Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 58)

Introduction:Agricultual chemicals include not only pesticides for protecting plants, such as insecticides, germicides, herbicides and rodenticides, but also fertilizers and growth regulating substances being used in agricultural production and horticulture. In poisoning cases with agricultural chemicals, the causative poisons are largely the pesticides. There are many cases, in which the poisoning due to exposure to an organophosphorus pesticide is obvious with clinical symptoms [1]. However, there are more than 5,000 agricultural chemicals registered and commercially available in Japanese markets [2]; it is essential to identify a causative chemical to make the final clinical diagnosis in a poisoning-suspected case. ...
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Drugs and Poisons in Humans - A Handbook of Practical Analysis (Part 58) 7.1II.7.1 Simultaneous analysis of pesticides by GC/MS by Shinji Kageyama and Makoto UekiIntroductionAgricultual chemicals include not only pesticides for protecting plants, such as insecticides,germicides, herbicides and rodenticides, but also fertilizers and growth regulating substancesbeing used in agricultural production and horticulture. In poisoning cases with agriculturalchemicals, the causative poisons are largely the pesticides. There are many cases, in which thepoisoning due to exposure to an organophosphorus pesticide is obvious with clinical symp-toms [1]. However, there are more than 5,000 agricultural chemicals registered and commer-cially available in Japanese markets [2]; it is essential to identify a causative chemical to makethe final clinical diagnosis in a poisoning-suspected case. Since sensitive and simultaneous analysis of multiple compounds is possible using GC/MS,the method is being widely used for analysis of pesticides for environmental specimens, suchas water and soil [3–6]. In this chapter, among main pesticides which had been reported caus-ative for poisoning cases [7], more than 30 kinds of pesticides have been picked up from or-ganophosphorus, organochlorine, carbamate and triazine pesticides, and a method for simul-taneous analysis of many pesticides by GC/MS is presented. For alkylpyridinium and aminoacid type herbicides, their analyses are described in other chapters.Reagents and their preparationi. Reagents• Pure n-hexane for organic trace analysis (Merck, Darmstadt, Germany and other manu- facturers) is directly used or redistilled befor use according to need.• Many of the authentic standards of pesticides can be purchased from Supelco, Bellefonte, PA, USA; but fenobucarb, salithion, thiometon, ethylthiomethon, propanil, cyanofenphos and isoxathion cannot be obtained from the above manufacturer, but can be obtained from Wako Pure Chemical Industries, Ltd., Osaka, Japan. As internal standard (IS), fenitrothion- d6 was obtained from (Hayashi Pure Chemical Ind., Ltd, Osaka, Japan). Other common chemicals used were of the highest purity commercially abailable.ii. Preparation• Standard solutions for each pesticide are prepared by dissolving each compound in ethanol (1 mg/mL); each retention times were determined by GC. The 35 compounds were divided into 3 groups, where each peak did not overlap or interfere with each other as shown in > Figure 1.1. Such 3 mixture standard solutions with known compounds at 1 mg/mL each are also prepared.© Springer-Verlag Berlin Heidelberg 2005528 Simultaneous analysis of pesticides by GC/MS • A 10-mL volume of 12 M hydrochloric acid solution is carefully diluted with purified water to prepare 100 mL solution. • To 2-mL volume each of blank whole blood or urine, which had been obtained from healthy and unexposed subjects, a 100 µL of each standard solution (1 mg/mL) is added to be used as a calibrator a. Analytical conditions Instrument: HP-6890 type GC/HP-5973 type MS equipped with an HP-6890 type autosampler (all from Agilent Technologies, Palo Alto, CA, USA). GC column: Ultra-2 (25 m × 0.2 mm i. d., film thickness 0.33 µm, 5 %-phenylmethylsilicone, Agilent Technologies). Evaporator: REN-1EN type (Asahi Technoglass, Chiba, Japan). Vials for sampling are those usable for the autosampler. Before analysis, impurities arising from the vials and caps should be checked. Other tools are common ones commercially avail- able. GC/MS conditions; column (oven) temperature: 50 °C (1 min) → 20 °C/min → 200 °C → 7 °C/min → 290 °C (8 min); analysis time: 29.4 min; injection mode: splitless; injection tem- perature: 250 °C; injection pressure: about 17 psi (helium pressure at 50 °C of oven tempera- ture); septum purge flow rate: 11.0 mL/min; purge time: 1.0 min; total flow rate: 14.3 mL/min; column flow rate: 1.0 mL/min (constant flow-rate mode); interface temperature: 150 °C; MS ionization mode: EI; electron energy: 70 eV; scan range: m/z 40–550; dwell time of SIM mea- surements: 10 s; SIM ions to be used: listed in > Table 1.1. Procedure i. A 2-mL volume of whole blood or urineb is mixed well with 3 mL of purified water. ii. A 100-µL volume of IS (fenitrothion-d6) solution is added to the above mixture and mixed well. iii. The pH of the mixture is adjusted to 3.5 by adding 1.2 M hydrochloric acid solution. iv. A 8-mL volume of n-hexane is mixed with the above mixture and shaken for 10 min for extractionc. ...