High-sensitivity direct analysis of aflatoxins in peanuts and cereal matrices by ultra-performance liquid chromatography with fluorescence detection involving a large volume flow cell

Dietary Mycotoxins: An Overview on Toxicokinetics, Toxicodynamics, Toxicity, Epidemiology, Detection, and Their Mitigation with Special Emphasis on Aflatoxicosis in Humans and Animals

Mycotoxins are secondary metabolites of filamentous fungi and ubiquitous dietary contaminants. Aflatoxins, a group of mycotoxins with high prevalence and toxicity, have raised a high level of public health concern, the most prevalent and toxic being aflatoxin B1 (AFB1). Many aspects appertaining to AFB1 poisoning are not well understood. Yet this information is necessary to devise appropriate surveillance and mitigation strategies against human and animal aflatoxicosis. This review provides an in-depth update of work carried out on mycotoxin poisoning, particularly aflatoxicosis in humans and animals, to identify gaps in knowledge. Hypotheses explaining the functional significance of mycotoxins in fungal biology and their dietary epidemiological data are presented and briefly discussed. The toxicology of aflatoxins and the challenges of their mitigation are discussed in depth. It was concluded that the identification of potential mycotoxin-hazard-prone food items and quantification of the associated risk of cancer ailments in humans is a prime priority. There is a dearth of reliable sampling methodologies for estimating AFB1 in animal feed. Data update on AFB1 in animal feed and its implication in animal production, mitigation strategies, and elucidation of risk factors to this hazard is required. To reduce the burden of aflatoxins, surveillance employing predictive technology, and biocontrol strategies seem promising approaches.

Aflatoxins Contamination in Feed Commodities: From Occurrence and Toxicity to Recent Advances in Analytical Methods and Detoxification

Synthesized by the secondary metabolic pathway in Aspergilli, aflatoxins (AFs) cause economic and health issues and are culpable for serious harmful health and economic matters affecting consumers and global farmers. Consequently, the detection and quantification of AFs in foods/feeds are paramount from food safety and security angles. Nowadays, incessant attempts to develop sensitive and rapid approaches for AFs identification and quantification have been investigated, worldwide regulations have been established, and the safety of degrading enzymes and reaction products formed in the AF degradation process has been explored. Here, occurrences in feed commodities, innovative methods advanced for AFs detection, regulations, preventive strategies, biological detoxification, removal, and degradation methods were deeply reviewed and presented. This paper showed a state-of-the-art and comprehensive review of the recent progress on AF contamination in feed matrices with the intention of inspiring interests in both academia and industry.

Multi-mycotoxin analysis method using liquid chromatography with tandem mass spectrometry and fluorescence detection in Indian medicinal herbs: Development and validation

While medicinal plants are in high demand worldwide for their therapeutic properties, they can constitute a health concern to consumers when contaminated with mycotoxins. The unavailability of standardised methods for multiclass mycotoxin analysis to assess health risks has thus been realised. This study reports a simple, robust and precise method to estimate nine regulated mycotoxins in a range of Indian medicinal plant matrices including giloy (Tinospora cordifolia), ashwagandha (Withania somnifera), safed musli (Chlorophytum borivilianum), satavari (Asparagus racemosus) and tulsi (Ocimum sanctum). The sample preparation method involved extraction of homogenised matrices (12.5 g) using methanol:water (8:2, 100 mL) followed by cleanup through a multi-mycotoxin immunoaffinity column (IAC), which significantly reduced matrix interferences. The method was initially developed and validated using liquid chromatography tandem mass spectrometry (LC-MS/MS) for the simultaneous analysis of aflatoxins (B₁, B₂, G₁, G₂), ochratoxin A, zearalenone, deoxynivalenol, T-2 and HT-2 toxin. Later, it was validated using LC-fluorescence (LC-FLD) for aflatoxins, ochratoxin A and zearalenone. The optimised sample preparation protocol and analytical method provided acceptable results. Compared to LC-FLD, it was possible to attain a lower limit of quantification (LOQ) with LC-MS/MS for all the tested analytes except aflatoxins. However, LOQs of both instruments were lower than the maximum limits (MLs), with recoveries ranging between 71 and 110% and precision (RSD) of ≤10% across matrices. Despite matrix-induced signal suppressions in LC-MS/MS analysis, the matrix-matched calibrations corrected all recoveries. Considering its accuracy, reliability, robustness and time-effectiveness, this method is recommended for regulatory testing purposes.

Impact of different extraction processes on aflatoxin contamination in peanut oil

Aflatoxins (AFs) are genotoxic carcinogens and are a growing concern in peanuts and peanut products. This study aims to impact of different extraction processes on the transition of AFs from peanuts to oils. Peanuts were collected from nine different factories in Osmaniye, Turkey, during the period of November 2017-May 2018. While no aflatoxin G₁ (AFG₁) and aflatoxin G₂ (AFG₂) were detected in peanuts, aflatoxin B₁ (AFB₁) and aflatoxin B₂ (AFB₂) were determined in all peanut samples at levels varying from 26.7 to 234.7 µg kg^-1 and from 4.44 to 44.0 µg kg^-1, respectively. No AFs were quantified in oils obtained by the industrial application method. The ratios of AFB₁ transitions to oils obtained by solvent extraction, cold pressing of roasted peanuts and cold pressing methods were 9.0-79.8%, 11.3-75.3% and 9.3-77.6%, respectively. The concentrations of AFB₂ in oils obtained by solvent extraction, cold pressing of roasted peanuts and cold pressing methods were 0.46-17.2 µg kg^-1, 0.84-33.0 µg kg^-1 and 1.02-36.3 µg kg^-1, respectively. This is the first demonstration of the impact of different extraction processes on the transition of AFs from peanuts to oils.

A MIP-enabled stainless-steel hypodermic needle sensor for electrochemical detection of aflatoxin B1

Aflatoxin B1 (AFB1) has been identified as one of the most potent naturally occurring carcinogens with high toxicity. The maximum permissible levels of total aflatoxin contamination in food products are limited to 10-15 μg kg^-1, as established by the Codex Alimentarius Commission. The widespread occurrence of AFB1 in the food chain identifies them as significant agricultural contaminants of global concern. We herewith demonstrate a molecularly imprinted polymer (MIP)-enabled stainless steel hypodermic needle sensor for sensitive electrochemical detection of AFB1. The stainless-steel hypodermic needle sensor was fabricated using a layer by layer (LbL) film coating comprising multiwalled carbon nanotubes (MWCNTs), cellulose nanocrystals (CNC), and an AFB1 imprinted polyaniline (PANI) biomimetic receptor film. The PANI@MIP/CNC-CNT hypodermic needlesensor showed excellent electrochemical capacitance response (∼10 min) to AFB1 with a linear range of 0-25 nM and a limit of detection (LOD) of 3 nM. Demonstrating good reusability, a single PANI@MIP/CNC-CNT hypodermic needle AFB1 sensor could be reused up to 7 times with a 2.8% relative standard deviation (% RSD) in the sensor's capacitive response. The PANI@MIP/CNC-CNT hypodermic needle sensor was effective in the detection of AFB1 spiked in milk.

Simultaneous distribution of aflatoxins B1 and B2, and fumonisin B1 in corn fractions during dry and wet-milling

One of the limitations of the use of corn in the food chain is its contamination with mycotoxins. Reduction in their levels can be achieved by processing the grain, which in the case of corn can be achieved by wet or dry milling. The aim of this study was to compare the distribution of aflatoxins B1 and B2, and fumonisin B1 in corn fractions obtained by dry and wet milling, aiming to identify conditions to mitigate the risk of exposure to these contaminants. Naturally, contaminated corn kernels were subjected to laboratory milling. The wet-milling conditions containing 1% lactic acid in the steeping solution and 18 h of steeping were the most efficient for mycotoxin reduction in the endosperm fraction, reducing aflatoxins B1 and B2 contamination to levels below the limit of quantification. Dry-milling reduced the concentration of these mycotoxins in the endosperm (98-99%). Fumonisin B1 contamination increased in the germ and pericarp fraction by more than three times in both dry and wet milling. Dry-milling reduced fumonisin B1 contamination in the endosperm to levels below the limit of quantitation. Wet and dry milling processes can be an efficient control method to reduce aflatoxins and fumonisin in the corn endosperm fraction.

Supplementary Information

The online version contains supplementary material available at 10.1007/s13197-022-05373-9.

1 An HPLC-MS/MS Method Using a Multitoxin Clean-up Column for Analysis of Seven Mycotoxins in Aquafeeds

BACKGROUND

In Guangdong Province of China, the climate here is very wet, so there are many different fungus living in the aquatic feeds, which produce mycotoxins. These compounds contaminate agriculture products world-wide and represent a great threat to human health. It is necessary to determine their contamination level in aquatic feeds.

OBJECTIVE

A high performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method was developed for the quantitative analysis of aflatoxin B1, aflatoxin M1, T-2 toxin, HT-2 toxin, deoxynivalenol, ochratoxin, and zearalenone in the fish and shrimp feed.

METHODS

Samples were extracted with acetonitrile-water (V: V = 3:1), and degreased with acetonitrile-saturated hexane. Such obtained extract was cleaned up with a multitoxin column. The target compounds were separated on a C18 chromatographic column and analyzed simultaneously by electrospray ionization mass spectrometry in both positive or negative ion mode. Detected compounds were quantified by using the matrix-matched external standard method.

RESULTS

Under the optimized conditions, good linearities for the analytes in corresponding concentration range were obtained with correlation coefficients (r2) higher than 0.9948. LOD ranged from 1.83 to 12.63 μg/kg, and LOQ ranged from 5.49 to 37.89 μg/kg. Average recoveries for the target mycotoxins at three spiked levels ranged from 80.5% to 116.5% with RSD ranging from 2.4% to 10.4%. 23 real aquafeed samples were determined by this method, and 7 kinds of toxins were all detected.

CONCLUSIONS

Obtained results showed that developed method could be successfully applied for the simultaneous determination of mycotoxins in aquatic feeds.

Quantification of aflatoxin and ochratoxin contamination in animal milk using UHPLC-MS/SRM method: a small-scale study

Mycotoxin contamination in animal milk is an emerging concern around the globe. Here we developed and validated an ultrahigh-performance liquid chromatography and mass spectrometry-selected reaction monitoring (UHPLC/MS-SRM) method to quantify low concentrations of aflatoxins (AFs) and ochratoxins (OTs) in routinely consumed animal milk samples collected from southern India. Stable isotope dilution methodology was applied to quantify AFB1, AFB2, AFG1, AFG2, AFM1, AFM2 and OTA, OTB in n = 38 different milk samples, using 1 mL of milk. Bioanalytical parameters including method accuracy, precision, recovery, regression analysis and stability were assessed. Dynamic ranges for quantification were between 15.6-1000 pg/mL for AFB1, AFB2, AFG1, and OTA; 7.8-500 pg/mL for AFM1, AFM2 and OTB; 78.6-5000 pg/mL for AFG2. Method accuracy ranged between 80-120%, with ± 15% precision. Recoveries for spiked standards were > 88% in water and 75% in milk, with limits of quantification (LOQ) ranging between 31.3 pg/mL for AFB1, AFB2, AFG1 and OTA, 15.6 pg/mL for AFM1, AFM2 and OTB and 156 pg/mL for AFG2. R2 values for regression analyses ranged between 0.9991-0.9999. AFB2 [mean: 38 pg/mL (0.038 µg/kg)] was quantified in goat milk, AFM1 was quantified in cow, goat, pasteurized milk [mean: 331 pg/mL (0.331 µg/kg), 406 pg/mL (0.406 µg/kg), 164 pg/mL (0.164 µg/kg)]. Additionally, 90% of cow, goat and pasteurized milk samples were above European Union (EU) limits of 50 pg/mL (0.05 µg/kg) and 40% of cow and goat milk samples were above the Food Safety Standards Authority of India (FSSAI) limit of 500 pg/mL (0.5 µg/kg). AFM2 was also quantified in cow, goat, and pasteurized milk samples [mean: 249 pg/mL (0.249 µg/kg), 375 pg/mL (0.375 µg/kg), 81 pg/mL (0.081 µg/kg)]. Our dynamic ranges for quantification are lower than other published methods, with need for a smaller volume of milk. This validated method can be applied for routine quantification of mycotoxins in milk.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at (10.1007/s13197-021-04986-w).

High-throughput Analysis of Aflatoxins in Cereals, Nuts and Processed Products Involving Automated Immunoaffinity Cleanup and Inline HPLC-Fluorescence Detection

BACKGROUND

The testing of aflatoxins (AFs) in fresh and processed foods is highly demanded to comply with trade regulations. Consequently, commercial laboratories face huge AF sample loads in food consignments. Worldwide, there is a rising interest to implement automation to increase sample throughput in AF analysis.

OBJECTIVE

This study sought to evaluate the performance of an automated cleanup and HPLC analysis system for determination of regulated AFs (B1, B2, G1, G2) in rice, flattened rice, sorghum, raw and processed peanut, almond, peanut butter, and wheat-based cookies.

METHODS

The samples were extracted with methanol-water (80:20), diluted with Triton X-100 and subjected to automated analysis, where the cleanup step through immunoaffinity column (IAC) and HPLC-fluorescence analyses [involving post-column bromination-derivatisation] were performed in 10 and 11 min, respectively. The method was validated in all test matrices at the LOQ and higher levels. The method performance was also evaluated against a conventional workflow where cleanup and HPLC analysis were manually performed.

RESULTS

The LOQ for peanut, sorghum, rice, and flattened rice was 0.125 ng/g, while it was 0.5 ng/g for peanut butter, almond, and wheat-based cookies. In all matrices, the recoveries at LOQ and higher levels were satisfactory. The double-cartridge exchange system completed the analysis of ∼96 injections in 18 h. Each IAC could be reused for 15-times, without incurring any recovery loss. The automated-system provided a better precision (RSD<9%) than the conventional (RSD=12-15%) workflow.

CONCLUSIONS

Because of its high-throughput nature, this method is recommended for routine analysis of AFs.

HIGHLIGHTS

A high-throughput method is reported where cleanup and HPLC analysis of aflatoxins were automatically performed. Each immunoaffinity column could be used 15-times without any loss in recoveries. The method performance was better than the conventional approach and complied with the analytical quality control guidelines.

Evaluation of Automated Sample Preparation for Mycotoxin Analysis in Foods

BACKGROUND

In the present study, we developed a novel automated sample preparation workflow for the determination of mycotoxins in foods.

OBJECTIVE

This workflow integrates off-line devices such as a centrifuge, shaker, liquid and solid dispensing units into a unified platform to perform gravimetric and volumetric dispensing, capping/decapping, extraction, shaking, filtration, and centrifugation. Two robotic arms provide sample transportation without human assistance.

METHOD

Critical method performance attributes were characterized using spiked corn, milk and peanut butter containing aflatoxins, deoxynivalenol, fumonisins, ochratoxin A, HT-2 and T-2 toxins and zearalenone and certified reference materials. Prepared samples were analyzed by liquid chromatography mass spectrometry (LC-MS).

RESULTS

Recoveries of spiked samples range 100-120% with RSD<20% and the majority of measured values of certified reference materials are consistent with certified values within ±20%. Within- and between-batch variabilities of QC samples range 5-9% and 7-12% respectively.

CONCLUSIONS

Our workflow introduces a straightforward and automated sample preparation procedure for LC-MS-based multimycotoxin analysis. Further, it demonstrates how individual sample preparation devices, that are conventionally used off-line, can be integrated together.

HIGHLIGHTS

This study shows automated sample preparation will replace manual operations and significantly increase the degree of automation and standardization for sample preparation.

Development and Validation of a Method for Direct Analysis of Aflatoxins in Animal Feeds by Ultra-High-Performance Liquid Chromatography with Fluorescence Detection

BACKGROUND AND OBJECTIVE

Aflatoxin (AF) contamination is one of the major regulatory concerns for animal feed. As feed is a complex analytical matrix, validated methods on AFs in feed are scanty. The available methods involve a derivatization step before AF analysis by high-performance liquid chromatography (HPLC) with fluorescence detection (FLD). The aim of this study was thus to develop and validate a simple and rapid method for direct analysis of AFs (AFB1, AFB2, AFG1, AFG2) in a range of animal feed matrices.

METHODS

Feed samples were extracted with 80% methanol, followed by dilution with water and immmunoaffinity column cleanup. AFs were estimated using an ultra-high performance liquid chromatography (UHPLC) instrument. Use of a large volume flow cell in FLD allowed direct analysis of all AFs with high sensitivity. The method was thoroughly validated in a range of feed matrices.

RESULTS

This sample preparation workflow minimized co-extractives, along with matrix interferences. In pigeon pea husk feed, the method provided a limit of quantification (LOQ) of 0.5 ng/g for each AF with recoveries of AF- B1, B2, G1, and G2 as 71.5, 75.6, 82.4, and 78.2%, respectively. The precision (relative standard deviation, RSD) was below 5%. A similar method performance was also recorded in other matrices, including wheat bran feed and poultry feed.

CONCLUSIONS

The optimized method is suitable for regulatory testing because it is simple, robust, cost-effective, and high throughput in nature, with high sensitivity and selectivity.

HIGHLIGHTS

Our workflow has provided a straightforward method for the analysis of AFs in a wide range of animal feed matrices with high sensitivity, selectivity, throughput, and cost-effectiveness. The method allowed a direct analysis of AFs by UHPLC-FLD without a step of derivatization.

Development and validation of an analytical method for the multiresidue analysis of pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry

For the first time, an analytical method for the multiresidue analysis of multiclass pesticides in sesame seeds using liquid- and gas chromatography with tandem mass spectrometry (LC-MS/MS and GC-MS/MS) was developed and validated. At first, the sample was comminuted after adding water (1:2 w/v). The sample preparation workflow included acetonitrile extraction, followed by freeze-out of the extract at -80°C with a subsequent cleanup by dispersive solid phase extraction (dSPE) (100 mg of C₁₈ + 150 mg of MgSO₄ for LC-MS/MS and 100 mg of C₁₈ + 25 mg florisil + 150 mg of MgSO₄ for GC-MS/MS). As noted, these cleanup steps were quite effective in removing the fatty co-extractives. The optimised sample preparation method effectively minimised the matrix effects and offered a limit of quantification (LOQ) of 0.01 mg/kg for most compounds. The LC-MS/MS and GC-MS/MS methods were validated at three levels (0.01, 0.02 and 0.05 mg/kg) for 222 and 220 compounds respectively. The method accuracy and precision complied with the performance criteria of the SANTE/12682/2019 analytical quality control procedure. The results of the intra-laboratory (involving six analysts) and inter-laboratory studies (involving eight accredited laboratories) were comparable for all pesticides. Considering its performance efficiency and alignment with the regulatory guidelines, this method can be implemented across the food testing laboratories for the monitoring of pesticide residues in sesame seeds.

Improved Sample Selection and Preparation Methods for Sampling Plans Used to Facilitate Rapid and Reliable Estimation of Aflatoxin in Chicken Feed

Aflatoxin B1 (AFB1), a toxic fungal metabolite associated with human and animal diseases, is a natural contaminant encountered in agricultural commodities, food and feed. Heterogeneity of AFB1 makes risk estimation a challenge. To overcome this, novel sample selection, preparation and extraction steps were designed for representative sampling of chicken feed. Accuracy, precision, limits of detection and quantification, linearity, robustness and ruggedness were used as performance criteria to validate this modification and Horwitz function for evaluating precision. A modified sampling protocol that ensured representativeness is documented, including sample selection, sampling tools, random procedures, minimum size of field-collected aggregate samples (primary sampling), procedures for mass reduction to 2 kg laboratory (secondary sampling), 25 g test portion (tertiary sampling) and 1.3 g analytical samples (quaternary sampling). The improved coning and quartering procedure described herein (for secondary and tertiary sampling) has acceptable precision, with a Horwitz ratio (HorRat = 0.3) suitable for splitting of 25 g feed aliquots from laboratory samples (tertiary sampling). The water slurring innovation (quaternary sampling) increased aflatoxin extraction efficiency to 95.1% through reduction of both bias (-4.95) and variability of recovery (1.2-1.4) and improved both intra-laboratory precision (HorRat = 1.2-1.5) and within-laboratory reproducibility (HorRat = 0.9-1.3). Optimal extraction conditions are documented. The improved procedure showed satisfactory performance, good field applicability and reduced sample analysis turnaround time.

Decontamination of aflatoxin B1 in peanuts using various cooking methods

Peanut and its processed products are recurrently contaminated with aflatoxins (AFs) which are of potential public health concern. Among the different types of AFs, Aflatoxin B1 (B1) is the most frequently detected in peanuts over the maximum level (ML), and thus has warranted considerable research interest in the domain of food safety. In this study, we investigated the decontamination of B1 in three naturally-incurred lots (4, 12, and 40 µg/kg) of peanuts by a range of cooking treatments, including frying, pressure cooking, and roasting. B1 concentrations were determined by ultra-high performance liquid chromatography- fluorescence detection. The method provided a limit of quantification of 0.25 µg/kg for B1, which was much lower than any of its national and international MLs. The recoveries of B1 in fresh and cooked peanuts (positive-control) were in the range of 90-100%. Overall, all the cooking methods demonstrated a significant reduction in B1 loads. The degree to which the processing methods reduced the B1 content followed the pattern: roasting with a combination of NaCl and citric acid > pressure-cooking with a combination of NaCl and citric acid > frying. As the cooking procedures did not involve any complicated steps or sophisticated equipment, these could be readily adopted for decontamination or reduction in the level of B1 for a safer consumption of peanuts at the household level without affecting the organoleptic properties.

A Review: Sample Preparation and Chromatographic Technologies for Detection of Aflatoxins in Foods

As a class of mycotoxins with regulatory and public health significance, aflatoxins (e.g., aflatoxin B1, B2, G1 and G2) have attracted unparalleled attention from government, academia and industry due to their chronic and acute toxicity. Aflatoxins are secondary metabolites of various Aspergillus species, which are ubiquitous in the environment and can grow on a variety of crops whereby accumulation is impacted by climate influences. Consumption of foods and feeds contaminated by aflatoxins are hazardous to human and animal health, hence the detection and quantification of aflatoxins in foods and feeds is a priority from the viewpoint of food safety. Since the first purification and identification of aflatoxins from feeds in the 1960s, there have been continuous efforts to develop sensitive and rapid methods for the determination of aflatoxins. This review aims to provide a comprehensive overview on advances in aflatoxins analysis and highlights the importance of sample pretreatments, homogenization and various cleanup strategies used in the determination of aflatoxins. The use of liquid-liquid extraction (LLE), supercritical fluid extraction (SFE), solid phase extraction (SPE) and immunoaffinity column clean-up (IAC) and dilute and shoot for enhancing extraction efficiency and clean-up are discussed. Furthermore, the analytical techniques such as gas chromatography (GC), liquid chromatography (LC), mass spectrometry (MS), capillary electrophoresis (CE) and thin-layer chromatography (TLC) are compared in terms of identification, quantitation and throughput. Lastly, with the emergence of new techniques, the review culminates with prospects of promising technologies for aflatoxin analysis in the foreseeable future.

Developments in mycotoxin analysis: an update for 2017-2018

This review summarises developments that have been published in the period from mid-2017 to mid-2018 on the analysis of various matrices for mycotoxins. Analytical methods to determine aflatoxins, Alternaria toxins, ergot alkaloids, fumonisins, ochratoxins, patulin, trichothecenes, and zearalenone are covered in individual sections. Advances in sampling strategies are discussed in a dedicated section, as are methods used to analyse botanicals and spices, and newly developed comprehensive liquid chromatographic-mass spectrometric based multi-mycotoxin methods. This critical review aims to briefly discuss the most important recent developments and trends in mycotoxin determination as well as to address limitations of the presented methodologies.