Rapid Identification of Color Additives, Using the C18 Cartridge: Collaborative Study

1988 ◽  
Vol 71 (3) ◽  
pp. 458-461 ◽  
Author(s):  
Mary L Young
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Collaborative Study ◽  
Rapid Identification ◽  
The Other ◽  
Commercial Products ◽  
Layer Chromatography

Abstract Nine laboratories collaboratively studied a method for the separation and identification of the 7 permitted FD&C color additives (Red Nos. 3 and 40; Blue Nos. 1 and 2; Yellow Nos. 5 and 6; Green No. 3) and the banned FD&C Red No. 2 in foods. The method is based on use of a commercial C18 cartridge and spectrophotometry or thin layer chromatography. Collaborators analyzed 5 commercial products (noodles, candy, carbonated soda, flavored gelatin, and powdered drink) and 2 dye mixtures (one containing FD&C Red Nos. 2,3, and 40; the other containing FD&C Green No. 3 and Red No. 3). All of the colors were identified with little or no difficulty by 8 collaborators. The method has been adopted official first action.

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.

scholarly journals Rapid Identification and Quantitation of Clotrimazole, Miconazole, and Ketokonazole in Pharmaceutical Creams and Ointments by Thin-Layer Chromatography–Densitometry

1996 ◽  
Vol 79 (3) ◽  
pp. 656-660 ◽  
Author(s):  
Utpal Roychowdhury ◽  
Saroj K Das
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Uv Light ◽  
Internal Standard ◽  
Solvent System ◽  
Short Wave ◽  
Rapid Identification ◽  
Pharmaceutical Creams ◽  
Liquid Chromatographic ◽  
Layer Chromatography

Abstract Thin-layer chromatography (TLC)–densitometry was used to separate, identify, and quantitate clotrimazole, miconazole, and ketokonazole (alone or combined with other drugs) in various pharmacopoeial or proprietary creams and ointments. Clotrimazole was extracted from the cream or ointment with ethyl alcohol, and miconazole and ketokonazole were extracted with a mixture of equal volumes of chloroform and isopropyl alcohol. Active ingredients were separated from excipients and other drugs by TLC on a precoated silica gel F254 plate with a solvent system of n-hexane–chloroform–methanol–diethylamine (50 + 40 + 10 + 1, v/v). The 3 azoles were well separated and easily identified in this chromatographic system. The separated azoles were visualized under short-wave UV light and quantitated by scanning densitometry at 220 nm by comparing the integrated areas of samples with those of standard (one azole was used as internal standard for the other). Recoveries from samples spiked with known amounts of azoles were excellent. The method was validated further by comparison with official liquid chromatographic methods.

Analysis of Ochratoxins A and B and Their Esters in Barley, Using Partition and Thin Layer Chromatography. II. Collaborative Study

1973 ◽  
Vol 56 (4) ◽  
pp. 822-826
Author(s):  
Stanley Nesheim
Keyword(s):  
Thin Layer ◽  
Ochratoxin A ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Ethyl Esters ◽  
The Other ◽  
Average Recovery ◽  
Confirmation Test ◽  
Two Samples ◽  
Layer Chromatography

Abstract To test the method of Nesheim et al., 6 samples wert; analyzed in 13 laboratories. The samples encompassed a blank and 5 samples containing one or more ochratoxins in the range 50–200 μg/kg. Two samples were spiked with the 4 ochratoxin standards and 3 were spiked with barley naturally contaminated with ochratoxin A. The confirmation of identity of ochratoxins A and B by preparation of their ethyl ester derivatives was also tested. The average recovery of standard ochratoxin A was 112% at levels of 45 and 90 μg/kg, with a 27.1% coefficient of variation calculated from analysis of variance, one analyst, one replicate. Similar satisfactory results were obtained for the ethyl esters of A and B at a level of 120 μg/kg. The results were unsatisfactory for ochratoxin B and for the esters of A and B at the 60 μg/kg level. The chemical confirmation test was satisfactory for both ochratoxins A and B. The method, including chemical confirmation, has been adopted as official first action as quantitative for ochratoxin A and qualitative for the other toxins.

Specific Programmed Multiple Development–Thin Layer Chromatography of Furazolidone in Chicken, Turkey, Swine, and Bovine Tissues: Collaborative Study

1980 ◽  
Vol 63 (4) ◽  
pp. 720-726 ◽  
Author(s):  
James P Heotis ◽  
James L Mertz ◽  
Ronald J Herrett ◽  
Joseph R Diaz ◽  
Daniel C Van Hart ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Collaborative Study ◽  
Vacuum System ◽  
Specific Method ◽  
Extraction Solvent ◽  
Recovery Response ◽  
The Mean ◽  
Comparison Of The Results ◽  
Layer Chromatography

Abstract A specific method for assay of furazolidone at 2 ppb has been developed using programmed multiple development-thin layer chromatography (PMD-TLC) and the conversion of the drug to a fluorescent species which is quantitated by fluorodensitometry on the TLC plate. The method requires only 5 g tissue, specifies an automatic spotter for PMD-TLC, and is capable of measuring <1 ng of drug when the fluorodensitometer is coupled with a computing integrator. This procedure requires an average of 2 man-hours per sample and can be completed in one day. Six laboratories collaboratively studied the method for assay of furazolidone at the 2, 3, and 6 ppb levels in chicken, turkey, swine, and bovine tissues. Tissues were fortified by each laboratory and then processed through extraction, solvent partition, programmed multiple development-thin layer chromatography, and fluorodensitometry. Results showed satisfactory recoveries and accuracy. A statistical comparison of the results demonstrated that 5 of the 6 laboratories obtained similar results. The higher responses from the sixth laboratory appeared to be due to an exceptional vacuum system and the use of silated flasks. The mean drug recovery response for the tissues spiked at 2 ppb from the 5 laboratories was 2.2324 ng ± 20.2% (SD), which at the 99.7% confidence level gives no overlap with control tissue data. The results can be expected to be repeatable within and among laboratories.

Sugar-meal sources used by female black flies (Diptera: Simuliidae): a four-habitat study

1997 ◽  
Vol 75 (7) ◽  
pp. 1066-1072 ◽  
Author(s):  
Steven G. Burgin ◽  
Fiona F. Hunter
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
The Other ◽  
Black Flies ◽  
Layer Chromatography ◽  
Provincial Park

Adult black flies were sampled by sweep-netting vegetation in four habitats within Algonquin Provincial Park, Ontario: Davies Bog, the airfield, deciduous habitat, and coniferous habitat. Sugars in the crops and midguts of female flies (n = 773) were tested by thin-layer chromatography to determine whether the flies had fed on nectar or homopteran honeydew. Melezitose and stachyose were used as honeydew-indicator sugars. For Simulium venustum, it was found that significantly fewer black flies (19%) from the airfield contained honeydew sugars than black flies from the other three sites (34% from Davies Bog; 36% from deciduous habitat; 25% from coniferous habitat). We argue that black flies will feed on nectar or honeydew according to availability.

scholarly journals 5α-Androstane-3α,17β-Diol Is Formed in Tammar Wallaby Pouch Young Testes by a Pathway Involving 5α-Pregnane-3α,17α-Diol-20-One as a Key Intermediate

Endocrinology ◽  
2003 ◽  
Vol 144 (2) ◽  
pp. 575-580 ◽  
Author(s):  
Jean D. Wilson ◽  
Richard J. Auchus ◽  
Michael W. Leihy ◽  
Oleg L. Guryev ◽  
Ronald W. Estabrook ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Reductase Inhibitor ◽  
Tammar Wallaby ◽  
The Other ◽  
Synthetic Pathway ◽  
D 20 ◽  
17 Hydroxyprogesterone ◽  
Layer Chromatography

The synthetic pathway by which 5α-androstane-3α,17β-diol (5α-adiol) is formed in the testes of tammar wallaby pouch young was investigated by incubating testes from d 20–40 males with various radioactive precursors and analyzing the metabolites by thin-layer chromatography and HPLC. [3H]Progesterone was converted to 17-hydroxyprogesterone, which was converted to 5α-adiol by two pathways: One involves the formation of testosterone and dihydrotestosterone as intermediates, and the other involves formation of 5α-pregnane-3α,17α-diol-20-one (5α-pdiol) and androsterone as intermediates. Formation of 5α-adiol from both [3H]testosterone and [3H]progesterone was blocked by the 5α-reductase inhibitor 4MA. The addition of nonradioactive 5α-pdiol blocked the conversion of [3H]progesterone to 5α-adiol, and [3H]5α-pdiol was efficiently converted to androsterone and 5α-adiol. We conclude that expression of steroid 5α-reductase in the developing wallaby testes allows formation of 5α-reduced androgens by a pathway that does not involve testosterone as an intermediate.

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