Sensitive determination of bisphenol A and bisphenol F in canned food using a solid-phase microextraction fibre coated with single-walled carbon nanotubes before GC/MS

A reliable and sensitive method for simultaneous determination of bisphenol A (BPA) and bisphenol F (BPF) in canned food by gas chromatography-mass spectrometry (GC/MS) is described after extraction and pre-concentration by a new solid-phase microextraction (SPME) adsorbent. The potential of single-walled carbon nanotubes (SWCNTs) as SPME adsorbent for the pre-concentration of environmental contaminants has been investigated in recent years. This work was carried out to investigate the feasibility of SWCNTs as a headspace SPME adsorbent for the determination of bisphenol derivatives in canned food. Potential factors affecting the extraction efficiency, including extraction time, extraction temperature, desorption time, desorption temperature, and salinity were optimized. Calibration curves were linear (r ²≥ 0.994) over the concentration range from 0.30 to 60 µg kg^?1. For both target analytes, the limit of detection (LOD) at signal-to-noise (S/N) ratio of 3 was 0.10 µg kg^?1. In addition, a comparative study between the SWCNT and a commercial polydimethylsiloxane (PDMS) SPME fibre for the determination of bisphenol derivatives in canned food was conducted. SWCNT fibre showed higher extraction capacity, better thermal stability (over 350°C) and longer life span (over 150 times) than the commercial PDMS fibre. The method was successfully applied to determine BPA in canned food samples which were purchased from local markets. BPA was found in some of the samples within the concentration range from 0.5 to 5.2 µg kg^?1.     

Simultaneous determination of bisphenol A and bisphenol B in beverages and powdered infant formula by dispersive liquid–liquid micro-extraction and heart-cutting multidimensional gas chromatography-mass spectrometry

The purpose of this study was to establish a reliable, cost-effective, fast and simple method to quantify simultaneously both bisphenol A (BPA) and bisphenol B (BPB) in liquid food matrixes such as canned beverages (soft drinks and beers) and powdered infant formula using dispersive liquid–liquid micro-extraction (DLLME) with in-situ derivatisation coupled with heart-cutting gas chromatography-mass spectrometry (GC-MS). For the optimisation of the DLLME procedure different amounts of various extractive and dispersive solvents as well as different amounts of the derivative reagent were compared for their effects on extraction efficiency and yields. The optimised procedure consisted of the injection of a mixture containing tetrachloroethylene (extractant), acetonitrile (dispersant) and acetic anhydride (derivatising reagent) directly into an aliquot of beverage samples or into an aqueous extract of powdered milk samples obtained after a pretreatment of the samples. Given the compatibility of the solvents used, and the low volumes involved, the procedure was easily associated with GC-MS end-point determination, which was accomplished by means of an accurate GC dual column (heart-cutting) technique. Careful optimisation of heart-cutting GC-MS conditions, namely pressure of front and auxiliary inlets, have resulted in a good analytical performance. The linearity of the matrix-matched calibration curves was acceptable, with coefficients of determination (r2) always higher than 0.99. Average recoveries of the BPA and BPB spiked at two concentration levels into beverages and powdered infant formula ranged from 68% to 114% and the relative standard deviation (RSD) was <15%. The limits of detection (LOD) in canned beverages were 5.0 and 2.0?ng?l^–1 for BPA and BPB, respectively, whereas LOD in powdered infant formula were 60.0 and 30.0?ng?l^–1, respectively. The limits of quantification (LOQ) in canned beverages were 10.0 and 7.0?ng?l–1 for BPA and BPB, respectively, whereas LOQ in powdered infant formula were 200.0 and 100.0?ng?l^–1, respectively. BPA was detected in 21 of 30 canned beverages (ranging from 0.03 to 4.70?µg?l^–1) and in two of seven powdered infant formula samples (0.23 and 0.40?µg?l^–1) collected in Portugal. BPB was only detected in canned beverages being positive in 15 of 30 samples analysed (ranging from 0.06 to 0.17?µg?l^–1). This is the first report about the presence of BPA and BPB in canned beverages and powdered infant formula in the Portuguese market.     

Comparison of four analytical techniques based on atomic spectrometry for the determination of total tin in canned foodstuffs

Different techniques for the determination of total tin in beverages and canned foods by atomic spectrometry were compared. The performance characteristics of inductively coupled plasma-mass spectrometry (ICP-MS), hydride generation-inductively coupled plasma-atomic emission spectrometry (HG-ICP-AES), electrothermal atomisation-atomic absorption spectrometry (ETA-AAS) and inductively coupled plasma-atomic emission spectrometry (ICP-AES) were determined in terms of linearity, precision, recovery, limit of detection, decision limit (CCα) and detection capability (CCβ) (Decision 2002/657/EC). Calibration ranges were covered from ng?l^?1 to mg?l^?1 level. Limits of detection that ranged from 0.01, 0.05, 2.0 to 200?µg?l^?1 were reached for ICP-MS; HG-ICP-AES; ETA-AAS and ICP-AES, respectively. Precision, calculated according to ISO 5725-2 for repeatability and within-laboratory reproducibility and expressed as relative standard deviation (RSD), ranged from 1.6% to 4.9%; and recovery, based on Decision 2002/657/EC, was found to be between 95% and 110%. Procedures for the mineralisation or extraction of total tin were compared. Wet digestion, sequentially, with nitric acid and hydrogen peroxide provided the best results. The influence of possible interferences present in canned food and beverage was studied, but no interference in the determination of tin was observed. Since maximum levels for tin established by European Union legislation vary from 50?mg?kg^?1 in canned baby foods and infant foods up to 200?mg?kg^?1 in canned food, ICP-AES was chosen as the preferred technique for routine analysis thanks to its good precision, reliability and ease of use. The accuracy of this routine method was confirmed by participation in six proficiency test schemes with z-scores ranging from ?1.9 to 0.6. Several canned foodstuffs and beverage samples from a local market were analysed with this technique.     

Bisphenol A in domestic and imported canned foods in Japan

Bisphenol A (BPA) concentrations were surveyed in 100 domestic and 60 imported canned foods purchased from the Japanese market in 2011–12. BPA was extracted from the canned foods, derivatised by ethylation and analysed using GC-MS. In the domestic canned foods, the maximum and average BPA concentrations were 30 and 3.4 ng g^?1, respectively, while in the imported canned foods they were 390 and 57 ng g^?1, respectively. The BPA level in the domestic canned foods was significantly lower than that in the imported canned foods. Based on these results, the intakes of BPA from the domestic and imported canned foods in Japan were estimated as 644 ng person^?1 day^?1. The Japanese BPA intake was the second lowest following New Zealand, although imported canned foods increased. It was sufficiently lower than the tolerable daily intake of EFSA and the USEPA. The drastic reduction of BPA in the domestic canned foods should be due to the ‘BPA reduced cans’ that Japanese can manufacturers had developed in the late 1990s and became widely used in Japan.     

Analysis of perchlorate in baby food on Canadian (Ottawa) markets in 2009 and estimated dietary exposure

ABSTRACT

In order to determine the baseline levels of perchlorate in major brands of baby food, 200 baby food products were collected from retail stores in Ottawa, Canada and analysed for perchlorate in 2010. The seven food groups tested were fruit, juices, vegetables, meat, yogurt, mixed (vegetable mixed with meat) and other (e.g. vegetable mixed with meat and cereal, cheese, egg,). Samples were extracted with a mixture of methanol and 1% acetic acid (4:1, v/v). Determination was conducted by stable isotope dilution ion chromatography tandem mass spectrometry (ID-IC-MS/MS). The complexity of different food matrices required additional method validation. The perchlorate levels in 46 samples were found to be lower than the quantification limit (0.2 ng g^?1). The perchlorate levels in the other 154 baby food samples were also low; about 96.7% of the baby foods had perchlorate levels less than 10 ng g^?1 (ranged from 0.2 to 22.4 ng g^?1, median1.35 ng g^?1); only 5 samples had perchlorate levels higher than 10 ng g^?1. Dietary exposure to perchlorate from analysed baby food was conservatively estimated to range from 0.007 to 0.121 µg/kg bw/d based on the mean intake for children (1–5 years old).     

Survey of ochratoxin A in rice from Iran using affinity column cleanup and HPLC with fluorescence detection

This paper records the occurrence and levels of ochratoxin A (OTA) in rice using a HPLC technique preceded by an immunoaffinity clean-up step. The method was based on the extraction of finely ground rice sample with an acetonitrile/water (60?:?40, v/v) solution. Recovery was 98.9% while the limit of detection (LOD) was 0.2?ng?g^?1. A total of 182 rice samples were analyzed with a frequency of contamination of 6%. Levels of OTA in positive samples ranged 0.2–4.8?ng?g^–1, with an average contamination of all analyzed samples of 1.6?ng?g^–1.     

A Novel Method for Bisphenol A Analysis in Dairy Products Using Graphene as an Adsorbent for Solid Phase Extraction Followed by Ion Chromatography

A novel and reliable ion chromatography (IC) method using graphene (G) as a solid phase extraction (SPE) adsorbent for the rapid analysis of bisphenol A (BPA) in dairy products was developed. The performances of graphene (G) and commercial C18 for BPA extraction from dairy samples were evaluated; results showed that G had higher adsorption efficiency. IC coupled with an electrochemical detector (ED) is eco-friendly, labor and time saving compared to liquid chromatography mass spectrometry (LC-MS) and gas chromatography mass spectrometry (GC-MS). The effects of the experimental parameters of the IC-ED system were assessed, and the parameters were optimized to provide maximum sensitivity. The linear range is 5–20,000 ng?mL^?1 with an R value of 0.999. The limit of the detection is 0.8 ng?mL^?1 for a 25-μL injection loop. The mean relative recoveries ranged between 83.3 % and 104.6 %, the corresponding inter-day precision was below 5.3 % for 20, 200, 2,000, and 15,000 ng?mL^?1. This method was successfully employed to analyze BPA in dairy samples.     

Molecularly Imprinted Nanosilica Solid-Phase Extraction for Bisphenol A in Fish Samples

This paper reports a method using molecularly imprinted nanosilica as the solid-phase extraction sorbent to extract bisphenol A (BPA) from fish samples. The selective extraction efficiency of BPA from its structure-analogous by molecularly imprinted solid-phase extraction (MISPE) was compared with commercial C18 SPE column. The reproducibility of MISPE and optimal flow rate of sample were studied. There was a linear correlation in the concentration range of 0.7–114.1 μg l^?1 of BPA (r?=?0.997). The limit of detection (LOD) based on three times ratio of signal to noise was 0.11 μg l^?1. Under optimal conditions, the proposed method was applied to the analysis of BPA in fish samples. The amount of BPA in bream was 4.00 μg kg^?1, and both concentrations of BPA in crucian and weever were below the LOD. The recoveries of BPA standard solution spiked with fish samples were in the range of 92.56–102.3 % with the relative standard deviation less than 10 %.     

A survey of bisphenol A and other bisphenol analogues in foodstuffs from nine cities in China

Bisphenol A (BPA) is a high-production-volume chemical that is widely used in polycarbonate plastics and epoxy food-can coatings. Following several studies that have reported adverse effects of BPA over the past decade, other bisphenol analogues, such as bisphenol F (BPF), bisphenol S (BPS), bisphenol AF (BPAF), and bisphenol B (BPB), have been gradually developed as substitutes for BPA in several applications. Nevertheless, few studies have reported on the occurrence of compounds other than BPA in foodstuffs. In this study, 289 food samples (13 categories: cereals and cereal products, meat and meat products, fish and seafood, eggs, milk and milk products, bean products, fruits, vegetables, cookies/snacks, beverages, cooking oils, condiments, and others), collected from nine cities in China, were analysed for eight bisphenol analogues using high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). BPA and BPF were found widely in foodstuffs at concentrations ranging from below the limit of quantitation (LOQ) to 299 ng g^–1 (mean = 4.94 ng g^–1) and from below the LOQ to 623 ng g^–1 (mean = 2.50 ng g^–1), fresh weight, respectively. The highest total concentrations of bisphenols (∑BPs: sum of eight bisphenols) were found in the category of vegetables that included canned products (mean = 27.0 ng g^–1), followed by fish and seafood (16.5 ng g^–1) and beverages (15.6 ng g^–1). ∑BP concentrations (mean = 2–3 ng g^–1) in milk and milk products, cooking oils, and eggs were low. Food samples sold in metallic cans contained higher mean ∑BP concentrations (56.9 ng g^–1) in comparison with those packaged in glass (0.43 ng g^–1), paper (11.9 ng g^–1), or plastic (6.40 ng g^–1). The daily dietary intakes of bisphenols were estimated, based on the mean concentrations measured and daily consumption rates of foods, to be 646 and 664 ng kg^–1 bw day^–1 for men and women, respectively.     

Magnetic Dummy Template Silica Sol–Gel Molecularly Imprinted Polymer Nanospheres as Magnetic Solid-Phase Extraction Material for the Selective and Sensitive Determination of Bisphenol A in Plastic Bottled Beverages

In this study, a core–shell magnetic dummy molecularly imprinted polymer (MDMIP) was prepared with a novel and simple method. The imprinting layer was synthesized directly on the surface of Fe₃O₄ by only one step, which avoided further modification on the exterior of magnetic core. 4,4′-Dihydroxybiphenyl (DDBP) was used as dummy template instead of bisphenol A (BPA) to eliminate the effect of template leakage on quantitative analysis. When used as solid-phase extraction sorbent, a rapid, sensitive, and accurate method for the simultaneous extraction, concentration, and determination of trace BPA in plastic bottled beverage samples by MDMIP-SPE coupled with high-performance liquid chromatography (HPLC) was developed. Advantages of such method may be counted as the mild working temperature during the synthesis, simplicity of extraction procedure, avoidance of leakage of template, time-saving, and high binding capacity and affinity. Several parameters affecting the extraction efficiency of the analytes including the sorbent mass, the pH of sample solution, the HAc percentage in the elute, and the desorption time were investigated. Under optimized conditions, the calibration graph was linear over the range of 11.4–4560 ng mL^?1 with the limit of detection of 0.083 ng L^?1. In addition, the higher enrichment factors (400-fold) and good recoveries (88.6–99.5%) with relative standard deviation (RSD) values less than 9.5% were achieved. Moreover, the developed extraction protocol simplified the process of traditional solid-phase extraction (SPE) provided the possibility for separation and enrichment of BPA from complicated food matrices.     

Magnetic solid-phase extraction coupled with HPLC for the determination of Allura Red in food and beverage samples

A magnetic solid-phase extraction (MSPE) protocol prior to HPLC was developed for the extraction and determination of Allura Red in food samples. Magnetic nanoparticles were coated with tetraethylorthosilicate and 3-aminopropyltriethoxysilane and modified by graphene. Scanning electron microscopy, transmission electron microscopy and Fourier-transform infrared spectrometry were used to characterise the graphene-functionalised sorbents; and the main parameters affecting the extraction such as sample volume, temperature, pH and time were investigated and established. Under optimised conditions, the pre-concentration factor of Allura Red was 200, and the calibration curve was linear at a concentration range of 5–1500 μg kg^?1. The LOD was 2 μg kg^?1, the limit of quantification was 7 μg kg^?1, and the relative standard deviation was 3.3%. The prepared MSPE procedure was simple and fast, and it was successfully applied for the determination of Allura Red in beverages, candy and jelly.     

Cadmium content in fresh and canned squid (Loligo opalescens) from the Pacific coastal waters of California (USA)

Cadmium (Cd) levels were determined in 70 samples of mantle tissue and 70 whole individual squid (Loligo opalescens; commercially known as California squid). Samples were collected from the coastal zones of California (USA) during the period 2007/2008. To further investigate consumer exposure to processed fishery products, cadmium concentration was also determined in 200 canned samples of squid. Cd concentrations in raw mantle were low, between 0.01 and 0.29 mg kg^?1 and below the tolerance limit of current regulations (1 mg kg^?1). Respective concentrations in whole individuals were significantly higher, ranging from 0.51 to 1.18 mg kg^?1, attributed to the presence of the visceral portion in whole squid samples. Cd concentrations varied in relation to age and sex of squid, indicating that several physiological factors may influence accumulation. Furthermore, canning of squid substantially enhanced Cd levels. Cd concentration ranged 0.17–0.67 mg kg^?1 in canned mantle tissue and 0.86–2.07 mg kg^?1 in canned whole squid samples, due to both concentration after canning and movement of the metal between different tissues. Several biological compounds, including metallothioneins, nucleic acids and enzymes, may affect Cd concentrations in commercial fishery products.     

Application of enzyme-linked immunosorbent assay for quantification of the insecticides imidacloprid and thiamethoxam in honey samples

An enzyme-linked immunosorbent assay (ELISA) was used for the determination of residues of imidacloprid and thiamethoxam insecticides in honey after simple dilution of the samples without either extraction or cleanup. The ELISA enabled accurate determination of imidacloprid and thiamethoxam down to limits of 20 and 5 ng g^?1 in honey, respectively. Average recoveries of imidacloprid and thiamethoxam from the fortified honey samples were 90–120 and 96–122%, and coefficients of variation ranged 5–12 and 3–15%, respectively. The results from the ELISA agreed well with those by liquid chromatography–mass spectrometry (LC–MS) for the insecticide-spiked samples, with a correlation coefficient (r ²) of 0.96 and a regression coefficient (slope) of 1.03. The results indicate that ELISA is a suitable tool for the quantification of imidacloprid and thiamethoxam in honey.     

A survey of aflatoxin in cotton seed in Iran by HPLC with on-line photochemical derivatisation and fluorescence detection

The aflatoxins content of 140 cotton seed samples were determined using high-performance liquid chromatography. Samples were obtained from wholesalers in Iran between May 2010 and June 2011. Aflatoxin B₁ gave the highest incidence of contamination and was found in 129 of the 139 samples. The highest concentration of aflatoxin was 14.4?ng?g^?1. Thirteen cotton seed samples (9.35%) were above one of the regulatory limits of the European Union (5?ng?g^?1), but no sample was above the highest EU limit and the safety limit recommended by the FDA (20?ng?g^?1) and regulatory limits of Iran (50?ng?g^?1) for total aflatoxin.     

Survey of the histamine content in fish samples randomly selected from the Greek retail market

The histamine content of fish sold in the Greek retail market was surveyed and the performance of high-performance liquid chromatography (HPLC) and enzyme-linked immunoabsorbant assay (ELISA) methods for the determination of histamine were compared. A total of 125 samples of fresh and canned tuna, fresh and canned sardines, deep frozen swordfish, smoked and deep frozen mackerel, anchovies, salted and smoked herring were analysed by HPLC (55 samples), ELISA (106 samples) and both methods (36 samples). Histamine levels as determined by HPLC, ranged from 2.7 mg kg^?1 to 220 mg kg^?1. The highest histamine concentrations obtained by HPLC were found in herring and anchovy samples. Eight out of the 55 samples (14.5%) analysed by HPLC, exceeded the US Food and Drug Administration (USFDA) limit (50 mg kg^?1), while 16 out of the 106 samples (15%) analysed by ELISA exceeded the limit. The results show that for histamine concentrations below 50 mg kg^?1, there is good agreement between the ELISA and HPLC but above 50 mg kg^?1 big differences were found.     

Effect of initial aflatoxin concentration,heating time and roasting temperature on aflatoxin reduction in contaminated peanuts and process optimisation using response surface modelling

Response surface methodology was applied to optimise the aflatoxin reduction in both naturally and artificially contaminated samples using dry oven. The effect of initial aflatoxin concentration (0–400 ng g^?1), heating time (30–120 min) and temperature (90–150 °C) was evaluated. The maximum reduction of AFB1 (78.4%) and AFB2 (57.3%) of artificially contaminated samples with initial aflatoxin concentration of 237 and 68 ng g^?1, and those of AFG1 (73.9%) and AFG2 (75.2%) with initial aflatoxin concentration of 215 and 75 ng g^?1 was obtained at 150 °C. The maximum reduction of AFB1 (80.2%) and AFB2 (69.7%) of naturally contaminated samples with initial aflatoxin concentration of 174 and 25 ng g^?1 was obtained at 150 °C and 130 °C, respectively.     

Aflatoxins in sunflower and safflower seeds from Iran

Aflatoxin content of 173 sunflower and safflower seeds was determined by HPLC with immunoaffinity column (IAC) clean-up and fluorometric detection. Aflatoxin B₁ contamination was found in 111 samples: in 8 of the sunflower seed samples (16%) at a mean level of 40.68?ng?g^?1 and in 103 safflower seed samples (83.7%) at a mean level of 2.81?±?0.44?ng?g^?1. In 5 sunflower seed samples and 1 safflower seed sample, aflatoxin B₁ levels were higher than the maximum levels of AFB₁ under Iran regulations (5?ng?g^?1). Aflatoxin B₁ levels in 5 sunflower and 2 safflower seed samples were higher than the European Union maximum limit (2?ng?g^?1).     

The use of high-performance liquid chromatography to detect ochratoxin A in dried figs from the Spanish market

BACKGROUND: Detection and quantification of ochratoxin A (OTA) in dried fig samples purchased in Spain has been carried out using high‐performance liquid chromatography with fluorescence detection after extraction with methanol and sodium bicarbonate, and clean‐up by using an immunoaffinity column. RESULTS: The detection limit of the method was 0.06 ng g^?1, and the limit of quantification 0.18 ng g^?1. OTA was detected in 31 (88.6%) out of 35 samples of dried figs analysed, with concentrations that ranged from < 0.1 to 277 ng g^?1. However, only three samples contained OTA concentrations above the tolerable level set by European Commission regulations for dried vine fruits (10 ng g^?1). CONCLUSION: The results of this survey show the value of monitoring OTA in dried figs especially if they are home grown. Copyright © 2011 Society of Chemical Industry     

Optimized Ultrasound-Assisted Temperature-Controlled Ionic Liquid Microextraction Coupled with FAAS for Determination of Tin in Canned Foods

A simple and rapid method based on ultrasound-assisted temperature-controlled ionic liquid microextraction combined with flame atomic absorption spectrometry (FAAS) has been developed for determination of tin. In this method, Sn(IV)-ammonium pyrrolidinedithiocarbamate (APDC) complex was extracted into a small volume of 1-hexyl-3-methylimidazolium hexafluorophosphate as ionic liquid and after phase separation, the enriched analyte in the final solution is determined by FAAS. Experimental design approaches were used to obtain the best conditions. The variables of interest were temperature, pH, buffer volume, extraction time, centrifugation time and volumes of ionic liquid, methanol, and APDC. The Plackett–Burman design was employed for screening to determine the variables significantly affecting the extraction efficiency. Then, the significant factors were optimized by using a central composite design. In the optimal conditions the calibration graph was linear in the range of 0.10–6.0 mg?L^?1 with a correlation coefficient of 0.997. The limit of detection and relative standard deviation (n?=?5 for determination of 1.0 mg?L^?1) were 42 μg?L^?1 and 1.6 %, respectively. The preconcentration factor was calculated to be 52.7. Finally, the method was successfully applied to the determination of tin in various canned products including peach, pineapple and aloe vera juice, canned pea, and canned cheese.     

Immunoaffinity removal and immunoassay for rhodamine B in chilli powder

A rapid and simple immunoassay and a sol–gel‐based immunoaffinity chromatography (IAC) purification method for Rhodamine B (RB) were developed using spiked chilli powder. A polyclonal antibody against RB was generated by immunisation of rabbits with an immunogen hapten. An enzyme‐linked immunosorbent assay (ELISA) was developed that achieved a 50% inhibition (IC₅₀) value of 0.94 ± 0.05 ng mL^?1. The limit of detection of the ELISA method was 1 ng g^?1 in chilli powder. For the IAC, recovery was 68.1–86.2% at 1 ng g^?1 and 72.6–89.3% at 5 ng g^?1 in spiked chilli powder. Fortified samples were analysed by high performance liquid chromatography–mass spectrometry (HPLC–MS) after IAC purification, and the results showed a good agreement between the two methods. The ELISA could be a convenient tool for screening RB residue in foods, and the IAC cleanup procedure coupled with HPLC–MS could be an effective alternative method for the determination of RB in various substances.