scholarly journals Determination of Tilmicosin in Swine Feeds by Liquid Chromatography

1997 ◽  
Vol 80 (6) ◽  
pp. 1161-1170 ◽  
Author(s):  
Robin S Readnour ◽  
Susan L Helton-Groce ◽  
Sharon S Dixon
Keyword(s):  
Liquid Chromatography ◽  
Average Recovery ◽  
Coefficients Of Variation ◽  
Water Ph ◽  
Swine Feed ◽  
Run Time ◽  
Medicated Feeds ◽  
Millipore Water

Abstract This method determines tilmicosin in feeds over a concentration range of 100 to 600 mg/kg. Tilmicosin is extracted from swine feeds by adding 200 mL of a swine feed extractant (20 + 80, acetonitrile–Millipore water, pH 2.5, with 25 mM dibutylammonium phosphate) to 20 g feed and placing on a shaker table for 1 h. This extractant is filtered and analyzed by liquid chromatography (LC). A gradient LC method is used to separate ilmicosin from the feed matrix in 30 min of run time. The recovery of tilmicosin from fortified feeds ranged from 96.7 to 112%, with the coefficients of variation (CVs) ranging from 1.4 to 3.9%. The determination of tilmicosin in medicated feeds resulted in an average recovery of 92.7% of labeled claim for pelleted feeds at 200 mg/kg and 99.1% of labeled claim for mash feeds at 400 mg/kg. Determination of tilmicosin in medicated feeds resulted in CVs ranging from 2.6 to 3.8%. The method has shown no interference with 18 other drugs.

Quantitative Determination of Sorbic Acid in Cheddar Cheese by Gas-Liquid Chromatography

1971 ◽  
Vol 54 (2) ◽  
pp. 361-363
Author(s):  
D E LaCroix ◽  
N P Wong
Keyword(s):  
Liquid Chromatography ◽  
Ethylene Glycol ◽  
Quantitative Determination ◽  
Sorbic Acid ◽  
Cheddar Cheese ◽  
Gas Liquid Chromatography ◽  
Glycol Adipate ◽  
Average Recovery ◽  
Ethylene Glycol Adipate

Abstract A rapid method is described for the extraction and quantitative determination of sorbic acid in Cheddar cheese. Cheddar cheese is impregnated onto a Celite 545 column, extracted with acetonitrile, and analyzed for sorbic acid by gas-liquid chromatography, using a 7.5% ethylene glycol adipate + 2% H3PO4 column. Average recovery values for known amounts of sorbic acid were 107%.

Determination of Dephosphate Bromofenofos in Milk by Liquid Chromatography with Electrochemical Detection

1994 ◽  
Vol 77 (4) ◽  
pp. 904-908 ◽  
Author(s):  
Kazue Takeba ◽  
Takeshi Itoh ◽  
Masao Matsumoto ◽  
Hiroyuki Nakazawa
Keyword(s):  
Liquid Chromatography ◽  
Electrochemical Detection ◽  
Potassium Dihydrogen Phosphate ◽  
Reversed Phase ◽  
Gas Chromatography Mass Spectrometry ◽  
Dihydrogen Phosphate ◽  
Specific Method ◽  
Coefficients Of Variation ◽  
The Matrix

Abstract A sensitive, specific method for the determination of dephosphate bromofenofos (DBFF) in milk by liquid chromatography (LC) with electrochemical detection is described. DBFF, the only metabolite of bromofenofos (BFF, a fasciolicide), was extracted from milk by liquid–liquid partition with acetone, acetonitrile, and dichloromethane and purified by using a C18 cartridge. The compound was separated from the matrix peaks by reversed-phase LC and detected by dual-electrode coulometric detection on a Kaseisorb LC ODS-300-5 (250 × 4.6 mm id, 5 μm) column. The mobile phase was acetonitrile–0.05M potassium dihydrogen phosphate (55 + 45, v/v) at pH 3.0. The flow rate was 1 mL/min at 40°C. The applied potentials of detectors 1 and 2 were maintained at 0.30 and 0.45 V, respectively. Average recoveries (n = 5) of DBFF from milk spiked at 1 and 10 ng/mL were 73.1 and 82.7%, respectively; and coefficients of variation were 8.4 and 2.8%, respectively. The detection limit of DBFF in milk was 0.2 ng/mL. Fifty-nine raw and 181 commercial milks were analyzed. DBFF was detected in 4 raw milks (0.2–1.5 ng/mL; average, 0.6 ng/mL) and in 3 normal liquid commercial milks (0.3–0.7 ng/mL; average, 0.5 ng/mL). The identity of DBFF from milk was confirmed by gas chromatography/mass spectrometry.

Determination of nifedipine in serum or plasma by reversed-phase liquid chromatography.

1983 ◽  
Vol 29 (7) ◽  
pp. 1344-1348 ◽  
Author(s):  
P R Bach
Keyword(s):  
Liquid Chromatography ◽  
Reversed Phase ◽  
Extraction Column ◽  
Phase Extraction ◽  
Reversed Phase Liquid Chromatography ◽  
Ultraviolet Absorbance ◽  
Standard Curve ◽  
Coefficients Of Variation ◽  
Phase Liquid

Abstract Therapeutic concentrations of nifedipine in serum or plasma were measured by reversed-phase liquid chromatography, with detection by ultraviolet absorbance at 235 nm. In the procedure a disposable reversed-phase extraction column is used. A 1-mL sample is required. The method is sensitive to 3 micrograms of nifedipine per liter and the standard curve is linear to at least 400 micrograms/L. Coefficients of variation at 100 micrograms/L were 2.2% within-run, 2.8% between-run. The method has been used to determine nifedipine in patients involved in a test of its efficacy in treating muscular dystrophy.

Gas-Liquid Chromatographic Determination of Choline in Low and High Potency Multiple Vitamin Tablets and Liver Preparations

1974 ◽  
Vol 57 (2) ◽  
pp. 341-342
Author(s):  
Caesar B Garavelli
Keyword(s):  
Liquid Chromatography ◽  
Quantitative Determination ◽  
Chromatographic Determination ◽  
Gas Liquid Chromatography ◽  
High Potency ◽  
Average Recovery ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A procedure is described for the quantitative determination of 0.020—6.0 mg choline in low and high potency reference multiple vitamin tablets and standard liver preparations. The trimethylamine quantitatively produced in a sealed tube by treatment with aqueous 5 0% alkali is simultaneously extracted with 0.200—0.500 ml of an isobutanol-ethanol (1+1) mixture and determined by gas-liquid chromatography. An average recovery of 100 ± 3 % was obtained.

Determination of Methyl 2-Benzimidazolecarbamate in Wine by Competitive Inhibition Enzyme Immunoassay

1993 ◽  
Vol 76 (4) ◽  
pp. 851-856 ◽  
Author(s):  
Rodney J Bushway ◽  
Lance R Paradis ◽  
Lewis B Perkins ◽  
Titan S Fan ◽  
Barbara E S Young ◽  
...  
Keyword(s):  
Enzyme Immunoassay ◽  
Competitive Inhibition ◽  
White Wines ◽  
Average Recovery ◽  
Total Analysis Time ◽  
Coefficients Of Variation ◽  
Limit Of Quantitation ◽  
Total Analysis ◽  
Commercial Kit

Abstract A benomyl polyclonal enzyme immunoassay (EIA) commercial kit was used to quantitate methyl 2- benzimidazolecarbamate (MBC), a degradation product of benomyl in wine. Total analysis time, including sample preparation, was 30 min. As many as 8 samples can be analyzed simultaneously with a limit of quantitation of 5 ppb. The assay logarithmic response was linear from 0.4 to 26 ppb MBC. Intra-assay percent coefficients of variation (%CVs) ranged from 2.4 to 13 for standards and from 7.4 to 21 for actual wine samples. Interassay %CVs varied from 2.6 to 15 for the standards and from 6.9 to 23 for the samples. Average recovery from samples spiked at 10–10 000 ppb was 93% for evaporated red and white wines. MBC was determined in 134 different wines by immunoassay and liquid chromatography (LC). Of these samples, 98 were positive for MBC by both methods with a correlation coefficient (r) of 0.986. The other 36 samples had MBC levels that either were not detectable by either procedure or were below the 10 ppb limit of quantitation for LC. Concentrations of MBC in wine ranged from 5 to 1329 ppb, with the majority ranging from 10 to 300 ppb. Also, a mini-study was conducted using the plate EIA format.

Determination of iV-Methylcarbamate Pesticides in Liver by Liquid Chromatography

1989 ◽  
Vol 72 (4) ◽  
pp. 586-592 ◽  
Author(s):  
Sher M Ali
Keyword(s):  
Liquid Chromatography ◽  
Simultaneous Determination ◽  
Fluorescence Detection ◽  
Methylene Chloride ◽  
Gel Permeation Chromatography ◽  
Purification Technique ◽  
Coefficients Of Variation ◽  
Gel Permeation ◽  
Liquid Chromatographic

Abstract A liquid chromatographic (LC) method using a 2-step purification technique for the simultaneous determination of 10 carbamates in bovine, swine, and duck livers has been developed. Carbamates are extracted from liver samples with methylene chloride. After evaporation, the residues from the extract are dissolved in methylene chloride- cyclohexane (1 + 1) and cleaned up by gel permeation chromatography. The eluate containing carbamate residues is evaporated to dryness, reconstituted in methylene chloride, further purified by passing it through an aminopropyl Bond Elut extraction cartridge, and analyzed by liquid chromatography using post-column derivatization with orthophthalaldehyde and fluorescence detection. Excitation and emission are set at 340 and 418 nm, respectively. Liver samples for beef, pork, and duck were fortified with 5, 10, and 20 ppb of mixed carbamate standards. The average of 10 recoveries of 10 carbamates at all 3 levels of fortification was greater than 80% with coefficients of variation less than 17%.

scholarly journals Liquid Chromatographic Determination of Ivermectin in Feed

1998 ◽  
Vol 81 (4) ◽  
pp. 869-872 ◽  
Author(s):  
Stephen J Doherty ◽  
Allen Fox ◽  
David W Fink
Keyword(s):  
Solid Phase ◽  
Chromatographic Determination ◽  
Phase Extraction ◽  
Coefficients Of Variation ◽  
Significant Difference ◽  
Liquid Chromatographic Determination ◽  
Chromatographic Measurement ◽  
Liquid Chromatographic ◽  
Medicated Feeds

Abstract An analytical method for determining ivermectin in feed at 0.50- 3 ppm is presented. The method is based on liquid chromatographic measurement after sample preparation by adsorption chromatography on alumina and solid-phase extraction. Two complete, final, finished medicated feeds and the corresponding control feeds used in their preparation were analyzed. Recoveries from feeds fortified at 50-150% of the 2 ppm ivermectin use concentration also were determined. Mean recoveries from replicate analyses ranged from 90 to 100%, and coefficients of variation (CVs) were less than 4.5%. No significant interferences were found in control feeds. The pooled distribution of individual analytical results (n = 100) gave a mean recovery of 100%, a recovery range of 90-111%, and an overall CV of 5.5%. Resolution of the total variance into its 2 components gave a withinlaboratory CV of 4.1% and a between-laboratory CV of 3.4%. There was no significant difference in recoveries among laboratories, days, concentrations, and feed base or between fortified and medicated feeds (P > 0.2)

Collaborative Study of Three Methods for the Determination of Fluoride in Vegetation

1978 ◽  
Vol 61 (1) ◽  
pp. 150-153
Author(s):  
Jay S Jacobson ◽  
Laurence I Heller
Keyword(s):  
Mass Spectrometry ◽  
Liquid Chromatography ◽  
Polychlorinated Biphenyls ◽  
Collaborative Study ◽  
Bald Eagle ◽  
Gas Liquid Chromatography ◽  
Tissue Samples ◽  
Florisil Column ◽  
Average Recovery

Abstract A procedure is described for determining Kepone (decachlorooctahydro-l,3,4-metheno-2ffcyclobuta[ cd]pentalene-2-one) residues in avian egg, liver, and tissue. Samples were extracted with benzene-isopropanol, and the extract was cleaned up with fuming H2S04-concentrated H2SO4. Kepone was separated from organochlorine pesticides and polychlorinated biphenyls on a Florisil column and analyzed by electron capture gas-liquid chromatography (GLC). The average recovery from spiked tissues was 86%. The analyses performed on 14 bald eagle carcasses and livers, 3 bald eagle eggs, and 14 osprey eggs show measurable levels which indicate that Kepone accumulates in the tissues of fish-eating birds. Residues were confirmed by GLC-mass spectrometry

Determination of Deoxynivalenol in Wheat-Based Breakfast Cereals Marketed in Portugal

2001 ◽  
Vol 64 (11) ◽  
pp. 1848-1850 ◽  
Author(s):  
MARIA LÍGIA MARTINS ◽  
H. MARINA MARTINS
Keyword(s):  
Liquid Chromatography ◽  
Detection Limit ◽  
Natural Occurrence ◽  
Fungal Metabolites ◽  
Immunoaffinity Column ◽  
Breakfast Cereals ◽  
Average Recovery ◽  
Genus Fusarium ◽  
Natural Contamination

Deoxynivalenol (DON), also known as vomitoxin, is one of a group of closely related secondary fungal metabolites—the trichothecenes—and is produced predominantly by several species of the genus Fusarium, especially Fusarium graminearum. The present study was carried out to evaluate the natural occurrence of DON in different kinds of wheat-based breakfast cereals widely consumed by the population. A total of 88 commercially available samples of wheat-based breakfast cereals were randomly collected from different supermarkets in Lisbon, Portugal. The samples were analyzed using immunoaffinity column, and DON was quantified by liquid chromatography. Detection limit was 100 μg/kg. Average recovery of DON was 80%. Of 88 analyzed samples, 72.8% contained levels of DON between 103 and 6,040 μg/kg, with mean level of 754 μg/kg, and 24 samples (27.2%) were not contaminated (<100 μg/kg). These results indicate an incidence of this mycotoxin in these products, and the authors suggest a monitoring for the prevention of molds and mycotoxins. This is the first report in Portugal on natural contamination with DON in wheat-based breakfast cereals.

A Simple Procedure for the Determination of Carbamazepine in Plasma by High Pressure-Liquid Chromatography

1979 ◽  
Vol 16 (1-6) ◽  
pp. 213-216 ◽  
Author(s):  
C. K. Johnston ◽  
G. H. Lester
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
High Pressure Liquid Chromatography ◽  
Mobile Phase ◽  
Simple Procedure ◽  
Internal Standard ◽  
Reverse Phase ◽  
Coefficients Of Variation ◽  
Initial Results

We describe a simple, rapid procedure for the estimation of carbamazepine in plasma. Protein is precipitated, and extraction is achieved by the addition of acetonitrile containing the internal standard N-acetyltryptophan ethyl ester. Separation is by reverse-phase high-pressure liquid chromatography with an acetonitrile: water mobile phase, and detection is by UV absorption at 280 nm. Total retention time is less than 7 minutes. Initial results gave within-batch and between-batch coefficients of variation of less than 2 %, and mean recovery of 97 %. The method is free from interference by other common anticonvulsant drugs.

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