Determination of fumonisins B1 and B2 in corn by liquid chromatography/mass spectrometry with immunoaffinity column cleanup: single-laboratory method validation

A single-laboratory method validation was conducted to establish the effectiveness of an immunoaffinity column cleanup procedure followed by liquid chromatography/mass spectrometry (LCIMS) for the determination of fumonisins B1 and B2 (FBI + FB2) in corn. The test portion is extracted with acetonitrile-methanol-water (25 + 25 + 50). The extract is filtered, diluted with phosphate-buffered saline solution, and applied to an immunoaffinity column. FB1 + FB2 are removed with methanol and directly determined by reversed-phase LC with MS detection using selected-ion monitoring of 2 characteristic ions in each case. Test portions of blank corn samples were spiked with a mixture of FB1 + FB2 to give total levels of 200 and 500 ng/g, respectively. Recoveries of both FB1 and FB2 from spiked samples averaged 90.4-101%. Based on results for spiked raw corn (triplicates at 2 levels), the relative standard deviation for repeatability ranged from 2.8 to 7.1%. The accuracy of the method was demonstrated by analysis of Food Analysis Performance Assessment Scheme (FAPAS) test material. The method was also applied to a small survey of processed corn products such as corn chips, cornflakes, and popcorn.     

Determination of fumonisins B1 and B2 in corn and corn flakes by liquid chromatography with immunoaffinity column cleanup: collaborative study.

A liquid chromatographic (LC) method for the determination of fumonisins B1 (FB1) and B2 (FB2) in corn and corn flakes was collaboratively studied by 23 laboratories, which analyzed 5 blind duplicate pairs of each matrix to establish the accuracy, repeatability, and reproducibility characteristics of the method. Fumonisin levels in the corn ranged from <0.05 (blank) to 1.41 microg/g for FB1 and from <0.05 to 0.56 microg/g for FB2, whereas in the corn flakes they ranged from <0.05 to 1.05 microg/g for FB1 and from <0.05 to 0.46 microg/g for FB2. The method involved double extraction with acetonitrile-methanol-water (25 + 25 + 50), cleanup through an immunoaffinity column, and LC determination of the fumonisins after derivatization with o-phthaldialdehyde. Relative standard deviations for the within-laboratory repeatability (RSDr) of the corn analyses ranged from 19 to 24% for FB1 and from 19 to 27% for FB2; for the corn flakes analyses, RSDr ranged from 9 to 21 % for FB1 and from 8 to 22% for FB2. Relative standard deviations for the between-laboratories reproducibility (RSDR) of the corn analyses ranged from 22 to 28% for FB1 and from 22 to 30% for the FB2; for corn flakes analyses, RSDR ranged from 27 to 32% for FB1 and from 26 to 35% for FB2. Mean recoveries of FB1 and FB2 from corn spiked with FB1 at 0.80 microg/g and with FB2 at 0.40 microg/g were 76 and 72%, respectively; for corn flakes spiked at the same levels recoveries were 110 and 97% for FB1 and FB2, respectively. HORRAT ratios for the analyses of corn ranged from 1.44 to 1.53 for FB1 and from 0.96 to 1.48 for FB2, whereas for corn flakes they ranged from 1.60 to 1.82 for FB1 and from 1.39 to 1.68 for FB2.     

Evaluation of silica- and sepharose-based immunoaffinity sorbents for sample cleanup in determination of fumonisins B1 and B2 in corn products

Anti-fumonisin B1 polyclonal antibodies were isolated from the serum of rabbits, immobilized onto the surface of glutaraldehyde-activated silica or Sepharose CL-4B particles, and placed into empty small plastic solid-phase extraction cartridges. The immobilized antibodies were evaluated for their ability to retain fumonisin B1 and fumonisin B2. Cartridge capacity and elution conditions were determined, and the results were compared to those obtained with a commercially available cartridge. The cartridges, which were tested for their effectiveness to isolate the fumonisins from extracts of corn flour and nacho chips, detected fumonisins down to levels of about 20 ng/g. However, additional cleanup was required for detection at lower concentrations. With the use of a strong anion-exchange cartridge as a preliminary cleanup before immunoaffinity chromatography, the detection limit reached 2-5 ng/g in the products tested. The silica sorbent material exhibited strong interactions with the fumonisins, requiring acidified ethanol-water mixtures for elution and resulting in an additional degree of selectivity in isolating fumonisins from sample extracts. The silica-based immunoaffinity cartridges were successfully reused more than 10 times; the Sepharose-based cartridges were less robust. Liquid chromatography with fluorescence detection was used after prechromatographic derivatization with o-phthaldialdehyde-mercaptoethanol.     

Determination of total fumonisins in corn by competitive direct enzyme-linked immunosorbent assay: collaborative study

Fumonisins-mycotoxins produced by some Fusarium species-have been shown to be the causative agent of diseases in horses and other domesticated animals as well as possible carcinogens in humans. A collaborative study was conducted to evaluate the effectiveness of a competitive direct enzyme-linked immunosorbent assay (CD-ELISA) for the determination of total fumonisins (B1, B2, and B3) in corn. The test portion was extracted with methanol-water (7 + 3), filtered, diluted, and tested on the CD-ELISA. Naturally and artificially contaminated corn test portions were sent to 13 collaborators in the United States. Naturally contaminated field test portions were prepared at 3 different levels. Artificially contaminated test portions were spiked at 1.0, 3.0, and 5.0 mg/kg total fumonisins (B1, B2, and B3). Average recoveries of total fumonisins were 120, 100, and 90%, respectively. The relative standard deviations for repeatability ranged from 13.3 to 23.3% and the relative standard deviations for reproducibility ranged from 15.8 to 30.3% across all levels tested. HORRAT values, calculated for each individual sample, ranged from 1.24 to 1.94. This method demonstrated acceptable intra- and interlaboratory precision at the levels tested.     

Robotic automated clean-up for detection of fumonisins B1 and B2 in corn and corn-based feed by high-performance liquid chromatography

A high-performance liquid chromatography (HPLC) system with fluorescence detection and an automated on-line solid-phase extraction procedure for fumonisins B1 and B2 in corn and corn-based products is described. Different amounts of strong anion-exchange, C18 and end-capped C18 (C(18 ec)) silicas were tested for sample clean-up. Various HPLC parameters were analyzed. The best methodology was found to be extraction with acetonitrile-water and clean up on C(18 ec) disposable extraction cartridges. The system has the advantage of running in an unattended mode of operation and allows processing of 40 samples without system refuel, performing clean-up, o-phthaldialdehyde derivatization, injection and fumonisin detection by fluorescence detection linked to a computer integrator for automated data processing. Recoveries were performed with corn and corn-based feed samples (n=3) spiked with 0.1, 0.5, 1.0, 5.0 and 10 microg/g. Average recoveries for corn and corn-based feed were, respectively, 92.6 and 88.3% with relative standard deviations (RSDs) of 5.04 and 6.22%, for fumonisin B1 and 91.2 and 89.0% with RSDs of 5.84 and 7.88% for fumonisin B2. Detection limits (S/N=3) for corn and corn-based feed were approximately 0.03 microg/g for fumonisin B1 and 0.05 microg/g for fumonisin B2     

Effect of solvents on the fumonisins analysis by high-performance liquid chromatography with AccQ.Fluor as the derivatizing reagent

The effect of several solvent systems on the chromatographic response of fumonisin B₁ and B₂ derived with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AccQ.Fluor) is described. Naturally contaminated corn samples were extracted and purified by a standard method. Then, samples were dissolved in different solvents, derived with AccQ.Fluor reagent and analysed using HPLC. Results were solvent dependent, methanol being the best one among all assayed solvents for both fumonisins studied and acetonitrile the poorest. o-Phthaldialdehyde (OPA) reagent was used as a reference method.     

Analysis of fumonisins B(1), B(2) and B(3) in corn-based baby food by pressurized liquid extraction and liquid chromatography/tandem mass spectrometry

A sensitive and reliable method using pressurized liquid extraction (PLE) and liquid chromatography (LC)/electrospray ionization (ESI) tandem mass spectrometry with a triple quadrupole (QqQ) analyzer has been developed for the analysis of fumonisin B(1) (FB(1)), fumonisin B(2) (FB(2)) and fumonisin B(3) (FB(3)) in corn-based baby foods. Influence of several extraction parameters that affect PLE efficiency such as temperature, pressure, solvent extraction, number of cycles and dispersant/clean-up agents were studied. The selected PLE operating method was: 3g of sample was packed into 11 ml stainless-steel cell and fumonisins were extracted with methanol at 40 degrees C, 34 atm in one cycle of 5 min at 60% flush. The analytes were ionized in ESI operating with positive ion mode and identified by selecting two monitoring transitions, permitting quantification and confirmation in a single injection. Recoveries ranged from 68% to 83% at fortification levels of 200 microg kg(-1) with relative standard deviation (RSD) from 4% to 12%. The limits of quantification were from 2 microg kg(-1) for FB(1) and FB(2), and 5 microg kg(-1) for FB(3), which are below the maximum residue level established by the European Union legislation in infant formulas. The proposed method was successfully applied to the analysis of twenty seven samples of baby food products collected from different markets, and one positive sample with a content of 15.9 microg kg(-1) for FB(1), 9.2 microg kg(-1)for FB(2) and 5.8 microg kg(-1) for FB(3) was obtained. Given the simplicity and potential of the proposed procedure, its application for safety control is recommended.     

A reversed phase high performance liquid chromatography method for the determination of fumonisins B1 and B2 in food and feed using monolithic column and positive confirmation by liquid chromatography/tandem mass spectrometry

The development of a reversed phase high performance liquid chromatography fluorescence method for the determination of the mycotoxins fumonisin B(1) and fumonisin B(2) by using silica-based monolithic column is described. The samples were first extracted using acetonitrile:water (50:50, v/v) and purified by using a C(18) solid phase extraction-based clean-up column. Then, pre-column derivatization for the analyte using ortho-phthaldialdehyde in the presence of 2-mercaptoethanol was carried out. The developed method involved optimization of mobile phase composition using methanol and phosphate buffer, injection volume, temperature and flow rate. The liquid chromatographic separation was performed using a reversed phase Chromolith(?) RP-18e column (100 mm × 4.6 mm) at 30 °C and eluted with a mobile phase of a mixture of methanol and phosphate buffer pH 3.35 (78:22, v/v) at a flow rate of 1.0 mL min(-1). The fumonisins separation was achieved in about 4 min, compared to approximately 20 min by using a C(18) particle-packed column. The fluorescence excitation and emission were at 335 nm and 440 nm, respectively. The limits of detections were 0.01-0.04 μg g(-1) fumonisin B(1) and fumonisin B(2), respectively. Good recoveries were found for spiked samples (0.1, 0.5, 1.5 μg g(-1) fumonisins B(1) and B(2)), ranging from 84.0 to 106.0% for fumonisin B(1) and from 81.0 to 103.0% for fumonisin B(2). Fifty-three samples were analyzed including 39 food and feeds and 14 inoculated corn and rice. Results show that 12.8% of the food and feed samples were contaminated with fumonisin B(1) (range, 0.01-0.51 μg g(-1)) and fumonisin B(2) (0.05 μg g(-1)). The total fumonisins in these samples however, do not exceed the legal limits established by the European Union of 0.8 μg g(-1). Of the 14 inoculated samples, 57.1% contained fumonisin B(1) (0.16-41.0 μg g(-1)) and fumonisin B(2) (range, 0.22-50.0 μg g(-1)). Positive confirmation of selected samples was carried out using liquid chromatography-tandem mass spectrometry, using triple quadrupole analyzer and operated in the multiple reaction monitoring mode.     

Evaluation of Fumonitest Immunoaffinity Columns

Abstract

A method for the determination of fumonisins B1 and B2 in corn was developed. The method involves sample extraction with methanol:water (80:20) and the use of a commercially available Fumonitest column for sample cleanup. The capacity, selectivity, column-to-column and lot-to-lot reproducibility of the Fumonitest columns were evaluated. The total capacity of the column was found to be 1.2 μg fumonisin. Both fumonisins B1 and B2 had an equal affinity toward the Fumonitest column, with the sample matrix demonstrating little effect on the column performance. The maximum sample size was 0.5 g for samples containing total fumonisins of less than 2 ppm. After elution from the immunoaffinity column, fumonisins B1 and B2 were reacted with naphthalene-2, 3-dicarboxaldehyde (NDA) to produce a highly fluorescent derivative, 1-cyano-2-alkyl-benz[f]isoindole (CBI). The derivatives were then separated from the sample matrix on a reverse phase C-18 column with a mobile phase consisting of acetonitrile:water:acetic acid (55:45:1) Average recoveries of fumonisins B1 and B2 from corn samples spiked at a level of 1000 ng (500ng B1 + 500ng B2)/g were 85.4 and 87.1%, respectively. The detection limit for B1 and B2 was estimated to be 10 and 4 ppb, respectively. The coefficient of variations for fumonisins B1 and B2 were determined to be 10.2% and 10.6%, respectively.     

Development of supercritical fluid extraction with a solid-phase trapping for fast estimation of toxic load of polychlorinated dibenzo-p-dioxins-dibenzofurans in sawmill soil

A method consisting of automated supercritical fluid extraction (SFE) with simultaneous cleanup by a solid-phase trap was developed for fast analysis of polychlorinated dibenzo-p-dioxins (PCDDs) and dibenzofurans (PCDFs) in soil. SFE was optimised to replace conventional liquid-based methods in routine analyses of PCDD/PCDFs in sawmill soil contaminated by a chlorophenol formulation. PCDD/PCDFs were quantitatively extracted in 60 min using CO2 at 400 atm and 100 degrees C without a modifier. A trap containing a small amount of activated carbon mixed with Celite efficiently collected PCDD/PCDFs after SFE. After SFE co-extracted impurities were eluted out from the trap with 4 ml of hexane and PCDD/PCDFs were eluted with 10 ml of toluene. The concentrations and TCDD-equivalent of PCDD/PCDFs corresponded to the results of traditional solvent extraction method (Soxhlet) in six sawmill soils tested. The performance of the trap was maintained over a long period of time (nearly 100 extractions).     

Selective pressurized liquid extraction of polychlorinated biphenyls from fat-containing food and feed samples influence of cell dimensions, solvent type, temperature and flush volume

Sulphuric acid impregnated silica was used for the lipid free extraction of polychlorinated biphenyls from fat containing food and feed matrices using pressurized liquid extraction on a Dionex ASE300, with 34 mL cells. Data were compared to a previous publication where extractions had been performed on a Dionex ASE200, with 33 mL cells. Four different fat/fat retainer ratios (FFRs) were tested (0.100, 0.075, 0.050 and 0.025) at 50 and 100 degrees C using n-pentane, n-hexane or n-heptane as extraction solvent. The best results were obtained with a FFR of 0.025 when applying a temperature of 100 degrees C. Both n-pentane and n-heptane were capable of replacing n-hexane as extraction solvent. A flush volume of 60% was sufficient as suggested in US Environmental Protection Agency Method 3545. The applicability of the method was demonstrated for naturally contaminated fish meal as well as various spiked and certified materials.     

Accelerated solvent extraction of fluometuron from selected soils

Accelerated solvent extraction (ASE) is a recently developed extraction technique that is more rapid and produces less waste than do conventional liquid/liquid extraction methods. Optimal conditions were determined for ASE of fluometuron from 2 Weswood clay loam soils. Two solvents (acetonitrile and methanol), 2 temperatures (50 and 100 degrees C), and the number of static cycles (1, 2, and 3) were evaluated. The most efficient and reproducible extractions were obtained when methanol was combined with a 50 degrees C extraction temperature and the static cycle was repeated 3 times. These experiments indicated that existing extraction methods for fluometuron can easily be adapted for ASE.     

Superheated water extraction and phase transfer methylation of phenoxy acid herbicides from solid matrices

Phase transfer catalytic methylation was applied to directly derivatise chlorophenoxy acid herbicides in superheated water extracts from sand and soil samples. The extractions were carried out at 120 degrees C statically for 5 min and then dynamically for 10 min at 1.0 mL min(-1) using water at pH 11.0 for a sand matrix and a flow rate of 0.5 mL min(-1) at pH 7.0 for soil samples. The methylation was carried out on-line on the extraction solution with ultrasonication at 80 degrees C, using either 0.05 mmol tetrabutylammonium bromide (TBAB) or 0.0125 mmol cetyltrimethylammonium bromide (CTAB) as phase transfer catalysts with 0.20 mmol methyl iodide in 2.0 mL dichloromethane trapping solvent. The former catalyst provided a higher yield but the latter gave fewer interfering peaks. The recoveries of most chlorophenoxy acids using the TBAB catalyst ranged from 67 to 105% for sand and from 82 to 114% for soil sample, except phenoxyacetic acid, 2-(2, 4-dichlorophenoxy)propanoic acid and 1-naphthaleneacetic acid, while those by using CTAB were slightly lower. Detection limits of all the analytes extracted from sand using TBAB catalyst were in a range of 5.3-16 microg g(-1) analysed by using gas chromatography with flame ionization detection (GC-FID).     

A high-throughput platform for low-volume high-temperature/pressure sealed vessel solvent extractions

A high-throughput platform for performing parallel solvent extractions in sealed HPLC/GC vials inside a microwave reactor is described. The system consist of a strongly microwave-absorbing silicon carbide plate with 20 cylindrical wells of appropriate dimensions to be fitted with standard HPLC/GC autosampler vials serving as extraction vessels. Due to the possibility of heating up to four heating platforms simultaneously (80 vials), efficient parallel analytical-scale solvent extractions can be performed using volumes of 0.5-1.5 mL at a maximum temperature/pressure limit of 200°C/20 bar. Since the extraction and subsequent analysis by either gas chromatography or liquid chromatography coupled with mass detection (GC-MS or LC-MS) is performed directly from the autosampler vial, errors caused by sample transfer can be minimized. The platform was evaluated for the extraction and quantification of caffeine from commercial coffee powders assessing different solvent types, extraction temperatures and times. For example, 141±11 μg caffeine (5 mg coffee powder) were extracted during a single extraction cycle using methanol as extraction solvent, whereas only 90±11 were obtained performing the extraction in methylene chloride, applying the same reaction conditions (90°C, 10 min). In multiple extraction experiments a total of ~150 μg caffeine was extracted from 5 mg commercial coffee powder. In addition to the quantitative caffeine determination, a comparative qualitative analysis of the liquid phase coffee extracts and the headspace volatiles was performed, placing special emphasis on headspace analysis using solid-phase microextraction (SPME) techniques. The miniaturized parallel extraction technique introduced herein allows solvent extractions to be performed at significantly expanded temperature/pressure limits and shortened extraction times, using standard HPLC autosampler vials as reaction vessels. Remarkable differences regarding peak pattern and main peaks were observed when low-temperature extraction (60°C) and high-temperature extraction (160°C) are compared prior to headspace-SPME-GC-MS performed in the same HPLC/GC vials.     

Efficient "total" extraction of perfluorooctanoate from polytetrafluoroethylene fluoropolymer

To determine the optimum conditions for the complete extraction of perfluorooctanoate (PFO) from polytetrafluoroethylene fluoropolymers, sample preparation and pressurized solvent extraction (PSE) conditions were investigated. Solvent extraction temperature, solvent residence time, relaxation time between extractions, and the effects of heating before PSE showed that methanol at 150 degrees C extraction temperature and a 12 min solvent residence time were the most efficient conditions. Preheating the polymer before extraction at 150 degrees C for 24 h significantly enhanced the quantity of PFO removed. Heating above 150 degrees C resulted in loss of PFO. PFO was determined by liquid chromatography with tandem mass spectrometry.     

Development of a microwave-assisted-extraction-based method for the determination of aflatoxins B1, G1, B2, and G2 in grains and grain products

This article describes the use of microwave-assisted extraction (MAE) as a pretreatment technique for the determination of aflatoxins B₁, G₁, B₂, and G₂ in grains and grain products. The optimal operation parameters, including extraction solvent, temperature, and time, were identified to be acetonitrile as the extraction solvent at 80 °C with 15 min of MAE. The extracts were cleaned up using solid-phase extraction followed by derivatization with trifluoroacetic acid and were determined by liquid chromatography–fluorescence detection. A Sep-Pak cartridge was chosen over Oasis HLB and Bond Elut cartridges. By the use of aflatoxin M₁ as an internal standard, relative recoveries of the aflatoxins ranged from 90.7 to 105.7 % for corn and from 88.1 to 103.4 % for wheat, with relative standard deviations between 2.5 and 8.7 %. A total of 36 samples from local markets were analyzed, and aflatoxin B₁ was found to be the predominant toxin, with concentrations ranging from 0.42 to 3.41 μg/kg.

The extraction and speciation of arsenic in rice flour by HPLC-ICP-MS

Several solvent mixtures and techniques for the extraction of arsenic (As) species from rice flour samples prior to their analysis by HPLC-ICP-MS were investigated. Microwave-assisted extraction using water at 80 °C for 30 min provided the highest extraction efficiency. Total recoveries of extracted As species were in good agreement with the total As concentrations determined by ICP-MS after microwave-assisted acid digestion of the samples. Arsenite [As(III)], arsenate [As(V)] and dimethylarsinic acid (DMAA) were the main species detected in rice flour samples.     

Determination of fumonisins B1 and B2 in various maize products by a combined SAX + C18 column and immunoaffinity column

Fumonisins B1 and B2 were determined in 42 samples of different maize products from the Swedish market by 2 different methods based on cleanup steps using an immunoaffinity column and a combination of SAX + C18 columns, respectively. A simple "precipitation step" was included before the samples were added to the main column(s), giving less column clogging, fewer interfering peaks, and better recoveries for the different sample matrixes. Recovery, repeatability, and results from the survey showed comparable results with the methods. The limit of detection for both methods was 5 micrograms/kg for fumonisin B1 and 10 micrograms/kg for fumonisin B2. All 7 maize chips analyzed and 6 of 8 popcorn samples contained fumonisins (B1 + B2) with averages of 180 and 115 micrograms/kg, respectively. All other samples except a maize flour sample contained little or no fumonisins.     

Influence of extraction methodologies on the analysis of five major volatile aromatic compounds of citronella grass (Cymbopogon nardus) and lemongrass (Cymbopogon citratus) grown in Thailand

This paper deals with the systematic comparison of extraction of major volatile aromatic compounds (VACs) of citronella grass and lemongrass by classical microhydrodistillation (MHD), as well as modern accelerated solvent extraction (ASE). Sixteen VACs were identified by GC/MS. GC-flame ionization detection was used for the quantification of five VACs (citronellal, citronellol, geraniol, citral, and eugenol) to compare the extraction efficiency of the two different methods. Linear range, LOD, and LOQ were calculated for the five VACs. Intraday and interday precisions for the analysis of VACs were determined for each sample. The extraction recovery, as calculated by a spiking experiment with known standards of VACs, by ASE and MHD ranged from 64.9 to 91.2% and 74.3 to 95.2%, respectively. The extraction efficiency of the VACs was compared for three solvents of varying polarities (hexane, dichloromethane, and methanol), seven different temperatures (ranging from 40 to 160 degrees C, with a gradual increment of 20 degrees C), five time periods (from 1 to 10 min), and three cycles (1, 2, and 3 repeated extractions). Optimum extraction yields of VACs were obtained when extractions were carried out for 7 min with dichloromethane and two extraction cycles at 120 degrees C. The results showed that the ASE technique is more efficient than MHD, as it results in improved yields and significant reduction in extraction time with automated extraction capabilities.     

Use of liquid chromatography–high‐resolution mass spectrometry for isolation and characterization of hydrolyzed fumonisins and relevant analysis in maize‐based products

The synthesis of partially hydrolyzed fumonisins (PHFB₁ and PHFB₂) and hydrolyzed fumonisins (HFB₁ and HFB₂) by chemical hydrolysis of pure fumonisins (FB₁ and FB₂) is reported together with the isolation and characterization by liquid chromatography–high‐resolution mass spectrometry (LC–HRMS). Two structural isomers of partially hydrolyzed forms of FB₁ and FB₂ were identified, namely PHFB_1a and PHFB_1b and PHFB_2a and PHFB_2b. Reaction yields were 21% for PHFB₁ (sum of the two isomers), 52% for HFB₁, 31% for PHFB₂ (sum of the two isomers) and 30% for HFB₂. Purity of each isolated compound was >98%. An LC–HRMS method for the simultaneous determination of fumonisins and their partially and totally hydrolyzed derivatives was applied to 24 naturally contaminated samples of maize and maize‐based products. The majority of samples (18 out of 24) were contaminated with fumonisins B₁ and B₂. Fumonisins co‐occurred with both partially hydrolyzed and hydrolyzed fumonisins in four nixtamalized samples (three masa flours and one tortilla chips). Co‐occurrence of fumonisins with partially hydrolyzed fumonisins was also recorded in one sample of maize kernels and four samples of maize‐based products (i.e. maize meal, cous‐cous, corn‐cakes and cornflakes). Mycotoxins levels ranged from 60 to 5700 µg/kg for fumonisins (sum of FB₁ and FB₂), from 10 to 210 µg/kg for partially hydrolyzed fumonisins (sum of PHFB₁ and PHFB₂) and from 30 to 200 µg/kg for hydrolyzed fumonisins (sum of HFB₁ and HFB₂). This is the first report of the isolation of PHFB₂ and the co‐occurrence of FB_1, FB₂, PHFB₁, PHFB₂, HFB₁ and HFB₂ in maize products. Considering the growing use of nixtamalized and maize‐based products, the monitoring of fumonisins and their partially and totally hydrolyzed forms in these products may represent an important contributing factor in evaluating the relevant human risk exposure. Copyright © 2014 John Wiley & Sons, Ltd.