摘要
采用电喷雾多级串联质谱技术,研究了头孢噻吩钠、头孢西丁钠、头孢他美酯、头孢克肟4种头孢菌素类抗生素在金属钠离子诱导下的裂解规律,并与质子诱导下的裂解规律进行比较。结果发现,头孢菌素类化合物在钠离子诱导方式下的多数质谱行为与质子诱导下的一致:多数质谱断裂发生在7-氨基头孢烷酸母核的侧链取代基R1、R2、R3上;C(3)位侧链上的C—X(X=O、N、S)键容易断裂;C(2)位羧基上的CO2和C(8)位的CO容易丢失。此外,还发现金属钠离子可比质子诱导更多更复杂的断裂反应。质子化离子的β-内酰胺环开环方式单一,为N(1)—C(8)和C(6)—C(7)键断裂;而金属钠离子能够诱导新的β-内酰胺环断裂,如C(7)—C(8)、N(1)—C(6)和C(4)—S(5)三键断裂和N(1)—C(8)、N(1)—C(6)和C(4)—C(5)三键断裂。另外,在碱金属钠离子诱导下,结构重排更为频繁。
Effect of sodium cationization on the collision-induced dissociation（CID） of four cephalosporins,including cefalotin sodium,cefoxitin sodium,cefetamet pivoxil and cefixime were investigated using the electrospray ionization（ESI） tandem mass spectrometry.The result showed that most fragmentation patterns of the sodium cationized cephalosporins were similar to those of proton-induced cephalosporins,including the neutral loss of the substituent on the 7-aminocephalosporin nucleus（R1,R2,R3）,the cleavage of C—X（X=O,N and S） on C（3）,loss of CO2 in the site of C（2） and loss of CO in the site of C（8）.Compared with that of the protonated species,the fragmentation of sodium cationized species could result in more complex cleavage reactions.The protonated molecular ions of these four cephalosporins dissociated uniquely by β-lactam cleavages between N（1）—C（8） and C（6）—C（7）,while sodium cationization induced new dissociation pathways,such as β-lactam cleavages by C（7）—C（8）,N（1）—C（6） and C（4）—S（5） three single bond cleavage and N（1）—C（8）,N（1）—C（6） and C（4）—C（5） three single bond cleavage.Moreover,rearrangement was more favored in sodium cationized species.
出处
《分析测试学报》
CAS
CSCD
北大核心
2010年第12期1135-1142,共8页
Journal of Instrumental Analysis
基金
浙江省科技厅公益技术研究社会发展项目(2010C33074)
关键词
头孢菌素类抗生素
碱金属钠离子
电喷雾多级串联质谱
裂解
cephalosporins
sodium cationization
electrospray ionization tandem mass spectrometry
collision-induced dissociation
