Occurrence of four mycotoxins in cereal and oil products in Yangtze Delta region of China and their food safety risks

A total of 76 cereal and oil products collected from Yangtze Delta region of China were analyzed for occurrences of aflatoxins (AFs), aflatoxin B₁ (AFB₁), ochratoxin A (OTA), deoxynivalenol (DON) and zearalenone (ZEN). The mycotoxins were determined by the standard detection procedures using immunoaffinity column clean-up coupled with fluorometer (or HPLC-UV). ZEN was the most prevalent toxin, with the incidence of 27.6% (range = 10.0–440.0 μg kg⁻¹), and 9.2% of the evaluated samples were contaminated with a concentration higher than that of the legislation limit of China (60 μg kg⁻¹). AFs and AFB₁ were detected in 14.5% of the samples analyzed, the concentrations ranging 1.1–35.0 μg kg⁻¹ for AFs, and 1.0–32.2 μg kg⁻¹ for AFB₁; 4.0% of the samples had the concentrations of AFs and AFB₁ higher than that of the corresponding legislation limits of China (5.0, 10.0 and 20.0 μg kg⁻¹ for different products). OTA was detected in 14.5% of the cereal and oil products collected; the concentrations ranged 0.51–16.2 μg kg⁻¹. Only 2 samples showed OTA levels higher than that of the legislation limit of China (5.0 μg kg⁻¹). DON was detected in 7.9% of the samples; the concentrations ranged 100–700 μg kg⁻¹, and none of the samples showed DON concentration higher than that of the legislation limit of China (1.0 mg kg⁻¹). A total of 15.8% cereal and oil products were contaminated with at least two mycotoxins (multiple contaminations with different combinations including AFs-ZEN, AFs-OTA-ZEN, OTA-ZEN, ZEN-DON, OTA-ZEN-DON). The dietary exposure assessment results indicated that AFs (AFB₁), OTA, DON and ZEN from cereal-based products represented a series health risk to both adults and children in Yangtze Delta region of China. This is the first report of safety evaluation associated with major mycotoxins for the area.     

Multiple mycotoxin co-occurrence in maize grown in three agro-ecological zones of Tanzania

In this study, the co-occurrence of multiple mycotoxins in maize kernels collected from 300 households' stores in three agro-ecological zones in Tanzania was evaluated by using ultra high performance liquid chromatography/time-of-flight mass spectrometry (TOFMS) with a QuEChERS-based procedure as sample treatment. This method was validated for the analysis of the main eleven mycotoxins of health concern that can occur in maize: aflatoxin B₁ (AFB₁), aflatoxin B₂ (AFB₂), aflatoxin G₁ (AFG₁), aflatoxin G₂ (AFG₂), ochratoxin A (OTA), deoxynivalenol (DON), fumonisin B₁ (FB₁), fumonisin B₂ (FB₂), HT-2 toxin, T-2 toxin and zearalenone (ZEN). From each zone one major maize producing district for home consumption was chosen and 20 villages for each district were randomly selected for sampling. All mycotoxins of health concern, except for T-2 toxin, were detected in the maize samples. Particularly high levels of AFB₁ (50%; 3–1,081 μg kg⁻¹), FB₁ (73%; 16–18,184 μg kg⁻¹), FB₂ (48%; 178–38,217 μg kg⁻¹) and DON (63%; 68–2,196 μg kg⁻¹) were observed. Some samples exceeded the maximum limits set in Tanzania for aflatoxins or in European regulations for other mycotoxins in unprocessed maize. Eighty seven percent of samples were contaminated with more than one mycotoxin, with 45% of samples co-contaminated by carcinogenic mycotoxins, aflatoxins and fumonisins. Significant differences in contamination pattern were observed among the three agro-ecological zones. The high incidence and at high levels (for some) of these mycotoxins in maize may have serious implications on the health of the consumers since maize constitute the staple food of most Tanzanian population. Effective strategies targeting more than one mycotoxin are encouraged to reduce contamination of maize with mycotoxins.     

Effect of ozone treatment on aflatoxin B1 and safety evaluation of ozonized corn

This paper studies the ozone treatment effect on degradation of aflatoxin B₁ (AFB₁) in corn with different moisture content (MC). The toxicity of the degradation products (DPs) of the ozone-treated AFB₁-Contaminated Corn (ACC) was also evaluated using the human hepatocellular carcinoma cell line (HepG2) as model cells. The degradation rate of AFB₁ in corn increases with ozone concentration and treatment time. The results showed that ACC with 13.47% MC was easier to be degraded by ozone than with 20.37% MC. Treated with 90 mg L⁻¹ ozone for 20 min and 40 min, AFB₁ in corn with 13.47% MC decreased from 83 μg kg⁻¹ to 18.12 μg kg⁻¹ and 9.9 μg kg⁻¹, respectively, well meeting the China National Standard of AFB₁ in corn (20 μg kg⁻¹). In order to evaluate the safety of ozone used on ACC, the impacts of AFB₁ as well as untreated and ozone-treated ACC with the same level of AFB₁ content on HepG2's survival rate, morphology, and apoptosis were studied. The results showed that ACC had high cell toxicity while the toxicity of ozone-treated ACC had no significant difference with that of the AFB₁-free culture solution. It is concluded that ozonation can quickly and effectively degrade AFB₁ in corn and diminish ACC's toxicity, and therefore, ozonation is expected to be an effective, fast, and safe method for AFB₁ degradation in ACC.     

Determination of aflatoxins in walnut sujuk and Turkish delight by HPLC-FLD method

This study aims to assess the risk of aflatoxins (AFs) in traditional confectionery products (walnut sujuk and Turkish delight) of Turkey. A high performance liquid chromatography coupled with fluorescence detection (HPLC-FLD) method was used for the determination of AFs. Evaluation of the method showed good selectivity, linearity, recovery and precision. The limit of quantification (LOQ) ranged from 0.106 to 0.374 μg kg⁻¹. The expanded measurement uncertainty was less than 40% for all target analytes. The validated method was successfully applied to the determination of AFs in 112 traditional confectionery products containing nuts (hazelnuts and walnuts). AFs were detected in 43.8% of walnuts and 60.9% of hazelnuts used as ingredients in walnut sujuk and Turkish delight and at levels ranging from 0.58 to 15.2 μg kg⁻¹ and 0.43–63.4 μg kg⁻¹, respectively. This means that AFs levels in walnut sujuk and Turkish delight were up to levels of 6.1 and 9.5 μg kg⁻¹, respectively. Six walnut samples and twenty-one hazelnut samples were above the EU maximum limits (MLs) of 2 and 5 μg kg⁻¹ for aflatoxin B₁ (AFB₁), respectively.     

Multi-mycotoxins analysis in ginger and related products by UHPLC-FLR detection and LC-MS/MS confirmation

The aim of this study was to optimize and validate a powerful method for the simultaneous analysis of aflatoxins B₁ (AFB₁), B₂ (AFB₂), G₁ (AFG₁), G₂ (AFG₂) and ochratoxin A (OTA) in ginger and related products collected from local markets in Beijing, China. The optimized analytical procedure was based on immunoaffinity column (IAC) clean-up, followed by ultra-high performance liquid chromatography with fluorescence (UHPLC-FLR) detection. Limits of detection (LOD) and quantification (LOQ) for the five mycotoxins were 0.005–0.2 and 0.0125–0.5 μg kg⁻¹, respectively. The average recoveries ranged from 84.2 to 97.3% with relative standard deviations (RSDs) from 0.63 to 7.86% at three spiking levels. Good linearity was observed for the analytes with correlation coefficients all higher than 0.9995. The established method was applied to 30 samples of 10 different species of ginger and related products, and all positive samples were confirmed by liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). The results showed that 5 samples of ginger products were contaminated with AFB₁ at 0.13–1.38 μg kg⁻¹, while 3 samples of ginger and 2 samples of ginger products were contaminated with OTA at 0.31–5.17 μg kg⁻¹. All the contamination levels were below the legally allowable limits.     

Inactivation of aflatoxigenic fungi and the reduction of aflatoxin B1 in vitro and in situ using gamma irradiation

Detailed investigation on the effect of gamma (γ) irradiation on germination, sporulation, and growth of aflatoxigenic moulds (Aspergillus parasiticus 2999, Aspergillus flavus 305, and Aspergillus niger 388), as well as on the reduction of aflatoxin B₁ (AFB₁) level in artificially and naturally contaminated maize/feed samples was performed. The results of in vitro and in situ experiments with aflatoxigenic moulds demonstrated that 5 kGy-γ irradiation manages to prevent sporulation, germination and growth of the tested moulds both when in form of a pure and when in form of a mixed culture. In the feed samples artificially contaminated with AFB₁ (50 μg kg⁻¹) 5 kGy-γ irradiation reduced AFB₁ level by around 60%, while 10 kGy-dose reduce it for around 85%. Similarly, in feed samples spiked with AFB₁ in the concentrations of 100 μg kg⁻¹ 5 kGy-dose reduced the AFB₁ level by approximately 70%, while the dose of 10 kGy reduced it by approximately 90%. The experiments on naturally contaminated maize samples (n = 30) confirmed these observations; following a 5 kGy-irradiation, the overall mean AFB₁ reduction equalled to 69.8%, while the irradiation with a 10 kGy-dose achieved the overall mean toxin reduction of 94.5%. The obtained results indicate that γ irradiation can be used to prevent the growth of aflatoxigenic moulds and to reduce the AFB₁ levels in various goods intended for animal and human consumption, thus minimizing the animal and human exposure to this carcinogenic mycotoxin.     

Aflatoxin M1 survey on randomly collected milk powder commercialized in Argentina and Brazil

Aflatoxin M₁ (AFM₁), the main monohydroxylated of aflatoxin B₁ (AFB₁) formed in liver and excreted in the milk, has toxicological proprieties comparable to those of AFB₁, albeit a lower carcinogenic potency. The presence of AFM₁ was investigated in 30 samples of powdered milk purchased in Argentina and Brazil. The samples were analyzed using an immunoaffinity column for cleanup and HPLC-FLD for determining AFM₁. The quantification limit was 0.1 μg/kg. AFM₁ was found in all the samples at levels ranging from 0.1 to 0.92 μg kg⁻¹ with average concentration of 0.39 μg kg⁻¹.     

Multi-class determination of pesticides and mycotoxins in isoflavones supplements obtained from soy by liquid chromatography coupled to Orbitrap high resolution mass spectrometry

A methodology has been developed to identify and quantify 257 toxic substances (including pesticides and mycotoxins) in diverse isoflavones supplements obtained from soy. Two different extraction procedures were compared, QuEChERS and “dilute and shoot”. The best results were observed when the “dilute and shoot” methodology was applied using acetonitrile acidified with formic acid (1% v/v) as extraction solvent followed by a clean-up step with Florisil cartridges. Validation of the method was carried out evaluating trueness, repeatability and intermediate precision, obtaining recoveries between 70 and 120% with relative standard deviation (RSD) values lower than 20%. Limits of detection and quantification were below 5 and 10 μg kg⁻¹ respectively. The validated methodology was applied to the analysis of real samples, finding pesticides such as flutolanil (12.2 μg kg⁻¹) and etofenprox (48.2 μg kg⁻¹). Regarding mycotoxins, aflatoxin B1 (8.2–17.1 μg kg⁻¹) and aflatoxin G2 (6.4 μg kg⁻¹) were detected.     

In-house method validation,estimating measurement uncertainty and the occurrence of fumonisin B1 in samples of Brazilian commercial rice

Fumonisin B₁ was investigated in samples of rice intended for human consumption, including polished parboiled rice, whole grain rice and whole grain parboiled rice. Until the present, no studies on the occurrence of fumonisin B₁ have been performed on these types of rice that are commercially available in the south-eastern region of Brazil. A careful intralaboratory validation was carried out to demonstrate the fitness-of-purpose of the applied method for determining fumonisin B₁ in the three studied rice types. The performance criteria – selectivity, reliable limits of detection (50 μg kg⁻¹) and quantification (100 μg kg⁻¹), linearity (range 100–2500 μg kg⁻¹), precision (RSD values ≤ 17.0%) and recovery (71.7–112.0 %) were evaluated, and the expanded measurement uncertainty was estimated by using the data obtained from precision and recovery experiments. Matrix-matched calibration standards were employed to quantify the mycotoxin levels in the rice samples, in which the residual normality, homoscedasticity and independence were confirmed. In addition, the measurement uncertainty values are consistent with the maximum acceptable uncertainty established by European Union regulation for analytical methods for controlling mycotoxins in foodstuffs. Among the thirty-one commercial samples of rice analysed in the present study, five samples presented detectable levels of the mycotoxin, and these levels ranged from 64.8 to 163.0 μg kg⁻¹.     

Survey of aflatoxin B1 in helva,a traditional Turkish food,by TLC

A total of 102 helva samples consisting of 34 plain helva, 34 helva containing cacao, and 34 helva containing pistachio nuts purchased from helva-factories and supermarkets in Adana of Turkey were analysed for aflatoxin B₁ (AFB₁) by thin-layer chromatography. The detection limit of AFB₁ was 1 μg kg⁻¹. Recovery experiments were carried out with spiked samples in the range 2–10 μg kg⁻¹ of AFB₁. No AFB₁ was found in any plain helva and helva containing cacao samples. On the other hand, of 34 helva containing pistachio nuts AFB₁ was determined in eight samples. AFB₁ was found in excess of Turkish legal limit of 5 μg kg⁻¹ in 4 of 102 helva samples. This paper reports the data of the first survey for the presence of AFB₁ in helva in Turkey.     

Aflatoxin and fumonisin contamination of yam flour from markets in Nigeria

The natural occurrence of aflatoxins (AFs) and fumonisins (FBs) in yam flour samples (n = 100) obtained in south-western Nigeria was evaluated. AFs were determined by HPLC with fluorescence detection and FBs by HPLC coupled with mass spectrometry. Aflatoxin B₁ (AFB₁) and aflatoxin G₁ (AFG₁) were found in 57% and 21% of flours from white yam with concentrations ranging from <0.02 (limit of detection, LOD) to 3.2 μg kg⁻¹ (mean = 0.4 μg kg⁻¹) and from <0.05 to 3.5 μg kg⁻¹, respectively. AFB₁ was the only aflatoxin detected in samples from water yam, contaminating 32% of the samples with values ranging from <LOD to 0.6 μg kg⁻¹ (mean = 0.1 μg kg⁻¹). Fumonisin B₁ was found in 32% of the white yam samples (<0.5 (LOD) to 91 μg kg⁻¹; mean = 5 μg kg⁻¹) and in 5% of water yam samples (<LOD to 2 μg kg⁻¹). AFs and FBs were significantly higher (P < 0.05) in white yam flours compared to water yam flours. Preparation of amala from naturally-contaminated yam flour resulted in reduction of AFB₁ and AFG₁ by 44% and 51% respectively. From this study, only 7% of the samples contained AFs above the European standard limits for cereals intended for direct human consumption, while all the FBs-positive samples were well below the limits. The occurrence of ochratoxin A, zearalenone and deoxynivalenol was also evaluated in 20 samples; these mycotoxins were never detected.     

Deoxynivalenol in the wheat milling process and wheat-based products and daily intake estimates for the Southern Brazilian population

Fusarium head blight of wheat is caused by the Fusarium species that produces mycotoxins, such as deoxynivalenol (DON). The distribution of DON in wheat products can lead to high economic and health impacts. The objective of this study was to evaluate the natural distribution of DON in the wheat milling process and wheat-based products, as well as the daily intake estimates for the Southern Brazilian population. The fractions of wheat grains (milled wheat, finished flour and bran) were produced in a mill. Additionally, wheat-derived products, such as pasta, bread and crackers were analyzed. The bran fraction had the highest mean concentration of DON (2278 μg kg⁻¹), followed by milled wheat and finished flour (1895 μg kg⁻¹ and 1305 μg kg⁻¹). The distribution factor in the finished flour (69%) fraction demonstrates that DON was reduced when compared to milled wheat, by contrast of bran fraction that presents higher DON levels (120%). A percentage of 35% bran, 35% finished flour and 30% milled wheat samples would not be in compliance with future Brazilian regulations for DON levels. From the wheat-based products analyzed, 17% of whole bread and 10% of salted cracker products were contaminated with DON, with a median of 437 μg kg⁻¹ and 624 μg kg⁻¹, respectively. The finished flour was the fraction that most contributes to the daily intake of DON in Southern Brazil, representing 89.6% of the provisional maximum tolerable daily intake.     

Occurrence and co-occurrence of Fusarium mycotoxins in wheat grains and wheat flour from Romania

In this study, the presence of fourteen Fusarium mycotoxins, legislated by the European Union – deoxynivalenol, zearalenone, HT-2 and T-2 toxins (EC/1881/2006; 2013/165/EU), or non-legislated (five trichothecens and five “emerging” mycotoxins), was evaluated in 31 whole unprocessed wheat samples and 35 white wheat flour samples from different areas of Romania. For this purpose, a validated multi-mycotoxins liquid chromatography tandem mass spectrometry method was applied. Seventy three percent of the analyzed samples contained at least one mycotoxin. The highest occurrence was for enniatin B, 71% of the analyzed samples being positive (21–407 μg kg⁻¹). Regarding the legislated mycotoxins, deoxynivalenol was detected in 14% (111–1787 μg kg⁻¹) of the samples, while zearalenone was detected in 9% (51–1135 μg kg⁻¹). Only one sample was positive for neosolaniol. Concerning the co-occurrence, 42% of the samples were contaminated with two to five mycotoxins, the most frequent being the binary or tertiary combinations of enniatins. This is the first study applied to Romanian wheat grains and flour samples using a high sensitive multi-mycotoxins method, and which included also “emerging” mycotoxins.     

Occurrence of volatile and non-volatile N-nitrosamines in processed meat products and the role of heat treatment

Most of the available data on the occurrence of N-nitrosamines (NA) in processed meat products have been generated in the 1980s and 1990s and especially data on the occurrence of non-volatile NA (NVNA) are scarce. Therefore we have studied the levels of volatile nitrosamines (VNA) and NVNA in processed meat products on the Danish market (N = 70) and for comparison also products on the Belgian market (N = 20). The effect of heat treatment on the NA levels, in selected samples, was also studied, in order to enable an evaluation of how preparation before consumption affects the levels of NA. For the Danish products the mean levels of the VNA were generally low (≤0.8  μg kg⁻¹), whereas the mean levels of the NVNA were considerably higher (≤118 μg kg⁻¹). Slightly higher mean levels were indicated for the Belgian products (i.e. VNA ≤1.5  μg kg⁻¹ and NVNA ≤270 μg kg⁻¹). The sums of VNA were higher than 10 μg kg⁻¹ for one Danish sample and two Belgian samples. Levels of up to 2000 and 4000 μg kg⁻¹ of N-nitroso-thiazolidine-4-carboxylic acid (NTCA) an NVNA occurred in the Danish and the Belgian samples, respectively. The majority of the Danish processed meat products contain NVNA but also VNA occur. The levels of NA are comparable with those reported in previous and recent studies; however the frequency in which they are found may be lower and thereby also the mean contents. The levels of N-nitrosopiperidine (NPIP) increased by frying and baking, whereas varying impacts were observed for N-nitrosoproline (NPRO), N-nitrosodimethylamine (NDMA), N-nitrosopyrrolidine (NPYR), N-nitrosodiethylamine (NDEA) and N-nitrosomethylaniline (NMA) depending on the type of product and/or the heat treatment. The levels of the NVNA, NTCA and N-nitroso-2-methyl-thiazolidine 4-carboxylic acid (NMTCA) decreased after frying and baking.     

Aflatoxin contamination and exposure in processed cereal-based complementary foods for infants and young children in greater Accra,Ghana

In the study, aflatoxin levels were assessed in thirty five (35) cereal-based food products intended for infants and young children. Additionally, the results showed that 71% of the processed foods intended for infants contained AFB₁ (0.18 ± 0.01 to 36.10 ± 0.32 μgkg⁻¹) levels higher than the European Union permissible limits of 0.1 μg kg⁻¹. Aflatoxin intake was estimated using aflatoxin levels in the food products and the estimated individual consumption rates. The study also revealed mixed cereals as having the highest intake of aflatoxin B₁ contaminants (0.005–0.852 μgkg⁻¹bw d⁻¹; 0.004–0.657 μgkg⁻¹bwd⁻¹) with mean estimated daily intake (EDI) of 0.23 ± 0.16 μgkg⁻¹bwd⁻¹ and 0.153 ± 0.13 μgkg⁻¹bwd⁻¹ for infants and young children respectively. The estimated AFT intake recorded for infants and young children for all the cereal-based food ranged from 0.005 to 1.054 μgkg⁻¹bwd⁻¹ and 0.004–0.838 μgkg⁻¹bwd⁻¹ respectively.     

Aflatoxins and ochratoxin A in dried eggplant and green bell pepper

In this study, 50 dried eggplant and 50 dried green bell pepper samples were analyzed in terms of their aflatoxin and ochratoxin A (OTA) content. Aflatoxins G₂, G₁, B₂, and B₁, and OTA contents were analyzed using high-performance liquid chromatography with a flame ionization detector (HPLC–FID). Total aflatoxin and, as well as aflatoxin G₂, G₁, B₂, and B₁ content in dried eggplant samples were ranged between 0.82 and 2.58, 0.10–0.23, 0.32–1.35, 0.12–0.67, and 0.17–0.71 μg kg⁻¹, respectively. Total aflatoxin and, as well as aflatoxin G₂, G₁, B₂ and B₁ content in dried green bell pepper samples were 0.81–2.42, 0.11–0.22, 0.32–1.38, 0.13–0.66, and 0.18–0.91 μg kg⁻¹, respectively. OTA content was varied from 8.88 to 21.35 μg kg⁻¹ in eggplant samples, and from 15.38 to 24.70 μg kg⁻¹ in dried green bell pepper samples. Of the dried eggplant samples and dried green bell pepper samples, 36% and 24% of them, respectively, had aflatoxin B₁ values which were below the minimum limit of detection (LOD) of 0.05 μg kg⁻¹. None of the analyzed samples exceeded the legal limit values of 10 μg kg⁻¹ for total aflatoxin content, and 5 μg kg⁻¹ for aflatoxin B₁ content. However, 80% of the dried eggplant samples and 100% of the dried green bell pepper samples exceeded the legal limit value for OTA content (15 μg kg⁻¹). According to the results, it was concluded that dried vegetables should be examined in terms of their aflatoxins. It is essential to analyze OTA content more thoroughly, as it has the potential to pose a risk for public health, as well as for the economy.     

A reliable screening of mycotoxins and pesticide residues in paprika using ultra-high performance liquid chromatography coupled to high resolution Orbitrap mass spectrometry

In this study, an ultra-high performance liquid chromatography (UHPLC) coupled to a high resolution Orbitrap mass spectrometry (Orbitrap-HRMS) was demonstrated as a promising technique in high-throughput method development for the routine analysis and contamination control of mycotoxins and pesticide residues in spices. The method was applied for the analysis of fifty ground paprika samples containing blends of sweet and hot paprika harvested in Brazil and China. The efficiency and detection sensitivity of the used UHPLC-Orbitrap-HRMS technique were compared to the results obtained using a triple quadrupole tandem mass spectrometric detector (UHPLC-QqQ-MS/MS). The values of recovery (75–120%) and repeatability (8–15%) for both methods, calculated as the average (n = 5) from the results of spiked (10–500 μg kg⁻¹), paprika samples, were in good conformity to the relevant EU guidelines. The high resolution of the used Orbitrap-HRMS technique provided a better sensitivity for quantitative determination of several pesticide contaminants in paprika, compared to the results obtained by the QqQ-MS/MS method and were comparable in case of mycotoxins. The results of analysis demonstrated the ubiquitous presence of three mycotoxins (fumonisin B₁, ochratoxin A, and sterigmatocystin) and twelve pesticide residues in paprika. The concentrations of determined contaminants were below the MRLs set by the Regulations of the European Union with exception of iprovalicarb, which violated the EU MRL in two samples of hot paprika. In addition, a notable difference in the concentration of fumonisin B₁ was determined depending on the harvest period (2009–2013), reaching the maximum concentrations of 33 μg kg⁻¹ in sweet paprika and 140 μg kg⁻¹ in hot paprika. There was no significant correlation found between the determined mycotoxin contamination levels and the pesticide residues, with the sole exception of decreased fumonisin B₁ content in samples with an elevated concentration of metalaxyl fungicide.     

Development and validation of an accurate and rapid LC-ESI-MS/MS method for the simultaneous quantification of aflatoxin B1, B2, G1 and G2 in lotus seeds

An accurate and rapid LC-ESI-MS/MS analytical method was developed and validated for the simultaneous determination of aflatoxin B₁, B₂, G₁ and G₂ in lotus seeds. The samples were firstly extracted with methanol-water solution (80:20, v/v), and then cleaned up by immunoaffinity columns. The mass spectrometer was operated in the positive ionization electrospray (ESI+) mode using multiple reaction monitoring (MRM) for analysis of four aflatoxins. The transitions of m/z 313 → 285 (AFB₁, CE 33 eV), m/z 315 → 259 (AFB₂, CE 37 eV), m/z 329 → 243 (AFG₁, CE 37 eV) and m/z 331 → 257 (AFG₂, CE 37 eV) were used to quantify these four aflatoxins, respectively. The limits of detection (LODs) of aflatoxin B₁, B₂, G₁ and G₂ were 0.007, 0.005, 0.003 and 0.005 μg kg^?1 based on a signal-to-noise ratio of 3:1, respectively. The limits of quantification (LOQs) of aflatoxin B₁, B₂, G₁ and G₂ were 0.02, 0.015, 0.01 and 0.015 μg kg^?1 based on a signal-to-noise ratio of 10:1, respectively. Recoveries for samples of spiked lotus seeds were all above 66% with relative standard deviation all below 15% for all compounds. Nineteen out of twenty batches of lotus seeds collected from different drug stores or markets in China were found to be contaminated with aflatoxins at different levels ranging from 0.02 to 688.4 μg kg^?1.     

Application of solid phase extraction and two-dimensional gas chromatography coupled with time-of-flight mass spectrometry for fast analysis of polycyclic aromatic hydrocarbons in vegetable oils

A fast and simple solid-phase extraction (SPE) method followed by comprehensive two-dimensional gas chromatography coupled to time-of-flight mass spectrometry (GC × GC–TOFMS) has been developed for analysis of 15 + 1 carcinogenic polycyclic aromatic hydrocarbons (PAHs) in vegetable oils. Of three critically assessed sample preparation approaches – (i) gel permeation chromatography (GPC), (ii) GPC followed by silica based SPE, and (iii) SPE employing PAHs-dedicated molecularly imprinted polymers (MIPs), the latter one was selected as the best option. Recoveries of the overall analytical procedure ranged from 70 to 99%, with repeatabilities in the range of 2–11%. Limits of quantitation (LOQs) ranging for individual PAHs from 0.1 to 0.3 μg kg⁻¹, were fairly below the maximum level 2 μg kg⁻¹ established for the PAHs representative, benzo[a]pyrene (BaP), by EU Legislation for this commodity. Within the mini-survey in which the new method was employed for examination of 35 samples of various kinds of vegetable oils collected at the Czech market, the highest PAH4 levels, i.e. the sum of BaP, benz[a]anthracene (BaA), benzo[b]fluoranthene (BbFA) and chrysene (CHR) were found in sea buckthorn (708 μg kg⁻¹) followed by rapeseed oil (99.8 μg kg⁻¹). Altogether 8 samples from 35 examined vegetable oils exceeded the maximum limit 2 μg kg⁻¹ for BaP and 10 samples exceeded 10 μg kg⁻¹ set for PAH4 which is fixed by Commission Regulation (EU) no 835/2011 for oils.     

Determination of organophosphorous pesticides in summer crops using ultrasound-assisted solvent extraction followed by dispersive liquid–liquid microextraction based on the solidification of floating organic drop

The ultrasound-assisted solvent extraction (UASE) followed by dispersive liquid–liquid microextraction based on the solidification of floating organic drop (DLLME-SFO) has been developed for extraction and determination of organophosphorous pesticides from summer crops. Organophosphorous pesticides were determined by high performance liquid–liquid chromatography-ultraviolet detector (HPLC-UV). Some effective parameters on extraction were studied and optimized. Under the optimum conditions, recoveries for different fruits are in the range of 44.0–61.0%. The calibration graphs are linear in the range of 5–800 μg kg⁻¹ and limit of detections (LODs) are in the range of 1–4 μg kg⁻¹. The relative standard deviations (RSDs) for 100 μg kg⁻¹ of OPPs in different fruits are in the range of 5.5–9.1 (n = 5). The obtained results show that UASE–DLLME-SFO combined with HPLC-UV is a fast and simple method for the determination of pesticides in summer crops.