Fast determination of 14 mycotoxins in chestnut by dispersive solid‐phase extraction coupled with ultra high performance liquid chromatography‐tandem mass spectrometry

A dispersive solid‐phase extraction coupled with ultra high performance liquid chromatography with tandem mass spectrometry method was developed and validated for the simultaneous determination of T‐2 toxin, penicillic acid, fumonisins B₁, B₂, and B₃, aflatoxins B₁, B₂, G₁, and G₂, ochratoxin A, deoxynivalenol, 3‐acetyldeoxynivalenol, 15‐acetyldeoxynivalenol, and zearalenone in chestnut samples. The method was used to analyze 136 samples obtained from Shandong province in China. The mycotoxins were extracted using a dispersive solid‐phase extraction method and cleaned using an improved quick, easy, cheap, effective, rugged, and safe approach. The mycotoxins were then detected using a triple‐quadrupole mass spectrometer. The limits of detection and quantification ranged from 0.02 to 1 and 0.1 to 2 μg/kg, respectively. The recovery rates ranged from 74.2 to 109.5%, with relative standard deviations below 15%. A total of 71 samples were contaminated with seven mycotoxins at concentrations ranging from 1.2 to 105.5 μg/kg, with a number of samples exceeding the maximum limits set in the European regulations for mycotoxins in unprocessed chestnuts.     

Determination of fumonisins B1 and B2 in Portuguese maize and maize-based samples by HPLC with fluorescence detection

Fumonisins B₁ (FB₁) and fumonisin B₂ (FB₂) are the main members of a family of mycotoxins produced by Fusarium verticillioides, Fusarium proliferatum, and other fungi species of the section Liseola. The present work shows the results of comparative studies using two different procedures for the analysis of fumonisins in maize and maize-based samples. The studied analytical methods involve extraction with methanol/water, dilution with PBS, and clean-up through immunoaffinity columns. Two reagents (o-phthaldialdehyde and naphthalene-2,3-dicarboxaldehyde) were studied for formation of fluorescent derivatives. The separation and identification were carried out by high-performance liquid chromatography with fluorescence detection. The optimized method for analysis of fumonisins in maize involved extraction with methanol/water (80:20), clean-up with an immunoaffinity column, and derivatization with naphthalene-2,3-dicarboxaldehyde (NDA). The limit of detection was 20 μg kg⁻¹ for FB₁ and 15 μg kg⁻¹ for FB₂. Recoveries of FB₁ and FB₂ ranged from 79% to 99.6% for maize fortified at 150 μg kg⁻¹ and 200 μg kg⁻¹, respectively, with within-day RSDs of 3.0 and 2.7%. The proposed method was applied to 31 samples, and the presence of fumonisins was found in 14 samples at concentrations ranging from 113 to 2,026 μg kg⁻¹. The estimated daily intake of fumonisins was 0.14 μg kg⁻¹ body weight per day.     

Sequential Voltammetric Determination of Uranium,Cadmium and Lead by Using the ex situ Bismuth Film Electrode: Application to Phosphate Fertilizers

A sequential voltammetric procedure for the determination of uranium, cadmium and lead was investigated at an ex situ bismuth film electrode (BiFE). First, the adsorptive stripping voltammetry was applied to assay the U(VI)‐cupferron complex in the differential pulse mode (detection limit of 1.0 µg L^?1, 200 s accumulation time). Through the manipulation of the same aliquot of the sample, efforts were made to quantify cadmium and lead by square wave anodic stripping voltammetry. Detection limits of 2.03 µg L^?1 for Cd (II) and 2.43 µg L^?1 for Pb (II) were calculated (100 s accumulation time). The methodology was successfully applied to phosphate fertilizer samples after open vessel wet decomposition (HNO₃/H₂O₂). The following value ranges were evaluated: U (VI) 37.2–150 mg kg^?1, Pb (II) 78.3–204 mg kg^?1 and Cd (II) 44.1–71.6 mg kg^?1. Validation was performed by using the standard reference materials SRM‐695 – phosphate fertilizer – and SRM‐1643e – water.     

Simultaneous analysis of three avermectins in soils by high-performance liquid chromatography with fluorescence detection

A simple and sensitive method has been developed and validated for the determination of abamectin B_1a (ABA B_1a), emamectin B_1a (EMA B_1a) benzoate and ivermectin H₂B_1a (IVM H₂B_1a) in soils. The avermectins (AVMs) residues were extracted from soils with acetonitrile/water (9?:?1, v/v) and then were purified on C₁₈ solid-phase extraction (SPE) cartridge. After being derivatised by N-methylimidazole (N-MIM) and trifluoroacetic anhydride (TFAA), the residues of three AVMs were analysed by high-performance liquid chromatography with fluorescence detection (HPLC-FLD). The method was validated in terms of system suitability, linearity, selectivity, precision, recovery, specificity and stability. There was a good linear relationship (R ^2?>?0.99) for three AVMs ranged from 0.01 to 5?µg?mL^?1. The LOD and LOQs of ABA B_1a, EMA B_1a benzoate and IVM H₂B_1a for standard solutions were 1.1–1.7 and 3.6–5.7?µg?L^?1 respectively. The accuracy of AVMs in soils was from 83.7 to 115.5% with precision less than or equal to 12.4%. Using the developed method, 9 soil samples with 9.3–12806.3?µg?kg^?1 of AVMs residues had been detected.     

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.     

Validation of QuEChERS-based UPLC-MS/MS method for determination of quinoid niclosamide (LDS) residue in water,soil and rice samples

A sensitive, rapid and easy analytical method was validated for the determination of quinoid niclosamide (LDS) molluscicide in water, rice and soil using a QuEChERS extraction procedure and ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) detection. The LDS was extracted by using acetonitrile and then cleaned up by using dispersive solid-phase extraction with florisil and C18 sorbents. The determination of the target compound was achieved in less than 3 min using an electrospray ionisation source in negative mode. The overall average recoveries for this method in water, rice and soil matrix at three fortified levels ranged from 82.54 to 99.9%, with relative standard deviations in the range of 1.51 to 4.86% (n = 5). The calculated limits of detection were lower than 0.1 µg kg^?1 and quantification was 5 µg kg^?1; these values were much lower than the maximum residue levels established by the Australian standard (0.01 mg kg^?1). The results of the method validation confirmed that this proposed method is convenient and reliable for the determination of LDS molluscicide in water, rice and soil samples.     

Levels of polycyclic aromatic hydrocarbons,polychlorinated byphenyls,methylmercury and butyltins in the natural UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay,Spain)

Polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs), methylmercury (MeHg⁺) and butyltins (mono-, di- and tri-butyltin, MBT, DBT and TBT) were monitored in oysters (Crassostrea sp.) and sediments collected in different sampling points of the UNESCO reserve of the biosphere of Urdaibai (Bay of Biscay) from March 2006 to June 2007. In the case of oyster samples, concentrations in the 290–1814 µg kg^?1 (PAHs), 70–475 µg kg^?1 (PCBs), 75–644 µg kg^?1 (MeHg⁺) and 200–1300 µg kg^?1 (as a sum of the three butyltins) ranges were obtained. In most samples TBT was the most abundant butyltin, followed by DBT and MBT. It should be highlighted that most samples exceeded the highest range (367 µg kg^?1) found in the last mussel watch programme carried out by the National Oceanic and Atmospheric Administration (NOAA) for butyltins in oyster samples. This could be due to the presence of a shipyard in the estuary. Sediment concentrations ranged as follows: total PAHs (856–3495 µg kg^?1) and total PCBs (58–220 µg kg^?1). Organometallic species were always below the limits of detection (LODs) (0.24 µg kg^?1 for MeHg⁺, 0.6 µg kg^?1 for MBT, 0.48 µg kg^?1 for DBT and 1.1 µg kg^?1 for TBT). In both sediment and oyster PAH sources were mostly combustion. In the case of PCBs, 4-6 chlorine-atom congeners were the most abundant ones. Slight differences in the profile of PAHs as well as PCBs can be detected when the matrices were compared with each other. Finally, in the case of PAHs, sediment and water column played the main role in the accumulation pathway into the organisms in all the sampling stations.     

Simultaneous determination of aflatoxins B1, B2, G1, G2 in Fructus Bruceae by high‐performance liquid chromatography with online postcolumn photochemical derivatization

A simple, reliable, and highly sensitive method for the simultaneous determination of aflatoxin B₁, B₂, G₁, G₂ in Fructus Bruceae was developed using high‐performance liquid chromatography coupled to online postcolumn photochemical derivatization and fluorescence detection. Aflatoxins were first extracted by a methanol/water mixture and then cleaned up with an AflaTest? immunoaffinity column. Different clean‐up and derivatization methods were compared and optimized. The established method was extensively validated to show satisfactory performance of linearity (R² ≥ 0.9997), recovery (74.3–100.8%), and precision (RSDs ≤ 2.8%) for the investigated aflatoxins. This proposed method was also applied to 11 F. Bruceae samples and the results showed that 10 out of 11 were contaminated with aflatoxins ranging from 0.26 to 27.52 μg/kg and the occurrence of aflatoxin B₁, the most toxic one, was as high as 91% in all the samples, highlighting the severe contamination and the necessity to set legal limits for aflatoxins in F. Bruceae.     

Determination of Aflatoxin M1 in Milk by a Magnetic Nanoparticle-Based Fluorescent Immunoassay

A sensitive and rapid magnetic nanoparticle-based fluorescent immunoassay for the determination of aflatoxin M1 in raw milk was developed. Aflatoxin M1 was converted to aflatoxin M1-o-carboxymethyl oxime. The aflatoxin M1-oxime was used for the preparation of aflatoxin M1-oxime-fluoresceinamine conjugate through the carbodiimide reaction. The aflatoxin M1-oxime-fluoresceinamine conjugate was characterized by ultraviolet–visible and infrared spectroscopy. Magnetic nanoparticles (Fe₃O₄) were synthesized and modified by 3-(aminopropyl)triethoxysilane. The size of initial (139?nm) and functionalized magnetic nanoparticles (147?nm) was determined by particle analysis. The optimal mass of immobilized antibody (25?µg) and optimal concentration of aflatoxin M1-oxime-fluoresceinamine conjugate (15?µg?mL^?1) for magnetic nanoparticle-based fluorescent immunoassay were determined. The developed immunoassay provided a linear aflatoxin M1 concentration range from 3.0 to 100?pg?mL^?1 in bovine milk. The detection limit was 2.9?pg?mL^?1. The results of aflatoxin M1 magnetic nanoparticle-based fluorescent immunoassay in heat-treated milk and phosphate-buffered saline at pH 6.6 were compared. The influence of the somatic cell count, pH, and fat concentration in bovine milk on the aflatoxin M1 immunoassay was investigated. The influence of the milk species on the immunoassay was also characterized. The high fat concentration ovine milk depressed the sensitivity of the aflatoxin M1 immunoassay.     

Wide‐scope analysis of pesticide and veterinary drug residues in meat matrices by high resolution MS: detection and identification using Exactive‐Orbitrap

A multiresidue and multiclass method for the simultaneous determination of more than 350 compounds including pesticides, biopesticides and veterinary drugs in different meat matrices (beef, pork and chicken) by ultra‐high performance liquid chromatography coupled to Orbitrap MS has been developed. In the present study, the determination of fragments was accomplished as an essential tool for a reliable identification of compounds using high resolution MS. To obtain these fragments, different strategies have been carried out in order to ensure an appropriate fragment assignment and identification. The analytical method is suitable for qualitative analysis, and it was also evaluated for quantitative analysis. Generic extraction conditions were optimized, obtaining adequate recovery and precision values for most of the studied analytes (>290). The limits of detection ranged from 2 to 16 µg kg^?1. Limits of quantification were 10 µg kg^?1 with the exception of few compounds with a higher value (50 or 100 µg kg^?1). Limits of identification were also established, and they ranged from 2 to 150 µg kg^?1. This method was applied to the analysis of 18 meat samples and some veterinary drugs as enrofloxacin and sulfadiazine were detected and further identified/quantified (with triple quadrupole) in two different samples at 33 µg kg^?1 and trace levels, respectively. No pesticides were detected in the analyzed samples. Copyright © 2014 John Wiley & Sons, Ltd.     

Synthetic and antimicrobial studies on new gold(I) complexes of imidazolidin‐2‐ylidenes

Six new 1,3‐diorganylimidazolidin‐2‐ylidene (NHC) gold(I) complexes of the type [Au(NHC)₂]⁺ (1–6), were synthesized by reacting [AuCl(PPh)₃] with 1,3‐dimesitylimidazolidin‐2‐ylidene or bis(1,3‐dialkylimidazolidin‐2‐ylidene). The complexes 1–6 were fully characterized by elemental analyses and spectroscopic data. The placement of mesityl or para‐substituted benzyl groups on the nitrogen atoms of the ring of the complexes leads to the particularly active antibacterial agents evaluated in this work. It is worth noting that the p‐methoxybenzyl derivative (2) inhibited the growth of Pseudomona aeruginosa, Staphylococcus epidermidis, Staphylococcus aureus and Enterococcus faecalis with minimum inhibitory concentration (MIC) values of 3.12 µg ml^?1, 6.25 µg ml^?1, 3.12 µg ml^?1 and 3.12 µg ml^?1 respectively. In contrast, the analogous p‐dimethylaminobenzyl derivative (3) is effective only against Escherichia coli (MIC = 3.12 µg ml^?1). Copyright © 2004 John Wiley & Sons, Ltd.     

Development and validation of an LC–MS method for the simultaneous determination of sulfadiazine,trimethoprim, and N4-acetyl-sulfadiazine in muscle plus skin of cultured fish

An analytical method for the determination of both sulfadiazine (SDZ) and trimethoprim (TMP), and also N⁴-acetyl-sulfadiazine (AcSDZ), the main metabolite of SDZ, in fish muscle plus skin has been developed and validated. Dapsone was used as internal standard. The method involves extraction of the analytes from fish tissue by pressurized liquid extraction using water as extractant. Sample cleanup was carried out by solid phase extraction using Abselut Nexus cartridges. Target analytes were quantitatively determined by liquid–chromatography mass spectrometry using single ion monitoring. The developed method was validated according to the European Union requirements (decision 2002/657/EC). The limit of detection for SDZ and AcSDZ was 3.0 and 2.5 µg kg^?1 for TMP. The limit of quantification (LOQ) was 10 µg kg^?1 for SDZ and AcSDZ and 7.5 µg kg^?1 for TMP. The recovery experiments carried out included the concentration levels of 0.5, 1 and 1.5 times the MRLs for SDZ and TMP. Concentration levels for AcSDZ were the same as SDZ. The values obtained were higher than 92.0% with coefficient of variation (CV, %) below 8.6%. The precision of the method, calculated as CV (%), ranged from 0.2 to 6.8% and from 0.8 to 8.9% for intra–day and inter–day analysis, respectively. Decision limit (CC_α) was calculated as 104.3, 53.7 and 105.3 µg kg^?1 for SDZ, TMP and AcSDZ, respectively. Detection capability (CC_β) was calculated as 110.0, 58.8 and 109.7 µg kg^?1 for SDZ, TMP and AcSDZ, respectively. “Matrix effect” and “relative matrix effect” were also evaluated. The method was used for the analysis of fish samples purchased from local markets.     

Study of Transition States of Melamine for Micromixing with Wax Emulsion+4‐Nonyl Phenol Ethoxylate,Estimated with SEM Technique

Densities (ρ/10³kg m^?3), apparent molar volume (V₂/10^?6m³mol^?1), and viscosities (η/0.1 kg m^?1s^?1) for 5.0 to 60.0 millimol kg^?1 (m mol kg^?1) 1,3,5 triazine (melamine) at interval of 5.0 m mol kg^?1 were determined. The data were regressed and extrapolated to infinite dilution (m→0) and referred to as limiting apparent molal volume (V¯₂ ⁰) and intrinsic viscosity (B) and used to calculate free energy of activation (Δµ₂ ^0*/KJ mol^?1). Such functions illustrate feasibility of micromixing of melamine with paraffin wax emulsifier+4‐nonyl phenol ethoxylate, a nonionic surfactant in aqueous solution. The Δµ₂ ^0* decides micromixing of melamine stabilized by poly(acrylic acid) of 4500 g mol^?1 molecular weight, known as superabsorber for water. Paraffin wax emulsion was stabilized by a nonyl phenol ethoxylate and wax particles observed to adhere to melamine surface due to interactions between poly(acrylic acid) dispersant and ethoxylate group of surfactant, resulting in sedimentation of mixed particles. Thus V¯₂ ⁰, B, and Δµ₂ ^0* values conclude to ‐NH₂ group interactions for micromixing and scanning electron micrograph (SEM) elucidates microstructure and uniformity of micromixing.     

Comparison of the acute toxicity of tributyltin and copper to veliger larvae of Nassarius reticulatus (L.)

The ban on the use of tributyltin (TBT) is promoting an increasing use of copper as an active biocide in antifouling paints, with consequent rising levels of this metal in the environment. This study assesses the acute toxicity of copper and tributyltin to the larvae of the mollusc gastropod Nassarius reticulatus. Recently hatched veligers were exposed to nominal TBT‐Sn concentrations of 0.9, 1.4, 1.9, 2.8, 3.8, 4.7 and 5.6 µg l^?1 and nominal copper concentrations of 9.4, 23.4, 46.9, 70.3, 93.8, 117.2, 140.6 and 164.1 µg l^?1 for up to 96 h, under static conditions (17 ± 1 °C and 33 ± 1 psu). The percentage of larval mortality was determined for each organometal/metal concentration and exposure time (1, 24, 48, 72 and 96 h). Both TBT and copper had a highly significant effect on larvae survival (p < 0.001) for all times of exposure, except for the first hour in the particular case of TBT. The lowest observed effect concentration for TBT‐Sn decreased over time from 3.8 µg l^?1 at 24 h to 1.9 µg l^?1 at 96 h, whereas for copper it remained constant over time (46.9 µg l^?1). The median lethal concentration (LC₅₀) for TBT‐Sn decreased from 4.87 µg l^?1 at 24 h to 1.78 µg l^?1 at 96 h, and the LC₅₀ for copper decreased from 83.08 µg l^?1 at 24 h to 58.84 µg l^?1 at 96 h. TBT is far more toxic to N. reticulatus larvae than copper. However, owing to the higher copper environmental concentrations, the risk factors of the two biocides may approach each other. This stresses the need to find adequate substitutes for organotin biocides in future antifouling paints. Copyright © 2005 John Wiley & Sons, Ltd.     

Innovative determination of polar organophosphonate pesticides based on high‐resolution Orbitrap mass spectrometry

The determination of compounds showing a very low molecular weight (i.e. < 200 Da) can be complicated when low‐resolution mass spectrometry is used in the selected‐reaction monitoring mode, since the possible number of product ions is reduced and the obtained reactions are not selective enough to overcome background noise and/or matrix interferences. In this study, the use of high‐resolution mass spectrometry based on Exactive Orbitrap was applied for the determination of a group of polar organophosphonate pesticides and transformation products (TPs), which show the aforementioned features, in agricultural soils. Namely, glyphosate, glufosinate, ethephon and their TPs, aminomethyl phosphonic acid (AMPA), 3‐methylphosphinicopropionic acid, N‐acetyl‐glufosinate and 2‐hydroxyethylphosphonic acid were analyzed. The [M‐H]^‐ ions 168.00564, 180.04202, 142.96593, 110.00016, 151.01547, 222.05259 and 124.99982 were used, respectively, for the detection and identification of the compounds. Confirmation was carried out by using accurate mass measurements of ion fragments for each compound, from neutral losses of CO₂, H₂O and H₂CO (formaldehyde). Furthermore, the recently reported tool, relative isotopic mass defect (RΔm), was also used to support the confirmation protocol. The optimized method was fully validated at low levels, including the estimation of a not commonly used parameter: the limit of confirmation (LOC). This LOC is expressed as the lowest concentration of compound that can be confirmed using a fragment or the RΔm, and it ranged from 10 to 50 µg kg^?1 for all compounds. All the data was obtained in a single injection. Finally, the method was applied to real soil samples, and glyphosate and AMPA were found at 265 µg kg^?1 and 105 µg kg^?1, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

Multi-mycotoxin analysis of maize silage by LC-MS/MS

This paper describes a method for determination of 27 mycotoxins and other secondary metabolites in maize silage. The method focuses on analytes which are known to be produced by common maize and maize-silage contaminants. A simple pH-buffered sample extraction was developed on the basis of a very fast and simple method for analysis of multiple pesticide residues in food known as QuEChERS. The buffering effectively ensured a stable pH in samples of both well-ensiled maize (pH < 4) and of hot spots with fungal infection (pH > 7). No further clean-up was performed before analysis using liquid chromatography–tandem mass spectrometry. The method was successfully validated for determination of eight analytes qualitatively and 19 quantitatively. Matrix-matched calibration standards were used giving recoveries ranging from 37% to 201% with the majority between 60% and 115%. Repeatability (5–27% RSD_r) and intra-laboratory reproducibility (7–35% RSD_IR) was determined. The limit of detection (LOD) for the quantitatively validated analytes ranged from 1 to 739 μg kg⁻¹. Validation results for citrinin, fumonisin B₁ and fumonisin B₂ were unsatisfying. The method was applied to 20 selected silage samples and alternariol monomethyl ether, andrastin A, alternariol, citreoisocoumarin, deoxynivalenol, enniatin B, fumigaclavine A, gliotoxin, marcfortine A and B, mycophenolic acid, nivalenol, roquefortine A and C and zearalenone were detected.     

Three kinds of lateral flow immunochromatographic assays based on the use of nanoparticle labels for fluorometric determination of zearalenone

Colloidal gold, quantum dots and polystyrene microspheres were used as labels in three kinds of lateral flow immunochromatographic assays (ICAs) for the detection of zearalenone (ZEN) in cereal samples. The assays allow ZEN to be quantified within 20 min. The LODs are 10 μg·L^?1 of ZEN for the colloidal gold-based ICA, and 1 μg·L^?1 for both the quantum dot and polystyrene microsphere based ICAs. The respective data are 60 μg·kg^?1, 6 μg·kg^?1 and 6 μg·kg^?1, respectively, for spiked samples and cereals. Only minor cross-sensitivity occurred between ZEN and fusarium toxins, and no cross-sensitivity if found for aflatoxin B₁, T-2 mycotoxin, ochratoxin A, deoxynivalenol, and fumonisin B₁. LODs of the three assays are lower than the maximum limits of ZEN set by most standardization agencies.

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Graphical abstract Schematic presentation of three lateral flow immunochromatographic assays (ICAs) based on the use of (a) colloidal gold (CG), (b) fluorescent quantum dots (QD), and (c) polystyrene microspheres (PMs) as signalling labels for the rapid and sensitive determination of zearalenone (ZEN) in cereal samples.

     

The determination of chlorinated long-chain paraffins in water,sediment and biological samples

Methods are described for the routine determination of traces of industrial chloro-n-paraffins having 13–30 carbon atoms and chlorine contents of 42–45% (frw/w), in environmental samples of water, sediments and biota. The procedures are based on thin-layer chromatography detection and measurement. All samples are cleaned up by liquid—solid adsorption chromatography and thin-layer chromatography but those rich in lipids require preliminary solvent extraction. The methods distinguish between chloro-n-paraffins based on long carbon chains (C₂₀–C₃₀) and those based on shorter chains (C₁₃–C₁₇). The methods cover the ranges 500 ng l^?1 to 8 μg l^?1 for water (i.e. from about the solubility limit upwards) and 50 μg kg^?1 to 16 mg kg^?1 for sediments and biota. The precision of the methods ranges from ± 50% relative at the lowest concentrations to ± 12% relative at the highest. Recoveries are about 90% for water, 80% for sediments and between 80 and 90% for biota according to sample type.     

Selective and Sensitive Determination of Uranyl Ions in Complex Matrices by Ion Imprinted Polymers‐Based Electrochemical Sensor

We report on the design of a UO₂²⁺‐selective electrode based on the use of UO₂²⁺ imprinted polymer nanoparticles (IP‐NPs), and its application for the differential pulse adsorptive cathodic stripping voltammetry determination of uranyl ions. A carbon paste electrode was modified with the IP‐NPs, and differential pulse adsorptive cathodic stripping voltammetry was applied as the detection technique after open‐circuit sorption of UO₂²⁺ ions. The modified electrode responses to UO₂²⁺ was linear in the 0.1 µg L^?1 to 10 µg L^?1 and in the 0.01 mg L^?1 to 10 mg L^?1. The method detection limit of the sensor was 0.03 µg L^?1.     

Fast Determination of Fumonisin B1 and B2 in Corn Using a Modified QuEChERS Method and LC–MS–MS

A fast analytical method for the simultaneous determination of fumonisin B₁ (FB₁) and fumonisin B₂ (FB₂) in corn using a novel QuEChERS method and LC–MS–MS was developed and validated. Samples were extracted with methanol–water (3:1 v/v) by means of ultrasonic extraction. The extract was purified with a novel modified QuEChERS method. Firstly, FB₁ and FB₂ in the extract were retained with primary secondary amine (PSA). Then, FB₁ and FB₂ were released from PSA with 1.0 % formic acid in methanol. The final eluate was diluted with water, and analyzed by LC–MS–MS on a Waters Acquity BEH C₁₈ column with 0.1 % formic acid in water/methanol as mobile phase with gradient elution. Mean recoveries of 83.5–102.4 % with CVs of 3.6–10.5 % were obtained at fortification levels of 2, 50 and 1,000 μg kg⁻¹. The limit of quantification was 2.0 μg kg⁻¹.