High Pressure Liquid Chromatography of Zearalenone and Zearalenols in Rat Urine and Liver

1982 ◽  
Vol 65 (1) ◽  
pp. 8-13
Author(s):  
Lynda J James ◽  
Larry G McGirr ◽  
Trevor K Smith
Keyword(s):  
High Pressure ◽  
Methylene Chloride ◽  
Internal Standard ◽  
Free Form ◽  
Chromatographic Technique ◽  
Rat Urine ◽  
Glucuronide Conjugation ◽  
In Series ◽  
Internal Standardization ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic technique with internal standardization has been developed for determining zearalenone and metabolites in rat urine and liver. Following extraction with methylene chloride and solvent partition, samples are cleaned up by applying the extract to a Sephadex LH-20 column and eluting with a mixture of benzene-methanol (85 + 15). Compounds were resolved on 2 Partisil- 10 columns (25 cm × 4.6 mm id) in series with a mobile phase of isooctane-chloroform-methanol (35 + 25 + 3), and detected at 280 nm. The internal standard was 6'αa-acetoxyzearalane. Limits of detection were about 2.0 ng for zearalenone and 5.0 ng for zearalenols (6'-hydroxyzearalane). Zearalenone and zearalenols were excreted mainly in free form with relatively little glucuronide conjugation. Metabolism of zearalenone to free zearalenol was minor compared with formation of bound forms.

High Pressure Liquid Chromatography of Captan in Formulations: Collaborative Study

1980 ◽  
Vol 63 (6) ◽  
pp. 1231-1237
Author(s):  
A Aner Carlstrom ◽  
◽  
M Akerblom Bryant ◽  
G C Allochuku ◽  
J B Audino ◽  
...  
Keyword(s):  
High Pressure ◽  
Methylene Chloride ◽  
Collaborative Study ◽  
Internal Standard ◽  
Peak Height ◽  
Diethyl Phthalate ◽  
Response Factors ◽  
Simple Method ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic

Abstract A simple method for measuring captan was tested by 18 collaborators. Formulations are extracted with methylene chloride which contains diethyl phthalate as an internal standard, and detected at 254 nm after high pressure liquid chromatographic separation in a 25 cm × 4 mm column packed with 10 µm silica gel. After inert materials are removed, the supernate is added directly to the column with methylene chloride as the mobile phase; peak height ratios are used for quantitation. Most pesticides commonly formulated with captan do not interfere. Retention times and UV response factors relative to captan are listed for 34 pesticides formulated with captan. The collaborators made single determinations on 6 samples (3 pairs of duplicates). The coefficients of variation were 0.67% for the technical, 1.16% for the 50% wettable powder, and 1.71% for the 5% dust. Several collaborators were unable to separate carbaryl and diethyl phthalate on a combination dust containing captan, dicofol and carbaryl; therefore, the method has been adopted as official first action only for captan formulations containing no other active ingredients.

High Pressure Liquid Chromatography of Folpet in Formulations: Collaborative Study

1977 ◽  
Vol 60 (5) ◽  
pp. 1157-1163
Author(s):  
A Aner Carlstrom
Keyword(s):  
High Pressure ◽  
Methylene Chloride ◽  
Collaborative Study ◽  
Internal Standard ◽  
Peak Height ◽  
Response Factors ◽  
Coefficients Of Variation ◽  
Liquid Chromatographic Separation ◽  
Liquid Chromatographic ◽  
Gel Formulations

Abstract A simple, rapid method is described for measuring folpet, specifying ultraviolet (UV) detection after high pressure liquid chromatographic separation in a 30 cm by 4 mm column packed with 10 μm diameter silica gel. Formulations are extracted with methylene chloride which contains dibutyl phthalate as an internal standard. After inert materials are precipitated, the supernate is added directly to the column, and the compound is quantitated by peak height ratios. Most pesticides commonly formulated with folpet do not interfere, nor do the related compounds captan and captafol. Retention times and UV response factors relative to folpet are listed for the pesticides most commonly formulated with folpet. Sixteen collaborators made single determinations on 6 samples. The average coefficients of variation were 0.95% for the 2 technical samples, 1.77% for the two 50% wettable powders, and 1.12% for the two 5% dusts. No systematic error was detected. The method has been adopted as official first action.

High Pressure Liquid Chromatographic Determination of N-3-Pyridylmethyl-N′-p-nitrophenylurea in Rodenticides

1977 ◽  
Vol 60 (6) ◽  
pp. 1375-1378
Author(s):  
Carl W Sims ◽  
Richard K Gard
Keyword(s):  
High Pressure ◽  
Methylene Chloride ◽  
Internal Standard ◽  
Chromatographic Determination ◽  
Liquid Chromatograph ◽  
Two Samples ◽  
High Pressure Liquid Chromatograph ◽  
Liquid Chromatographic Determination ◽  
Liquid Chromatographic

Abstract A simple and rapid method is described for determining N′-3-pyridylmethyl-N′-p-nitrophenylurea (RH-787) in Vacor Ratkiller rodenticide. The bait is extracted with acetone, the extract is evaporated to dryness, an internal standard is added, and the solution is injected into a high pressure liquid chromatograph. The sample is analyzed by normal phase chromatography on a Partisil 10 column with a mobile phase of methanol-methylene chloride (10+90). An 8 μl injection containing 4 μg pyridine internal standard and 8 μg RH-787 produces half-scale peaks at 254 nm with a full scale absorbance of 0.5 absorbance unit. In an alternative procedure, the active ingredient is extracted from the bait with acetone and titrated to a methyl red end point with 0.1N perchloric acid dissolved in acetic acid. Two samples of Vacor Ratkiller and a spiked blank were analyzed by both procedures.

Isomer Specific Assay of Ester and Salt Formulations of 2,4-Dichlorophenoxyacetic Acid by High Pressure Liquid Chromatography: Collaborative Study

1978 ◽  
Vol 61 (5) ◽  
pp. 1163-1165 ◽  
Author(s):  
Timothy S Stevens ◽  
Norman E Skelly ◽  
Robert B Grorud
Keyword(s):  
High Pressure ◽  
Collaborative Study ◽  
Internal Standard ◽  
Dichlorophenoxyacetic Acid ◽  
High Pressure Liquid Chromatographic ◽  
Coefficients Of Variation ◽  
Standard Solution ◽  
2,4 Dichlorophenoxyacetic Acid ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic (HPLC) assay of ester and salt formulations of 2,4-D has been collaboratively studied. The method is specific for 2,4-D isomer and resolves all known impurities from 2,4-D and the internal standard p-bromophenol. In situ saponification, at room temperature, is performed by adding a combined saponification-internal standard solution to ester products. The same saponification- internal standard solution is added to amine salts and the analytical standard. The injected aqueous potassium salt solution of 2,4-D is then converted to the acid form by an acidic buffered mobile solvent of 20% acetonitrile in water. Optimum chromatography is attained by a mobile solvent pH of 2.95 in a reverse phase microparticulate column, by ion suppression. Each of the 9 collaborators received 3 different ester and 2 different amine formulations of 2,4-D. The coefficients of variation of 2,4-D acid equivalent ranged from 1.22 to 1.59%. The method has been adopted as official first action.

High Pressure Liquid Chromatography of Ester and Salt Formulations of 2-Methyl-4-Chlorophenoxyacetic Acid

1979 ◽  
Vol 62 (4) ◽  
pp. 738-741
Author(s):  
Timothy Stevens ◽  
Robert B Grorud
Keyword(s):  
High Pressure ◽  
Liquid Chromatography ◽  
Collaborative Study ◽  
Internal Standard ◽  
Hplc Method ◽  
Hplc Assay ◽  
High Pressure Liquid Chromatographic ◽  
Chlorophenoxyacetic Acid ◽  
Liquid Chromatographic ◽  
Selection Of

Abstract A high pressure liquid chromatographic (HPLC) assay of amine salt and ester formulations of MCPA has been collaboratively studied. The AOAC 2,4-D HPLC method has been modified for application to MCPA products. The MCPA methodology is identical to that of 2,4-D except in strength of mobile solvent, pH of mobile solvent, heating of ester formulations to 50°C to ensure complete saponification, and the use of glass microfiber filters. The method is specific and separates all known impurities. Examination of chromatograms and percentage results from 8 collaborators indicate that selection of a practical internal standard would improve precision in the procedure and a second collaborative study is recommended.

Application of Gel Permeation Chromatography and Nonaqueous Reverse Phase Chromatography to High Pressure Liquid Chromatographic Determination of Retinyl Palmitate in Fortified Breakfast Cereals

1980 ◽  
Vol 63 (1) ◽  
pp. 131-136 ◽  
Author(s):  
William O Landen
Keyword(s):  
High Pressure ◽  
Vitamin A ◽  
Methylene Chloride ◽  
Colorimetric Method ◽  
Gel Permeation Chromatography ◽  
Retinyl Palmitate ◽  
Reverse Phase ◽  
High Pressure Liquid Chromatographic ◽  
Gel Permeation ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic (HPLC) method was developed for determining retinyl palmitate in cereals. Retinyl palmitate is fractionated from other methylene chloride-soluble components by using high pressure gel permeation chromatography (HP-GPC) followed by quantitation with nonaqueous reverse phase HPLC (RPHPLC). HP-GPC fractionation was accomplished using 2 µStyragel (100Å) columns connected in series on sample extracts in methylene chloride with methylene chloride as the mobile phase. A valve designed to facilitate the collection of the vitamin A fraction was installed in-line between the refractive index and absorbance detectors. RPHPLC quantitation was achieved on µBondapak C18 (10 µm) using methylene chloride–acetonitrile (30+70). Based on 23 repetitive analyses, recovery of vitamin A as retinyl palmitate in cereal products was 95.4±4.2% with spiking levels between 21.4 and 140 µg/g. Vitamin A in 15 cereals, representing bran, corn, oats, rice, and wheat, ranged from 34 to 194% of the declared level. The HPLC procedure was compared with the AOAC official colorimetric method and with an ultraviolet spectrophotometric method.

High Pressure Liquid Chromatographic Determination of Melengestrol Acetate in Dry Feed Supplements

1981 ◽  
Vol 64 (3) ◽  
pp. 661-664
Author(s):  
Jose E Roybal
Keyword(s):  
High Pressure ◽  
Standard Deviation ◽  
Methylene Chloride ◽  
Animal Feed ◽  
Confirmatory Test ◽  
High Pressure Liquid Chromatographic ◽  
Melengestrol Acetate ◽  
Feed Supplements ◽  
Liquid Chromatographic

Abstract A high pressure liquid chromatographic (HPLC) method is described for the quantitative determination of melengestrol acetate (MGA) in dry animal feed supplements containing 0.000027-0.000220% MGA (0.125-1.00 mg/lb). Ground feed is Soxhletextracted with hexane, and the extract is partitioned from hexane into aqueous methanol and then into methylene chloride, followed by mixed column chromatography. MGA is then quantitated by HPLC. Average recovery of standard MGA through the method at 1.00 ppm (0.454 mg/lb).was 94.8% with a 3.58% standard deviation. Average spike recovery of MGA in fortified feed at 0.100 ppm (0.0454 mg/lb) to 2.00 ppm (0.907 mg/lb) level was 97.8% with a standard deviation of 5.39%. In addition, the method includes a 2-dimensional thin layer chromatographic confirmatory test for MGA.

Liquid-chromatographic measurement of endogenous and exogenous glucocorticoids in plasma.

1979 ◽  
Vol 25 (11) ◽  
pp. 1944-1947 ◽  
Author(s):  
F J Frey ◽  
B M Frey ◽  
L Z Benet
Keyword(s):  
Therapeutic Response ◽  
Methylene Chloride ◽  
Internal Standard ◽  
Peak Height ◽  
Specific Method ◽  
Silica Column ◽  
Acid And Base ◽  
Chromatographic Measurement ◽  
Liquid Chromatographic ◽  
Lower Limits

Abstract The therapeutic response to and side effects of glucocorticoids will be better recognized and the recovery of the adrenals during the tapering of therapy with steroids better evaluated if endogenous and exogenous glucocorticoids are separately assessed. We describe a specific method for simultaneously measuring the concentrations of cortisone, cortisol, prednisone, and prednisolone in plasma by "high-pressure" liquid chromatography. The steroids, together with an internal standard, dexamethasone, are extracted from 1 mL of plasma with methylene chloride-ether, washed with acid and base, and separated isocratically on a normal-phase silica column with a mobile phase consisting of methylene chloride/tetrahydrofuran/methanol/glacial acetic acid (96.85/1/2.1/0.05 by vol) at a flow rate of 1.3 mL/min. The steroids are detected at 254 nm and quantitated by peak-height measurements; their retention times range from 6 to 20 min. The lower limits for routine detection of all four compounds is 10 microgram/L. The analytical recoveries are about 75%; the intra-day variability (CV) is 1 to 9%, and the inter-day variability 2 to 11%. Of 26 drugs and 20 steroids tested, only theophylline presents an interference problem.

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