Laganà A, Fago G, Marino A
Department of Chemistry, La Sapienza University, Roma, Italy.
Anal Chem. 1998 Jan 1;70(1):121-30. doi: 10.1021/ac9707491.
This paper describes the simultaneous quantification of the imidazolinone herbicides (IMIs) imazapyr, m-imazamethabenz, p-imazamethabenz, m,p-imazamethabenz-methyl, imazethapyr, and imazaquin in two types of samples. (a) Groundwater, lake water, and river water samples were enriched by off-line solid-phase extraction with a Carbograph-1 cartridge and analyzed by reversed-phase liquid chromatography using a UV detector (lambda = 240 nm). The overall recoveries of IMIs extracted from 1 L of groundwater (fortified with 500-100 ng/L), 0.5 L of lake water (fortified with 500-100 ng/L), and 0.5 L of river water (fortified with 1000-200 ng/L) samples were not lower than 89%. The mean relative standard deviation (RSD) was 5.1% (ranging from 4.1% to 6.8%) in natural water. The detection limits were 30-39 ng/L in groundwater, 43-51 ng/L in lake water, and 55-67 ng/L in river water. The method involves confirmatory analysis by LC/ES-MS in full-scan mode. The dependence of the ion signal intensities on proton concentration in the mobile phase was investigated with a view to optimizing the sensitivity of the ES-MS detector. When LC/ES-MS was used, the limit of detection, calculated from extracted-ion current profiles (EICPs), was 4-7 ng/L for ground-water and 9-13 ng/L for river water. (b) Soil sample analysis utilized combined soil column extraction (SCE) and off-line solid phase extraction (SPE) for sample preparation, analyzing with LC/ES-MS under selected ion monitoring (SIM). Several different extractants were evaluated for the purpose of SCE optimization. The system that best optimizes the extractability IMIs from the soil was found to be the mixture CH3OH/(NH4)2CO3 (0.1 M, 50:50 v/v). The effect of IMI concentration in the matrix on recovery was evaluated. The total recovery of each IMI from soil at each of the two levels investigated ranged from 87% to 95%. Under three ion SIM conditions, the limit of detection (S/N = 3) was 0.1-0.05 ng/g in soil samples.
本文描述了对两种类型样品中咪唑啉酮类除草剂（IMIs）——咪草烟、甲基咪草烟（间位异构体）、甲基咪草烟（对位异构体）、甲基咪草烟（间位和对位异构体混合物）、咪草酯和灭草喹的同时定量分析。（a）地下水、湖水和河水样品通过使用Carbograph - 1柱进行离线固相萃取富集，并采用配备紫外检测器（波长λ = 240 nm）的反相液相色谱进行分析。从1 L地下水（加标浓度为500 - 100 ng/L）、0.5 L湖水（加标浓度为500 - 100 ng/L）和0.5 L河水（加标浓度为1000 - 200 ng/L）样品中萃取的IMIs的总回收率不低于89%。天然水中的平均相对标准偏差（RSD）为5.1%（范围为4.1%至6.8%）。地下水的检测限为30 - 39 ng/L，湖水为43 - 51 ng/L，河水为55 - 67 ng/L。该方法包括采用全扫描模式的液相色谱/电喷雾质谱（LC/ES-MS）进行确证分析。为了优化电喷雾质谱检测器的灵敏度，研究了离子信号强度对流动相中质子浓度的依赖性。当使用LC/ES-MS时，根据提取离子电流图谱（EICPs）计算得出的检测限，地下水为4 - 7 ng/L，河水为9 - 13 ng/L。（b）土壤样品分析采用土壤柱萃取（SCE）和离线固相萃取（SPE）相结合的方法进行样品制备，并在选择离子监测（SIM）模式下用LC/ES-MS进行分析。为了优化SCE，对几种不同的萃取剂进行了评估。发现从土壤中最佳萃取IMIs的体系是甲醇/碳酸铵（0.1 M，体积比50:50）混合物。评估了基质中IMIs浓度对回收率的影响。在所研究的两个加标水平下，每种IMIs从土壤中的总回收率范围为87%至95%。在三种离子SIM条件下，土壤样品的检测限（信噪比S/N = 3）为0.1 - 0.05 ng/g。
