Rapid, Low Cost Thin-Layer Chromatographic Screening Method for the Detection of Ochratoxin A in Green Coffee at a Control Level of 10 μg/kg

A low-cost thin-layer chromatographic method has been developed for the presumptive measurement of ochratoxin A (OTA) at 5 μg/kg in green coffee beans. The analytical method consisted of extracting OTA by shaking the beans with a mixture of methanol and aqueous sodium bicarbonate solution, which was then purified by liquid-liquid partition into toluene. OTA was separated by normal-phase two-dimensional thin-layer chromatography and detected by visual estimation of fluorescence intensity under a UV lamp at 365 nm. The chromatography solvents were toluene–methanol–formic acid (8:2:0.03) for the first development and petroleum ether–ethyl acetate–formic acid (8:10:1) for the second dimension development. This method was tested with uncontaminated green coffee bean samples spiked with an OTA standard at four different concentrations (5, 10, 20, and 30 μg/kg). The method is rapid, simple, and very easy to implement in coffee-producing countries. It is highly selective and does not involve the use of chlorinated solvents in the sample extraction step. This inexpensive method has been applied to different types of green coffee samples from various countries (Zimbabwe, Brazil, India, Uganda, Colombia, and Indonesia) and different manufacturers, and no OTA below the detection limit of 5 μg/kg was detected in any samples analyzed.

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/58.2.258 ◽

1975 ◽

Vol 58 (2) ◽

pp. 258-262 ◽

Cited By ~ 2

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.

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

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/60.6.1369 ◽

1977 ◽

Vol 60 (6) ◽

pp. 1369-1371 ◽

Cited By ~ 1

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.

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Immunoaffinity column clean-up and thin layer chromatography for determination of ochratoxin A in green coffee

Food Additives & Contaminants ◽

10.1080/02652030110213717 ◽

2002 ◽

Vol 19 (5) ◽

pp. 447-458 ◽

Cited By ~ 44

Author(s):

E. A. Santos ◽

E. A. Vargas

Keyword(s):

Thin Layer ◽

Thin Layer Chromatography ◽

Ochratoxin A ◽

Green Coffee ◽

Immunoaffinity Column ◽

Layer Chromatography

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Simultaneous Thin Layer Chromatographic Determination of Aflatoxin B1 and Ochratoxin A in Black Olives

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/67.3.611 ◽

1984 ◽

Vol 67 (3) ◽

pp. 611-612

Author(s):

Bernard Le Tutour ◽

Abdelrhafour Tantaoui-Elaraki ◽

Abdelhadi Aboussalim

Keyword(s):

Thin Layer ◽

Simultaneous Determination ◽

Ochratoxin A ◽

Aflatoxin B1 ◽

Lead Acetate ◽

Screening Method ◽

Chromatographic Determination ◽

Aqueous Methanol ◽

Layer Chromatography

Abstract A screening method has been developed for simultaneous determination of aflatoxin B1 and ochratoxin A in black olives. The technique includes extraction of both mycotoxins with aqueous methanol, cleanup using lead acetate, defatting with hexane, partitioning in chloroform, and thin layer chromatography. Detection limits are 5–7 μg aflatoxin B1 and 20 μg ochratoxin A/kg.

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Screening Method for the Detection of Aflatoxin, Ochratoxin, Zearalenone, Penicillic Acid, and Citrinin

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/59.1.125 ◽

1976 ◽

Vol 59 (1) ◽

pp. 125-127 ◽

Cited By ~ 2

Author(s):

David M Wilson ◽

William H Tabor ◽

Mary W Trucksess

Keyword(s):

Phosphoric Acid ◽

Thin Layer ◽

Ochratoxin A ◽

Screening Method ◽

The Other ◽

Official Method ◽

Penicillic Acid ◽

Initial Extraction

Abstract A modification of the official method for ochratoxins and a screening method for zearalenone, aflatoxin, and ochratoxin is described and expanded to include citrinin and penicillic acid. The method uses 0.5N phosphoric acid-chloroform (1+10) in the initial extraction; the extract is divided and eluted from 2 columns to provide a quantitative thin layer chromatographic (TLC) method for aflatoxin and ochratoxin in com and dried beans. Aflatoxin and zearalenone are eluted from one column and ochratoxin, penicillic acid, and citrinin from the other. Ochratoxin A recoveries are low (50%) in peanuts. Zearalenone, penicillic acid, and citrinin were qualitatively recovered from com and beans; zearalenone and penicillic acid were recovered from peanuts but citrinin was not. Several TLC solvents were used to separate interferences.

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Detection of Twelve Mycotoxins in Mixed Animal Feedstuffs, Using a Novel Membrane Cleanup Procedure

Journal of AOAC INTERNATIONAL ◽

10.1093/jaoac/58.6.1178 ◽

1975 ◽

Vol 58 (6) ◽

pp. 1178-1181 ◽

Cited By ~ 1

Author(s):

Basil A Roberts ◽

Deryck S P Patterson

Keyword(s):

Thin Layer ◽

Ochratoxin A ◽

Screening Method ◽

Detection Limits ◽

Basic Method ◽

Cleanup Procedure ◽

Animal Feedstuffs ◽

Mixed Feeds

Abstract A multimycotoxin thin layer chromatographic screening method is described which is applicable to most animal feedstuffs. Interference from nonspecific lipid, pigment, and other components of simple and mixed feeds is reduced to a minimum by using a membrane cleanup step. Aflatoxins B1, B2, G1, and G2, citrinin, diacetoxyscirpenol, ochratoxin A, patulin, penitrem A, sterigmatocystin, T-2 toxin, and zearalenone may be reliably detected. The sensitivity of the method is generally low for mixed feeds but even so aftatoxin B4 can be detected at a level of 3 ppb and ochratoxin A at 80 ppb. While the basic method is less sensitive for sterigmatocystin (330 ppb), patulin (600 ppb), zearalcnone (1000 ppb), and the trichothecenes (1000–4000 ppb), it may be adapted so as to reduce the above detection limits when the presence of these toxins is suspected. Lower levels may be detected in extracts of simple feeds.

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Comparison of UV- and Derivative-Spectrophotometric and HPTLC UVDensitometric Methods for the Determination of Amrinone and Milrinone in Bulk Drugs

Current Pharmaceutical Analysis ◽

10.2174/1573412914666180627141659 ◽

2020 ◽

Vol 16 (3) ◽

pp. 246-253

Author(s):

Marcin Gackowski ◽

Marcin Koba ◽

Stefan Kruszewski

Keyword(s):

Thin Layer ◽

Thin Layer Chromatography ◽

High Performance ◽

Low Cost ◽

Uv Spectra ◽

Derivative Spectrophotometry ◽

Therapeutic Monitoring ◽

Bulk Drug ◽

Layer Chromatography ◽

Standard Solutions

Background: Spectrophotometry and thin layer chromatography have been commonly applied in pharmaceutical analysis for many years due to low cost, simplicity and short time of execution. Moreover, the latest modifications including automation of those methods have made them very effective and easy to perform, therefore, the new UV- and derivative spectrophotometry as well as high performance thin layer chromatography UV-densitometric (HPTLC) methods for the routine estimation of amrinone and milrinone in pharmaceutical formulation have been developed and compared in this work since European Pharmacopoeia 9.0 has yet incorporated in an analytical monograph a method for quantification of those compounds. Methods: For the first method the best conditions for quantification were achieved by measuring the lengths between two extrema (peak-to-peak amplitudes) 252 and 277 nm in UV spectra of standard solutions of amrinone and a signal at 288 nm of the first derivative spectra of standard solutions of milrinone. The linearity between D252-277 signal and concentration of amironone and 1D288 signal of milrinone in the same range of 5.0-25.0 μg ml/ml in DMSO:methanol (1:3 v/v) solutions presents the square correlation coefficient (r2) of 0,9997 and 0.9991, respectively. The second method was founded on HPTLC on silica plates, 1,4-dioxane:hexane (100:1.5) as a mobile phase and densitometric scanning at 252 nm for amrinone and at 271 nm for milrinone. Results: The assays were linear over the concentration range of 0,25-5.0 μg per spot (r2=0,9959) and 0,25-10.0 μg per spot (r2=0,9970) for amrinone and milrinone, respectively. The mean recoveries percentage were 99.81 and 100,34 for amrinone as well as 99,58 and 99.46 for milrinone, obtained with spectrophotometry and HPTLC, respectively. Conclusion: The comparison between two elaborated methods leads to the conclusion that UV and derivative spectrophotometry is more precise and gives better recovery, and that is why it should be applied for routine estimation of amrinone and milrinone in bulk drug, pharmaceutical forms and for therapeutic monitoring of the drug.

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Electrocardiogram lead selection for intelligent screening of patients with systolic heart failure

Scientific Reports ◽

10.1038/s41598-021-81374-6 ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Yu-An Chiou ◽

Jhen-Yang Syu ◽

Sz-Ying Wu ◽

Lian-Yu Lin ◽

Li Tzu Yi ◽

...

Keyword(s):

Heart Failure ◽

Low Cost ◽

Screening Method ◽

Systolic Heart Failure ◽

Rapid Screening ◽

Ecg Signals ◽

Testing Dataset ◽

Lead Selection ◽

Ecg Leads ◽

Intelligent Screening

AbstractElectrocardiogram (ECG)-based intelligent screening for systolic heart failure (HF) is an emerging method that could become a low-cost and rapid screening tool for early diagnosis of the disease before the comprehensive echocardiographic procedure. We collected 12-lead ECG signals from 900 systolic HF patients (ejection fraction, EF < 50%) and 900 individuals with normal EF in the absence of HF symptoms. The 12-lead ECG signals were converted by continuous wavelet transform (CWT) to 2D spectra and classified using a 2D convolutional neural network (CNN). The 2D CWT spectra of 12-lead ECG signals were trained separately in 12 identical 2D-CNN models. The 12-lead classification results of the 2D-CNN model revealed that Lead V6 had the highest accuracy (0.93), sensitivity (0.97), specificity (0.89), and f1 scores (0.94) in the testing dataset. We designed four comprehensive scoring methods to integrate the 12-lead classification results into a key diagnostic index. The highest quality result among these four methods was obtained when Leads V5 and V6 of the 12-lead ECG signals were combined. Our new 12-lead ECG signal–based intelligent screening method using straightforward combination of ECG leads provides a fast and accurate approach for pre-screening for systolic HF.

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