods:The mobile phase was ammonixim dihydrogen phosphate at 0.067 mol/L(mixed with triethylamine;pH value was adjusted to 6.5).The chromatographic column was Kromasil C18(250 mm × 4.6 mm;5.0μm)and the relative standard deviation(RSD)of the drug content level was 1.25%.The injection volume was set to 20μL,the detection wavelength was set to 210 nm,the external standard method was used to complete the quantitative work,and the theoretical plate number should be more than 1000 according to the drug peak calculation.The effect of HPLC on the determmation of azithromycin was analyzed.Results:The concentration of azithromycin was 1.40-3.40 mg/mL,and the linear relationship was good.RSD of the drug content level was 1.25%.The representative test product had strong stability within 8.0 hours and the method had good repeatability.According to the recovery experiment method,the recovery rates of three standard samples from low to high were 99.87%,100.15%,and 100.62%.The average recovery rate was 100.21%.RSD value was 0.39%.It means that the recovery rate of HPLC is good.Conclusion:In the determination of azithromycin,the use of HPLC to complete the work was of high sensitivity,simple,and fast.The method had good repeatability in the determination of drug components which is worthy of further promotion.
文摘The standards of plant toxins were separated by a C18 column with gradient elution with 0.1% formic acid/water (V/V) and 0.1% formic acid/acetonitrile (V/V) as mobile phase and acquired by ion mobility-quadrupole time of flight mass spectrometry (IM-QTOF MS) in positive ion mode. A database of 308 plant toxins including retention time, collision cross-section (CCS) and its fragment ions was established. Honey dissolved in water or herbal beverage was extracted by acetonitrile and purified with PSA sorbent, and then acquired by ultrahigh-performance liquid chromatography IM-QTOFMS. The acquired data were processed by comparing with the database we established to confirm the target compounds. The average recoveries for samples at two levels ranged from 60.6% - 120.1%, with relative standard deviation (n = 6) less than 25%. The limit of quantitation for plant toxins ranged from 1 - 20 μg/kg. The developed screening method was used in determination of honey, herbal beverage and honey flavored tea beverage samples. The results showed that berberine was detected in one honey with 1 μg/kg and caffeine was present in some beverages with the concentration from 200 and 5500 μg/kg. This method could meet the requirement for rapid screening of plant toxins in honey and herbal beverage. It can be used for the quality control of honey and herbal beverage in enterprises or quality inspection departments. It also can be used in the rapid screening of food poisoning.
基金Supported by National Natural Science Foundation of China,Grant No.81360356Scientific Research Foundation of Xinjiang Medical University,Grant No.XJC201221
文摘AIM:To perform plasma free amino acid(PFAA)profiling of esophageal squamous cell carcinoma(ESCC)patients at different pathological stages and healthy subjects.METHODS:Plasma samples from ESCC patients(n=51)and healthy control adults(n=60)were analyzed by high-performance liquid chromatography(HPLC).The ESCC patients included moderate/poorly-differentiation(n=24),lymph node metastasis(n=17)and clinical stage>Ib2(n=36).Partial least squares discriminant analysis was performed to demonstrate that the PFAA metabolic patterns enabled discrimination between ESCC patients and controls,and the Student t test was applied to assess significant differences in PFAA concentrations between the two groups.RESULTS:There were significant differences in the PFAA profiles between controls and ESCC patients.Compared with healthy controls,the levels of Asp,Glu,Gly,His,Thr,Tau,Ala,Met,Ile,Leu,and Phe were decreased in ESCC patients,but Cys was increased.There exists a strong correlation between PFAA profiles and clinicopathological characteristics in ESCC patients.The levels of many PFAAs(i.e.,Glu,Asp,Ser,Gly,Tau,Ala,Tyr,Val,Ile,and Leu)were related to pathological grading,lymph node metastasis,and ESCC clinical stage.Very good discrimination between ESCC patients and control subjects was achieved by multivariate modeling of plasma profiles.CONCLUSION:HPLC-based plasma profiling analysis was shown to be an effective approach to differentiate between ESCC patients and controls.PFAA profiles may have potential value for screening or diagnosing ESCC.
基金the financial support provided by Fundacao para a Ciência e a Tecnologia,Portugal(PTDC/DTP-FTO/1057/2012)
文摘A simple, accurate and sensitive high-performance liquid chromatography(HPLC) method was developed,validated and applied to the determination of either theophylline or paracetamol in milk-based samples. The method allowed drug quantification in fresh and powdered milk with a relatively short run time of analysis and it was also successfully applied to the quantification of the drugs in solid dosage forms intended for pediatric use. Moreover, the main significant advantages over other published works are the simplicity of the sample preparation, reduced assay time and sample loss. The method meets the International Conference on Harmonization guideline for analytical methods validation regarding specificity, linearity, accuracy, precision,specificity and robustness as required by health authorities and applied by industry while designing and marketing new drug products. The technique encompasses the separation of the analytes with a reverse phase C_(18) column under isocratic conditions and UV detection at 272 nm and 243 nm, respectively, for theophylline and paracetamol. The lower limit of quantification for both drugs was determined as 0.2 μg/m L and the between-batch accuracy was 99.7%. This HPLC method allows quantification of theophylline and paracetamol in milk matrices and it can be applied in the design, development and production of milk-based pediatric dosage forms.
文摘A new reversed-phase high performance liquid chromatography method was developed to quantitate the activity of xanthine oxidase involved in milk fat globule membrane with xanthine as the substrate and the separation of product (uric acid). The increment of uric acid in the reaction system was used to calculate the total activity of XO. The optimized assay conditions, linearity of detection, recovery of uric acid and chromatogram were developed in text, indicating this method is simple, rapid and efficient. It is an alternative potential method for the determination of the activity of XO in milk.
基金Supported by the National Natural Science Foundation of China(No. 30472053)
文摘To investigate the pharmacokinetics of felodipine in the plasma of healthy Chinese volunteers, 30 healthy volunteers received a single oral dose of 5 mg of extended release felodipine tablets. The felodipine was extracted from the matrix with a liquid-liquid extract procedure and analyzed by high-performance liquid chromatography-tandem mass spectrometry in the multiple reaction monitoring(MRM) mode using an electrospray ion source with positive ion detection. The method was validated over a felodipine concentration range of 0.05—10.00 ng/mL in human plasma. Its main pharmacokinetic parameters values were: ρ_ max =(1.67±0.84) ng/mL, occurring at (3.93±2.49) h; the plasma elimination half-life: (23.08±9.48) h and the area under the plasma concentration versus time curve: (29.94±14.39) ng·h/mL. The validation results demonstrated that this method showed a satisfactory precision and accuracy across the calibration range. The procedure involved minimal drug administration, sample preparation, and a 2.5-min chromatographic run time. It was well suited to clinical studies of the drug involving large numbers of samples.
文摘Chromatography fingerprint (CFP) of 10 samples of hongqi were studied. 23 common peaks were analyzed, their average similarity was 97.29%. CFP were positioned with main index composition such as formononetin, calycosin and then the contents of index composition were determined. The character and exclusive of CFP of 10 samples of hongqi were clear. CFP and content determination of index composition of hongqi could be used to evaluate the quality of hongqi comprehensively.
基金supported by Science Research Funds of Medical Course, HUST
文摘A simple method has been proposed for the determination of clozapine (CLZ) and chlorpromazine (CPZ) in human urine by dispersive liquid-liquid microextraction (DLLME) in combination with high-performance liquid chromatography-ultraviolet detector (HPLC-UV). All important variables influencing the extraction efficiency, such as pH, types of the extraction solvent and the disperser solvent and their volume, ionic strength and centrifugation time were investigated and optimized. Under the optimal conditions, the limit of detection (LODs) and quantification (LOQs) of the method were 13 and 39 ng/mL for CLZ, and 2 and 6 ng/mL for CPZ, respectively. The relative standard deviations (RSDs) of the targets were less than 5.1% (C=0.100 μg/mL, n=9). Good linear behaviors over the tested concentration ranges were obtained with the values of R2>0.999 for the targets. The absolute extraction efficiencies of CLZ and CPZ from the spiked blank urine samples were 98.3% and 97.8%, respectively. The applicability of the technique was validated by analyzing urine samples and the mean recoveries for spiked urine samples ranged from 93.3% to 105.0%. The method was successfully applied for the determination of CLZ and CPZ in real human urine.
文摘A rapid, sensitive and specific ultra-high-performance liquid chromatography tandem mass spectrometry (UPLC-MS) method was developed for the analysis of tetracycline antibiotics, including tetracycline (TC), oxytetracycline (OTC), chlortetracycline (CTC) and their 4-epimers (4-epiTCs) in agricultural soil fertilized with swine manure. Soil samples were extracted and cleaned-up with 10 mL EDTA-McIlvaine buffer solution (pH 4.0), then cleaned-up and pre-concentrated using the Oasis MAX cartridge and then eluted with 1 mL solution by mixing formic acid, methanol and water at a ratio of 2:15:83 (v/v/v). The purified samples were separated by an ACQUITY UPLC BEH C18 column using acetonitrile and water containing 0.1% formic acid mobile phase and detected by a single quadrupole MS. The limits of detection for the soil extraction method (LODsoil) ranged from 0.6-2.5 μg kg-1 with recoveries from 23.3-159.2%. Finally, the method was applied to an agricultural field in an area with intensive pig-fattening farming. Tetracyclines were detected in soil from 2.8 to 42.4 μg kg-1 soil. These results demonstrate that soil from swine farms can become severely contaminated with tetracycline antibiotics and their metabolites.
基金supported by the National Natural Science Foundation of China(No.21275088)
文摘Creatinine, uric acid, hypoxanthine and xanthine are important diagnostic biomarkers in human urine for gouty arthritis or renal disease diacrisis. A simple method for simultaneous determination of these biomarkers in urine based on reversed-phase high-performance liquid chromatography(RPHPLC) with ultraviolet(UV) detector was proposed. After pretreatment by dilution, centrifugation and filtration, the biomarkers in urine samples were separated by ODS-BP column by elution with methanol/50 mM NaH2PO4 buffer solution at pH 5.26(5:95). Good linearity between peak areas and concentrations of standards was obtained for the biomarkers with correlation coefficients in the range of 0.9957–0.9993.The proposed analytical method has satisfactory repeatability(the recovery of data in a range of creatinine, uric acid, hypoxanthine and xanthine was 93.49–97.90%, 95.38–96.45%, 112.46–115.78% and90.82–97.13% with standard deviation of o5%, respectively) and the limits of detection(LODs, S/NZ3)for creatinine, uric acid, hypoxanthine, and xanthine were 0.010, 0.025, 0.050 and 0.025 mg/L,respectively. The established method was proved to be simple, accurate, sensitive and reliable for the quantitation of gouty arthritis' biomarkers in human urine samples. The ratio of creatinine to uric acid was found to be a possible factor for assessment of gouty arthritis.
基金Supported by the Key Science and Technology Program of Shaanxi Province,China(No.2015SF146).
文摘AIM:To determine moxonidine in aqueous humor and iris-ciliary body by reversed-phase high performance liquid chromatography(RP-HPLC),and to evaluate the retinal neuroprotective effect after topical administration with moxonidine in a high intraocular pressure(IOP)model.METHODS:The eyes of albino rabbits were administered topically and ipsilaterally with 0.2%moxonidine.A RPHPLC method was employed for the identification and quantification of moxonidine between 2 and 480 min,which presented in the aqueous humor and iris-ciliary body.Flash electroretinography(F-ERG)amplitude and superoxide dismutase(SOD)level were measured between day 1 and day 15 after topical administration with moxonidine in a rabbit model of high IOP.Histological and ultrastructural observation underwent to analyze the changes of retinal morphology,the inner retinal layers(IRL)thickness,and retinal ganglion cell(RGC)counting.RESULTS:Moxonidine was detectable between 2 and 480 min after administration,and the peak concentration developed both in the two tissues at 30 min,0.51μg/m Lin aqueous humor and 1.03μg/g in iris-ciliary body.In comparison to control,F-ERG b-wave amplitude in moxonidine eyes were significantly differences between day 3 and day 15(P<0.01)in the high IOP model;SOD levels were significantly higher at all time-points(P<0.01)with a maximum level of 20.29 U/mgprot at day 15;and RGCs were significantly higher(P<0.05).CONCLUSION:Moxonidine is a viable neuroprotective agent with application to high IOP model.All layers of retina,including RGC layer,retinal nerve fiber layer and INL,are more preserved after moxonidine administration.SOD plays a neuroprotective role in ocular hypertension-mediated RGC death.
基金Supported by National Natural Science Foundation of China (No. 30630075 and 20675056)Major State Basic Research Development Program of China ("973" Program) (No. 2006CB933303)
文摘5-Fluorouracil (5-FU) has a broad spectrum of anti-tumor activity, widely applied to the treatment of cancers. However, it is necessary to determine the plasma concentration of 5-FU in clinical practice due to its narrow therapeutic index. Therefore, a simple, economic and sensitive high-performance liquid chromatography (HPLC) method was developed and validated for the determination of 5-FU in human plasma. Ethyl acetate was chosen as extraction reagent. Chromatographic separation was performed on a Diamonsil C18 column (250 mm × 4.6 mm i.d., 5 μm) with the mobile phase consisting of methanol and 20 mmol/L ammonium formate using a linear gradient elution at a flow rate of 0.8 mL/min. 5-FU and 5-bromouracil (5-BU) were detected by UV detector at 265 nm. The calibration curve was linear over the concentration range of 5—500 ng/mL and the correlation coefficient was not less than 0.992 6 for all calibration curves. The intra- and inter-day precisions were less than 10.5% and 4.3%, respectively, and the accuracy was within ±3.7%. The recovery at all concentration levels was 80.1±8.6%. 5-FU was stable under possible conditions of storing and handling. This method is proved applicable to therapeutic drug monitoring and pharmacokinetic studies of 5-FU in human.
文摘The recent paper by I. Brondz (2018), “One-Step Procedure for Direct Purification of Pediocin-Like Bacteriocins and Cationic Antimicrobial Peptides from Complex Culture Medium on an Analytical, Semipreparative, and Preparative Scale. A New Type of Liquid Chromatography—Colloidal High-Performance Liquid Chromatography (CHPLC)” (International Journal of Analytical Mass Spectrometry and Chromatography, 6, 41-49, https://doi.org/10.4236/ijamsc.2018.63004), described a new type of CHPLC. This technique allows colloidal liquids and suspensions to be chromatographed directly despite the presence in the liquids of material such as bacteria, fungi, and other soft and hard particles. The significance of this development lies in enabling the single-step cleanup and concentration of the target substance from a complex mixture of soluble molecules in the presence of insoluble particles by high performance liquid chromatography (HPLC). The technique also allows the use of viscose liquids (as described in Brondz (2018) that are not suitable for analysis by conventional HPLC. In the previous paper, emphasis was placed on describing the applications of the techniques for the preparation of target substances such as small peptides, bacteriocins, bacitracin, and lysosome. Normally, the industrial preparation of these substances requires multistep procedures, which are time- and labor-consuming, and typically results in significant loss of target material and specific activity. In the present paper, the application of CHPLC for the isolation of alkaloids from crude raw material such as opium cake is demonstrated. In the opium cake, large amounts of hard vegetable particles and even sand corns are present together with the target alkaloids. Despite this, isolation by CHPLC of the desired compound was achieved in a single step by using a water/ethanol-based liquid. Isolation of alkaloids from such raw material normally requires a multistep procedure that includes the preparation of insoluble tartrate or picrate complex and this process includes dissolving the substance in flammable organic liquid. The isolation described here was performed in a single step by using the water/ethanol-based liquid.
基金Project(20776038)supported by the National Natural Science Foundation of China
文摘The chiral separation of phenylsuccinic acid(PSA)was studied by reversed phase high-performance liquid chromatography(RP-HPLC)with cyclodextrins(CDs)as chiral mobile phase additives.The effects of types of CDs,concentration of hydroxypropyl-β-cyclodextrin(HP-β-CD),percentage of organic modifier,pH value and column temperature on enantioselective separation were investigated.The quantification property of the developed RP-HPLC method was examined.The chiral recognition mechanism of PSA was also discussed.The results show that a baseline separation of PSA enantiomers is achieved on a Lichrospher C18 column(4.6 mm(inner diameter)×250 mm,5μm)with HP-β-CD as chiral mobile phase additive.The capacity factors of R-PSA and S-PSA are 3.94 and 4.80,respectively.The separation factor and resolution are respectively 1.22 and 8.03.The mobile phase is a mixture of acetonitrile and deionized water(20-80,volume ratio)containing 10 mmol/L HP-β-CD and 0.05% trifluoroacetic acid(pH 2.5,adjusted with triethylamine)with a flow rate of 1.0 mL/min.The ultraviolet(UV)detector is set at 254 nm.The likely roles are inclusion interaction,induction and hydrogen bonding between HP-β-CD and PSA enantiomers.
文摘Cation-exchange high-performance liquid chromatography(CE-HPLC) is a widely used laboratory test to detect variant hemoglobins as well as quantify hemoglobins F and A2 for the diagnosis of thalassemia syndromes. It's versatility, speed, reproducibility and convenience have made CE-HPLC the method of choice to initially screen for hemoglobin disorders. Despite its popularity, several methodological aspects of the technology remain obscure to pathologists and this may have consequences in specific situations. This paper discusses the basic principles of the technique, the initial quality control steps and the interpretation of various controls and variables that are available on the instrument output. Subsequent sections are devoted to methodological considerations that arise during reporting of cases. For instance, common problems of misidentified peaks, totals crossing 100%, causes of total area being above or below acceptable limits and the importance of pre-integration region peaks are dealt with. Ultimately, CE-HPLC remains an investigation, the reporting of which combines in-depth knowledge of the biological basics with more than a working knowledge of the technological aspects of the technique.
基金the National Natural Science Foundation of China(No.90709021)Knowledge Innovation Program of Chi-nese Academy of Sciences(No.KJCX2.YW.HO9)
文摘Some natural products,such as traditional Chinese medicines(TCMs),contain compounds with anticancer activity and have attracted a great interest in recent years as alternative anticancer therapies. A quick and convenient assay for screening antimicrotubule compounds in which in vitro microdialysis/high-performance liquid chromatography (HPLC) is used to monitor the binding of the compounds extracted from TCM Taxus cuspidata Siebold & Zucc(Taxus) to microtubules is reported. It was observed that the extract of Taxus contains at least five compounds which have affinity interaction with microtubules by biological fingerprinting analysis,and they were identified as the taxoids of taxol,baccatin Ⅲ,10-deacetylbaccatin Ⅲ(10-DAB),cephalomannine and 7-epi-10-deacetyltaxol (7-epi-10-DAT) based on the comparison of their high-performance liquid chromatographic/mass spectrometric and UV spectra with those of the standard samples,both assembly-promoting and disassembly-inhibiting characteristics of those compounds were evaluated. It was observed that baccatin Ⅲ and 10-DAB bound to microtubules and the binding degrees were influenced by GTP. Competitive binding behavior of taxol with other four taxoids to microtubules was also investigated.
文摘The applicability of hollow fiber liquid-phase microextraction (HF-LPME) combined with high-performance liquid chromatography-ultraviolet detection (HPLC-UV) was evaluated for the extraction and determination of tamoxifen (TAM) in biological fluids including human urine and plasma. The drug was extracted from a 15 mL aqueous sample (source phase;SP) into an organic phase impregnated in the pores of the hollow fiber (membrane phase;MP) followed by the back-extraction into a second aqueous solution (receiving phase;RP) located in the lumen of the hollow fiber. The effects of several factors such as the nature of organic solvent, compositions of SP and RP solutions, extraction time, ionic strength and stirring rate on the extraction efficiency were examined and optimized. An enrichment factor of 360 along with substantial sample clean up was obtained under the optimized conditions. The calibration curve showed linearity in the range of 1 - 500 ng?mL–1 and the limit of detection was found to be 0.5 ng?mL–1 in aqueous medium. A reasonable relative recovery (≥89%) and satisfactory intra-assay (3.7% - 4.2%, n = 3) and inter-assay (7.5% - 7.8%, n = 3) precision illustrated good performance of the analytical procedure in spiked human urine and plasma samples.
