摘要
建立火焰原子吸收光谱法测定牛奶中不同化学形态钙的方法。研究乙醇体积分数、离心温度、离心力和离心时间对蛋白沉淀效果的影响,确定最佳分离条件,即乙醇体积分数50%、离心温度2℃、离心力6000×g、离心时间6min,建立沉淀剂分离牛奶中元素结合态和非结合态的方法。探讨释放剂硝酸镧的质量浓度对吸光度的影响,确定最佳质量浓度为6.00mg/mL。在此条件下,测定牛奶中总钙的质量浓度为808.6μg/mL,其中结合态钙的质量浓度为641.8μg/mL,占总钙的质量分数为79.4%;非结合态钙的质量浓度为173.0μg/mL,占总钙的质量分数为21.4%。本法的精密度(RSD)小于3.3%,仪器检出限为0.11μg/mL,加标平均回收率为97.0%,RSD为1.7%。该方法准确、稳定,具有较高的实用价值。
An effective method was developed for speciation analysis of calcium in milk by flame atomic absorption spectrophotometry.The effects of ethanol concentration,centrifuge temperature,centrifugal force and centrifugation time on protein sedimentation were discussed.The best conditions for separating calcium from samples were found to be protein sedimentation with 50% and centrifugation at 2 ℃ and 6000 × g for 6 min.The best La（NO3）3 concentration for releasing bound calcium was 6.00 mg/mL as determined by analyzing the effect on absorbance.Under the optimized conditions,the total calcium concentration of milk was determined to be 808.6 μg/mL and the bound and free calcium concentrations were 641.8 μg/mL and 173.0 μg/mL,which accounted for 79.4% and 21.4% of the total calcium,respectively.The precision（RSD） of the developed method was less than 3.3%,and the limit of detection was 0.11 μg/mL.The average spike recoveries of calcium was 97.0% with a RSD of 1.7%.This method was accurate,stable and applicable.
出处
《食品科学》
EI
CAS
CSCD
北大核心
2012年第22期278-281,共4页
Food Science
关键词
火焰原子吸收分光光度法
化学形态
钙
flame atomic absorption spectrophotometry（FAAS）
speciation analysis
calcium
