Electron capture gas-liquid chromatographic method for the simultaneous analysis of 2,4-D, dicamba, and mecoprop residues in soil, wheat, and barley.

A method has been developed for the simultaneous analysis of 2,4-D (2,4-dichlorophenoxy-acetic acid), dicamba (2-methoxy-3,6-dichloro-benzoic acid), and mecoprop (MCPP; 2-[(4-chloro-o-tolyl) oxy] propionic acid) residues in soil, wheat, and barley. Soil and crop samples are extracted with acidic acetone and methanol, respectively. The extracts in diethyl ether are esterified with diazomethane and cleaned up by passing through a Florisil column. Extracts are analyzed by gas-liquid chromatography, using an electron capture detector to determine 2,4-D and dicamba residues. Mecoprop in the extract is not detected at low levels of concentration. However, bromination of the extract increases the response of the electron capture detector to mecoprop. The method is sensitive to about 0.05 ppm 2,4-D and dicamba and 0.5 ppm mecoprop. Recoveries of these 3 herbicides added to soil, wheat, and barley samples at 0.05, 0.1, 0.5, and 1.0 ppm levels were between 65 and 93%. The method was used for the simultaneous analysis of 2,4-D, dicamba, and mecoprop residues in wheat, barley, and soil samples obtained from fields sprayed with the herbicide formulation Kil-Mor.     

Identification and quantitation of volatile compounds in two heated model compounds, trilinolein and linoleic acid esterified propoxylated glycerol

Static headspace (HS) and capillary gas chromatography/infrared spectroscopy-mass spectrometry (GC/IR-MS) were used to collect, separate, identify, and quantitate the oxidative and thermal decomposition products in two heated model compounds, linoleic acid esterified propoxylated glycerol (EPG-08 linoleate) and trilinoleylglycerol, both without added antioxidants. Approximately 4 L of EPG-08 linoleate or trilinoleylglycerol was heated in a deep-fat fryer at 192 +/- 8 degrees C for 12 h each day until the oil sample contained > or =20% polymeric material, which occurred after 24 h of heating. The major volatile compounds both in heated EPG-08 linoleate and in heated trilinoleylglycerol were pentane, hexanal, 2-heptenal, 1-octen-3-ol, 2-pentylfuran, 2-octenal, and 2, 4-decadienal. The identified volatile compounds from heated EPG-08 linoleate are those generally expected from the oxidative and thermal decomposition of fats and oils containing linoleic acid, except acetoxyacetone (1-acetoxy-2-propanone). Acetoxyacetone was found at 2.1, 3, and 2.4 ppm in the unheated, 12 h heated, and 24 h heated samples, respectively.     

Direct determination of lead in evaporated milk and apple juice by anodic stripping voltammetry: collaborative study

A method for the direct determination of lead in evaporated milk and in fruit juice with no prior sample digestion was successfully collaborated by 13 laboratories. The anodic stripping voltammetric (ASV) method studied consisted of adding 0.2 mL aliquots of evaporated milk or 0.3 mL aliquots of fruit juice to 2.9 mL of a dechelating reagent, Metexchange. The reagent-sample mixture is then analyzed for lead by ASV with no further sample preparation. Each collaborator received 24 samples, 2 each at 5 different levels (0.07-0.70 ppm for spiked evaporated milk and 0.09-0.87 ppm for spiked apple juice) along with duplicate practice samples of labeled lead content at each of 2 levels for each sample type. All unknowns were coded with random numbers. Approximately 69% of the reporting laboratories had never analyzed either evaporated milk or fruit juice for lead. Average time between receipt of samples and reporting of results was 1.6 days for all laboratories. The pooled variations between duplicate determinations for apple juice and evaporated milk were 0.00059 and 0.00043, respectively. The method was adopted official first action for both fruit juice and evaporated milk.     

Antioxidant properties of roasted coffee residues

The antioxidant activity of roasted coffee residues was evaluated. Extraction with four solvents (water, methanol, ethanol, and n-hexane) showed that water extracts of roasted coffee residues (WERCR) produced higher yields and gave better protection for lipid peroxidation. WERCR showed a remarkable protective effect on oxidative damage of protein. In addition, WERCR showed scavenging of free radicals as well as the reducing ability and to bind ferrous ions, indicating that WERCR acts as both primary and secondary antioxidants. The HPLC analyses showed that phenolic acids (chlorogenic acid and caffeic acid) and nonphenolic compounds [caffeine, trigonelline, nicotinic acid, and 5-(hydroxymethyl)furfuraldehyde] remained in roasted coffee residues. These compounds showed a protective effect on a liposome model system. The concentrations of flavonoids and polyphenolic compounds in roasted coffee residues were 8,400 and 20,400 ppm, respectively. In addition, the Maillard reaction products (MRPs) remaining in roasted coffee residues were believed to show antioxidant activity. These data indicate that roasted coffee residues have excellent potential for use as a natural antioxidant source because the antioxidant compounds remained in roasted coffee residues.     

Residues of captan and folpet in strawberries and grapes

Fresh strawberries and grapes grown in Michigan and Indiana were surveyed for residues of captan and folpet, 2 fungicides commonly used on these crops. The fungicides were reportedly applied to the crops by overhead irrigation, tractor sprayer, or aerial spraying, in amounts ranging from 0.5 to 6 lb formulation/acre for captan and from 1 to 4 lb formulation/acre for folpet. Reported dates of last application ranged from just 2 days to nearly 5 months before samples were collected. Twenty-eight strawberry samples and 24 grape samples were collected of crops field-treated with one or both of these fungicides. Samples were analyzed by previously described methodology. Captan residues were found in all strawberry samples, ranging from less than 0.01 to 1.5 ppm. Folpet was found in only one strawberry sample at 0.041 ppm. Captan residues were found in only 6 grape samples, ranging from less than 0.01 to 0.082 ppm. Folpet residues were found in 12 grape samples, ranging from less than 0.01 to 0.50 ppm. All residues were well below the current tolerances of 25 ppm for both captan and folpet in strawberries and 50 ppm for captan and 25 ppm for folpet in grapes. Residue levels of these surface-applied, nonsystemic fungicides were inconsistent with amounts and dates of application, most likely because of variations in weather conditions, especially rainfall. Residues were quite stable in frozen sample homogenates, declining only 5-10% after 2 months.     

Metabolism of 2,4-dichlorophenoxyacetic acid in laying hens and lactating goats

2,4-Dichlorophenoxyacetic acid (2,4-D) labeled with (14)C was found to be rapidly eliminated by laying hens and lactating goats dosed orally for 7 consecutive days at 18 mg/kg of food intake and for 3 consecutive days at 483 mg/kg of food intake, respectively. Excreta of hens and goats contained >90% of the total dose within 24 h after the final dose. Tissue residues were low and accounted for <0.1% of the dose in these animals. For hens, the residues in muscle, liver, and eggs (0.006-0.030 ppm) were lower than those found in fat and kidney (0.028-0.714 ppm), 2,4-D equivalents. The tissue with highest residue in goat was the kidney at 1.44 ppm, 2,4-D equivalents. Milk, liver, composite fat, and composite muscle had significantly lower residue levels of 0.202, 0.224, 0.088, and 0.037 ppm, respectively. The most abundant tissue residue was 2,4-D and acid/base releasable residues of 2,4-D. A minor metabolite was identified as 2,4-dichlorophenol.     

Permethrin and its two metabolite residues in seven agricultural crops

Metabolite residues of permethrin are not reported in the literature for most agricultural crops. This paper reports residues of permethrin and its 2 metabolites (dichlorovinyl acid and metaphenoxybenzyl alcohol) in 7 different agricultural crops (Chinese cabbage, spinach, asparagus, raspberries, green peas, turnip roots, and turnip greens). Permethrin residues declined approximately 85% within 7 days after treatment in all crops. In most cases, the acid metabolite residues peaked at 3 days, and declined after that. Translocation of residues into turnip roots was very slight; the average was less than 0.05 ppm for permethrin and alcohol metabolite residues and none was detected for the acid metabolite residue. Permethrin residues in the turnip greens averaged approximately 2 ppm for the 0.112 kg ai/ha treatment, and 6 ppm for the 0.224 kg ai/ha treatment.     

U.S. market basket study to determine residues of the insecticide chlorpyrifos.

A market basket study was conducted to measure residues of the insecticide chlorpyrifos in samples of apples, applesauce, apple juice, fresh orange juice, tomatoes, peanut butter, whole milk, ground beef, and pork sausage collected during a 12-month period from 200 grocery stores across the United States. Approximately 90% of the samples contained no detectable levels of chlorpyrifos, and all residues detected were below tolerances, the legal limits for the United States. No values greater than the limit of quantitation (LOQ) were found in applesauce (LOQ = 0.008 ppm), apple juice (LOQ = 0.003 ppm), whole milk (LOQ = 0.006 ppm), ground beef (LOQ = 0.005 ppm), or pork sausage (LOQ = 0.007 ppm) samples. Only one fresh orange juice sample contained residues greater than the LOQ at 0.015 ppm. Only about 20% of the apples (maximum = 0.052 ppm), 20% of the tomato samples (maximum = 0.058 ppm), and 50% of the peanut butter samples (maximum = 0.021 ppm) contained quantifiable residues.     

Determination of tri-n-butyltin and di-n-butyltin compounds in fish by gas chromatography with flame photometric detection

An analytical method is described for the simultaneous quantitative determination of tri-n-butyltin and di-n-butyltin compounds in fish. The sample was extracted with 0.5N HCl-methanol, and the methanol solution was extracted with hexane. The extract was purified by gel permeation chromatography and treated with Grignard reagent to yield the methyl derivatives, which were determined by gas chromatography with flame photometric detection operated in the tin mode (610 nm). Recoveries of tri-n-butyltin chloride (Bu3SnCl) and di-n-butyltin dichloride (Bu2SnCl2) spiked to fish at the levels of 0.2 and 1.0 ppm ranged from 80 to 105%. Detection limits were 0.02 micrograms/g for both compounds. Tri-n-butyltin compounds equivalent to Bu3SnCl levels of 0.07-2.0 ppm and di-n-butyltin compounds equivalent to Bu2SnCl2 levels of 0.02-0.11 ppm were found in reared yellowtails, and these values showed good agreement with the results from gas chromatographic-mass spectrometric analysis.     

Determination of daminozide in apples by gas chromatography/chemical ionization mass spectrometry

A method using gas chromatography/chemical ionization mass spectrometry (GC/CIMS) for the determination of daminozide residues in apples has been developed. Daminozide was separated from the sample matrix by water extraction and cation exchange, converted to the methyl ester by treatment with HCl-methanol, and determined by GC/CIMS using succinonitrile as an internal standard. The detection level was 0.05 ppm. Recoveries were 92-104% from apples spiked at the 0.05-0.5 ppm levels. Of the 25 apple samples analyzed, only 2 were positive for daminozide (1.04 and 0.32 ppm).     

Salicylic acid, ethephon, and methyl jasmonate enhance ester regeneration in 1-MCP-treated apple fruit after long-term cold storage

Volatile esters, primarily synthesized in peel tissues, are major aromatic components of apple fruits [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.]. The use of cold storage combined with 1-methylcyclopropene (1-MCP) treatment prolongs the life of apples but represses the regeneration of esters during poststorage ripening. In this study, the regeneration of total esters was significantly increased in apple fruits treated with salicylic acid (SA) and Ethephon (ETH) that had been treated once or twice with 1-MCP. However, methyl jasmonate (MeJA) treatment resulted in regeneration of total esters after a single 1-MCP treatment. To determine the mechanism by which SA, ETH, and MeJA regulate ester regeneration, the apple alcohol acyltransferase gene (MdAAT2) was investigated at the mRNA, protein, and enzyme activity levels. Genes associated with ethylene perception were also investigated by RT-PCR. The results suggest that MdAAT2 controls ester regeneration and that MdETR1 plays a key role in ethylene perception and regulation of downstream MdAAT2 gene expression during poststorage. Ester compounds and concentrations differed in peels treated with different signal molecules, indicating that regulation of the pathway upstream of straight-chain ester biosynthesis depended on the regulation of lipoxygenase (LOX) and alcohol dehydrogenase (ADH) activity by SA, ETH, and MeJA during poststorage ripening.     

Uniformly (14)C-ring-labeled 2,4-dichlorophenoxyacetic acid: a metabolism study in bluegill sunfish, Lepomis macrochirus.

The fate of 2,4-dichlorophenoxyacetic acid (2,4-D), a mixture of [phenyl(U)-(14)C]-2,4-D and unlabeled 2,4-D, in bluegill sunfish was investigated after exposure to approximately 11 ppm under static conditions for 4 days. Total radioactive residues (TRR) in whole fish increased from 0.41 ppm on day 1 to 0.60 ppm on day 3. TRR levels in fillet (edible) and viscera (nonedible) of treated fish on day 4 were 0.41 and 1.9 ppm, respectively. Most residues in both matrices were acetonitrile soluble; small amounts were hexane soluble or unextractable with solvents. Acid and base hydrolyses with ethyl acetate partitioning were used to release the fillet unextractable residues. The identification of 2,4-D and 2,4-dichlorophenol (2,4-DCP) in the fillet was conclusively confirmed by GC-MS analysis. On the basis of the experimental data from this study, a metabolic pathway for 2,4-D in bluegill sunfish in which the 2,4-D is metabolized to 2,4-DCP and conjugates of 2,4-D and 2,4-DCP is proposed.     

Chemical composition, iron bioavailability, and antioxidant activity of Kappaphycus alvarezzi (Doty)

Kappaphycus alvarezzi, an edible seaweed from the west coast of India, was analyzed for its chemical composition. It was found that K. alvarezzi is rich in protein (16.24% w/w) and contains a high amount of fiber (29.40% w/w) and carbohydrates (27.4% w/w). K. alvarezzi showed vitamin A activity of 865 mug retinal equivalents/100 g of sample. It contained a higher quantity of unsaturated fatty acids (44.50% of the total), in which relative percentage of oleic acid was 11%, cis-heptadecanoic acid 13.50%, and linoleic acid 2.3% and 37.0% of saturated fatty acids (mainly heptadecanoic acid). K. alvarezziwas also found to be good source of minerals, viz 0.16% of calcium, 0.033% of iron, and 0.016% of zinc, which are essential for various vital biological activities. Bioavailability of iron by in vitro methods showed a higher efficiency in intestinal conditions than in stomach conditions. Ascorbic acid influenced higher bioavailability of iron. Successive extracts of n-hexane, acetone, ethyl acetate, ethanol, and direct extractables of chloroform/methanol (1:1 and 2:1) were screened for antioxidant activity using a beta-carotene linoleic acid model system (B-CLAMS), DPPH (alpha,alpha-diphenyl-beta-picrylhydrazyl) model system and hydroxyl radical scavenging activity. The chloroform/methanol (2:1) extract has shown 82.5% scavenging activity at 1000 ppm. Acetone fraction extracts at the 1000 ppm level showed 63.31% antioxidant activity in beta-carotene linoleic acid system. The acetone extract showed 46.04% scavenging activity at 1000 ppm concentration. In the case of hydroxyl radical scavenging activity, all the extracts showed better activity at the concentrations of 25 and 50 ppm, where at the 50 ppm level ethyl acetate extract showed 76.0%, acetone 75.12%, and hexane 71.15% activity, respectively. Results of this study suggest the utility of K. alvarezzi (Eucheuma) for various nutritional products, including antioxidant for use as health food or nutraceutical supplement.     

Gas chromatographic-olfactometric characterization of aroma compounds in two types of cashew apple nectar

Cashew apple nectar is a secondary product from the production of cashew nuts and possesses an exotic tropical aroma. Aroma volatiles in pasteurized and reconstituted (from concentrate) Brazilian cashew apple nectars were determined using GC-MS and split, time-intensity GC-olfactometry (GC-O)/GC-FID. Methional, (Z)-1,5-octadien-3-one, (Z)-2-nonenal, (E,Z)-2,4-decadienal, (E,E)-2,4-decadienal, beta-damascenone, and delta-decalactone were identified for the first time in cashew apple products. These compounds plus butyric acid, ethyl 3-methylbutyrate, 2-methylbutyric acid, acetic acid, benzaldehyde, homofuraneol, (E)-2-nonenal, gamma-dodecalactone, and an unknown were the most intense aroma volatiles. Thirty-six aroma volatiles were detected in the reconstituted sample and 41 in the pasteurized sample. Thirty-four aroma active components were common to both samples. Ethyl 3-methylbutyrate and 2-methylbutyric acid were character impact compounds of cashew apple (warm, fruity, tropical, sweaty). Using GC-pFPD, 2-methyl-3-furanthiol and bis(2-methyl-3-furyl) disulfide were identified for the first time in cashew apple. Both were aroma active (meaty).     

Method development and fate determination of pesticide-treated hops and their subsequent usage in the production of beer

The fate of residues of seven agrochemicals (chlorfenapyr, quinoxyfen, tebuconazole, fenarimol, pyridaben, and E- and Z-dimethomorph) from the treatment on hops to the brewing of beer was studied. First, a multi-residue analytical method was developed for the determination of pesticide residues in spent hops, trub, wort, and beer. Each matrix was validated over at least two levels of fortification, for all seven compounds, in the ranges 0.05-5.0, 0.001-1.0, 0.001-0.05, and 0.0005-1.0 ppm for spent hops, trub, wort, and beer, respectively. Recoveries ranged from 73 to 136%. Second, the matrixes prepared from hops, which were treated under commercial practices with each compound, were analyzed using the method developed. The use of treated hops resulted in the carryover of 0.001 ppm of tebuconazole, 0.008 Z-dimethomorph, and 0.005 ppm of E-dimethomorph into the wort. The bulk of the remaining residues of all seven compounds was found on the spent hops. Following fermentation, all compounds were found in levels less than 0.0005 ppm in beer, except Z- (0.006 ppm) and E-dimethomorph (0.004 ppm). Third, when all seven pesticides were spiked prior to the pitching of yeast into clean wort, most of the nonpolar compounds (chlorfenapyr, quinoxyfen, and pyridaben) partitioned into the organic material (trub) which settled to the bottom, while the more polar compounds (fenarimol, tebuconazole, and E- and Z-dimethomorph) were generally distributed evenly between the beer and the trub.     

Methylation methods for the quantitative analysis of conjugated linoleic acid (CLA) isomers in various lipid samples

Precise methylation methods for various chemical forms of conjugated linoleic acid (CLA), which minimize the formation of t,t isomers and allylmethoxy derivatives (AMD) with the completion of methylation, were developed using a 50 mg lipid sample, 3 mL of 1.0 N H(2)SO(4)/methanol, and/or 3 mL of 20% tetramethylguanidine (TMG)/methanol solution(s). Free CLA (FCLA) was methylated with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). CLA esterified in safflower oil (CLA-SO) was methylated with 20% TMG/methanol (100 degrees C, 5 min), whereas CLA esterified in phospholipid (CLA-PL) was methylated with 20% TMG/methanol (100 degrees C, 10 min), followed by an additional reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). Similarly, CLA esterified in egg yolk lipid (CLA-EYL) was methylated by base hydrolysis, followed by reaction with 1.0 N H(2)SO(4)/methanol (55 degrees C, 5 min). These results suggest that for the quantitative analysis of CLA in lipid samples by GC, proper methylation methods should be chosen on the basis of the chemical forms of CLA in samples.     

Penetrative and dislodgeable residue characteristics of 14C-insecticides in apple fruit

Infinite- and finite-dose laboratory experiments were used to study the penetrative and dislodgeable residue characteristics of (14)C-insecticides in apple fruit. The differences in dislodgeable and penetrated residues of three radiolabeled insecticides ((14)C-thiamethoxam, (14)C-thiacloprid, and (14)C-indoxacarb), applied in aqueous solution with commercial formulations, were determined after water and methanol wash extractions. The rate of sorption and extent of penetration into the fruit cuticles and hypanthium of two apple cultivars were measured after 1, 6, and 24 h of treatment exposure, using radioactivity quantification methods. For all three compounds, 97% or more of the treatment solutions were found on the fruit surface as some form of non-sorbed residues. For indoxacarb, sorption into the epicuticle was rapid but desorption into the fruit hypanthium was delayed, indicative of a lipophilic penetration pathway. For the neonicotinoids, initial cuticular penetration was slower but with no such delay in desorption into the hypanthium.     

Ozone and hydrogen peroxyacetic acid treatment to reduce or remove EBDCs and ETU residues in a solution.

Laboratory studies were conducted in a model system to determine the effects of ozone (1 and 3 ppm) and hydrogen peroxyacetic acid (HPA) (5 and 50 ppm) at pH 4.6, 7.0, and 10.7 and at 10 and 21 degrees C on the degradation of mancozeb in solution over a 30 min period. All samples were analyzed for residues by GLC and HPLC. Ozonation and HPA treatment were effective in degrading mancozeb in solution. Rate of mancozeb degradation was dependent on pH, with the fastest rate at pH 7.0. Ethylenethiourea (ETU) residue concentrations in the mancozeb solutions were monitored over 60 min. Under controlled conditions, the ETU residue concentrations increased during the 15 min reaction time and then decreased for all three pH values. At 3 ppm of ozone treatment, no ETU residues were detected at all three pH ranges after 15 min of reaction time. Degradation of ETU by HPA was greatest at pH 4.6, and no ETU residues remained after 5 min at either 5 or 50 ppm. The results showed that ozone and HPA gave excellent degradation of pesticide residues depending on pH and temperature. These experiments indicated the potential for the removal of pesticide residues on fruit and in processed products.     

Sulfamethazine and sulfathiazole determination at residue levels in swine feeds by reverse-phase liquid chromatography with post-column derivatization

Twenty g sample, to which sulfamerazine has been added as internal standard, is extracted with 0.3N HCl + 1.5% diethylamine in 25% methanol. The sample extract is chilled (to aid clarification), centrifuged, and filtered. The sulfonamides are separated from each other and from co-extracted materials on a C-18 reverse-phase column and detected at 450 nm following post-column derivatization with dimethylaminobenzaldehyde. Two isocratic mobile phases have been tested: (1) acetonitrile-2% acetic acid (17 + 83), with an analysis time of 13 min; and (2) acetonitrile-methanol-2% acetic acid (4 + 16 + 80), with an analysis time of 20 min but an improved analysis for some samples. As many as 40 samples have been analyzed at one time unattended with the aid of an autosampler. A total of about 1500 field samples have been assayed using the method. Method sensitivity is 0.1 ppm for either analyte in a hog finishing fed. Linearity for each of the analytes is satisfactory over a range of 0.4-25 ppm in spiked feeds. Coefficients of variation range from 13% at 0.5 ppm to 2% at 13 ppm as tested over a period of time in naturally contaminated samples. The absolute recovery of sulfamerazine varies with sample matrix, but, in the presence of sulfamerazine as internal standard, recovery has been 96.7-99.7% over the range of 0.1-10 ppm. Sulfamerazine and sulfamoxole were tested for their suitability as internal standards. Sulfamerazine is a good internal standard for sulfamethazine; neither is ideal for sulfathiazole.(ABSTRACT TRUNCATED AT 250 WORDS)     

Analysis of flonicamid and its metabolites in dried hops by liquid chromatography-tandem mass spectrometry

An analytical method was developed for the determination of the neo-nicotinoid insecticide flonicamid ( N-cyanomethyl-4-trifluoromethylnicotinamide) and its metabolites N-(4-trifluoronicotinoyl) glycine (TFNG), 4-trifluoronicotinic acid (TFNA), and 4-trifluoromethylnicotinamide (TFNA-AM) in dried hops. The method utilized C18 and polymeric solid phase extraction (SPE) column cleanups, liquid-liquid partitioning, and liquid chromatography (LC) with mass spectrometry (MS/MS). Method validation and concurrent recoveries from untreated dried hops ranged from 66 to 119% for all compounds over five levels of fortification (0.005, 0.02, 0.2, 2.0, and 4.0 ppm). Flonicamid-treated hop samples collected from three field sites had the following residues: flonicamid levels of 0.561-2.85 ppm, TFNA levels of 0.302-0.470 ppm, TFNA-AM levels of 0.038-0.177 ppm, and TFNG levels of 0.098-0.204 ppm. Untreated hop samples from all fields had residues <0.005 ppm for flonicamid, TFNA, TFNA-AM, and TFNG. The limit of quantitation and limit of detection for all compounds were 0.005 and 0.0025 ppm, respectively.