Journal of AOAC International最新文献

Background: Lauric arginate ethyl ester (LAE) is a natural cationic surfactant exhibiting excellent antimicrobial activity and has been approved as a safe additive in certain food according to the Codex Alimentarius Commission (CAC) General Standard for Food Additives (GSFA).

Objective: This study aimed to develop an analytical method based on liquid chromatography tandem mass spectrometry (LC-MS/MS) for the analysis of LAE in food using isotope-labeled LAE as internal standard.

Method: LAE in food was extracted by a mixture of acetonitrile (ACN)-water (9:1) and analyzed by LC-MS/MS via an internal standard calibration method using LAE-d23 hydrochloride as the internal standard.

Results: The limit of detection values of LAE were 0.32 mg/kg in liquid samples and 1.0 mg/kg in solid samples. The limit of quantitation values were 4.4 mg/kg and 14 mg/kg in liquid and solid samples, respectively. Spike recoveries consistently fell within the range of 90 to 110% at three different fortification levels, accompanied by a RSD below 10% in each instance.

Conclusions: An analytical method with LC-MS/MS detection for the analysis of LAE in various food matrixes was successfully developed, validated, and demonstrated to be fast, robust, and reliable.

Highlights: The developed analytical method with LC-MS/MS detection offered a fast and efficient way to analyze LAE in various food samples during a routine food surveillance program.

Background: Yersinia enterocolitica is one of the most common foodborne pathogens worldwide. Currently, most detection methods are primarily focused on pathogenic strains of Y. enterocolitica; while it has been frequently observed that traditionally believed "non-pathogenic" strains of Y. enterocolitica can also cause human disease.

Objective: Herein, we have developed a novel dual-recombinase-aided amplification (RAA)-lateral flow test strip assay targeting both of a pathogenic marker (ail) and a conserved gene (foxA) for the rapid detection of both pathogenic and non-pathogen Y. enterocolitica strains in food samples.

Methods: Primers and probes were designed and optimized for the detection of ail and foxA genes using RAA technology. The optimal RAA-LFS assay was then evaluated for specificity and sensitivity, and validated in both chicken samples spiked with a series of ten-fold diluted Y. enterocolitica cultures and 100 natural food samples including milk, chicken, beef, pork, and salmon.

Results: The newly designed assay demonstrated 100% specificity and achieved a detection limit of 17 CFU/reaction for both targets, with the entire sample preparation and detection process completed within 25 min. Additionally, the assay showed high sensitivity in spiked chicken samples, achieving a detection limit of 1.03 × 10-1 CFU/mL for both targets. Validation with the natural food samples confirmed the robustness of the assay, as the results from this new assay were in agreement with those from the commonly used traditional techniques.

Conclusions: In summary, the dual RAA-LFS assay integrates two genetic markers into a single test strip, providing a rapid, cost-effective, specific, and sensitive tool for on-site detection of pathogenic and common Y. enterocolitica strains.

Highlights: A novel dual RAA-LFS assay for the rapid detection of both pathogenic and common Y. enterocolitica strains was developed.

Background: Rhizoma Paridis (RP) is economically significant but identifies complex traditional medicine materials, which can be accidentally contaminated, deliberately substituted, or admixed with other species of similar morphological characteristics. This issue can affect quality and safety issues.

Objective: In this study, the screening technique to detect adulteration in RP was developed using multiple fingerprints and chemometrics.

Methods: Fourier transform infrared (FT-IR) spectroscopy and high-performance liquid chromatography (HPLC) combined with chemometrics, including similarity analysis (SA), principal component analysis (PCA), orthogonal partial least squares discriminant analysis (OPLS-DA), and hierarchical clustering analysis (HCA), were applied for the identification of RP and its adulterants.

Results: HPLC analysis was more sensitive than FT-IR for differentiating RP from its contaminants. Except for the slight overlapping between Paris polyphylla var. chinensis (Franch.) Hand.-Mazz. and Paris mairei H.Lév., the remaining species could be successfully differentiated by the chemometrics method.

Conclusions: This study indicates that the fingerprint of FT-IR and HPLC combined with chemometrics may be a valuable tool for discriminating RP and its adulterants.

Highlights: FT-IR and HPLC combined with chemometrics analysis were developed to discriminate between RP and adulterants. The chemometrics analysis using SA and OPLS-DA indicates significant differentiation in the chemical composition of these species. This research provides important chemotaxonomic references in species identification.

Background: Produced naturally by lactic acid bacteria, L-lactic acid is found in many fermented milk products and also in pickled vegetables, cured meats, and fish. It serves as a quality parameter in wine, beer, whole egg, whole egg powder, and juices.

Objective: To validate the performance of the Enzytec™ Liquid L-Lactic acid for the determination of L-lactic acid in food and beverages such as milk and (fermented) milk products, fermented vegetable products, wines, beer, fruit and vegetable juices, egg, and egg powder.

Methods: The method is based on enzymes that are part of a prepackaged kit that contains two ready-to-use components which are suitable for automation. L-lactic acids react in the presence of NAD and L-lactate dehydrogenase to pyruvate and NADH. The NADH formed is equivalent to the amount of L-lactic acid converted.

Results: Ascorbic acid, 3-hydroxybutyric acid, and sulfite were found to interfere at concentrations higher than 0.2, 0.05, and 0.05 g/L in the test solution, respectively. Oxaloacetic acid and D-fructose do not interfere at concentrations at or below 0.2 and 10 g/L, respectively. The calculated LOD when using a test volume of 100 µL is 3.8 mg/L and the limit of quantitation is 10 mg/L. The practical upper measurement range is 600 mg/L. Relative intermediate precision was between 3.0 and 7.3% for pineapple juice, sauerkraut juice, wine, and liquid egg. Certified reference materials (cream cheese and wine) showed recoveries between 100 and 104%. For automation, three applications with different test volumes were validated. Linearity is given from 0.75 to 3125 mg/L.

Conclusions: The method is robust and accurate for manual and automated applications. The method was approved as an AOAC Official Method of Analysis℠.

Highlights: The components of the test kit have a shelf life of at least 24 months.

Background: D-Glucose and D-fructose are present in honey, wine and beer, and in a range of other foodstuffs such as bread, pastries, or chocolate. Both sugars can occur as a monosaccharide or in di-, oligo-, and polysaccharides.

Objective: To validate the performance of the Enzytec™ Liquid D-Glucose/D-Fructose test kit for the determination of D-glucose and D-fructose in food and beverages such as fruit and vegetable juices, soft drinks, wines, and beer.

Methods: The method is based on enzymes that are part of a prepackaged kit that contains three ready-to-use components. Both sugars are phosphorylated by a hexokinase. Glucose-6-phosphate (G-6-P) and nicotinamide adenine dinucleotide (NAD) are converted to gluconate-6-phosphate and reduced nicotinamide adenine dinucleotide (NADH). NADH is measured at 340 nm. Phosphoglucose isomerase converts fructose-6-phosphate to G-6-P, which in turn is converted to gluconate-6-phosphate and NADH.

Results: The test is specific to D-glucose and D-fructose and shows no side-activities or interferences with the exception of mannose and sulphite that interfere at 5.1 and 1.25 g/L or more, respectively. The measurement range is from 6.1 to 2000 mg/L for D-glucose and 5.6 to 1000 mg/L for D-fructose (100 µL test volume). Trueness was evaluated using NIST SRM 3282 (cranberry juice) and one reference wine. The recoveries ranged from 101 to 102%. Spiking of wine, beer, soft drinks, and juices resulted in recoveries between 93 and 105%. Intermediate precision is below 6% for concentrations at 25 mg/L and below 4% for higher concentrations. For automation, three applications with different test volumes and different measurement ranges were validated. Linearity is given from 5.0 to 10 000 mg/L for the sum of both sugars.

Conclusion: The method is robust and accurate for manual and automated applications and was approved as an AOAC Official Method of Analysis℠.

Highlights: The ready-to-use components of the test kit have a shelf life of at least 29 months.

Background: Nitrosamines have gained significant attention in the pharmaceutical industry. However, due to the significant daily dosage of large volume parenteral (LVP), the detection limit for these products should be in the ng per liter range, which many published methods cannot achieve.

Objective: This study aimed to develop and validate a sensitive LC-MS/MS method for the simultaneous determination of several nitrosamines in LVP drug products.

Method: Nitrosamines and related internal standards were separated on a Waters ACQUITY UPLC HSS T3 (100 × 2.1 mm, 1.8 µm) column on a LC-MS/MS system with gradient elution. Prior to the LC injection, a Carbon A solid phase extraction (SPE) column was used to pretreat the test solutions. The mobile phase was composed of 0.1% formic acid in water as mobile phase A, and neat methanol as mobile phase B. Analytes were detected via multiple reaction monitoring (MRM) mode and quantitated against internal reference standards with a quantitation limit of 2.5 ng/L for N-nitrosodimethylamine (NDMA), 0.75 ng/L for other nitrosamine analytes.

Results: The LC-MS/MS method was able to separate all analytes of interest by gradient elution within 15 min. The method was validated according to the guidelines described in the International Conference on Harmonization guideline ICH Q2(R2). The LOQ for NDMA is 2.5 ng/L, while for other nitrosamines, it is 0.75 ng/L in peritoneal dialysis and saline matrices. For haemofiltration solution, the LOQ is 1.0 ng/L for NDMA and 0.3 ng/L for other nitrosamines. The RSD% (n = 9) of the recovery did not exceed 25% in the method accuracy evaluation. Comparative testing in three laboratories revealed that all three laboratories are capable of accurately measuring nitrosamine levels at 10 ng/L within the intricate LVP matrix.

Conclusions: The LC-MS/MS method for several nitrosamines was successfully developed, validated, and demonstrated to be accurate, robust, and specific.

Highlights: The performance of this method can reach single-digit ng/L level in LVP matrices. Comparative testing was conducted in three laboratories located in China, Germany, and the United States to ensure reproducibility of the method.

Background: Tetracycline (TC) is widely utilized in aquaculture as a broad-spectrum antibiotic with notable bactericidal properties. Nevertheless, the inappropriate or excessive application of TC may result in the presence of antibiotic residues in edible tissues, presenting significant risks to human health. In this study, a TC-sensitive electrochemical sensor was developed by modifying glassy carbon electrodes with gold nanoparticles (AuNPs)/graphene oxide (GO)/TC-templated molecularly imprinted polymer (MIP) composites.

Objective: A highly sensitive sensor for the detection of TC in milk.

Methods: The MIP, synthesized by thermal polymerization, acted as a selective recognition element and pre-concentrating agent for TC. To improve the conductivity of the MIP film and enhance the transfer of electrons across the electrode surface, AuNPs/GO composites were embedded in the MIP film. The morphology, structure, thermal stability, and electrochemical properties of the AuNPs/GO-MIP film were characterized through the utilization of scanning electron microscopy (SEM), FTIR spectroscopy, thermogravimetric analysis (TA), and electrochemical impedance spectroscopy (EIS).

Results: The modified electrode, featuring a composite film, exhibited a broad linear detection range (1-30 μg/L, 0.03-0.5 mg/L, and 0.5-20 mg/L), low detection limit (0.7 μg/L; S/N = 3), and high selectivity toward TC.

Conclusios: The proposed sensor effectively quantified TC in milk.

Highlights: In this study, AuNPs/GO composites were embedded to improve the conductivity of the composites; conductive MIP films were prepared and used as recognition elements and signal amplifiers. We present an electrochemical sensor for sensitive and selective detection of TC; the sensor can effectively quantify TC in milk.

Background: The Horwitz equation models an empirically observed relationship between inter-laboratory relative standard deviation RSDR and analyte concentration expressed as a mass fraction. The Horwitz ratio (HorRat) is the ratio of observed RSDR to the corresponding calculated RSDR from the Horwitz equation. The empirical acceptable range is 0.5 to 2.0 for a successful multi-laboratory method validation trial.

Objective: This work examines data from multi-laboratory trials on food analyses conducted between 2011 and 2017 for trends in analytical method precision and the applicability and relevance of the Horwitz model.

Methods: Data on method precision from 20 multi-laboratory trials consisting of 961 data points were analyzed. The scope was limited to methods employing modern chromatographic and spectroscopic techniques and to well-defined small-molecule analytes and elements. Within-laboratory and inter-laboratory precision and their ratio, HorRat, goodness of fit to the Horwitz model, and variation of precision across the analytical range were examined.

Results: The variance of inter-laboratory precision is largely (86%) independent of concentration and remains unexplained by the Horwitz equation. Only 52% of all data points fell within the Horwitz band (0.5-2.0), with 46% falling under 0.5, indicating substantially better inter-laboratory precision than predicted by the Horwitz equation at all concentration levels. Near-constant precision was confirmed across the analytical range of methods, even near the limit of quantitation.

Conclusion: The analysis of the data in scope demonstrates that the analytical method precision routinely achievable with modern chromatographic and spectroscopic techniques, proper laboratory controls, and training is much better than that predicted by the Horwitz equation. HorRat has lost its relevance as a method performance criterion for judging the success of a multi-laboratory trial.

Highlights: Recent data do not follow the Horwitz model. HorRat values <0.5 can be routinely achieved. Method precision is mostly independent of analyte concentration. Method-related factors have greater impact on precision.

Background: The AOAC Expert Review Panel (ERP) approved a method for the quantification of folic acid in various dietary supplement dosage forms containing tablets, 2-piece capsules, powder drinks, softgels, and gummies with First Action Official MethodSM status.

Objective: The previously published method summarized a single-laboratory validation with parameters of linearity, LOD, LOQ, repeatability, recovery, specificity, and system suitability. Based on the request from the ERP, the recovery test for the gummies has been reperformed with a revised procedure.

Methods: Determination of Folic Acid in Various Dietary Supplement Dosage Forms UPLC/PDA.

Results: The recovery range of 94.6-106.5% was achieved by spiking 20, 50, and 80% in the gummy samples. Other adjustments or clarification of the method and minor typos were also addressed.

Conclusion: After the revised method, report, and results were analyzed and discussed, the ERP adopted the method and provided recommendations for achieving Final Action status.

Highlights: The revised method meets the requirements of Standard Method Performance Requirement (SMPR®) 2022.002.

Background: The increasing prevalence of gluten-related disorders, such as celiac disease, has raised the demand for gluten-free (GF) products, highlighting a significant economic and public health challenge.

Objective: The purpose of this study is to create high-quality, nutritious GF pasta using rice flour, corn starch, pregelatinized starch, and carboxymethyl cellulose gum (CMC) as a substitute for semolina.

Methods: To assess the impact of CMC on pasta dough quality, samples with 0.5, 1, and 1.5% CMC were prepared, along with a control (0% CMC) and a semolina sample. The resulting pasta was analyzed for chemical properties, cooking quality, texture, color, and sensory evaluation, comparing it to the control, a market GF pasta, and semolina pasta.

Results: Rheological analysis showed that the storage modulus (G') was higher than the loss modulus (G'') in all formulations. Semolina pasta had a protein content of 13%, which was higher than that of the prepared GF pasta (4%) and market samples (8%). The addition of CMC reduced cooking loss from 11.07% (0% CMC) to 7.31% (1.5% CMC). Colorimetric assessments showed no significant differences among the GF samples. The sample with 1% CMC had the best texture and cooking quality.

Conclusion: The addition of 1% CMC improves dough rheology, product quality, and consumer acceptance as an effective gluten substitute. This research highlights the potential of CMC gum to improve GF pasta quality, meeting consumer expectations for taste and texture while also inspiring innovations in various GF products across various food categories.

Highlights: GF pasta was made using rice flour and corn starch. Adding 1% CMC improved the sensory evaluation, texture, and cooking quality of the GF pasta, with no significant effect on its color. In the frequency tests, G' was consistently greater than G'', indicating that the doughs were more elastic than viscous.