Determination of stilbenes and resorcylic acid lactones in bovine, porcine and poultry muscle tissue by liquid chromatography–negative ion electrospray mass spectrometry and QuEChERS for sample preparation

An automated accelerated salting-out assisted solvent extraction (A-ASASE) of stilbenoids from Vitis vinifera L. branches: False proof or a proof of concept?

An automated accelerated salting-out assisted solvent extraction (A-ASASE) was developed. This approach made full use of the advantages of both the accelerated solvent extraction (ASE) technique and salting-out assisted liquid-liquid extraction (SALLE), without any modifications at the level of the ASE machine. The A-ASASE combined an automated extraction at high temperature/pressure and an enrichment step using eco-friendly solvents (e.g., water and ethanol) in a fully integrated and simple way that required only low volumes of solvents. The A-ASASE was successfully applied to extract three stilbenoids, namely E-resveratrol, E-ε-viniferin and E-vitisin B, present in grapevine (Vitis vinifera L.) by-products as a proof-of-concept compound. First, factors affecting the yield of stelbenoids by SALLE were investigated by means of a design of experiment model (DOE). The SALLE was then incorporated into ASE. Various ASE operational parameters such as temperature and number of cycles were also investigated. The highest yield was obtained using a mixture of ethanol-water, 70:30 (v/v) at 60 °C, using three extraction cycles and with 5 min of contact each. The highest yields of stilbenoids were 5.87 ± 0.28 g kg-1 dry weight, 3.27 ± 0.72 g kg-1 dry weight and 1.81 ± 0.2 g kg-1 dry weight for resveratrol, E-ϵ-viniferin and vitisin B, respectively. The A-ASASE was then successfully applied to extract the same stilbenoids from the roots of Vitis vinifera L. These results highlight the applicability of A-ASASE methodology to the extraction and enrichment of the extract in compounds of medium-high polarity in an easy and fully automated way.

Occurrence of resorcyclic acid lactones in porcine urine: discrimination between illegal use and contamination

Zeranol (α-zearalanol, α-ZAL), is a resorcyclic acid lactone (RAL). Its administration to farm animals to improve meat production has been prohibited in the European Union due to the potential risk to human health. However, it has been demonstrated that α-ZAL may be present in livestock animals due to Fusarium fungi that produce fusarium acid lactones contamination in feed. The fungi produce a small amount of zearalenone (ZEN), which is metabolized to zeranol. The potential endogenous origin of α-ZAL makes it difficult to correlate positive samples to a potential illicit treatment with α-ZAL. We present two experimental studies that investigated the origin of natural and synthetic RALs in porcine urine. Urine samples from pigs that were either fed with ZEN-contaminated feed or administered α-ZAL by injection were analyzed by liquid chromatography coupled to tandem mass spectrometry, with the method validated according to Commission Implementing Regulation (EU) 2021/808. The data show that although the concentration of α-ZAL in the ZEN feed-contaminated samples is significantly lower than in the illicit administration samples, α-ZAL can occur in porcine urine via natural metabolism. Additionally, the feasibility of using the ratio of forbidden/fusarium RALs in porcine urine as a reliable biomarker for illicit treatment with α-ZAL administration was evaluated for the first time. This study demonstrated that the obtained ratio in the contaminated ZEN feed study was close to 1, while in the illegally administered α-ZAL samples the ratio is always higher than 1 (up to 135). Therefore, this study proves that the ratio criteria (already used when a forbidden RAL is detected in bovine urine) may also be used for porcine urine.

Detection of ethinyl estradiol and resorcylic acid lactones in poultry meat according to the national residue plan

The aim of this study was the detection of ethinyl estradiol and resorcylic acid lactones (zeranol and taleranol) in poultry meat samples as unauthorized substances included in the Italian national residue plan. The samples were purified by a solid phase extraction using a C₁₈ column combined with alumina, and the analytes were detected by two specific enzyme-linked immunosorbent assay (ELISA) kits. As they were collected in the frame of official control activities, the method was also validated according to the Commission Decision 2002/657/EC requirements for screening methods with qualitative purpose. Specificity and detection capability were the performance criteria considered for the validation study, and the latter parameter showed a value of 0.5 μg/kg for both the investigated compounds. Such result was well comparable with the data reported by using chromatographic techniques as confirmation methods, and therefore, the ELISA kits tested in this study could be used for the screening of large numbers of samples.

A multi-class multi-residue method for the analysis of polyether ionophores, tetracyclines and sulfonamides in multi-matrices of animal and aquaculture fish tissues by ultra-high performance liquid chromatography tandem mass spectrometry

An ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) based multiclass multi-residue method for the simultaneous analysis of 5 polyether ionophores, 4 tetracycline and 10 sulfonamides in animal and aquaculture fish tissues was developed and validated. Sample extraction and clean-up were based on a modified QuEChERS method. The method was validated using an in-house validation based on performance characteristics modified from Commission Decision 2002/657/EC. Both matrix effect and uncertainties associated with sample preparation and instrumental analysis were minimised by the use of matrix-matched calibrations. Recoveries of analytes were generally satisfactory and typically fell between 80% and 113%. The repeatability and intermediate reproducibility measured as relative standard deviations were in most cases less than 15% (n = 63). The decision limit (CCα) and detection capability (CCβ) ranged from 110.7 to 125.8 and 121.5 to 151.7 µg kg^-1 for tetracyclines, 113.4 to 118.3 and 116.8 to 126.5 µg kg^-1 for sulfonamides and 50.8 to 52.4 and 51.5 to 55.6 µg kg^-1 for polyether ionophores, respectively. The method displayed its fitness for purpose through satisfactory results obtained in international proficiency testing schemes. The method was applied to animal and aquaculture fish tissues obtained from different sources in South Africa. Polyether ionophores were predominantly detected in samples in the range 4.26-290.10 µg/kg. Oxytetracycline was found in one porcine liver sample; however, none of the targeted analytes were present above the detection limit in the aquaculture samples.

Fast analysis of 19 anabolic steroids in bovine tissues by high performance liquid chromatography with tandem mass spectrometry

For the detection of 19 steroid hormones in bovine muscle, a fast and sensitive liquid chromatography with electrospray ionization tandem mass spectrometry method was developed using both positive and negative ionization mode. Chromatographic separation on Poroshell 120-EC C18 column was achieved in less than 10 min using isocratic elution of mobile phase of acetonitrile/methanol/water. The compounds were extracted from muscle tissue using ethyl acetate and quick, easy, cheap, effective, rugged, and safe technique. The purification of the obtained extract was performed by dispersive solid-phase extraction with sorbents C18, primary secondary amine and magnesium sulphate. The method was validated in accordance with the Commission Decision 2002/657/EC. For all steroids tested good recoveries were obtained (from 51.2 to 121.4%) in the concentration range from decision limits until 5 µg/kg. The values of decision limits and the detection capabilities for individual compounds were in the range 0.10-0.48 and 0.17-0.95 µg/kg, respectively. The method was characterized by satisfactory linearity for most compounds (correlation coefficients   > 0.99) and the reproducibility was lower than 35%. The elaborated procedure has met the criteria for confirmatory methods and is currently used in the official control of hormones.

The determination of zearalenone and its major metabolites in endometrial cancer tissues

Endometrial cancer is one of the most commonly diagnosed cancers in women. The search for factors that contribute to the development of cancer cells in reproductive organs should involve the detection of xenoestrogens, in particular zearalenone (ZEA) and its metabolites. Xenoestrogens are endocrine disruptors-ZEA and its metabolites are structurally similar to estrogens (macrocyclic lactone ring) and show high affinity for estrogen receptors. This study proposes a new method for the preparation of samples of human tissues with endometrial cancer by the use of the QuEChERS technique. Analytical parameters such as centrifugation temperature, extraction solvent, and adsorbents were modified to obtain satisfactory recovery for ZEA (R = 82.6%, RSD = 2.9%) and one of its metabolites, α-zearalenol (R = 50.1%, RSD = 3.2%). High-performance liquid chromatography (HPLC) with fluorescence detection and tandem mass spectrometry (LC-QTOF-MS) were used for the identification and quantitative determination of the analyzed compounds. The developed procedure was applied for analyses of human tissues with endometrial cancer. The presence of α-zearalenol was detected in 47 out of the 61 examined tissue samples. Graphical Abstract Methodology for isolation and identification of zearalenone and its major metabolites.

Development and validation of a confirmatory method for the determination of stilbene estrogens in ostrich serum

A simple and accurate ultra-high-performance liquid chromatography tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the first time as a confirmatory method for the simultaneous determination of stilbenes - hexestrol and diethylstibestrol in serum. Extraction was based on a simple acid denaturation of protein followed by liquid-liquid extraction using methyl tert butyl ether. Extracts were directly injected into the UHPLC-MS/MS without further purification. Excellent recoveries in the range 82-99% and 91-128% were obtained for hexestrol and diethylstibestrol, respectively. Both within-day repeatability and between-day reproducibility were generally satisfactory with RSD <20%. The linearity of the internal standard based matrix-matched calibration curve measured as the coefficient of regression (r²) was generally >0.99 for both hexestrol and diethylstibestrol. Both matrix effect and uncertainties associated with sample preparation and instrumental analysis were significantly reduced with the use of a deuterated compound (hexestrol-d4) as internal standard. The LOD and LOQ were 0.09 and 0.08 ng/ml, and 0.28 and 0.25 ng/ml, respectively, for hexestrol and diethylstibestrol. The method was found to be suitable for the simultaneous determination of hexestrol and diethylstibestrol in serum.

Simple and sensitive monitoring of β2-agonist residues in meat by liquid chromatography-tandem mass spectrometry using a QuEChERS with preconcentration as the sample treatment

A liquid chromatography with tandem mass spectrometric detection (LC-MS/MS) method was established for the simultaneous determination of the levels of 10 β2-agonists in meat. The samples were extracted using an aqueous acidic solution and cleaned up using a Quick, Easy, Cheap, Effective, Rugged and Safe (QuEChERS) technique utilising a DVB-NVP-SO3Na sorbent synthesised in-house. First, the β2-agonist residues were extracted in an aqueous acidic solution, followed by matrix solid-phase dispersion for clean-up. The linearities of the method were R(2)=0.9925-0.9998, with RSDs of 2.7-15.3% and 73.7-103.5% recoveries. Very low limits of detection (LOD) and quantitation (LOQ) of 0.2-0.9 μg/kg and 0.8-3.2 μg/kg, respectively, were achieved for spiked meat. The values obtained were lower than the maximum residue limits (MRLs) established by the EU and China. These results clearly demonstrate the feasibility of the proposed approach. The evaluated method provided reliable screening, quantification and identification of 10 β2-agonists in meat.

Developments in mycotoxin analysis: an update for 2013-2014

This review highlights developments in the determination of mycotoxins over a period between mid-2013 and mid-2014. It continues in the format of the previous articles of this series, emphasising on analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes and zearalenone. The importance of proper sampling and sample preparation is briefly addressed in a dedicated section, while another chapter summarises new methods used to analyse botanicals and spices. As LC-MS/MS instruments are becoming more and more widespread in the determination of multiple classes of mycotoxins, another section is focusing on such newly developed multi-mycotoxin methods. While the wealth of published methods during the 12 month time span makes it impossible to cover every single one, this exhaustive review nevertheless aims to address and briefly discuss the most important developments and trends.