Asperger A, Efer J, Koal T, Engewald W
Leipzig University, Institute of Analytical Chemistry, Germany.
J Chromatogr A. 2001 Dec 7;937(1-2):65-72. doi: 10.1016/s0021-9673(01)01296-1.
The API-MS signal response of several pesticides (atrazine, simazine, isoproturon, diuron, chlorfenvinphos, chlorpyrifos, alachlor, trifluralin) depending on the flow-rate of eluent entering the MS interface was investigated. The investigations were based on API-MS-MS analyses of standard pesticide mixtures in the flow injection mode (FIA) at systematically varied eluent flow-rates using both an ESI interface (Turboionspray) and a heated nebulizer type APCI source. In the result, the individual compounds included in this study showed significant differences in their signal response behaviour depending on the flow-rate of eluent applied. The most hydrophobic compounds among the investigated pesticides (chlorpyrifos and trifluralin) showed drastic losses of sensitivity with increasing eluent flow-rate in both ESI and APCI, while more hydrophilic compounds like atrazine, simazine and isoproturon showed the expected signal response (concentration-sensitive in ESI, mass-flow-sensitive in APCI) at least within a certain range of flow-rates (200-600 microl/min in ESI, 200-2000 microl/min in APCI). These findings lead to the conclusion that application of a programmed HPLC eluent flow-rate may be advantageous to achieve maximum sensitivity of API-MS detection for all pesticides of interest. This is exemplified by the implementation of a flow gradient into an online SPE-HPLC-APCI-MS/MS method for improved analysis of pesticides in drinking water.
研究了几种农药（莠去津、西玛津、异丙隆、敌草隆、毒虫畏、毒死蜱、甲草胺、氟乐灵）的大气压电离质谱（API-MS）信号响应与进入质谱接口的洗脱液流速之间的关系。这些研究基于在流动注射模式（FIA）下，使用电喷雾接口（Turboionspray）和加热雾化器型大气压化学电离源（APCI），对标准农药混合物进行大气压串联质谱（API-MS-MS）分析，系统地改变洗脱液流速。结果表明，本研究中所包含的各个化合物，其信号响应行为随所施加的洗脱液流速不同而存在显著差异。在所研究的农药中，疏水性最强的化合物（毒死蜱和氟乐灵）在电喷雾电离（ESI）和大气压化学电离（APCI）模式下，随着洗脱液流速的增加，灵敏度急剧下降，而亲水性更强的化合物，如莠去津、西玛津和异丙隆，至少在一定流速范围内（ESI模式下为200 - 600微升/分钟，APCI模式下为200 - 2000微升/分钟）表现出预期的信号响应（ESI模式下为浓度敏感型，APCI模式下为质量流量敏感型）。这些发现得出结论：对于所有目标农药，采用程序控制的高效液相色谱洗脱液流速，可能有利于实现大气压电离质谱检测的最大灵敏度。这一点通过在在线固相萃取 - 高效液相色谱 - 大气压化学电离串联质谱（SPE-HPLC-APCI-MS/MS）方法中实施流速梯度来改进饮用水中农药的分析得到了例证。
