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.

Collaborative Study of a Method for the Determination of Ochratoxin A in Green Coffee

1975 ◽  
Vol 58 (2) ◽  
pp. 258-262 ◽  
Author(s):  
Colette P Levi
Keyword(s):  
Thin Layer ◽  
Ochratoxin A ◽  
Collaborative Study ◽  
Green Coffee ◽  
Average Recovery ◽  
Semiquantitative Determination ◽  
Chromatographic Methods ◽  
Green Coffee Beans ◽  
Coffee Beans

Abstract A method for the semiquantitative determination of ochratoxin A in green coffee has been studied collaboratively by 11 laboratories. The average recovery for the 7 samples spiked at 3 levels of ochratoxin A was 69.1%, ranging from 60.5 to 85.6%. This is comparable to other visual thin layer chromatographic methods of mycotoxin detection. The method has been adopted as official first action for the determination of ochratoxin A in green coffee beans.

Quantitative Fluorodensitometric Determination and Survey of Aflatoxins in Nutmeg

1975 ◽  
Vol 58 (2) ◽  
pp. 263-271
Author(s):  
Paul E Beljaars ◽  
Jan C H M Schumans ◽  
Paul J Koken
Keyword(s):  
Thin Layer ◽  
Coefficient Of Variation ◽  
Analytical Procedure ◽  
Confirmatory Test ◽  
Average Recovery ◽  
Different Types ◽  
Tlc Plates ◽  
Aoac Official ◽  
Layer Chromatography ◽  
Flying Spot

Abstract A study is presented for the quantitative fluorodensitometric analysis of aflatoxins in spices, in particular nutmeg (Semen myristicae). Samples were extracted with chloroform, followed by silica gel column cleanup according to the AOAC official first action method, 26.019(a), and by 2-dimensional thin layer chromatography according to the antidiagonal technique. The method includes a confirmatory test for aflatoxins by hemiacetal formation. The concentrations of aflatoxins in samples were determined by measurement of the fluorescent intensities of the separated aflatoxin spots from sample and standards on the same chromatoplate with a reflectance flying-spot densitometer. With such a technique, a coefficient of variation value of 5.22±1.24% (P < 99%) was calculated for a series of 5 standard B, spots and averaged for 13 TLC plates, demonstrating the precision of the chromatographic and densitometric procedures. An average recovery of 108.4±5.8% (P < 95%) was obtained for 11 spiked nutmeg extracts (5.0–20.0 μg B1 added/kg), whereas an average recovery of 92.6±4.9 (P < 95%) was established for 13 spiked nutmeg samples (5.0–20.0 μg B1 added/kg). The coefficient of variation of the complete analytical procedure for ground nutmeg was 8.80%. In a survey on the occurrence of aflatoxins in 40 commercial nutmeg samples (covering 12 different brands) in The Netherlands, aflatoxins were detected in 30 ground samples (32 ground samples analyzed) in concentrations ranging from 1.0 to 23.2 μg B1/kg or from 2.7 to 36.5 μg B1 + B2 + G1 + G2/kg, whereas no aflatoxins were present in whole nutmeg kernels (8 samples analyzed). The lowest level of detection was 1.0 μB1/kg. In addition, 50 commercial spices consisting of 19 different types of commodities other than nutmeg were assayed for aflatoxins according to the same procedure. No aflatoxins were detected in these samples, with the exception of 1 sample of bay leaf which contained 5.1 μg B1/kg.

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.

Screening Method for the Detection of Aflatoxins, Ochratoxin, Patulin, Sterigmatocystin, and Zearalenone in Cereals

1977 ◽  
Vol 60 (6) ◽  
pp. 1369-1371 ◽  
Author(s):  
B G Egon Josefsson ◽  
Tord E Möller
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Ochratoxin A ◽  
Screening Method ◽  
Gel Filtration ◽  
Limits Of Detection ◽  
Layer Chromatography

Abstract A screening method has been developed for the detection of aflatoxins, ochratoxin A, patulin, sterigmatocystin, and zearalenone in cereals. After extraction, the sample is cleaned up by gel filtration. The mycotoxins are separated by thin layer chromatography. The limits of detection are about 5 μg aflatoxins, 10 ochratoxin A, 50 μg patulin, 10 μg sterigmatocystin, and 35 μg zearalenone/kg.

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.

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.

Gas Chromatographic Methods for Determination of γ-BHC in Technical Emulsifiable Concentrates and Water-Dispersible Powder Formulations and in Lindane Shampoo and Lotion: Collaborative Study

1984 ◽  
Vol 67 (4) ◽  
pp. 834-837
Author(s):  
James W Miles ◽  
Dwight L Mount ◽  
◽  
T J Beckmann ◽  
S K Carrigan ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Internal Standard ◽  
The Other ◽  
Water Dispersible ◽  
Coefficients Of Variation ◽  
Aoac Method ◽  
Liquid Chromatographic ◽  
Gas Chromatographic Separation

Abstract Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.

Selection of a Simple and Sensitive Method for Detecting Zearalenone in Corn

1994 ◽  
Vol 77 (4) ◽  
pp. 939-941 ◽  
Author(s):  
Nora M Quiroga ◽  
Inés Sola ◽  
Edith Varsavsky
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Lead Acetate ◽  
Limit Of Detection ◽  
Acetate Solution ◽  
Average Recovery ◽  
Lead Acetate Solution ◽  
Layer Chromatography ◽  
Selection Of ◽  
Sensitive Method

Abstract A simple, rapid, and sensitive method for determining zearalenone in corn was selected. The toxin was extracted from 50 g test portions with 180 mL acetonitrile and 20 mL 4% KCl solution. A portion of the extract was defatted with isooctane. The acetonitrile extract was cleaned up with 20% lead acetate solution. The zearalenone was partitioned into toluene. The toluene solution was dried, and the residue was redissolved in benzene. The toxin was determined by thin-layer chromatography with silica gel plates and chloroform–acetone (9 +1) as the developing solvent. The overall average recovery of zearalenone from corn was 97%. The limit of detection was 50 μg/kg; this limit may be lowered by using fast violet B salt as spray reagent. The method was compared with 2 previous methods that determine zearalenone in biologically contaminated corn.

Determination of Zearalenone in Corn: Collaborative Study

1976 ◽  
Vol 59 (3) ◽  
pp. 666-670
Author(s):  
Odette L Shotwell ◽  
Marion L Goulden ◽  
Glenn A Bennett
Keyword(s):  
Statistical Analysis ◽  
Thin Layer ◽  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Corn Sample ◽  
Yellow Corn ◽  
Coefficients Of Variation ◽  
The Mean

Abstract Corn samples spiked at levels of 100, 300, 1000, and 2000 μg zearalenone/kg were sent to 22 collaborators for analysis by the Eppley method. All samples were yellow corn except one white corn sample spiked at 2000 μg/kg. Results from 16 collaborators were statistically analyzed. Only 4 of 16 collaborators detected zearalenone in the sample containing 100 μg/kg, but 11 detected the toxin in the sample containing 300 μg/kg. Average recoveries from all samples were 129% at 300 μg/kg, 101% at 1000 μg/kg, and 88% at 2000 μg/kg. The between-laboratory coefficients of variation were 53.0% at 300 μg/kg, 38.2% at 1000 μg/kg, and 27.0% at 2000 μg/kg. Five naturally contaminated corn samples, one in triplicate, were also provided. The mean level of zearalenone in the naturally contaminated samples ranged from 431 to 7622 μg/kg. The mean coefficient of variation for all samples was 40.5%. Two collaborators measured quantities of zearalenone on thin layer chromatographic plates densitometrically. Their results were not included in the statistical analysis, but the results indicated that densitometric measurement, given proper dilutions of solutions, could be used. The method has been adopted as official first action.

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