scholarly journals Liquid Chromatographic Determination of N-Methyl Carbamate Pesticide Residues at Low Parts-Per-Billion Levels in Eggs

2006 ◽  
Vol 89 (1) ◽  
pp. 196-200 ◽  
Author(s):  
Frank J Schenck ◽  
Lynda V Podhorniak ◽  
James Hobbs ◽  
John Casanova ◽  
Dan Donoghue
Keyword(s):  
Pesticide Residues ◽  
Solid Phase ◽  
Dietary Exposure ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Piperonyl Butoxide ◽  
Extraction Column ◽  
Liquid Chromatographic ◽  
Carbamate Pesticide

Abstract A reversed-phase liquid chromatographic (LC) method is presented for the analysis of N-methyl carbamate pesticide residues and piperonyl butoxide in eggs at levels as low as 2 gkg (ppb). The study was undertaken to provide data for dietary exposure estimates used in risk analysis. The method uses an acetonitrile extraction followed by liquidliquid partitioning and normal-phase aminopropyl solid-phase extraction column cleanup. Determination of residues is by reversed-phase LC with an inline postcolumn reaction followed by fluorescence detection. The average recoveries of 21 fortified (most at 2.0 and 20.0 ppb) N-methyl carbamate pesticide residues and the carbamate metabolite 1-naphthol from eggs ranged from 70 to 107%. Recoveries of the pesticide synergist piperonyl butoxide ranged from 63 to 106%. Single-comb White Leghorn hens were treated with the carbamate carbaryl, and the eggs subsequently produced were analyzed for carbaryl and 1-naphthol residues.

Liquid Chromatographic Determination of Zearalenone and a- and 0-Zearalenols in Milk

1988 ◽  
Vol 71 (6) ◽  
pp. 1176-1179 ◽  
Author(s):  
Peter M Scott ◽  
Guillaume A Lawrence
Keyword(s):  
Methylene Chloride ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Extraction Column ◽  
Hydrophilic Matrix ◽  
Unknown Factor ◽  
Liquid Chromatographic Determination ◽  
Phase Liquid ◽  
Liquid Chromatographic

Abstract Previous research has demonstrated transmission of zearalenone and α- and β-zearalenols into the milk of cows and other animals. Since human intake of zearalenone and its metabolites via milk is an unknown factor in risk assessment of zearalenone and because appropriate methodology for their determination in milk is not available, a rapid and sensitive analytical method has been developed. Essentially, the method includes extraction with basic acetonitrile, acidification, partition into methylene chloride on a hydrophilic matrix, cleanup on an aminopropyl solid phase extraction column, and reverse- phase liquid chromatography with fluorescence detection. Recoveries from milk averaged 84% for zearalenone, 93% for α-zearalenol, and 90% for β-zearalenol at spiking levels of 0.5 to 20 ng/ mL. As little as 0.2 ng/mL of zearalenone and a-zearalenol and 2 ng/mL of 0-zearalenol can be detected in milk. These 3 compounds are stable in refrigerated milk for at least 2 weeks and in milk brought to boiling. Enzymes (β-glucuronidase and aryl sulfatase) may be added to milk prior to extraction to hydrolyze any conjugates

scholarly journals Liquid Chromatographic Determination of Mebendazole and its Metabolites, Aminomebendazole and Hydroxymebendazole, in Eel Muscle Tissue

1996 ◽  
Vol 79 (3) ◽  
pp. 645-651 ◽  
Author(s):  
Christiaan A J Hajee ◽  
Nel Haagsma
Keyword(s):  
Muscle Tissue ◽  
Mobile Phase ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Extraction Column ◽  
Phase Extraction ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract An analytical method is presented for liquid chromatographic (LC) determination of mebendazole (MBZ), hydroxymebendazole (MBZ-OH), and aminomebendazole (MBZ-NH2) in eel muscle tissue. Muscle tissue is extracted with ethyl acetate at pH 7.5. After addition of n-hexane, the extract is cleaned up and concentrated on an aminopropyl solid-phase extraction column. The test solutions are analyzed isocratically on a ChromSpher B LC column with acetonitrile–phosphate buffer, pH 6.2, as mobile phase. Limits of detection and quantitation were 0.7 and 1.1 ¼g/kg, respectively, for MBZOH; 1.4 and 2.3 ¼g/kg, respectively, for MBZ; and 1.5 and 2.1 ¼g/kg, respectively, for MBZ-NH2. Interand intraday coefficients of variation were 3.5 and 3.4%, respectively, for MBZ-OH; 2.5 and 3.1%, respectively, for MBZ; and 5.8 and 4.8%, respectively, for MBZ-NH2. Mean recoveries were 90% for MBZ, 74% for MBZ-NH2, and 92% for MBZ-OH. A linear range of applicability of at least 10–1000 ¼g/kg was found for each analyte. Incurred MBZ-NH2 (181.3 ¼g/kg) was identified in eel muscle tissue apart from MBZ (23.7 ¼g/kg) after 48 h exposure ina treatment bath containing MBZ at 1 mg/L.

scholarly journals Liquid Chromatographic Determination of Fosthiazate Residues in Environmental Samples and Application of the Method to a Fosthiazate Field Dissipation Study

2005 ◽  
Vol 88 (6) ◽  
pp. 1827-1833 ◽  
Author(s):  
Nicholas G Tsiropoulos ◽  
Dimitrios T Likas ◽  
Dimitrios G Karpouzas
Keyword(s):  
Liquid Chromatography ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Physicochemical Characteristics ◽  
Reversed Phase ◽  
Subsequent Elution ◽  
Water And Soil Samples ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A method was developed and validated for the determination of residues of the organophosphorus nematicide fosthiazate in soil and water by using reversed-phase liquid chromatography with UV detection. Good recoveries (>85%) of fosthiazate residues were obtained from water samples (drinking water, groundwater, and liquid chromatography water) after passage of 0.5–2 L water through solid-phase extraction (SPE) C-18 cartridges and subsequent elution with ethyl acetate. Residues in soil were extracted with methanol–water (75 + 25, v/v) on a wrist-action shaker, and the extract was cleaned up on C-18 SPE cartridges before analysis. The method was validated by analysis of a range of soils with different physicochemical characteristics; recoveries exceeded 87% at fortification levels ranging from 0.02 to 5.0 mg/kg. The precision values obtained for the method, expressed as repeatability and reproducibility, were satisfactory (<11%). Fosthiazate detection limits were 0.025 μg/L and 0.005 mg/kg for water and soil samples, respectively. The decline in the levels of fosthiazate residues in soil was measured after application of fosthiazate to protected tomato cultivation. The dissipation of fosthiazate residues followed first-order kinetics with a calculated half-life of 21 days.

Matrix Solid-Phase Dispersion Extraction and Liquid Chromatographic Determination of Nicarbazin in Chicken Tissue

1992 ◽  
Vol 75 (4) ◽  
pp. 659-662 ◽  
Author(s):  
Frank J Schenck ◽  
Steven A Barker ◽  
Austin R Long
Keyword(s):  
Solid Phase ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Chicken Liver ◽  
Tissue Samples ◽  
Chicken Tissue ◽  
Cleanup Procedure ◽  
Tissue Matrix ◽  
Liquid Chromatographic

Abstract This method outlines the necessary steps for the isolation and determination of the drug nicarbazin in chicken liver and muscle tissue. Tissue samples were blended with octadecylsilyl-derivatized silica packing material (C18). A column made from the C18-tissue matrix is first washed with hexane, and then the 4,4-dinitrocarbanilide (DNC) portion of the nicarbazin complex is eluted with acetonitrile. After further cleanup using alumina cartridge chromatography, DNC is determined by reversed-phase liquid chromatography with UV detection at 340 nm. Recoveries based on DNC were 95.8 and 83.7% from liver and muscle tissues, respectively. This method and a classical ethyl acetate extraction method gave comparable results on 4 chicken liver and 3 muscle samples that contained incurred nicarbazin residues. C18 sorbents from different manufacturers as well as lipophilic sorbents other than ds were also studied. The proposed extraction and cleanup procedure requires less than 30 mL solvent, fewer sample manipulations, and does not require solvent partitioning or backwashing of extracts. This combination of characteristics makes this method more attractive than classical isolation procedures for nicarbazin.

Liquid Chromatographic Method for Rapid Determination of Total Avermectin B1 and 8,9-Z-Avermectin B1 Residues in Apples

1995 ◽  
Vol 78 (2) ◽  
pp. 419-422 ◽  
Author(s):  
Janice A Cobin ◽  
Nelson A Johnson
Keyword(s):  
Chromatographic Method ◽  
Limit Of Detection ◽  
Solid Phase ◽  
Rapid Determination ◽  
Reversed Phase ◽  
Extraction Column ◽  
Liquid Chromatographic Method ◽  
Limit Of Quantitation ◽  
Liquid Chromatographic

Abstract A liquid chromatographic method has been developed and validated for the rapid determination of avermectin B1 and 8,9-Z-avermectin B1 residues in apples. The avermectins are extracted from the crop matrix with an acetonitrile–water–hexane mixture; the extract is cleaned up on an aminopropyl solid-phase extraction column. The avermectins are derivatized with trifluoroacetic anhydride and analyzed by reversed-phase liquid chromatography with fluorescence detection. Recoveries of avermectins from apples fortified with about 2–77 ppb avermectin B1a or 2-27 ppb 8,9-Z-avermectin B1a averaged 85%. The limit of quantitation is 2 ppb (signal- to-noise [S/N] ratio, 12) and the limit of detection is 1 ppb (S/N ratio, 6) for each analyte. The assay is a simple, rapid, and sensitive method for monitoring the total amount of avermectin residues in apples.

scholarly journals Mixed-Mode Solid-Phase Extraction and Cleanup Procedures for the Liquid Chromatographic Determination of Thiabendazole and Carbendazim in Fruit Juices

2001 ◽  
Vol 84 (2) ◽  
pp. 556-562 ◽  
Author(s):  
Michael S Young ◽  
Dorothy J Phillips ◽  
Pamela C Iraneta ◽  
Jim Krol
Keyword(s):  
Solid Phase Extraction ◽  
Cation Exchange ◽  
Mixed Mode ◽  
Solid Phase ◽  
Chromatographic Determination ◽  
Reversed Phase ◽  
Phase Extraction ◽  
Grape Juices ◽  
Liquid Chromatographic

Abstract Solid-phase extraction (SPE) procedures were developed for rapid cleanup and determination of thiabendazole and carbendazim in orange, apple, and grape juices. Samples were prepared by using an SPE cartridge containing a mixed-mode sorbent with both reversed-phase and strong cation-exchange chemistries. Analysis was by liquid chromatography with photodiode-array UV detection. Orange juice was analyzed by mixed-mode cation-exchange extraction with reversed-phase cleanup; the other juices were analyzed by reversed-phase extraction with cation-exchange cleanup. Recoveries >80% for carbendazim and >90% for thiabendazole. Quantitation limits were 20 μg/L for both analytes.

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