Optimisation of a liquid chromatography-tandem mass spectrometric method for the determination of acrylamide in foods

A robust and fitted routine method resulting from an analytical optimisation has been applied for the determination of acrylamide in several foods including mainly potato and cereal products. For the sample treatment, different materials were evaluated for filtration and purification of the extract. To increase the performances in terms of sensitivity, a preconcentration to small volume was introduced before liquid chromatography coupled to tandem mass spectrometry analysis on a μ-Bondapak C₁₈ column using d₃-acrylamide as internal standard. For identification, relative retention time and two diagnostic ions were monitored. A limit of detection of 10 μg kg⁻¹, a limit of quantitation of 20 μg kg⁻¹, mean recoveries ranging from 100 to 115%, coefficients of variation from 1.36 to 8.06% for repeatability and from 3.3 to 18.2% for reproducibility within the laboratory and a measurement uncertainty of 42% were obtained during an in-house validation procedure. Results of tests, validation data and Z-score obtained during participation to proficiency studies are presented.     

Immunochemical-based method for detection of hazelnut proteins in processed foods

A competitive enzyme-linked immunosorbent assay (ELISA) was developed to detect hazelnut by using polyclonal antibodies generated against a protein extract of roasted hazelnut. No cross-reactivity was observed in tests against 39 commodities, including many common allergens, tree nuts, and legumes. Hazelnut protein standard solutions at 0.45 ng/mL [inhibition concentration (IC80) of the competitive test] were clearly identified by the ELISA. An extraction and quantification method was developed and optimized for chocolate, cookies, breakfast cereals, and ice cream, major food commodities likely to be cross-contaminated with undeclared hazelnut during food processing. No sample cleanup was required when extracts were diluted 10-fold. Recovery results were generated with blank matrixes spiked at 4 levels from 1 to 10 microg/g hazelnut protein. With the developed extraction and sample handling procedure, hazelnut proteins were recovered at 64-83% from chocolate and at 78-97% from other matrixes. A confirmatory technique was developed with sodium dodecyl sulfate-polyacrylamide gel electrophoresis and Western transfer. The developed methods were applied to a small market survey of chocolate products and allowed the identification of undeclared hazelnut in these products.     

On-line stacking techniques for the nonaqueous capillary electrophoretic determination of acrylamide in processed food

In the present study, field amplified sample stacking (FASS) techniques in the nonaqueous capillary electrophoresis method (NACE) were introduced for the on-line concentration of the acrylamide to improve acrylamide detection at 210 nm by diode-array detection. Acetonitrile (ACN) as a nonaqueous solvent permits acrylamide to be protonated through the change of its acid-base chemistry, allowing capillary electrophoretic separation of this compound. Choosing 30 mmol L(-1) HClO(4), 20 mmol L(-1) NaClO(4), 218 mmol L(-1) CH(3)COOH in ACN as the separation electrolyte and employing sample stacking methods, the LOD value of acrylamide was decreased to 2.6 ng mL(-1) with electrokinetic injection and 4.4 ng mL(-1) with hydrodynamic injection. Optimized stacking conditions were applied to the determination of acrylamide in several foodstuffs. The method is simple, rapid, inexpensive, and widely applicable for the determination of acrylamide in food samples.     

Development and single-laboratory validation of a reversed-phase liquid chromatography-electrospray-tandem mass spectrometry method for identification and determination of acrylamide in foods

A rapid and accurate method using reversed-phase liquid chromatography-tandem mass spectrometry interfaced with electrospray was developed for determination of acrylamide in cooked food samples. A simplified sample treatment procedure using an extraction step with acidified water without cleanup was developed. A C18 column with an aqueous formic acid-methanol mixture as the mobile phase was used under isocratic conditions. The method was validated in-house for robustness, limits of detection (LOD) and quantitation (LOQ), linearity, recovery, and accuracy both on standard and baked-product and potato flour matrixes. Good results in the low ppb level were obtained for LOD (< 15 microg/kg) and LOQ (< 25 microg/kg) of acrylamide in samples. Excellent linearity (r2 = 0.999-1.000) was established over 2 orders of magnitude by performing statistical tests. The absence of both constant and proportional systematic errors demonstrated good method accuracy. Excellent results were obtained for intraday repeatability (RSD < 1.5%) and between-day precision (RSD < 5%). Extraction recoveries from food products were calculated in the 97 +/- 3-99 +/- 2% (n = 6) range with a labeled internal standard (13C3-acrylamide). The applicability of the method to determination of acrylamide in cooked food products was demonstrated.     

Trace level determination of acrylamide in cereal-based foods by gas chromatography-mass spectrometry

A quantitative method has been developed for the determination of trace levels (<50 microg/kg) of acrylamide in cereal-based foods. The method is based on extraction of acrylamide with water, acidification and purification with Carrez I and II solutions, followed by bromination of the acrylamide double bond. The reaction product (2,3-dibromopropionamide) is extracted with ethyl acetate/hexane (4:1, v/v), dried over sodium sulfate, and cleaned up through a Florisil column. The derivative is then converted to 2-bromopropenamide by dehydrobromination with triethylamine and analyzed by gas chromatography coupled to mass spectrometry (GC-MS), employing (13C3)acrylamide as internal standard. In-house validation data for commercial and experimental cereal products showed good precision of the method, with repeatability and intermediate reproducibility relative standard deviations below 10%. The limit of detection and limit of quantitation are estimated at 2 and 5 microg/kg, respectively, and recoveries of acrylamide from samples spiked at levels of 5-500 microg/kg ranged between 93 and 104% after correction of analyte loss by the internal standard. Finally, a comparative test organized with two independent laboratories provided additional confidence in the good performance of the method, particularly at very low concentration levels.     

An improved method validation for rapid determination of acrylamide in foods by ultra-performance liquid chromatography combined with tandem mass spectrometry

An improved method was validated for the determination of acrylamide in foods using ultra-performance liquid chromatography (UPLC) coupled to eletrospray ionization tandem mass spectrometry (MS/MS) in the present study. This improved method supplies a rapid quantitative procedure of acrylamide with a run time of only 3 min. Results showed a good repeatability (RSD< or =4.5%) with 50, 100, 250, 500 and 1000 microg/kg spiked concentrations in potato crisps in within-day (n=5) and day-to-day (n=10) precision tests. Meanwhile, good recoveries (81.6-99.0%) were obtained with the same spiked concentrations in acrylamide-free cereal samples (n=3). The excellent method validation data and proficiency test results (Z-score: -0.1) of the official Food Analysis Performance Assessment Scheme (FAPAS) suggested that the present quantitative method could be applied for rapid determination of acrylamide in many investigations.     

食品中磷的检测方法

磷是人体内的重要元素之一,对人体生命活动有十分重要的作用,如何快速、简便、准确、灵敏地检测食品中磷的含量已经引起了世界各国的重视.本文总结了前人的研究工作,概述了近年来食品中总磷及有机磷农药的检测研究进展,分析了各种检测方法的优势和局限性,展望了未来该领域研究的发展趋势.     

A new simple sensitive differential pulse polarographic method for the determination of acrylamide in aqueous solution

A new simple sensitive differential pulse polarographic (DPP) method was investigated for the determination of acrylamide (AA) directly in a neutral aqueous solution. The AA showed a well-defined and well-resolved peak in pure aqueous LiCl at −1.84 V in the potential range from −1.6 V to −1.97 V at nitrogen pressure of 0.5 kg cm⁻². Among the various electrolytes studied, the AA showed good DPP response in the presence of LiCl and tetra methyl ammonium iodide, while it showed poor response in the presence of tetra butyl ammonium hydroxide and tetra butyl ammonium bromide due to their strong adsorption on the surface of electrode which hindered its reduction. The effect of LiCl concentration, the cyclic voltammetric response and the drop time study showed that AA exhibited an irreversible adsorptive electrochemical behavior. The good electrochemical response in pure aqueous medium suggested that hydrogen bonding might be involved which may favor the electrode reaction. Under optimized conditions, the peak current was linear in the entire concentration range from 0.2 mg L⁻¹ to 20 mg L⁻¹ with the correlation coefficient of R² = 0.9998. The method showed good reproducible results with R.S.D. of 0.3% (n = 16). The detection limit (LOD) was 27 μg L⁻¹. The influence of various interfering agents was also studied. The method was applied successfully for the quantification of AA in water samples without any interference effect from alkali metals.     

Interlaboratory evaluation of two enzyme-linked immunosorbent assay kits for the determination of crustacean protein in processed foods

The labeling of foods containing material derived from crustaceans such as shrimp and crab is to become mandatory in Japan because of increases in the number of allergy patients. To ensure proper labeling, 2 novel sandwich enzyme-linked immunosorbent assay (ELISA) kits for the determination of crustacean protein in processed foods, the N kit (Nissui Pharmaceutical Co., Ltd, Ibaraki, Japan) and the M kit (Maruha Nichiro Holdings, Inc., Ibaraki, Japan), have been developed. Five types of model processed foods containing 10 and/or 11.9 microg/g crustacean soluble protein were prepared for interlaboratory evaluation of the performance of these kits. The N kit displayed a relatively high level of reproducibility relative standard deviation (interlaboratory precision; 4.0-8.4% RSDR) and sufficient recovery (65-86%) for all the model processed foods. The M kit displayed sufficient reproducibility (17.6-20.5% RSDR) and a reasonably high level of recovery (82-103%). The repeatability relative standard deviation (RSDr) values regarding the detection of crustacean proteins in the 5 model foods were mostly < 5.1% RSDr for the N kit and 9.9% RSDr for the M kit. In conclusion, the results of this interlaboratory evaluation suggest that both these ELISA kits would be very useful for detecting crustacean protein in processed foods.     

A generic static headspace gas chromatography method for determination of residual solvents in drug substance

In order to increase productivity of drug analysis in the pharmaceutical industry, an efficient and sensitive generic static headspace gas chromatography (HSGC) method was successfully developed and validated for the determination of 44 classes 2 and 3 solvents of International Conference of Harmonization (ICH) guideline Q3C, as residual solvents in drug substance. In order to increase the method sensitivity and efficiency in sample equilibration, dimethylsulfoxide (DMSO) was selected as the sample diluent based on its high capacity of dissolving drug substance, stability and high boiling point. The HS sample equilibration temperature and equilibration time are assessed in ranges of 125–150 °C and 8–15 min, respectively. The results indicate that the residual solvents in 200 mg of drug substance can be equilibrated efficiently in HS sampler at 140 °C for 10 min. The GC parameters, e.g. sample split ratio, carrier flow rate and oven temperature gradient are manipulated to enhance the method sensitivity and separation efficiency. The two-stage gradient GC run from 35 to 240 °C, using an Agilent DB-624 capillary column (30 m long, 0.32 mm I.D., 1.8 μm film thickness), is suitable to determine 44 ICH classes 2 and 3 solvents in 30 min. The method validation results indicate that the method is accurate, precise, linear and sensitive for solvents assessed. The recoveries of most of these solvents from four drug substances are greater than 80% within the method determination ranges. However, this method is not suitable for the 10 remaining ICH classes 2 and 3 solvents, because they are too polar (e.g. formic acid and acidic acid), or have boiling points higher than 150 °C, (e.g. anisol and cumene). In comparison with the previous published methods, this method has a much shorter sample equilibration time, a better separation for many solvents, a higher sensitivity and a broader concentration range.     

A simplified UV spectrometric method for determination of peroxide value in thermally oxidized canola oil

The aim of present study was to develop a simple method on UV spectrometer for the determination of peroxide value (PV) of the frying oil. The basis of the PV determination was the stoichiometric reaction of triphenylphosphine (TPP) with the hydroperoxides present in frying oil to produce triphenylphosphine oxide (TPPO), which exhibits a readily measurable absorption band at 240 nm by ultraviolet region. The PV ranged between 0.15 and 11.66 meq. of active oxygen per kilogram of oil as the canola oil was heated from 0 to 12 h in the fryer at 180 °C. The proposed method was correlated with official AOCS titration method and best correlation coefficient (R² = 0.99525) was achieved, proving that there is no significant difference in the results. Therefore, developed method could serve as an alternative to the titration method, for the determination of PV in frying oils.     

A preamplification approach to GMO detection in processed foods

DNA is widely used as a target for GMO analysis because of its stability and high detectability. Real-time PCR is the method routinely used in most analytical laboratories due to its quantitative performance and great sensitivity. Accurate DNA detection and quantification is dependent on the specificity and sensitivity of the amplification protocol as well as on the quality and quantity of the DNA used in the PCR reaction. In order to enhance the sensitivity of real-time PCR and consequently expand the number of analyzable target genes, we applied a preamplification technique to processed foods where DNA can be present in low amounts and/or in degraded forms thereby affecting the reliability of qualitative and quantitative results. The preamplification procedure utilizes a pool of primers targeting genes of interest and is followed by real-time PCR reactions specific for each gene. An improvement of Ct values was found comparing preamplified vs. non-preamplified DNA. The strategy reported in the present study will be also applicable to other fields requiring quantitative DNA testing by real-time PCR.     

Determination of deoxynivalenol in processed foods

Deoxynivalenol (DON), commonly referred to as vomitoxin, belongs to a class of naturally occurring mycotoxins produced by Fusarium fungi. The presence of DON in foods is a human health concern. The frequency of occurrence of DON in wheat is high, although cleaning prior to milling can reduce DON concentration in final products, and food processing can partially degrade the toxin. This paper describes a method for the determination of DON in some major wheat food products, including bread, breakfast cereals, pasta, pretzels, and crackers. Test samples containing 5% polyethylene glycol were extracted with water. After blending and centrifuging, the supernatant was diluted with water and filtered through glass microfiber filter paper. The filtrate was then passed through an immunoaffinity column and the toxins eluted with methanol. The toxins were then subjected to RPLC separation and UV detection. The accuracy and repeatability characteristics of the method were determined. Recoveries of DON spiked at levels from 0.5 to 1.5 microg/g in the five processed foods were >70%. SD and RSD values ranged from 2.0 to 23.5% and from 2.0 to 23.2%, respectively. HorRat values were <2 for all of the matrixes examined. The method was found to be acceptable for the matrixes examined. LC/MS/MS with multiple-reaction monitoring was used to confirm the identity of DON in naturally contaminated test samples.     

Rapid method for the determination of vitamins A and E in foods using ultra-high-performance liquid chromatography

A rapid and novel ultra-HPLC (u-HPLC) method for the determination of vitamins A (retinol) and E (alpha-, gamma-, and delta-tocopherol) in foods was validated in terms of its precision, accuracy, and linearity. The u-HPLC separation was performed on an RP C18 column (particle size 2 microm, id 2 mm, and length 75 mm), followed by fluorescence detection. The recovery of retinol was more than 84.58%; the LOD and LOQ of the u-HPLC analysis were 0.015 and 0.045 mg/kg, respectively. The intraday and interday precision was less than 9.12%. The recoveries of alpha-, gamma-, and delta-tocopherol were more than 81.37%; the LOD and the LOQ were 0.014, 0.002, and 0.001 mg/kg and 0.042, 0.005, and 0.004 mg/kg, respectively. All calibration curves had good linearity (r2 = 0.99) within the test ranges. The novel, rapid method coupled to u-HPLC can provide significant improvements in the speed, sensitivity, and resolution compared with a conventional HPLC method.     

Kinetic spectrophotometric method for rapid determination of trace formaldehyde in foods

A simple and sensitive kinetic-spectrophotometric method was developed for the determination of ultra trace amount of formaldehyde in food samples. The method was based on the oxidation of rhodamine B (RhB) by potassium bromate in sulfuric acid medium (formaldehyde as catalyst). The reaction was monitored by measuring the decrease in absorbance of the dye at 515 nm after 6 min. The developed method allowed the determination of formaldehyde in the range of 10–100 μg L⁻¹ with good precision, accuracy and the detection limit was down to 2.90 μg L⁻¹. The relative standard deviations for the determination of 10 and 60 μg L⁻¹ of formaldehyde were 3.0% and 1.9% (n = 10), respectively. The method was found to be sensitive, selective and was applied to the determination of formaldehyde in foods with satisfactory results.     

Liquid scintillation method for determination of solvent-extracted phosphorus-32 in foods

A method for solvent extraction of radioactive phosphorus as phospho-molybdic acid in foods is described. The use of a carrier can be eliminated due to the quantity of the stable element present in foods. The use of a liquid scintillation technique for counting is discussed, showing the effective elimination of color and chemical quench. The efficiency resulting from the liquid scintillation method of counting makes possible the detection of 10^-5 μc levels of activity in the original sample.     

Use of a multifunctional column for the determination of deoxynivalenol in grains, grain products, and processed foods

Deoxynivalenol (DON), also known as vomitoxin, belongs to a class of naturally occurring mycotoxins produced by Fusarium spp. DON, 12, 13-epoxy-3,7 trihydroxytrichothec-9-en-8-one, is one of the most frequently detected mycotoxins in agricultural commodities worldwide. A method consisting of extraction, filtration, column cleanup, and RP-HPLC-UV separation and quantitation was validated for the determination of DON in grains (rice and barley), grain products (whole wheat flour, white flour, wheat germ, and wheat bran), and processed foods (bread, breakfast cereals, and pretzels). A 25 g test portion was extracted with 100 mL acetonitrile-water (84 + 16, v/v). After blending for 3 min, the supernatant was applied to a multifunctional column (MycoSep 225). The purified filtrate (2 mL) was evaporated to dryness and redissolved in the mobile phase. The toxins were then subjected to RP-HPLC-UV analysis. The accuracy and repeatability characteristics of the method were determined. Recoveries of DON added at levels ranging from 0.5 to 1.5 microg/g for all test matrixes were from 75 to 98%. SD and RSD(r) ranged from 0.7 to 11.6% and 0.9 to 12.7%, respectively. Within-laboratory HorRat values were from 0.1 to 0.7 for all matrixes analyzed. The method was found to meet AOAC method performance criteria for grains, grain products, and processed foods. The identity of DON in naturally contaminated test sample extracts was confirmed by HPLC/MS/MS analysis.     

Rapid determination of acrylamide contaminant in conventional fried foods by gas chromatography with electron capture detector

Gas chromatography coupled with electron capture detector (GC-ECD) was successfully developed and applied for the rapid determination of acrylamide in conventional fried foods, such as potato crisps, potato chips, and fried chicken wings. The method included defatting with n-hexane, extraction with aqueous solution of sodium chloride (NaCl), derivatization with potassium bromate (KBrO3) and potassium bromide (KBr), and liquid-liquid extraction with ethyl acetate. The final acrylamide extract was analyzed by GC-ECD for quantification and by GC-MS for confirmation. The chromatographic analysis was performed on the HP-INNOWax capillary column, and good retention and peak response of acrylamide were achieved under the optimal conditions (numbers of theoretical plates N = 83,815). The limit of detection (LOD) was estimated to be 0.1 microg kg(-1) on the basis of ECD technique. Recoveries of acrylamide from conventional samples spiked at levels of 150, 500 and 1000 microg kg(-1) (n = 4 for each level) ranged between 87 and 97% with relative standard deviations (RSD) of less than 4%. Furthermore, the GC-ECD method showed that no clean-up steps of acrylamide derivative would be performed prior to injection and was slightly more sensitive than the MS/MS-based methods. Validation and quantification results demonstrated that this method should be regarded as a new, low-cost, and robust alternative for conventional investigation of acrylamide.     

Characterization of liquid chromatography-tandem mass spectrometry method for the determination of acrylamide in complex environmental samples

This work describes the characterization of a solid-phase extraction (SPE) and liquid-chromatography-tandem mass spectrometry-based method for the analysis of acrylamide (AA) in complex environmental waters. The method involved the SPE of AA using activated carbon, and the AA was detected with tandem mass spectrometry after separating on an ion exclusion high-performance liquid chromatography column. The method incorporated two labeled AA standards for quantification using isotope dilution and to assess absolute extraction recovery. The method was evaluated for inter- and intra-day precision and accuracy. The method was both accurate (i.e., <30 % error) and precise (i.e., <20 % relative standard deviation), with absolute extraction recoveries averaging 37 %. The mass spectrometry provided excellent sensitivity, with instrumental limits of detection and quantitation values of 23 and 75 pg, respectively. The method detection limit was determined to be 0.021 μg/L. The analysis of AA was successfully performed in real-world samples that contained total dissolved solids concentrations ranging from 23,600 to 297,000 mg/L and AA concentrations ranging from 0.082 to 1.0 μg/L.

A rapid extractive spectrophotometric method for the determination of tin in canned foods with 5,7-dichloro-8-quinolinol

A rapid method for the spectrophotometric determination of tin in canned foods, based on formation of the binary Sn(IV)-5,7-dichloro-8-quinolinol complex and extraction into chloroform has been developed. The absorption maximum at 390nm ( = 1.26 x 10(4) l.mole(-1).cm(-1)) is used for the determination. Beer's law is obeyed up to 6mug of tin per ml. Organic matter is destroyed by digestion with acid. Potential interferences have been studied. The detection limit for tin is 2.5mg kg .