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A method for determining 68 pesticides in river water using stir bar sorptive extraction (SBSE)-thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) is described. SBSE sampling was optimized for sample solution pH, salting-out and methanol addition. Although salting-out enhanced the ability of the method to extract most of the pesticides with low absolute recoveries, the absolute recoveries of four pesticides were not improved by salting-out. The detection limits of the method for the pesticides ranged from 0.2 to 20 ng/l. Analyte recoveries from a river water sample spiked with standards at 10 and 100 ng/l were 58.5-132.0% (RSD: 1.8-15.8%) and 61.0-121.3% (RSD: 1.4-20.2%), respectively.

A serious problem in analyzing pesticide residues in foods by gas chromatography/mass spectrometry (GC/MS) is the matrix enhancement e ect. e matrix e ect of pesticides in 5 types of representative samples preprocessed by the Positive List System was measured at 100 ppb. e mean matrix e ect value of pesticides in potato, spinach, orange, brown rice, and soybean sample was 129%, 191%, 171%, 225%, and 146%, respectively. Continuing research showed that the sample solutions contained high amounts of some matrix components, such as tocopherols, sterols, and monoacylglycerols. In order to investigate which component causes the matrix e ect, each matrix solution was prepared at 1-1000 ppm (monoacylglycerols: 1-500 ppm), and the pesticide mixture was forti ed to 100 ppb. e matrix e ect depended on the concentration of the matrix solution, and we concluded that monoacylglycerols were the most attributable components to the matrix e ect.

Isovaleric acidemia (IVA) is an organic acid disease caused by a deficiency of isovaleryl-CoA dehydrogenase. Deficiency of this enzyme leads to accumulation of organic acids, such as isovalerylcarnitine and isovalerylglycine. The proposed IVA treatments include leucine restriction and l-carnitine and/or glycine supplementation, which convert isovaleric acid into non-toxic isovalerylcarnitine and isovalerylglycine, respectively. We examined the therapeutic response using the leucine load test and performed a 10-year follow-up in the patient.MethodsWe evaluated the patient with IVA beginning at 5 years of age, when he presented with a mild to intermediate metabolic phenotype. Ammonia, free carnitine, isovalerylcarnitine, and isovalerylglycine were analyzed in the urine and blood after a meal consisting of 1600 mg leucine with glycine alone (250 mg/kg/day), l-carnitine alone (100 mg/kg/day), or both glycine and l-carnitine for four days each.Results(Leucine load test) Three hours after the meal, serum ammonia levels increased most dramatically with glycine treatment alone, then with both in combination, and least with l-carnitine alone. Urinary isovalerylglycine levels increased 2-fold more with glycine supplementation than those following supplementation with both agents or with l-carnitine alone. Treatment with both agents resulted in a gradual increase in urinary acylcarnitine levels during the 6-h period following the leucine load, reaching concentrations comparable to those observed with l-carnitine alone. (Clinical course) After initiation of both glycine (200 mg/kg/day) and l-carnitine (100 mg/kg/day) supplementation at 5 years of age, doses were gradually reduced to 111.7 mg/kg/day and 55.8 mg/kg/day, respectively, at 15 years of age. His mind and body had developed without any sequelae.DiscussionWe concluded that l-carnitine conjugated isovaleric acid earlier than glycine. Additionally, during the 10-year follow-up period, the patient displayed no clinical deterioration.