A normal phase HPTLC method for the quantitative determination of ochratoxin A in rice

Analytical methods for determination of mycotoxins: a review

Mycotoxins are small (MW approximately 700), toxic chemical products formed as secondary metabolites by a few fungal species that readily colonise crops and contaminate them with toxins in the field or after harvest. Ochratoxins and Aflatoxins are mycotoxins of major significance and hence there has been significant research on broad range of analytical and detection techniques that could be useful and practical. Due to the variety of structures of these toxins, it is impossible to use one standard technique for analysis and/or detection. Practical requirements for high-sensitivity analysis and the need for a specialist laboratory setting create challenges for routine analysis. Several existing analytical techniques, which offer flexible and broad-based methods of analysis and in some cases detection, have been discussed in this manuscript. There are a number of methods used, of which many are lab-based, but to our knowledge there seems to be no single technique that stands out above the rest, although analytical liquid chromatography, commonly linked with mass spectroscopy is likely to be popular. This review manuscript discusses (a) sample pre-treatment methods such as liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE), (b) separation methods such as (TLC), high performance liquid chromatography (HPLC), gas chromatography (GC), and capillary electrophoresis (CE) and (c) others such as ELISA. Further currents trends, advantages and disadvantages and future prospects of these methods have been discussed.

A rapid high-performance liquid chromatography with fluorescence detection method developed to analyze ochratoxin A in wine

A rapid, sensitive, reproducible, and inexpensive method of high-performance liquid chromatography with fluorescence detection (HPLC-FLD) for the analysis of ochratoxin A (OTA) in wine was developed. It is characterized by direct injection of the wine into the HPLC apparatus, with no need of extraction or cleanup. The method uses acetonitrile, water, and acetic acid (49:49:2, vol/vol/vol, respectively) as the isocratic mobile phase and a 5-microm monolithic C18 column (100 by 3 mm inside diameter). The relative standard deviation obtained in the OTA determination varied between 0.22 and 1.76%, with a mean value of 0.89%, in samples with concentrations between 0.10 and 100 ng/ml. The recovery of OTA ranged from 102% in samples spiked with 1 ng/ml OTA to 120% in samples with 0.10 ng/ml OTA. The method compared favorably with a published method based on an immunoaffinity column cleanup and a chromatographic assay with a C18 conventional HPLC column.

Performance of new clean-up column for the determination of ochratoxin A in cereals and foodstuffs by HPLC-FLD

The performance of the newly developed Mycosep 229 Ochra and Multisep 229 Ochra clean-up columns for ochratoxin A (OTA) determination was evaluated. OTA was subsequently analysed using RP-HPLC with fluorescence detection. Recoveries for frequently contaminated commodities, like cereals, red wine, raisins and green coffee, were estimated. The recoveries obtained for the Mycosep 229 Ochra column were in the range from 87.9 +/- 12.5% (n = 6) for wheat to 99.4 +/- 2.7% (n = 24) for raisins. For Multisep 229 Ochra, recoveries from 76.5 +/- 8.0% (n = 6) for barley to 86.4 +/- 1.4% (n = 24) for raisins were achieved. Limits of detection for all matrices investigated (maize, wheat, rice, barley, raisins, green coffee beans, red wine) were in the range 0.4-2.4 microg kg(-1). The trueness of the method was tested using a certified reference material.

Methods of analysis for ochratoxin A

The mycotoxin ochratoxin A (OTA) is produced by the fungi Aspergillus alutaceus and Penicillium verrucosum and has carcinogenic, nephrotoxic, teratogenic and immunosuppressive properties. The levels of OTA in foodstuffs are regulated in several countries, so reliable and sensitive methods are necessary for its determination. Procedures for extraction of OTA from ground foods generally use an organic solvent in the presence of acid or an extraction solvent containing aqueous sodium bicarbonate. Cleanup procedures include partition into aqueous sodium bicarbonate, solid phase extraction (SPE) columns and immunoaffinity chromatography. The latter technique allows detection of sub-ppb levels of OTA in a wide variety of foods and in plasma. The most widely used determinative procedure is reversed phase liquid chromatography (LC) with detection by fluorescence (excitation 330-340 nm, emission 460-470 nm) or, more recently, by tandem mass spectrometry. ELISA methods are also available. Certified reference materials containing OTA have been prepared.

Solid-phase extraction applied to the determination of ochratoxin A in wines by reversed-phase high-performance liquid chromatography

A reversed-phase high-performance liquid chromatographic method is described for the analysis of Ochratoxin A at low microg l(-1) levels in samples of artificially contaminated wines. The method involves solid-phase extraction of samples using octadecylsilane cartridges and an additional preconcentration step prior to chromatography with isocratic elution and fluorimetric detection. The method was evaluated for accuracy and precision with relative standard deviations lower than 10%. Recoveries of ochratoxin A added to commercial wines over the range 0.1-3.0 microg l(-1) were higher than 80% in the assays. The performance of the octadecylsilane cartridge method tested compared very favourably with results of other published studies of ochratoxin A which use immunoaffinity columns or solvent extraction techniques.

Thin-layer chromatography in food and agricultural analysis

The TLC analysis of agricultural products, foods, beverages, and plant constituents is reviewed for the period from mid-1995 to mid-1999. Techniques and applications for a wide range of analyte and sample matrix types are covered, with specification of the particular layers, mobile phases, detection methods, and quantification conditions in many cases.

Thin-layer chromatography of mycotoxins and comparison with other chromatographic methods

This paper highlights the status of thin-layer chromatography (TLC) of mycotoxins in various sample matrices. The outstanding merits of TLC in the field of the qualitative and quantitative determination of mycotoxins have been briefed. A comparison between different TLC methods and TLC with HPLC, enzyme-linked immunosorbent assay and GC methods, etc. is made, in general.