Journal of AOAC International (J AOAC INT )

Publisher: AOAC International

Description

The Journal of AOAC International publishes fully refereed contributed papers in the fields of chemical and biological analysis: on original research on new techniques and applications, collaborative studies, authentic data of composition, studies leading to method development, meeting symposia, newly adopted AOAC approved methods and invited reviews.

Impact factor 1.39

Publications in this journal

  • [Show abstract] [Hide abstract]
    ABSTRACT: An electrochemical technique for the determination of catechin, protocatechuic acid, and L-lactic acid has been developed using ferroceneboronic acid (FBA) as an electrochemical probe. The principle is based on the changes in voltammograms of FBA associated with selective binding of the analytes to FBA. A cyclic voltammogram and a differential pulse voltammogram (DPV) of FBA were recorded on a glassy carbon electrode in the presence of the analytes. The oxidation or reduction peak currents of FBA were decreased in the presence of the analytes, depending on their concentrations. The DPV measurements provided useful calibration graphs in the concentration range of 0.5–4.0 × 10–3 M catechin, 0.1–1.2 × 10–5 M protocatechuic acid, and 0.5–40 × 10–5 M L-lactic acid. The proposed method was successfully applied to the analysis of catechin in abdominal pain water medicine.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: The research on manipulation of crop genomes for transgenic development is continuously increasing due to several benefits. The major concerns linked to the effect of transgenic crops are human health and environment sustainability. To monitor transgenic samples in the food chain, several highly sensitive and specific DNA-based and protein-based detection methods are being used. However, real-time immuno-PCR (RT-IPCR) assay would be able to provide a sensitive detection of trace amounts of transgenic proteins or allergens in the samples and help in monitoring these materials. In the present study, we developed a novel RT-IPCR method to monitor Cry1Ac transgenic protein in samples with an LOD of 100 pg/mL. The assay may also be useful in the evaluation of functional stability of transgenes inserted in the plant genome.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: LDN Labor Diagnostika Nord GmbH & Co. KG has developed an ELISA for the rapid semiquantitative or quantitative determination of histamine in different kinds of fish samples. Fresh/frozen tuna, canned tuna, fresh/frozen mahi mahi, canned sardines, and fish meal were used to validate the method under the requirements of the AOAC Research Institute Performance Tested Methods SM Program. The results all fell within the defined acceptance criteria. Linearity was given throughout the 0–300 ppm measuring range. Cross reactivity to similarly structured food spoilage indicators (tyramine and cadaverine) was minimal, less than 1%. Overall recoveries for all tested matrixes were within the determined acceptable range (80–120%), and the repeatability of precision was less than 10% overall and less than 5% at the defect action level of 50 ppm set by the U.S. Food and Drug Administration. The LOQ for the ELISA was determined to be 1.27 ppm. No lot-to-lot differences were observed. A 2-year claimed shelf life, at 2–8°C, was confirmed through accelerated stability testing. After the introduction of minor procedural variations to the test, no differences in histamine levels were observed. Independent lab testing revealed that the ELISA works as well in the hands of minimally trained technicians as it does with expert developers. A strong correlation (r = 0.97) between the LDN ELISA and the AOAC 977.13 fluorometric method was observed. This study revealed that the LDN ELISA is equivalent to the AOAC Official Method 977.13 for the precise and accurate measurement of histamine in fresh/frozen tuna, canned tuna, fresh/frozen mahi mahi, canned sardines, and fish meal.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: The performance of InstantLabs®Salmonella Species Food Safety Kit to detect Salmonella in four food matrixes was validated against the International Organization for Standardization (ISO) reference method 6579:2002. The matrixes (raw ground beef, raw chicken breast, raw ground chicken, and lettuce) were inoculated with low levels of Salmonella (Escherichia coli O157:H7 at two to five times the level of Salmonella. Samples were validated using 375 g (meat) or 25 g (lettuce and poultry) test portions enriched in FASTGRO™ SE at 42 ± 1°C for 12 h and 10 h, respectively. All samples were confirmed using the ISO reference method, regardless of initial screen result. The InstantLabs test method was shown to perform as well as or better than the reference method for the detection of Salmonella species in ground beef, chicken breast, ground chicken, and lettuce. Inclusivity and exclusivity testing revealed no false negatives among the 100 Salmonella serovars and no false positives among the 30 non-Salmonella species examined, respectively.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A simple and rapid method for the separation and preconcentration of trace amounts of Cd(II) and Pb(II) in milk powder and water samples by magnetic SPE has been developed. The application of silica-coated magnetite nanoparticles (SCMNPs), modified with an anionic surfactant as an effective sorbent material for the microextraction and determination of trace amounts of Cd(II) and Pb(II) from food samples was investigated. The synthesized SCMNPs modified with sodium dodecyl sulfate have the ability to adsolubilize the metal ions after complexation with 1-(2-pyridylazo)-2-naphthol. These magnetic nanoparticles which are carrying the target metals can be easily separated from the aqueous solution by applying an external magnetic field, and the complexed metals can be desorbed using a proper eluent. The effect of pH, concentration of complexing agent, eluent, extraction time, capacity, and desorp tion conditions were investigated. Under the optimized conditions, preconcentration of a 50.0 mL sample solution permitted the LODs of 0.147 and 2.02 μg/L; and the RSDs (n = 7) for 0.05 μg/mL of Cd(II) and 0.2 μg/mL of Pb(II) were 2.96 and 1.3%, respectively. The maximum sorption capacity was 8.8 and 9.5 mg/g for Cd(II) and Pb(II), respectively.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: An ultrasensitive, quick, and simple approach for the determination of pg levels of diphacinone (DPN) by flow injection chemiluminescence (CL) analysis is proposed for the first time. It is based on the quenching effect of DPN on the CL intensity from a luminol–bovine serum albumin (BSA) CL system, for which the CL intensity decrease was linearly proportional to the logarithm of DPN concentration in the range of 5.0 to 5000 pg/mL. The LOD for DPN determination was as low as 2.0 pg/mL (3σ), and the RSD values were less than 5.0%. One determination cycle that included sampling and washing could be performed in 0.5 min with a sample throughput of 120/h under the optimum experimental conditions. This proposed method was successfully applied to determining DPN in human gastric juice and serum samples with recoveries from 91.8 to 114.3%, and to continuous monitoring of the degradation of DPN in water samples exposed to sunlight during 43 h with a variation ratio of 99.99%. The possible interaction behavior of BSA–DPN is briefly discussed.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A novel, simple, direct, and selective stability-indicating GC/MS procedure was developed for the determination of the anti-ischemic drug trimetazidine dihydrochloride (TMZ) in the presence of two of its related substances (potential impurities), namely, 2,3,4-trimethoxybenzyl alcohol (T1) and 2,3,4-trimethoxybenzaldehyde (T2). The method involved resolution of the underivatized compounds using a 100% dimethylpolysiloxane (Rtx-1) capillary column, and MS detection was carried out in the electron-impact mode. The peaks of the three compounds eluted at retention times 11.69, 11.92, and 15.47 min for T1, T2, and TMZ, respectively. Quantification of the parent drug TMZ was based on measuring its peak area. The reliability and analytical performance of the proposed method, including linearity, range, precision, accuracy, selectivity, detection, and quantification limits, were statistically validated. The calibration curve of TMZ was linear over the range 100–600 μg/mL. The proposed method was successfully applied to the assay of TMZ in several commercially available pharmaceutical formulations with recoveries not less than 96.2%.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: The total selenium (Se) was determined in herbal and pharmaceutical supplements used for liver diseases. The total Se contents were determined in different pharmaceutical and herbal supplements by hydride generation atomic absorption spectrometry (HGAAS) and graphite furnace atomic absorption spectrometry (GFAAS) after microwave-assisted acid digestion. The accuracy of the techniques was evaluated by using certified reference material and the standard addition method. The recoveries of total Se were 99.4 and 99.0% for HGAAS and GFAAS, respectively. The precision of the techniques expressed as RSD were 2.34 and 4.54% for HGAAS and GFAAS measurements, respectively. The LOD values for HGAAS and GFAAS were 0.025 and 0.052 μg/g, respectively. The concentrations of Se in pharmaceutical and herbal supplements were found in the range of 19.2–53.8 and 25.0–42.5 μg/g, respectively, corresponding to 35–76% and 45–76% of the total recommended dose of Se for adults.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: The InstantLabs®Salmonella Species Food Safety Kit was validated against the International Organization for Standardization (ISO) reference method 6579:2002 for the detection of Salmonella species. The matrixes (unprocessed rolled oats, wheat flour, and oat flour) were inoculated with 1 CFU/test portion of Salmonella to generate fractional positives (5–15) in 20 inoculated samples. The matrixes were co-inoculated with Escherichia coli O157:H7 at 2–5 times the level of Salmonella to demonstrate the potential for using the same enrichment culture in the future to detect of multiple organisms. Samples were validated using 750 g test portion enriched in FASTGRO SE at 42 ± 1°C for 16–20 h. All samples were confirmed using the ISO reference method, regardless of initial screen result. The InstantLabs test method performed as well as or better than the reference method for the detection of Salmonella species in unprocessed rolled oats, wheat flour, and oat flour. Inclusivity and exclusivity testing revealed no false negatives and no false positives among the 100 Salmonella serovars and 30 non-Salmonella species examined. Finally, the method was shown to be robust when variations to enrichment time, DNA extract hold time, and DNA volume were varied (data not shown).
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A direct injection LC/MS/MS method for the determination of the pesticide oxadixyl in wines was developed and validated. A sample divert valve was used to deliver the fraction that contained oxadixyl to the mass spectrometer's electrospray ionization source. Oxadixyl was monitored and quantitated using two transitions in multiple reaction monitoring mode. The method demonstrated recoveries of 99.2 ± 2.0 and 96.7 ± 5.2% for red and white wines, respectively, a linearity range of 2–20 μg/L, LOD at 0.7 μg/L, LOQ of 2.0 μg/L, and precision values of 8.2% (RSDr) and 6.2% (RSDR). Direct injection of the wine onto a C18 ultra-performance LC column allowed automation and high throughput screening. Benefits of this approach include minimal sample preparation, short (3 min) run times, and the use of matrix-matched calibration standards, which minimize the matrix effect due to interferences from wine phenolics, sugars, and various other components. The method's performance characteristics were not statistically different for white and red wines. An additional interlaboratory validation study involved 12 laboratories and demonstrated good data agreement with HorRat values ranging from 0.23 to 0.52.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: The 3M™ Petrifilm™Salmonella Express (SALX) System is a simple, ready-to-use chromogenic culture medium system for the rapid qualitative detection and biochemical confirmation of Salmonella spp. in food and food process environmental samples. The 3M Petrifilm SALX System was compared using an unpaired study design in a multilaboratory collaborative study to the U.S. Department of Agriculture/Food Safety and Inspection Service (USDA/FSIS) Microbiology Laboratory Guidebook (MLG) 4.07 (2013) Isolation and Identification of Salmonella from Meat, Poultry, Pasteurized Egg and Catfish Products and Carcass and Environmental Sponges for raw ground beef and the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA/BAM) Chapter 5, Salmonella (2011) reference method for dry dog food following the current AOAC validation guidelines. For this study, a total of 17 laboratories located throughout the continental United States evaluated 1872 test portions. For the 3M Petrifilm SALX System, raw ground beef was analyzed using 25 g test portions, and dry dog food was analyzed using 375 g test portions. For the reference methods, 25 g test portions of each matrix were analyzed. The two matrices were artificially contaminated with Salmonella at three inoculation levels: an uninoculated control level (0 CFU/test portion), a low inoculum level (0.2–2 CFU/test portion), and a high inoculum level (2–5 CFU/test portion). Each inoculation level was statistically analyzed using the probability of detection statistical model. For the raw ground beef and dry dog food test portions, no significant differences at the 95% confidence interval were observed in the number of positive samples detected by the 3M Petrifilm SALX System versus either the USDA/FSIS-MLG or FDA/BAM methods.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A method was developed for rapid toxicological analysis of eperisone, tolperisone, and tizanidine in human serum using a MonoSpin® C18 extraction column and LC/MS/MS. The method was validated for LOD, linearity, precision, and extraction recovery. This method was rapid with an LOD of 0.5 ng/mL, linearity range 1–500.0 ng/mL (r2 = 0.999), and RSD value below 14.6%. Extraction recovery from the sample was greater than 98.6, 98.8, and 88.5% for eperisone, tolperisone, and tizanidine, respectively. Results showed that combination of the MonoSpin C18 extraction column and LC/MS/MS is a simple and rapid method for the analysis of these three analytes, and a method is described for simultaneous quantitative determination of the analytes in human serum by LC/MS/MS. This method was used to determine the serum levels of eperisone in a patient with eperisone poisoning, and could be successfully applied for screening analyses in clinical cases other than poisoning.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A new method using a multi-injection technique combined with SPE was developed for the determination of copper (Cu) in environmental samples. The method is based on SPE of copper ions on naphthalene as its 2-(5-bromo-2-pyridylazo)-5-diethylaminophenol (5-Br-PADAP)-ammonium tetraphenylborate complex, in the pH range 6.0–9.5, and determined by electrothermal atomic absorption spectrometry. No chemical modifier is required in the graphite furnace. The detection limit can be reduced to 1.5 ng/L using an injection volume of 25.0 μL (five 5.0 μL) without interference by the matrixes. The optimum pyrolysis and atomization temperatures were 500 and 2200°C, respectively, for the concentrated solution of Cu. The sensitivity for 1% absorption was 2.6 pg Cu. Eight replicate determinations for 0.1 μg Cu in 5.0 mL dimethylformamide gave an RSD of 2.3% for a single injection and 2.7% for a multi-injection. The procedure was validated with certified reference materials and successfully applied to the determination of copper in water and plant samples.
    Journal of AOAC International 12/2014; 97(6).
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    ABSTRACT: A sensitive and reliable analytical method based on HPLC/MS/MS has been developed for the simultaneous determination of 15 nitroimidazoles in cosmetics. A diversity of cosmetic samples, including powder, lotion, shampoo, and cream were collected. The samples were ultrasonically extracted with aqueous methanol, and the extracts were then subjected to cleanup by SPE using an Oasis HLB cartridge followed by filtration with a 0.20 μm membrane filter. Afterwards, chromatographic separation was performed on an XSelect CSH C18 column (2.1 × 150 mm, 3.5 μm) maintained at 30°C within 15 min by a gradient of acetonitrile–0.1% aqueous formic acid solution at a flow rate of 0.25 mL/min. The mass spectrometric detection was carried out using electrospray positive ionization under the multiple reaction monitoring mode. A good linearity was observed over the concentration range from 0.5 to 500 ng/mL. The intraday and interday precisions, which were investigated by determining all target compounds in cosmetics seven times/day and on 7 consecutive days, were below 5.00%. The mean recoveries at three spiked levels ranged from 80.42 to 100.83% with the RSDs from 0.45 to 9.02%. The LOQs were determined to be between 0.01 and 0.1 mg/kg. The method was sufficiently rapid, reliable, and sensitive for the determination of 15 nitroimidazoles in cosmetics.
    Journal of AOAC International 12/2014; 97(6).
  • Journal of AOAC International 11/2014; 97(6):1497-1502.
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    ABSTRACT: The Crystal Diagnostics MultiPath System™ provides rapid detection of Escherichia coli O157 in fresh raw ground beef, raw beef trim, and spinach. The Crystal Diagnostics system combines patented Liquid Crystal technology with antibody-coated paramagnetic microspheres to selectively capture and detect E. coli O157 in food matrixes. This is the only liquid crystal-based biosensor commercially available for the detection of pathogens. The Crystal Diagnostics system expeditiously provides the sensitivity and accuracy of the U.S. Department of Agriculture Food Safety Inspection Service (USDA-FSIS) and the U.S. Food and Drug Administration Bacteriological Analytical Manual (FDA-BAM) methods for detecting as low as one CFU of E. coli O157 per 375 g of raw ground beef and raw beef trim, or 200 g of raw spinach. An internal inclusivity validation demonstrated detection of all 50 tested strains of E. coli O157. The internal and independent laboratory tests demonstrate that the method is rapid and sensitive for detecting of E. coli O157 in fresh raw ground beef, beef trim, and spinach.
    Journal of AOAC International 11/2014; 97(6):1592-1600(9).
  • Wentao Zhou, Yuxia Zhou, Lili Sun, Qiaogen Zou, Ping Wei, Pingkai Ouyang
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    ABSTRACT: During the synthesis of Azilsartan (AZS), it was speculated that 15 potential impurities would arise. This study investigated the possible mechanism for the formation of 14 of them, and their structures were characterized and confirmed by IR, NMR, and MS techniques. In addition, an efficient chromatographic method was developed to separate and quantify these impurities, using an Inertsil ODS-3 column (250 x 4.6 mm, 5 pm) in gradient mode with a mixture of acetonitrile and the potassium dihydrogen orthophosphate buffer (10 mM, pH adjusted to 3.0 with phosphoric acid). The HPLC method was validated for specificity, precision, accuracy, and sensitivity. LOQ of impurities were in the range of 1.04-2.20 ng. Correlation coefficient values of linearity were >0.9996 for AZS and its impurities. The mean recoveries of all impurities in AZS were between 93.0 and 109.7%. Thus, the validated HPLC method is suitable for the separation and quantification of all potential impurities in AZS.
    Journal of AOAC International 11/2014; 97(6):1552-62.
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    ABSTRACT: Asparagus racemosus (AR) is a popular botanical present in several Ayurvedic medicines and nutritional and dietary supplements with immunomodulatory, galactogogue, and anticancer activity. A steroidal saponin known as shatavarin IV is one of the active constituents of AR. A new, selective, and rapid HPLC/MS/MS method has been developed and validated for quantitative estimation of shatavarin IV in crude, processed, and marketed samples of AR. The analytes were separated on a Luna C18 column using simple isocratic elution with water (0.1% acetic acid)–acetonitrile (0.1% acetic acid; 70 + 30, v/v) at a flow rate of 0.8 mL/min. The analytes were detected by electrospray ionization (ESI)-MS/MS and quantified using multiple reaction monitoring techniques in the positive ion mode. The method showed excellent linearity (r2 > 0.998) over the concentration range of 7.5 to 254 ng/mL with LOD of 2.5 ng/mL. Precision (RSD) and accuracy (recovery) were found in the ranges of 2.00 to 5.15 and 102 to 110%, respectively. The validated HPLC/ESI-MS/MS method was successfully applied to the quantification of shatavarin IV in crude, processed, and marketed (single or multiherb) AR samples. Therefore, this method could be used for QC and standardization of pharmaceutical or nutritional products containing AR.
    Journal of AOAC International 11/2014; 97(6):1497-1502.