A method was developed to determine pesticides in wines. The pesticides were extracted from the wine using solid-phase extraction on a polymeric cartridge, and the coextractives were removed with an aminopropyl-MgSO(4) cartridge. Analysis was performed using capillary gas chromatography with electron impact mass spectrometric detection in selective ion monitoring mode (GC-MSD/SIM). Three injections are required to analyze all 153 organohalogen, organonitrogen, organophosphate, and organosulfur pesticides and residues. Pesticides were confirmed by retention times of the target ions and three qualifier-to-target ion ratios. Detection limits for most of the pesticides were less than 0.005 mg/L, and quantitation was determined from approximately 0.01 to 5 mg/L. Spike recoveries were performed by fortifying red and white wines at 0.01 and 0.10 mg/L. At the 0.01 ppm level, the spike recoveries were greater than 70% for 116 and 124 pesticides (out of 153) in red and white wines, respectively, whereas at the higher spike concentration of 0.10 mg/L, the recoveries were greater than 70% for 123 and 128 pesticides in red and white wines, respectively. The recoveries of less than 70% were most likely from pesticide polarity or lability, resulting in the inefficient adsorption of the pesticide to the polymeric sorbent, ineffective elution of the pesticide from the sorbent, or thermal degradation of the pesticide under GC-MSD conditions.

Fipronil insecticide dissipated in California rice fields, producing half-lives of 10.5 to 125 h in water and 44.5 to 533 h in soil, depending on the formulation applied and the resulting differences in water solubility. The major degradation products were desthiofipronil in water and fipronil-sulfide in soil, while the sulfone and amide were less abundant. Fipronil was photolyzed rapidly to desthiofipronil in deionized water in the laboratory (t1/2 = 7.97-9.42 h) and even faster in the presence of H2O2 (t1/2 = 0.874-4.51 h). Fipronil was also hydrolyzed to amide in base (t1/2 = 542 h at pH 9) and volatilized slowly from water (H = 6.60 x 10(-6) m3.atm/mol), properties not explaining its rapid field water dissipation. Desthiofipronil was more stable than fipronil to direct photolysis (t1/2 = 120-149 h), was indirectly photolyzed in the presence of H2O2 (t1/2 = 0.853-3.76 h), and was nonvolatile from water. The desthiofipronil observed in field water was formed photochemically from fipronil, accumulated due to slower photolysis and lack of volatility from water, but eventually dissipated.

The phenylpyrazole insecticide fipronil (I) photolyzes to its desthio product (II) in aqueous solution. However, the necessity of an intervening oxidation to a sulfone intermediate (III) has not been resolved, and the photodegradation products of II have not been identified. Using GC-MS, HPLC-UV/vis, electrospray MS, (19)F NMR, and GC-TSD, our objective was to characterize the photodegradation pathways of I, which would clarify the role of III, identify products of II, and explain unbalanced mass accounts in previous studies. Findings showed that II is formed directly and photochemically from I, confirmed by the greater stability of III (t(1/2) 112 h), and that successive oxidations of I to III and then a sulfonate (IV) comprise a second pathway. Compound II underwent photodechlorination, substitution of chlorine by trifluoromethyl, and pyrazole ring cleavage. This work is significant to understanding the photochemistry of novel phenylpyrazole pesticides in the environment.

The chemical analysis of gamma-hydroxybutyric acid (GHB) in most forensic laboratories is complicated by the highly polar nature of the GHB molecule, which makes it unsuitable for direct analysis by gas chromatography (GC). Consequently, a popular analytical approach is to convert GHB into the corresponding lactone or a derivative compound that is then identified by mass spectrometry employed in conjunction with GC (GC/MS). An alternative approach is presented here where GHB may be isolated as a free acid specie from complex aqueous solutions employing a liquid-liquid extraction technique. This approach can yield a relatively pure residue of GHB that presents an infrared transmission spectrum that is sufficiently distinct for identification purposes. Infrared spectroscopy (IR) is a very popular technique that is available to most crime laboratories. The liquid-liquid extraction behavior of GHB is examined in detail and the uniqueness of the infrared spectrum is discussed.

A method was developed to determine pesticides in malt beverages using solid phase extraction on a polymeric cartridge and sample cleanup with a MgSO4-topped aminopropyl cartridge, followed by capillary gas chromatography with electron impact mass spectrometry in the selected ion monitoring mode [GC-MS(SIM)]. Three GC injections were required to analyze and identify organophosphate, organohalogen, and organonitrogen pesticides. The pesticides were identified by the retention times of peaks of the target ion and qualifier-to-target ion ratios. GC detection limits for most of the pesticides were 5-10 ng/mL, and linearity was determined from 50 to 5000 ng/mL. Fortification studies were performed at 10 ng/mL for three malt beverages that differ in properties such as alcohol content, solids, and appearance. The recoveries from the three malt beverages were greater than 70% for 85 of the 142 pesticides (including isomers) studied. The data showed that the different malt beverage matrixes had no significant effect on the recoveries. This method was then applied to the screening and analysis of malt beverages for pesticides, resulting in the detection of the insectide carbaryl and the fungicide dimethomorph in real samples. The study indicates that pesticide levels in malt beverages are significantly lower than the tolerance levels set by the United States Environmental Protection Agency for malt beverage starting ingredients. The use of the extraction/cleanup procedure and analysis by GC-MS(SIM) proved effective in screening malt beverages for a wide variety of pesticides.