Tak Vijay, Kanaujia Pankaj K, Pardasani Deepak, Kumar Rajesh, Srivastava R K, Gupta A K, Dubey D K
Vertox Laboratory, Defence Research and Development Establishment, Jhansi Road, Gwalior 474002, India.
J Chromatogr A. 2007 Aug 17;1161(1-2):198-206. doi: 10.1016/j.chroma.2007.05.079. Epub 2007 May 31.
A qualitative method was developed for the determination of degraded products of nerve agents by using ion-pair liquid chromatography electrospray ionization tandem mass spectrometry (IP-LC-ESI-MS(n)). Generally, alkylphosphonic acids (APAs) and O-alkyl alkylphosphonic acids (AAPAs) give deprotonated molecular ion M-H in negative mode. Interestingly, first time we obtained the molecular radical anion M of phosphonic acids in negative mode by using tri-n-butyl amine as an ion-pairing agent. We interpreted this observation as an indication of electrochemical reduction of phosphonic acids in electrospray needle. Three variables such as sheath gas flow, electrospray needle voltage and pH of the mobile phase were investigated to enhance the molecular radical anion M signal of each analyte. The Doehlert design was used to obtain the region in which the optimum value of such variables is simultaneously achieved. Limit of detection achieved was 0.5 microg mL(-1) for AAPAs and 10 microg mL(-1) for APAs. Excellent precision was observed with less than 8.61% RSD. Finally, the method was applied for the detection of ethyl methylphosphonic in aqueous extract of soil sample.
建立了一种使用离子对液相色谱-电喷雾电离串联质谱法（IP-LC-ESI-MS(n)）测定神经毒剂降解产物的定性方法。一般来说，烷基膦酸（APAs）和O-烷基烷基膦酸（AAPAs）在负离子模式下给出去质子化分子离子M-H。有趣的是，我们首次使用三正丁胺作为离子对试剂在负离子模式下获得了膦酸的分子自由基阴离子M。我们将这一观察结果解释为电喷雾针中膦酸发生电化学还原的迹象。研究了鞘气流量、电喷雾针电压和流动相pH值这三个变量，以增强各分析物的分子自由基阴离子M信号。采用Doehlert设计来获得能同时实现这些变量最佳值的区域。AAPAs的检测限为0.5 μg mL(-1)，APAs的检测限为10 μg mL(-1)。观察到精密度极佳，相对标准偏差（RSD）小于8.61%。最后，该方法应用于土壤样品水提取物中乙基甲基膦酸的检测。
