Ling Y C, Lin L, Chen Y T
Department of Chemistry, National Tsing Hua University, Hsinchu, Taiwan.
Rapid Commun Mass Spectrom. 1998;12(6):317-27. doi: 10.1002/(SICI)1097-0231(19980331)12:6<317::AID-RCM159>3.0.CO;2-#.
Comparative studies of the matrix-assisted laser desorption/ionization (MALDI) of 30 antibiotics were made using alpha-cyano-4-hydroxycinnamic acid (HCCA), 2,5-dihydroxybenzoic acid (DHB), 5,10,15,20-tetrakis(4-hydroxyphenyl)-21H,23H-porphyrin and meso-tetra(N-methyl-4-pyridyl)porphyrin matrices. Most antibiotics generated intense protonated molecules in HCCA and DHB matrices, and sodium or potassium adduct ions in porphyrin matrices. Using sulfonamide antibiotics as model compounds, DHB was found to be the most suitable matrix for quantitative analysis. Detection limits were about 1 picomole. Linear correlation (R2 > 0.97), between the sample quantity over the range 1 to 100 picomole and the signal response, was obtained when ratios of the sum of peak areas of protonated molecules and sodium adduct ions, with reference to that of a structurally analogous internal standard (acetaminophen), were measured. The precision was found to be in the range of 4 to 32% relative standard deviation, dependent on the type and concentration of the analyte. A simple acylation derivatization process was developed to confirm the presence of suspected antibiotic residues. It is demonstrated that MALDI is a viable technique for the quantitative analysis of low molecular weight antibiotics.
使用α-氰基-4-羟基肉桂酸（HCCA）、2,5-二羟基苯甲酸（DHB）、5,10,15,20-四（4-羟基苯基）-21H,23H-卟啉和中-四（N-甲基-4-吡啶基）卟啉基质，对30种抗生素进行了基质辅助激光解吸/电离（MALDI）的比较研究。大多数抗生素在HCCA和DHB基质中产生强质子化分子，在卟啉基质中产生钠或钾加合离子。以磺胺类抗生素作为模型化合物，发现DHB是最适合定量分析的基质。检测限约为1皮摩尔。当测量质子化分子和钠加合离子的峰面积总和与结构类似的内标（对乙酰氨基酚）的峰面积总和之比时，在1至10皮摩尔范围内的样品量与信号响应之间获得了线性相关性（R2>0.97）。发现精密度在相对标准偏差4%至32%的范围内，这取决于分析物的类型和浓度。开发了一种简单的酰化衍生化方法来确认可疑抗生素残留的存在。结果表明，MALDI是一种用于低分子量抗生素定量分析的可行技术。
