Thin Layer Chromatographic Method for the Detection of Uric Acid: Collaborative Study

1978 ◽  
Vol 61 (4) ◽  
pp. 903-905
Author(s):  
Joel J Thrasher ◽  
Annette Abadie
Keyword(s):  
Uric Acid ◽  
Thin Layer ◽  
Chromatographic Method ◽  
Phosphotungstic Acid ◽  
Collaborative Study ◽  
Lithium Carbonate ◽  
Improved Method ◽  
Color Development ◽  
Collaborative Tests ◽  
Layer Chromatography

Abstract A collaborative study has been completed on an improved method for the detection and confirmation of uric acid from bird and insect excreta. The proposed method involves the lithium carbonate solubilization of the suspect excreta material, followed by butanol-methanol-water-acetic acid thin layer chromatography, and trisodium phosphate-phosphotungstic acid color development. The collaborative tests resulted in 100% detection of uric acid standard at the 50 ng level and 75% detection at the 20–25 ng level. No false positives were reported during tests of compounds similar to uric acid. The proposed method has been adopted official first action; the present official final action method, 44.161, will be retained for screening purposes.

Thin Layer Chromatographic Method for Determination of Deoxynivalenol in Wheat: Collaborative Study

1986 ◽  
Vol 69 (1) ◽  
pp. 37-40 ◽  
Author(s):  
Robert M Eppley ◽  
Mary W Trucksess ◽  
Stanley Nesheim ◽  
Charles W Thorpe ◽  
Albert E Pohland ◽  
...  
Keyword(s):  
Winter Wheat ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Aluminum Chloride ◽  
Chloride Solution ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Sample Extraction ◽  
Layer Chromatography

Abstract A collaborative study of a rapid method for the determination of deoxynivalenol (DON) in winter wheat was successfully completed. The method involves sample extraction with acetonitrile-water (84 + 16), cleanup using a disposable column of charcoal, Celite, and alumina, and detection by thin layer chromatography after spraying with an aluminum chloride solution. Each of the 15 collaborators analyzed 12 samples, 2 of which were naturally contaminated, and 10 to which DON was added, in duplicate, at levels of 0,50,100,300, and 1000 ng/ g. Average recoveries of DON ranged from 78 to 96% with repeatabilities of 30-64% and reproducibilities of 33-87%. The results of the study show that false positives were not a problem and that all of the analysts could detect DON at the 300 ng/g level or higher. The method has been adopted official first action.

Identification of Mammalian Feces by Thin Layer Chromatography of Coprostanol: Collaborative Study

1987 ◽  
Vol 70 (3) ◽  
pp. 499-501
Author(s):  
George P Hoskin
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
False Positives ◽  
False Negatives ◽  
Test Portion ◽  
Portion Sizes ◽  
Layer Chromatography

Abstract Mammalian feces contain coprostanol (5β-cholestan-3/J-ol). In this study, 7 collaborators each tested 45 unknown specimens by a thin layer chromatographic method that uses coprostanol as an indicator of feces. The materials tested were 5 replicates each of 3 test portion sizes (0.5,1.0, and 5.0 mg) of cockroach excreta (negative), and cow and rat feces (both positive). Of 315 specimens tested, 261 (82.9%) were correctly identified; there were 5 false positives, 26 false negatives, and from 1 collaborator, 23 inconclusive results.

Improved Spray Reagent for Thin Layer Chromatographic Method for Detecting Uric Acid: Collaborative Study

1986 ◽  
Vol 69 (3) ◽  
pp. 499-503
Author(s):  
Robert S Ferrera ◽  
Jack L Boese ◽  
Joel J Thrasher
Keyword(s):  
Uric Acid ◽  
Thin Layer ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
False Negative ◽  
False Negative Rate ◽  
Ph Indicator ◽  
Specificity And Sensitivity ◽  
Dilute Aqueous Solution ◽  
Low Levels

Abstract A collaborative study was conducted to validate the substitution of an improved single spray in the official AOAC thin layer chromatographic method for identifying uric acid (UA) from bird and insect excreta. The proposed reagent, which is a dilute aqueous solution of ferric chloride and potassium ferricyanide, requires neither a heating step nor a pH indicator. Its preparation time, specificity, and sensitivity to low levels (5-50 ng) of UA were compared with those of the official sprays. The improved spray took 1/5 as long to prepare as the official sprays. Neither the proposed spray nor the official sprays gave false positive reactions with compounds similar to UA. For bird and insect excreta samples, at the 95% confidence limits, the false negative rate was between 0 and 9.7% for the proposed spray and between 0.7 and 18.7% for the official sprays. Sensitivity results showed that the proportion positive for the proposed spray was significantly higher (P<0.05) than for the official sprays at the 15 ng UA level. The proposed changes have been adopted official first action.

Collaborative Study of a Fluorometric and Thin Layer Chromatographic Determination of Aminacrine and Its Salts in Drug Preparations

1967 ◽  
Vol 50 (3) ◽  
pp. 680-682
Author(s):  
Laura A Roberts
Keyword(s):  
Standard Deviation ◽  
Thin Layer ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Chromatographic Determination ◽  
Assay Method ◽  
The Mean ◽  
Layer Chromatography ◽  
Mean Concentration

Abstract Eight collaborators studied a fluoromelric and thin layer chromatographic method for aminacrine and its salts in powder and cream drug preparations. Recovery of aminacrine.HCI by fluorometer in both preparations averaged 100% for powder and 102% for cream. The mean concentration of aminacrine.HCI found in the powder was 0.108% with a standard deviation of ± 0.001%. The mean concentration of aminacrine found in the cream was 0.191% with a standard deviation of ± 0.003%. Seven of the 8 collaborators successfully used thin layer chromatography to identify the aminacrine in both sample forms supplied. The assay method for aminacrine and its salts in drug preparations is recommended for adoption as official, first action

Collaborative Study of a Chromatographic Method for Determination of Patulin in Apple Juice

1974 ◽  
Vol 57 (3) ◽  
pp. 621-625 ◽  
Author(s):  
Peter M Scott
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Column Chromatography ◽  
Apple Juice ◽  
Chromatographic Method ◽  
Collaborative Study ◽  
Spray Reagent ◽  
Contamination Levels ◽  
Layer Chromatography

Abstract Collaborators in 20 laboratories studied a method for the determination of patulin in apple juice. The collaborators mixed patulin solutions with the apple juice to obtain 9 spiked samples (of which 2 were blanks) and 1 practice sample. After column chromatography of the apple juice extract, patulin was estimated visually by thin layer chromatography, using 3-methyl-2-benzothiazolinone hydrazone.HCl as the spray reagent. Mean recoveries of patulin ranged from 69.8 to 98.3% for 3 contamination levels. The method has been adopted as official first action for the determination of patulin in apple juice.

scholarly journals Determination of 1,3-Benzodioxanes in Piper mullesua by High-Performance Thin-Layer Chromatography

2000 ◽  
Vol 83 (6) ◽  
pp. 1484-1488
Author(s):  
Shaifali Srivastava ◽  
Madan M Gupta ◽  
Ram K Verma ◽  
Sushil Kumar
Keyword(s):  
Liquid Chromatography ◽  
Thin Layer ◽  
High Performance ◽  
Chromatographic Method ◽  
Solvent System ◽  
Chromatographic System ◽  
Color Development ◽  
Layer Chromatography ◽  
Methyl Nonanoate

Abstract A new, simple, precise, and rapid high-performance thin-layer chromatographic method was developed for the determination of 6 benzodioxanes in Piper mullesua extract: 1′,3′-benzodioxole-5′-(2,4,8-triene-isobutyl nonanoate), 1′,3′-benzodioxole-5′-(2,4,12-triene-isobutyl tridecanoate), fargesin, sesamin, asarinin, 1′,3′-benzodioxole-5′-(2,4,8-triene-methyl nonanoate). The ingredients were separated on a precoated Silica Gel 60 F254 plate with a solvent system of toluene–acetone (92 + 8). The 6 benzodioxanes were well separated and easily identified in this chromatographic system. The separated benzodioxanes were visualized by color development with a spray reagent consisting of 1 g vanillin dissolved in 100 mL H2SO4–ethanol (5 + 95, v/v). Quantitation was performed by scanning the spots and comparing the integrated areas of compounds in samples with those of standards. Recoveries from samples spiked with known amounts of the benzodioxanes were excellent. The results were comparable with those estimated by liquid chromatography.

Analysis of Dairy Products for Chlorinated Insecticide Residues by Thin Layer Chromatography

1966 ◽  
Vol 49 (4) ◽  
pp. 795-800
Author(s):  
William A Moats
Keyword(s):  
Aluminum Oxide ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Silica Gel ◽  
Color Development ◽  
Tlc Plates ◽  
One Step ◽  
Rf Values ◽  
Tlc Analysis ◽  
Layer Chromatography

Abstract Butterfat and milk samples were analyzed for chlorinated insecticides by thin layer chromatography (TLC) on aluminum oxide or silica gel plates containing a small amount of silver nitrate. The adsorbent was washed with distilled water before preparing the plates. A one-step cleanup on a partially inactivated Florisil column was performed prior to TLC analysis. For color development, the TLC plates were sprayed lightly with hydrogen peroxide to suppress possible interference from fat and then steamed before exposure to ultraviolet light to accelerate and intensify the color reaction. Rf values for a number of solvent systems on aluminum oxide and silica gel plates are given. With this procedure, 0.05 μg or less of insecticide can be detected in a 0.4 g butterfat sample or the extract from 10 ml milk.

Identification of Acetic, Propionic, and Sorbic Acids in Bakery Products by Thin Layer Chromatography

1971 ◽  
Vol 54 (5) ◽  
pp. 1150-1151
Author(s):  
G H Tjan ◽  
J Th A Jansen
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Chromatographic Method ◽  
Thin Layer Plate ◽  
Alkaline Solutions ◽  
Bakery Products ◽  
Layer Chromatography

Abstract A rapid and sensitive thin layer chromatographic method has been described for detecting acetic, propionic, and sorbic acids in bakery products. Acetic, propionic, and sorbic acids were steam distilled from an acidified mixture of the samples into a solution of NaOH. After concentration of the alkaline solutions, samples were spotted on a thin layer plate; the chromatoplate was developed and the acids were identified by spraying with bromcresol purple.

Analysis of Chloroxuron Technical and Its Formulations: Collaborative Study

1978 ◽  
Vol 61 (6) ◽  
pp. 1499-1503
Author(s):  
Werner Heizler ◽  
Juerg Meier ◽  
Klaus Nowak ◽  
Rolf Suter ◽  
Hans P Bosshardt
Keyword(s):  
Thin Layer ◽  
Alkaline Hydrolysis ◽  
Collaborative Study ◽  
Acid Extraction ◽  
Wettable Powder ◽  
Good Repeatability ◽  
Aoac Method ◽  
Layer Chromatography ◽  
Hydrolysis Of ◽  
Good Agreement

Abstract Chloroxuron technical and its 50% wettable powder were analyzed by 17 participants in a CIPAC collaborative study. The analytical method used involves acid extraction to remove interfering free amines, followed by alkaline hydrolysis of the extraction residue, distillation, and titration of the liberated dimethylamine. Related byproducts which may interfere are determined by semiquantitative thin layer chromatography. Results obtained from 17 government and industrial collaborators showed good repeatability within laboratories. Good agreement was also achieved between laboratories. A reproducibility of about 1.5% was obtained. The method has been adopted as an interim official CIPAC-AOAC method.

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