The authors performed screening of a wide range of mycotoxins by ultra-high-performance liquid chromatography combined with tandem mass spectrometry (UHPLC-MS/MS) in various tea products distributed on the RF market. Samples were selected in retail outlets and obtained from wholesalers. Seventy-seven tea samples were examined: 54 out of them were Camellia sinensis tea, not packed (semi-finished product) and packed; 23 were mono-and multi-component herbal tea. The analytes were 29 mycotoxins including regulated in food products (aflatoxins, ochratoxin A, deoxynivalenol, fumonisins, T-2 toxin and zearalenone), their derivatives and structural analogues (A and B trichothecenes, structural analogues of zearalenone); emergent mycotoxins (sterigmatocystin, mycophenolic acid, moniliformin, enniatins, beauvericin and Alternaria toxins). C. sinensis tea samples, both green and black, were the least contaminated. In contrast, multi-component herbal tea samples tended to be simultaneously contaminated with several mycotoxins (over five) both regulated in food products and emergent ones. Beauvericin, mycophenolic acid and enniatin B were the most frequently detected. Toxigenic properties of mixed tea microflora were examined in vitro. Model experiments were carried out on a substrate consisting of C. sinensis green tea leaves in the absence of any growth factors. Mixed mycoflora from tea, which contained potentially toxigenic species of mold species proved to be capable to simultaneously produce substantial quantities of several mycotoxins including emergent ones. Mycotoxins accumulation amounted to 290 and 5,600 µg/kg of fumonisins B1 and B2 accordingly; 130 µg/kg of zearalenone; 14 µg/kg of sterigmatocystin; 160 µg/kg of alternariol methyl ester. The present survey indicates there is a potential health risk associated with mycotoxins in teas, especially herbal ones. The systematic study of contamination of tea products distributed in the RF with mycotoxins and their producers has been performed for the first time. Long-term monitoring over variety of mycotoxins in this kind of food products is essential for assessing its safety.

Standard solutions of mycotoxins prepared in RP HPLC solvents from neat standards are usually used for analytical method development. Multi-mycotoxin HPLC-MS/MS methods necessitate stability estimation for the wide spectrum of fungal metabolites. The stability of individual diluted stock standard solutions of mycotoxins in RP-HPLC solvents and multi-analyte HPLC-MS/MS calibrants was evaluated under standard storage and analysis conditions. Individual stock standard solutions of aflatoxins, sterigmatocystin, A-and B-trichothecenes, zearalenone and its analogues, ochratoxin A, fumonisins, Alternaria toxins, enniatins and beauvericin, moniliformin, citrinin, mycophenolic, cyclopiazonic acids and citreoviridin were prepared in RP-HPLC solvents and stored at −18 • C for 14 months. UV-spectroscopy was utilized to monitor the stability of analytes, excluding fumonisins. The gradual degradation of α-, β-zearalenol and α-, β-zearalanol in acetonitrile was detected. Aflatoxins and sterigmatocystin, zearalenone, Alternaria toxins, enniatins and beauvericin, citrinin, mycophenolic, cyclopiazonic acids and citreoviridin can be referred to as stable. The concentration of the majority of trichothecenes should be monitored. Diluted multi-mycotoxin standard in water/methanol (50/50 v/v) solutions acidified with 0.1% formic acid proved to be stable in silanized glass at 23 • C exposed to light for at least 75 h (CV ≤ 10%). An unexpected manifestation of MS/MS signal suppression/enhancement was discovered in the course of multi-mycotoxin standard solution stability evaluation. Key Contribution:The stability of the wide spectrum of mycotoxins in individual standard solutions in RP-HPLC solvents and multi-analyte HPLC-MS/MS calibrants under standard storage and analysis conditions is discussed basing on experimental and literature data.

Recent surveys report the occurrence of Aspergillus and Penicillium metabolites (aflatoxins (AFLs), ochratoxin A (OTA), cyclopiazonic and mycophenolic acids (MPA), sterigmatocystin (STC), citrinin), Fusarium (trichothecenes, zearalenone (ZEA), fumonisins (FBs), enniatins (ENNs)) and Alternaria (alternariol (AOH), its methyl ether (AME), tentoxin (TE), and tenuazonic acid (TNZ)) toxins in dry Camellia sinensis and herbal tea samples. Since tea is consumed in the form of infusion, correct risk assessment needs evaluation of mycotoxins’ transfer rates. We have studied the transfer of AFLs, OTA, STC, deoxynivalenol (DON), ZEA, FBs, T-2, and HT-2 toxins, AOH, AME, TE, ENN A and B, beauvericin (BEA), and MPA from the spiked green tea matrix into an infusion under variation of preparation time and water characteristics (total dissolved solids (TDS) and pH). Analytes were detected by HPLC-MS/MS. The main factors affecting transfer rate proved to be mycotoxins’ polarity, pH of the resulting infusion (for OTA, FB2, and MPA) and matrix-infusion contact period. The concentration of mycotoxins increased by 20–50% within the first ten minutes of infusing, after that kinetic curve changed slowly. The concentration of DON and FB2 increased by about 10%, for ZEA, MPA, and STC it stayed constant, while for T-2, TE, AOH, and AFLs G1 and G2 it went down. Maximum transfer correlated well with analytes polarity. Maximum transfer of ENNs, BEA, STC, ZEA, and AOH into infusion was below 25%; AFLs—25–45%; DON, TE, and T-2 toxins 60–90%, FB1—80–100%. The concentration of OTA, MPA, and FB2 in the infusion depended on its pH. At pH about four, 20%, 40%, and 60% of these toxins transferred into an infusion, at pH about seven, their concentrations doubled. Water TDS did not affect transfer significantly.

The paper dwells on the results obtained via long-term monitoring over food grain (wheat, barley, corn, oats, and rye) contamination with mycotoxin deoxynivalenol (DON). From 1989 to 2018 6,800 grain samples from Central, Southern, Volga, Ural, Siberian, North-Caucasian, Far Eastern, and North-western Federal Districts (FD) of the RF were analyzed. Depending on a year harvest, DON occurrence varied from 0 to 42 % and maximum toxin content reached 6.65 mg/kg. Over the whole examined period 10 % samples turned out to be contaminated and one forth of them contained the toxin in quanti- ties exceeding maximum permissible levels (MPL). DON occurrence amounted to 24–42 % in years of mass epiphytoties (1989, 1992 and 1993) as well as in crops gathered in 2014 and 2017; DON was detected in quantities exceeding MPL in 9–27 % of examined samples in those years. 78 % contaminated samples came from Southern and North-Caucasian FD and another 10 % were from Far Eastern FD. A significant correlation between DON occurrence and a number of rainy and sunny days in May was established on the example of wheat samples from Krasnodar region. Analysis of contamination dy- namics has revealed that over the last years there has been an ascending trend in frequency of DON detection in wheat that came not only from regions where Fusarium head blight was widely spread but also from regions in North-western, Siberian and Volga FD. Health risks related to DON intake with wheat grains processing products were assessed; the assessment revealed that DON intake higher than tolerable daily intake (TDI) for the residents of Southern and North-Caucasian FD in 1992, 1993, 2014 and 2017. Average occurrence of DON was 4.2; 11.9; 3.0 and 0.6 % for barley, corn, rye, and oats samples and its maximum contents amounted to 8.95; 0.95; 0.96 and 0.44 mg/kg accordingly. Just as it was the case with wheat, the most of contami- nated samples came from Southern, North-Caucasian and Far Eastern FD. Contamination tended to grow for all the exam- ined grains and it calls for relevant measures aimed at controlling food grains safety

Mycotoxins are natural food contaminants, associated with adverse health effects due to acute intoxication and, what is much more common, chronic exposure. The most hazardous and widespread mycotoxins are subjected to regulation in food in most countries. Alongside with regulated, a wide list of mycotoxins is monitored in various foods. Traditionally mycotoxins in tea are determined in a dry sample, not taking into account their transfer rate into the infusion. This study was aimed at the determination of the transfer rate of several mycotoxins from naturally contaminated herbal tea samples into an infusion. Seven of the most contaminated samples were pre-selected during the monitoring of mycotoxins in Camellia sinensis and herbal tea available in the Russian Federation. Ochratoxin A (OTA), sterigmatocystin (STE), mycophenolic acid (MPA), tentoxin (TTX), alternariol (AOH), its methyl ether (AME), zearalenone (ZEN), enniatins A and B (ENN A and B), beauvericin (BEA) were detected in these samples in the range of several μg/kg to several mg/kg. HPLC-MS/MS was used for dry tea samples and their infusion analysis. Mycotoxin polarity and infusion pH (for analytes possessing carboxylic groups) appeared to be factors determining transfer rate. STE transferred into infusion at the average rate of 10%. Average transfer of Alternaria toxins varied from 73% (TTX) to 45% (AOH) and about 11% (AME). A third part of ZEN was detected in the infusion. Transfer of ENNs and BEA was low and did not exceed 7%. Infusion pH affected MPA transfer rate; it increased from 23% to 96% in the pH range from 5.5 to 6.3. 83% of OTA was detected in the infusion of a single contaminated sample. Consideration of the mycotoxin transfer rate to herbal tea infusions resulted in the change of the model herbal tea input into mean chronic dietary exposure for most studied mycotoxins.