scholarly journals Comparison of thin-layer chromatography, spectrofluorimetry and bright greenish-yellow fluorescence test for aflatoxin detection in corn

2010 ◽  
Vol 53 (3) ◽  
pp. 687-692 ◽  
Author(s):  
Elisabete Yurie Sataque Ono ◽  
Marcelo da Silva ◽  
Ricardo Marcelo Reche Ribeiro ◽  
Mario Augusto Ono ◽  
Luciana Hayashi ◽  
...  
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
False Negative ◽  
Screening Method ◽  
Yellow Fluorescence ◽  
Negative Results ◽  
Greenish Yellow ◽  
False Negative Results ◽  
Fluorescence Test ◽  
Layer Chromatography

In this study the bright greenish-yellow fluorescence test, widely used by the corn milling industry, was compared to the thin-layer chromatography (TLC) and spectrofluorimetry methods for aflatoxin detection in 40 corn samples naturally contaminated by the Aspergillus section Flavi. According to the corn processing industry criteria, all the samples were adequate for human and animal consumption by the bright greenish-yellow fluorescence test, but TLC and spectrofluorimetry analysis detected aflatoxins above the maximum tolerated limit (20 µg/kg) in 7 and 8 samples, respectively. Aflatoxins were detected in 16 (40%) corn samples by TLC, with levels ranging from 4.0 to 54.0 µg/kg (mean 19.97 ± 15.97 µg/kg), and in 25 (62.5%) samples by spectrofluorimetry, with levels ranging from 1.0 to 58.66 µg/kg (mean 17.14 ± 17.81 µg/kg). The results indicated a good correlation (ρ = 0.97) between TLC and spectrofluorimetry for aflatoxin determination in naturally contaminated corn. The bright greenish-yellow fluorescence test was simple and quick, but it showed 20% false-negative results, suggesting its use only as screening method for detecting the suspected lots of grains that should be tested further for aflatoxin by more sensitive methods.

Improved Hydrophobic Grid Membrane Filter Method, Using EF-18 Agar, for Detection of Salmonella in Foods: Collaborative Study

1990 ◽  
Vol 73 (5) ◽  
pp. 734-742
Author(s):  
Phyllis Entis
Keyword(s):  
Membrane Filter ◽  
Collaborative Study ◽  
False Negative ◽  
Screening Method ◽  
Culture Method ◽  
Soy Flour ◽  
Poultry Meat ◽  
Filter Method ◽  
Negative Results ◽  
False Negative Results

Abstract A collaborative study was carried out in 30 laboratories to validate Improvements to the official final action hydrophobic grid membrane filter (HGMF) screening method for Salmonella in foods, 985.42, by comparing the performance of the improved HGMF method against that of the AOAC/BAM conventional culture method. Six products were Included In the collaborative study: milk chocolate, raw deboned poultry meat, black pepper, soy flour, egg yolk powder, and nonfat dry milk. The raw deboned poultry meat was naturally contaminated with Salmonella, and the remaining 5 products were each Inoculated In advance with low levels of Individual Salmonella serotypes. The AOAC/BAM method produced 11 false negative results and the Improved HGMF method produced 18 false negative results. The improved HGMF Salmonella method has been approved Interim official first action for all foods to replace the HGMF official final action method, 985.42.

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.

scholarly journals Factitious Diarrhea Induced by Stimulant Laxatives: Accuracy of Diagnosis by a Clinical Reference Laboratory Using Thin Layer Chromatography

2007 ◽  
Vol 53 (1) ◽  
pp. 85-90 ◽  
Author(s):  
Joseph H Shelton ◽  
Carol A Santa Ana ◽  
Donald R Thompson ◽  
Michael Emmett ◽  
John S Fordtran
Keyword(s):  
United States ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Stool Specimen ◽  
False Negative ◽  
The United States ◽  
Positive Zero ◽  
Reference Laboratory ◽  
Clinical Value ◽  
Layer Chromatography

Abstract Background: Surreptitious ingestion of laxatives can lead to serious factitious diseases that are difficult to diagnose. Most cases involve ingestion of bisacodyl or senna. Thin layer chromatography (TLC) of urine or stool is the only commercially available test for these laxatives. Such testing is considered highly reliable, but its accuracy in clinical practice is unknown. Our aim was to evaluate the reliability of TLC laxative testing by a clinical reference laboratory in the United States. Methods: Diarrhea was induced in healthy volunteers by ingestion of bisacodyl, senna, or a control laxative (n = 11 for each laxative group). Samples of urine and diarrheal stool were sent in blinded fashion to the clinical reference laboratory for bisacodyl and senna analysis. Results: TLC testing for bisacodyl-induced diarrhea revealed a sensitivity of 73% and specificity of 91% when urine was tested and sensitivity and specificity of 91% and 96%, respectively, when stool was analyzed. When diarrhea was induced by senna, the TLC assay for senna failed to identify even a single urine or stool specimen as positive (zero% sensitivity). Conclusions: Considering the expected prevalence of surreptitious laxative abuse in patients with chronic idiopathic diarrhea (2.4%–25%, depending on the clinical setting), TLC of urine or stool for bisacodyl by this reference laboratory would often produce misleading results, and testing for senna would have no clinical value. The major problems are false-positive tests for bisacodyl and false-negative tests for senna.

High efficiency screening of nine lipid-lowering adulterants in herbal dietary supplements using thin layer chromatography coupled with surface enhanced Raman spectroscopy

2017 ◽  
Vol 9 (10) ◽  
pp. 1595-1602 ◽  
Author(s):  
Qingxia Zhu ◽  
Mengyun Chen ◽  
Lu Han ◽  
Yongfang Yuan ◽  
Feng Lu
Keyword(s):  
Raman Spectroscopy ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
High Efficiency ◽  
Screening Method ◽  
Surface Enhanced Raman Spectroscopy ◽  
Lipid Lowering ◽  
Surface Enhanced ◽  
Surface Enhanced Raman ◽  
Layer Chromatography

A high efficiency screening method was developed to analyze lipid-lowering adulterants in complicated HDS systems.

Comparison between VIDAS Automatic Enzyme-Linked Fluorescent Immunoassay and Culture Method for Salmonella Recovery from Pork Carcass Sponge Samples

2002 ◽  
Vol 65 (10) ◽  
pp. 1656-1659 ◽  
Author(s):  
KUANG-SHENG YEH ◽  
CHIN-EN TSAI ◽  
SHIH-PING CHEN ◽  
CHAO-WEI LIAO
Keyword(s):  
False Negative ◽  
Screening Method ◽  
Culture Method ◽  
Automated System ◽  
Rapid Screening ◽  
Assay Method ◽  
Intensive Culture ◽  
Negative Results ◽  
False Negative Results ◽  
Potential Alternative

VIDAS Salmonella (VIDAS-SLM) is an automated system that uses the enzyme-linked fluorescent assay method to detect Salmonella species. This study evaluated the efficacy of the VIDAS-SLM method in detecting Salmonella species in pork carcass sponge samples gathered from 10 slaughter plants in Taiwan. Two hundred fifty-seven pork carcass sponge samples were screened by the VIDAS-SLM method and by the culture method in parallel. While 18 sponge samples were found to test positive by both methods, the VIDAS-SLM method detected four additional positive samples for which the culture method failed to recover Salmonella. The specificity of the VIDAS-SLM method was found to be 0.98, and its sensitivity was 1.0, since no false-negative results occurred. Artificially inoculated Salmonella at concentrations as low as 5.0 × 100 CFU/ml was detected in the heat-inactivated sponge sample in the presence or absence of 5.0 × 104 CFU of Citrobacter freundii per ml. Thus, the VIDAS-SLM method is a rapid screening method and a potential alternative to the time- and labor-intensive culture method.

scholarly journals The Study of Ranitidine Interference With Morphine Detection Test by Thin-Layer Chromatography

2018 ◽  
Vol 6 (1) ◽  
pp. 21-23
Author(s):  
Amir Miri ◽  
Amir Karami ◽  
Fourogh Nadi ◽  
Fatemeh Zeraati
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Drugs Of Abuse ◽  
False Negative ◽  
Urine Samples ◽  
Urine Drug Screen ◽  
Test Results ◽  
Two Samples ◽  
Before And After ◽  
Layer Chromatography

Background: Drug abuse is a global and critical problem. One of the most frequent practices done in order to detect the drugs of abuse is Urine Drug Screen. However, for changing the drug test results, adulterants and urine substitutes are being designed. As the referring people’s background has shown, ranitidine is one of the interfering drugs in morphine detection test. Therefore, in the present study, the interference of ranitidine in morphine detection test will be studied. Methods: Ten healthy volunteers who had not used any kind of drug for 72 hours before the test were recruited into the study. First, 2 doses of ranitidine (150 and 300 mg) were administered to the subjects orally and 100-mL urine samples were collected from them before and after taking ranitidine. The second urine sample was collected at 6-8 am. Ten micrograms morphine was added to both urine samples of each individual. The urine samples were tested using thin-layer chromatography (TLC) technique. The experiment was repeated after 1 week using ranitidine 300 mg. Results: The TLC test was carried out on 40 urine samples. Twenty samples were tested before and, the rest, after ranitidine consumption. The TLC test results were positive before ranitidine consumption but negative for 18 samples and positive for two samples after taking ranitidine. Conclusion: Ranitidine may change the urine morphine screening test results via TLC method and induce a false negative result.

scholarly journals Evaluation of an adenosine 5'-triphosphate assay as a screening method to detect significant bacteriuria

1976 ◽  
Vol 3 (1) ◽  
pp. 42-46
Author(s):  
D N Alexander ◽  
G M Ederer ◽  
J M Matsen
Keyword(s):  
False Negative ◽  
Screening Method ◽  
Culture Method ◽  
Clinical Microbiology Laboratory ◽  
University Of Minnesota ◽  
Atp Assay ◽  
Negative Results ◽  
False Negative Results ◽  
Significant Bacteriuria ◽  
Urine Specimens

The bioluminescent reaction of adenosine 5'-triphosphate (ATP) with luciferin and luciferase has been used in conjunction with a sensitive photometer (Lab-Line's ATP photometer) to detect significant bacteriuria in urine. This rapid method of screening urine specimens for bacteriuria was evaluated by using 348 urine specimens submitted to the clinical microbiology laboratory at the University of Minnesota Hospitals for routine culture using the calibrated loop-streak plate method. There was 89.4% agreement between the culture method and the ATP assay, with 7.0% false positive and 27.0% false negative results from the ATP assay using 10(5) organisms/ml of urine or greater as positive for significant bacteriuria and less than 10(5) organisms/ml as negative for significant bacteriuria.

A Screening Method for Sulfonamides Extracted from Animal Tissues

1975 ◽  
Vol 58 (1) ◽  
pp. 44-47 ◽  
Author(s):  
Wendell F Phillips ◽  
John E Trafton
Keyword(s):  
Quantitative Analysis ◽  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Screening Method ◽  
Qualitative And Quantitative Analysis ◽  
Animal Tissues ◽  
Qualitative And Quantitative ◽  
Poultry Tissues ◽  
Layer Chromatography

Abstract A screening method for the estimation of possible residues of sulfonamides in poultry tissues is described. The method utilizes thin layer chromatography (TLC) to separate Bratton-Marshall positive reactants. In the absence of interference and the identification of 1 sulfonamide by TLC, the colorimctric method is recommended for quantitation. When interferences are present, TLC should be used for both qualitative and quantitative analysis. The screening method has a sensitivity of less than 0.05 ppm and a recovery of greater than 80%.

scholarly journals Development of quantitative HPTLC methods for dolutegravir, lamivudine, and tenofovir disproxil fumarate in a combination pharmaceutical product using a model process published earlier for transfer of minilab TLC screening methods to HPTLC-densitometry

2020 ◽  
Vol 32 (3) ◽  
pp. 199-202
Author(s):  
Y. Gu ◽  
B. Zeng ◽  
J. Sherma
Keyword(s):  
Thin Layer ◽  
Thin Layer Chromatography ◽  
Transfer Process ◽  
Mobile Phase ◽  
Screening Method ◽  
Ammonium Hydroxide ◽  
Standard Addition ◽  
Screening Methods ◽  
Chromatography Method ◽  
Layer Chromatography

High-performance thin-layer chromatography (HPLTC)–densitometry methods are described for the analysis of the anti(retro)virals dolutegravir (D), lamivudine (L), and tenofovir disoproxil fumarate (TDF) in a pharmaceutical tablet product. To the best of our knowledge, no previous quantitative planar chromatography method has been reported in the literature for this combination formulation. The method for L was transferred from a thin-layer chromatography (TLC) screening method published in the Global Pharma Health Fund (GPHF) Minilab Manual designed for identification of counterfeit and substandard drug products using a model process published earlier. D and TDF are not included in the list of drugs for which TLC screening methods are published for the Minilab, but HPTLC–densitometry procedures were developed for them using the transfer process guidelines. L was analyzed simultaneously with TDF on Merck Premium Purity silica gel 60 F plates using the mobile phase ethyl acetate–methanol–acetone–concentrated ammonium hydroxide (30:7:3:1) and densitometric scanning at 254 nm. D was analyzed on a second plate by scanning at 366 nm after chromatography with the chloroform–methanol–formic acid (32:8:2) mobile phase. Data for all three drugs are shown to meet the requirements of the model transfer process for calibration curve r values, assay of tablets relative to their label values, peak purity/peak identity tests, and validation by standard addition analysis of samples spiked at 50%, 100%, and 150% of the label value of active ingredients. A TLC screening method for TDF in the combination product was developed and published online with open access.

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