Determination of type B trichothecenes and macrocyclic lactone mycotoxins in field contaminated maize

Application of a liquid chromatography–tandem mass spectrometric method to multi-mycotoxin determination in raw cereals and evaluation of matrix effects

A multi-analyte method for the liquid chromatography-tandem mass spectrometric determination of mycotoxins in crude grain extracts without clean-up has been applied to the analysis of spelt, rice and barley. Method performance characteristics were determined after spiking blank samples at multiple levels and were found to be comparable for all investigated matrices as regards linearity (linear calibration functions were obtained for all analyte/matrix combinations except for moniliformin), precision (coefficient of variations <6%) and sensitivity. Matrix-induced signal suppression/enhancement was studied in detail and varied significantly between the investigated matrices, as well as between individual samples (relative standard deviation was as high as 40% within three rice varieties) and individual toxins. It was concluded that a reliable quantitative analysis using matrix-matched calibration requires careful consideration of the model matrix, which should match the investigated samples as close as possible.

Purification of deoxynivalenol from Fusarium graminearum rice culture and mouldy corn by high-speed counter-current chromatography

Deoxynivalenol (DON) is a mycotoxin produced by several Fusarium species and is toxic to a wide range of organisms, including human beings and livestock. To produce large amounts of pure DON for research purposes, a novel method using high-speed counter-current chromatography (HSCCC) was developed. Rice cultured with Fusarium graminearum and field mouldy corn infected by F. graminearum were extracted with methanol and found to contain 1.16 and 1.30 mg DON/g, respectively. The extracts were concentrated and then separated using a biphasic solvent system consisting of ethyl acetate-water (1:1, v/v). Collected fractions were analyzed by high-performance liquid chromatography (HPLC) and identified by congruent retention time and UV/vis spectrum and mass spectrometric data. Fractions containing DON were combined and freeze-dried. This method produced 116 mg and 65 mg DON with a purity of greater than 94.9% from 200 g of the rice culture and the mouldy corn, respectively. The HSCCC method had a recovery rate of DON at 88% from the crude extracts of both samples. This one-step purification method provided a simple and effective tool for obtaining a large amount of DON, an essential material for studies related to toxicology and detoxification of this mycotoxin.

Trace mycotoxin analysis in complex biological and food matrices by liquid chromatography–atmospheric pressure ionisation mass spectrometry

Mycotoxins are toxic secondary metabolites produced by filamentous fungi that are growing on agricultural commodities. Their frequent presence in food and their severe toxic, carcinogenic and estrogenic properties have been recognised as potential threat to human health. A reliable risk assessment of mycotoxin contamination for humans and animals relies basically on their unambiguous identification and accurate quantification in food and feedstuff. While most screening methods for mycotoxins are based on immunoassays, unambiguous analyte confirmation can be easily achieved with mass spectrometric methods, like gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS). Due to the introduction of atmospheric pressure ionisation (API) techniques in the late 80s, LC/MS has become a routine technique also in food analysis, overcoming the traditional drawbacks of GC/MS regarding volatility and thermal stability. During the last few years, this technical and instrumental progress had also an increasing impact on the expanding field of mycotoxin analysis. The aim of the present review is to give an overview on the application of LC-(API)MS in the analysis of frequently occurring and highly toxic mycotoxins, such as trichothecenes, ochratoxins, zearalenone, fumonisins, aflatoxins, enniatins, moniliformin and several other mycotoxins. This includes also the investigation of some of their metabolites and degradation products. Suitable sample pre-treatment procedures, their applicability for high sample through-put and their influence on matrix effects will be discussed. The review covers literature published until July 2006.

New possibilities of matrix-assisted laser desorption ionization time of flight mass spectrometry to analyze barley malt quality. Highly sensitive detection of mycotoxins

The occurrence of mycotoxins in agricultural commodities is a major health concern for livestock, humans, and the environment. Barley and subsequently malt quality is of fundamental importance to obtain good quality beer. Classical methods of analysis often require tedious, laborious, and expensive processes. Matrix-assisted laser desorption ionization time of flight mass spectrometry (MALDI-TOF MS) instrumentation enables highly sensitive and fast analysis and/or detection using a very small sample. The possibilities of MALDI-TOF MS for he identification and/or detection of trichothecene mycotoxins (deoxynivalenol (DON) and nivalenol (NIV), respectively) in barley malt were examined, and it was found that almost all classical MALDI matrices failed to ionize the compounds being studied. This detailed study of the ionization conditions and the search for unconventional matrices led to the discovery of suitable MALDI matrices, which enable ionization of trichothecene mycotoxins. These were: fine powdered synthetic diamond, sodium azide, or hydrazine hydrate. It is possible to detect 8.5 x 10(-12) mol (2.5 ng) of deoxynivalenol or 64 x 10(-12) mol (20 ng) of nivalenol in just 1 microL of barley malt extract (equivalent to 600 microg of DON in 1 kg of barley malt). The procedure developed enables fast determination of DON and NIV in barley, malt, or similar products.

Stable isotope dilution analysis of theFusariummycotoxins deoxynivalenol and 3-acetyldeoxynivalenol

Trichothecenes are secondary metabolites produced by several fungi of the Fusarium genus during their growth period. They inhibit protein biosynthesis in eukaryotic cells resulting in numerous toxic effects such as diarrhea, vomiting, and gastro-intestinal inflammation. Considering its occurrence in food and feedstuff, deoxynivalenol (DON) is one of the most important trichothecenes. We report the synthesis of stable isotope labeled 15-d(1)-deoxynivalenol (15-d(1)-DON) from its natural precursor 3-acetyldeoxynivalenol (3-AcDON) as starting material. Furthermore, a method for the analysis of DON and 3-AcDON using HPLC-MS/MS with stable isotope labeled 15-d(1)-DON and 3-d(3)-AcDON as internal standards has been developed. In total, 18 cereal product samples were analyzed with contamination levels ranging from 10-301 microg/kg for DON and 5-14 microg/kg for 3-AcDON. This is the first report of an isotope dilution MS method for the analysis of type B-trichothecenes.

Liquid chromatography/tandem mass spectrometric confirmatory method for determining aflatoxin M1 in cow milk

A liquid chromatography/electrospray (ESI)-tandem mass spectrometric method for the measurement of aflatoxin M1 (AFM1) in milk is described. Milk sample after protein precipitation with acetone was cleaned-up with a Carbograph-4 cartridge. Performances of the ESI source were compared with those of the atmospheric pressure photoionization source (APPI). Although a method quantification limit (MQL) of 6 ng/kg could be achieved operating with APPI source with respect to an MQL of 12 ng/kg with ESI, all the other performances being similar, then ESI was preferred as being more robust and widespread at present.

Identification and mass spectrometric characterization of glycosylated flavonoids in Triticum durum plants by high-performance liquid chromatography with tandem mass spectrometry

A mass spectrometric method for extensive detection and semi-quantitative determination of flavonoid glycosides in stem and leaves of young Triticum durum plants is presented. About 100 g of sample were lyophilized and ground, and the compounds of interest were then extracted, cleaned-up, and fractionated using high-performance liquid chromatography (HPLC). Tandem mass spectrometry analyses were performed using a quadrupole-linear ion trap instrument with an information-dependent data acquisition (IDA) protocol that looped two experiments, enhanced MS scan and enhanced product ion scan. Various glycoconjugates, which are all derivatives of only four flavones, apigenin, luteolin, chrysoeriol and tricin, were identified and belong to the following categories: 7 monoglycosides, 31 diglycosides, 15 triglycosides and 1 tetraglycoside. Among these some acylated glycosides were found. Tricin derivatives are present exclusively as O-glycosides, while apigenin and luteolin are present always as C-glycosides. Semi-quantitative estimation was performed by using the monoglycoside and diglycoside of quercetin as internal standards.