Repeatability Relative Standard Deviation Research Articles

Determination of Cyromazine in Livestock Products by LC-MS/MS on an Anion-Cation Exchange Mode ODS Column

Cyromazine in livestock products was determined using a validated LC-MS/MS method. There are three key points in our methods. First, the extraction was performed with two solutions, methanol and pH 3.0 McIlvaine buffer. The process was optimized for each type of sample. Secondly, cleanup was performed using a reversed-phase and strong cation exchange mixed-mode cartridge. The cartridge was washed with 0.14％ ammonium solution. Thirdly, the chromatographic separation was performed on an anion-cation exchange mode ODS column. There was no matrix effect on the extraction and determination for five livestock products. The quantification was carried out using an external standard calibration curve. This new method satisfies the Japanese guideline criteria. Recovery ranged from 77.2 to 92.1％, the relative standard deviation of repeatability （RSDr） was under 2.2％, and RSDwr was under 6.1％. Residual cyromazine was detected in raw milks and eggs.

Inter-laboratory Study of an HPLC-UV Method for Free Asparagine in Grains

In order to validate an HPLC-UV method for the determination of free asparagine, which is a precursor of acrylamide, in grains using dansyl derivatization, an inter-laboratory study was performed in 9 laboratories using 5 kinds of grains (non-glutinous brown rice flour, corn flour, strong flour, whole wheat flour, and whole rye flour), which naturally contain free asparagine. The relative standard deviations for repeatability (RSDr) and reproducibility (RSDr) were in the ranges of 0.5-2.2 and 2.3-5.9%, respectively. The HorRat values ranged from 0.4 to 0.6. These results were within the range of the procedural manual of the Codex Alimentarius Commission, and therefore the method is effective.

A Novel Sensitive Cell-Based Immunoenzymatic Assay for Palytoxin Quantitation in Mussels.

The marine algal toxin palytoxin (PLTX) and its analogues are some of the most toxic marine compounds. Their accumulation in edible marine organisms and entrance into the food chain represent their main concerns for human health. Indeed, several fatal human poisonings attributed to these compounds have been recorded in tropical and subtropical areas. Due to the increasing occurrence of PLTX in temperate areas such as the Mediterranean Sea, the European Food Safety Authority (EFSA) has suggested a maximum limit of 30 µg PLTX/kg in shellfish meat, and has recommended the development of rapid, specific, and sensitive methods for detection and quantitation of PLTX in seafood. Thus, a novel, sensitive cell-based ELISA was developed and characterized for PLTX quantitation in mussels. The estimated limits of detection (LOD) and quantitation (LOQ) were 1.2 × 10−11 M (32.2 pg/mL) and 2.8 × 10−11 M (75.0 pg/mL), respectively, with good accuracy (bias = 2.5%) and repeatability (15% and 9% interday and intraday relative standard deviation of repeatability (RSDr), respectively). Minimal interference of 80% aqueous methanol extract allows PLTX quantitation in mussels at concentrations lower than the maximum limit suggested by EFSA, with an LOQ of 9.1 µg PLTX equivalent/kg mussel meat. Given its high sensitivity and specificity, the cell-based ELISA should be considered a suitable method for PLTX quantitation.

Validation of a major modification of the mobile phase in the European Pharmacopoeia LC-UV human insulin assay

To prevent the buildup of salt crystals inside the chromatograph tubing and pump that occurs with the high mobile phase sodium sulfate concentration (148 mM) used in the European Pharmacopoeia method for the quantification of human insulin, the use of a lower concentration was proposed. A minimal concentration of 37 mM sodium sulfate maintained the chromatographic performance while avoiding instrumental damage. This buffer concentration modification is considered as a major change by the European Pharmacopoeia and this improved method therefore had to be validated. Using a single-point calibration (600 µg.mL−1) yielded adequate precision (the highest relative standard deviations for repeatability and intermediate precision were <5% and <8%, respectively) and accuracy (bias values between −8% and +7%) for the quantification of human insulin in solutions of known concentration and in commercial insulin preparations. The limits of detection and quantification (1.6 and 4.5 µg.mL−1, respectively) were largely sufficient for the purpose of the method.

Determination of Ethanol in Kombucha, Juices, and Alcohol-Free Beer by EnzytecTMLiquid Ethanol: Single-Laboratory Validation, First Action 2017.07

EnzytecTM Liquid Ethanol is an enzymatic test for the determination of ethanol in kombucha, juices, and alcohol-free beer. The kit contains two components in a ready-to-use format. Quantification is based on the catalytic activity of alcohol dehydrogenase, which oxidizes ethanol to acetaldehyde and converts NAD+ to NADH. Measurement is performed in 3 mL cuvettes at 340nm within 20min. Samples with alcohol contents around 0.5% alcohol by volume need to be diluted 1:20 or 1:50 with water before measurement. Acetaldehyde interferes at concentrations higher than 3000mg/L, whereas sulfite interferes at concentrations higher than 300mg/L. The linear measurement range is from 0.03 up to 0.5g/L ethanol, whereas LOD and LOQ are 1.9 and 3.3mg/L ethanol, respectively. Kombucha with concentrations between 2.85 and 5.82g/L showed relative repeatability standard deviation around 1%, whereas juices were below 2%. Results from a reproducibility experiment revealed that at a concentration of 0.1g/L, the RSDR was at 2.5%, whereas at higher concentrations between 0.2 and 0.3g/L, coefficients around 1% were obtained. Trueness was checked by using Cerilliant aqueous ethanol solutions and beer with concentration of 0.4 and 4g/L (BCR-651 and BCR-652). Spiking of kombucha and juice samples resulted in recoveries between 95% and 104%. Acceptable stability was found for the whole test kit under accelerated conditions at 37°C for 2 weeks. The kit is also not susceptible to short freezing-thawing cycles and harsh transport conditions.

Green and simple analytical method to determine benzimidazoles in milk samples by using salting-out assisted liquid-liquid extraction and capillary liquid chromatography

A green and simple multiresidue method using capillary liquid chromatography (CLC) with UV-diode array detection (DAD) has been developed for the determination of sixteen benzimidazoles (BZs) and its metabolites in milk samples. The separation was achieved in <32 min, using a Zorbax XDB-C18 column (150 mm × 0.5 mm I.D, 5 μm), with a mobile phase consisting of 50 mM ammonium acetate (solvent A) and a mixture of acetonitrile/methanol (1:1 v/v) (solvent B), at a flow rate of 9 μL min−1. The temperature of the column was 20 °C and 6 μL of sample were injected. In spite of the complexity of milk samples, an effective, simple and fast sample preparation method called salting out-assisted liquid-liquid extraction (SALLE) was developed for the analysis of these compounds in cow milk samples. To obtain satisfactory extraction efficiencies for the studied analytes, several parameters affecting the SALLE procedure were optimized including the amount of sample, type and volume of the extraction solvent, and the nature and amount of the salt. Good linearity was obtained (R2 > 0.9985 for all BZs) with limits of detection (LOD) between 1.0 and 2.8 μg kg−1. Relative standard deviations of repeatability and intermediate precision were below 1.6 and 14.2%, respectively. Satisfactory recoveries between 79.1 and 99.6% were also obtained for three types of milk samples (cow, sheep and goat). The advantages of a miniaturized technique such as CLC in terms of better efficiencies and reduced solvent consumption, combined with the simplicity of the SALLE procedure, make this method a useful alternative for the monitoring of these residues at trace level.

ULTRAVIOLET-SPECTROPHOTOMETRIC METHOD DEVELOPMENT AND VALIDATION FOR THE DETERMINATION OF NORFLOXACIN PRESENT IN TASTE MASKED DRUG RESIN COMPLEX

Objective: The objective of this study was developed and validated a novel, specific, precise, and simple ultraviolet (UV)-spectrophotometric method for the estimation of norfloxacin present in taste masked drug-resin complex.Methods: UV-spectrophotometric determination was performed with ELICO SL 1500 UV-visible spectrophotometer using 0.1 N HCl as a medium. The spectrum of the standard solution was run from 200 to 400 nm range for the determination of absorption maximum (λ max). λ max of norfloxacin was found at 278 nm. The absorbance of standard solutions of 1, 2, 3, 4, and 5 μg/ml of drug solution was measured at an absorption maximum at 278 nm against the blank. Then, a graph was plotted by taking concentration on X-axis and absorbance on Y-axis which gave a straight line. Validation parameters such as linearity and range, selectivity and specificity, limit of detection (LOD) and limit of quantification (LOQ), accuracy, precision, and robustness were evaluated as per the International Conference on Harmonization (ICH) guidelines.Results: Linearity for the UV-spectrophotometric method was noted over a concentration range of 1–5 μg/ml with a correlation coefficient of 0.9995. The LOD and LOQ for norfloxacin were found at 0.39 μg/ml and 1.19 μg/ml, respectively. Accuracy was in between 99.00% and 99.17%. % relative standard deviation for repeatability, intraday precision, and interday precision was found to be 0.600, in between 0.291 and 0.410, and in between 0.682 and 1.439, respectively. The proposed UV spectrophotometric method is found to be robust.Conclusion: The proposed UV-spectrophotometric method was validated according to the ICH guidelines, and results and statistical parameters demonstrated that the developed method is sensitive, precise, reliable, and simple for the estimation of norfloxacin present in taste masked drug-resin complex.

An Imaging Surface Plasmon Resonance Biosensor Assay for the Detection of T-2 Toxin and Masked T-2 Toxin-3-Glucoside in Wheat

A sensitive, rapid, and reproducible imaging surface plasmon resonance (iSPR) biosensor assay was developed to detect T-2 toxin and T-2 toxin-3-glucoside (T2-G) in wheat. In this competitive assay, an amplification strategy was used after conjugating a secondary antibody (Ab2) with gold nanoparticles. Wheat samples were extracted with a methanol/water mixture (80:20 v/v), then diluted with an equal volume of primary antibody (Ab1) for analysis. Matrix-matched calibration curves were prepared to determine T-2 toxin and T2-G. Recovery studies were conducted at three spiking levels in blank wheat. Mean recoveries ranged from 86 to 90%, with relative standard deviations for repeatability (RSDr) of less than 6%. Limits of detection were 1.2 ng/mL of T-2 toxin and 0.9 ng/mL of T2-G, equivalent to their levels in wheat, of 48 and 36 µg/kg, respectively. The developed iSPR assay was rapid and provided enough sensitivity for the monitoring of T-2 toxin/T2-G in wheat. This is the first iSPR assay useful for detecting the “masked” T2-G in wheat.

Determination of organic acids in the fermentation process of cabbage kimchi by HPLC

A high performance liquid chromatographic(HPLC)method was established for the simultaneous determination of 9 organic acids in kimchi. This method was then used to determine the contents of organic acids in the fermentation process of cabbage kimchi. The procedure of HPLC analysis was carried out on a Agilent TC-C18 column using methanol and 0.01 mol/L potassium dihydrogen phosphate(3∶97)(pH2.80)as the mobile phase. The flow rate was 1 mL/min and the detection wavelength was 210 nm. The nine organic acids were effective separated and determined under the chosen experimental conditions. Relative standard deviations(RSD)of precision was 0.06%~0.26%(n=6)and RSD of repeatability was 0.67%~4.85%(n=6).The recovery rates were in the range of 95.23%~104.76%. The method was convenient,rapid,accurate and applicable to determine organic acids in kimchi.

Development and Validation of a Spectrofluorimetric Method for the Assay of Tetracycline in Capsules

The purpose of this study is to develop and validate a method for the analysis of tetracycline capsules by spectrofluorimetry. A pH 9 borate buffer was used as diluent of tetracycline after reaction with magnesium salt at the excitation wavelength of 372 nm and 516 nm of emission. A linear response was observed between 0.25 μg/mL and 1.5 μg/mL with a correlation coefficient (R) of 0.9998. The detection and quantification limits found are 0.0125 μg/mL and 0.0412 μg/mL respectively. The proposed method proved trueness with a recovery between 99.88% and 101.10%. The relative standard deviations of repeatability and intermediate precision found ≤2.88% reflected a good precision of the method. The proposed method is therefore valid within the limits of 90% to 110%. The proposed method was applied to the quality control of 9 tetracycline samples from market and gave results in accordance with the pharmacopoeia standards.

Validation of Arxula Yeast Estrogen Screen assay for detection of estrogenic activity in water samples: Results of an international interlaboratory study

Endocrine-active substances can adversely impact the aquatic ecosystems. A special emphasis is laid, among others, on the effects of estrogens and estrogen mimicking compounds. Effect-based screening methods like in vitro bioassays are suitable tools to detect and quantify endocrine activities of known and unknown mixtures.This study describes the validation of the Arxula-Yeast Estrogen Screen (A-YES®) assay, an effect-based method for the detection of the estrogenic potential of water and waste water. This reporter gene assay, provided in ready to use format, is based on the activation of the human estrogen receptor alpha. The user-friendly A-YES® enables inexperienced operators to rapidly become competent with the assay.Fourteen laboratories from four countries with different training levels analyzed 17β-estradiol equivalent concentrations (EEQ) in spiked and unspiked waste water effluent and surface water samples, in waste water influent and spiked salt water samples and in a mixture of three bisphenols. The limit of detection (LOD) for untreated samples was 1.8ng/L 17β-estradiol (E2). Relative repeatability and reproducibility standard deviation for samples with EEQ above the LOD (mean EEQ values between 6.3 and 20.4ng/L) ranged from 7.5 to 21.4% and 16.6 to 28.0%, respectively. Precision results are comparable to other frequently used analytical methods for estrogens.The A-YES® has been demonstrated to be an accurate, precise and robust bioassay. The results have been included in the ISO draft standard.The assay was shown to be applicable for testing of typical waste water influent, effluent and saline water. Other studies have shown that the assay can be used with enriched samples, which lower the LOD to the pg/L range.The validation of the A-YES® and the development of a corresponding international standard constitute a step further towards harmonized and reliable bioassays for the effect-based analysis of estrogens and estrogen-like compounds in water samples.

Quantification of glycerophospholipids and sphingomyelin in human milk and infant formula by high performance liquid chromatography coupled with mass spectrometer detector.

Phospholipids and sphingomyelin have a central role in infant nutrition, phospholipid acting as a nutrient carrier of long chain polyunsaturated fatty acids and sphingomyelin having an important role in cognitive function. However, analytical methods to precisely characterize and quantify these compounds in maternal milk are needed. Phospholipids and sphingomyelin were extracted using chloroform and methanol and separated on Polaris 3 Si column 250×2.0mm from Varian and analyzed by high performance liquid chromatography (HPLC) coupled with mass spectrometer detector (MS). The analytical method was validated and repeatability, intermediate reproducibility, and recovery values were calculated. The relative standard deviation of repeatability (CV(r)) and intermediate reproducibility (CV(iR)) values ranged between 2.3 and 7.2% and 9.5 and 17.8%, respectively and the recovery values between 96 and 109%. Finally, the validated method was tested on human milk samples and on infant formula which were analysed also by HPLC coupled with evaporative light scattering detector (ELSD). In human milk, sphingomyelin (9.28mg100mL-1) was the most abundant compound, followed by phosphatidylcholine (5.39mg100mL-1), phosphatidylethanolamine (2.85mg100mL-1) and phosphatidylinositol (1.82mg100mL-1).

Gold nanoparticle-enhanced multiplexed imaging surface plasmon resonance (iSPR) detection of Fusarium mycotoxins in wheat

A rapid, sensitive and multiplexed imaging surface plasmon resonance (iSPR) biosensor assay was developed and validated for three Fusarium toxins, deoxynivalenol (DON), zearalenone (ZEA) and T-2 toxin. The iSPR assay was based on a competitive inhibition format with secondary antibodies (Ab2) conjugated to gold nanoparticles (AuNPs) used as a signal amplification tag. Signal was amplified nearly 25-fold for DON, 90-fold for ZEA and 12-fold for T-2 toxin assay using Ab2-AuNPs. Analyses, including steps to regenerate the sensor, took 17.5min. The antigen coated sensor chip was used for more than 46 cycles without affecting signal intensity (< 12%). Matrix matched calibration curves were used to determine Fusarium toxins in wheat. The mean recoveries ranged from 87% to 103% with relative standard deviations of repeatability of less than 5%. The limits of detection were 15µg/kg for DON, 24µg/kg for ZEA and 12µg/kg for T-2 toxin. This provided sufficient sensitivity to monitor contamination of these mycotoxins in wheat in accordance with European Commission (EC) limits. Cut off levels for all three Fusarium toxins were validated using blank wheat and wheat spiked either at the EC regulated levels (100µg/kg for ZEA and T-2 toxin) or at one third of the EC level (for DON: 400µg/kg). The assay was successfully applied and further validated with naturally contaminated wheat samples. This is the first reported AuNP enhanced iSPR assay to detect and classify three agriculturally important Fusarium toxins in wheat.

Development and Validation of High-Performance Thin-Layer Chromatography Method for Estimation of Teneligliptin in Bulk and in Pharmaceutical Formulation

A high-performance thin layer chromatographic method for determination of Teneligliptin was developed and validation as per ICH guidelines. HPTLC separation was performed on aluminum plates precoated with silica gel 60F254 and Methanol: Toluene: Triethylamine (1:3:1% v/v) as optimized mobile phase at detection wavelength of 245 nm. The retardation factor (Rf) value for Teneligliptin were 0.63 respectively. Accuracy for the marketed formulation teneza was found to be 98.31-100.51%.The percent relative standard deviation for repeatability and intermediate precision studies was found to be < 2%. The propose development HPTLC method can be applied for identification and quantitative determination of Teneligliptin

Determination of the raw material feeding of honeysuchle flowers extract and baikal skullcap root extract in Yinhuang capsules by HPLC-MS/MS

Objective To develop a HPLC-MS/MS method for comprehensive monitoring and control of the raw material feeding (honeysuchle flowers extract and baikal skullcap root extract) , and simultaneous determination of chlorogenic acid and baicalin in Yinhuang capsules. Methods The separation was performed on an Inertsil ODS-3 (2.1 mm × 150 mm, 5 μm) analytical column with the mobile phase consisting of methanol- 10 mmol/L ammonium acetate solution by gradient elution program, and the column temperature was 40 ℃. Active ingredients were separated by HPLC, and the Electrospray Ionization Mass (API) source was applied and operated in the negative ion mode, and reactions ion monitoring mode (MRM) for quantitative analysis were selected. Results The samples and the mixed Extract have the same characteristic peak in MS and MS/MS. According to the prescription feeding process, the proprietary Chinese medicine wasdetermined. The results showed that the palladium residue of 6 batches samples were up to the standard by HPLC/MS/MS chromatographic peak areas. The calibration cruve of chlorogenic acid and baicalin were linear: 0.60-4.80 μg/ml (r = 0.998 9), 2.87-14.40 μg/ml (r = 0.998 6), with the relative standard deviation of repeatability by 0.69% and 0.69% respectively, and the mean recovery rate were 95%-102%, 95%-103%, respectively. Conclusions The method was proven to be simple, accurate, reliable, high sensitive and can be used for determination and control of the raw material feeding (honeysuchle flowers extract and baikal skullcap root extract) and quality in Yinhuang capsules. Key words: Chlorogenic acid; Baicalin; Liquid chromatography-mass spectrometry; Yinhuang capsules

Determination of mancozeb residue in fruit by derivatization and a modified QuEChERS method using ultraperformance liquid chromatography-tandem mass spectrometry.

A liquid chromatography-tandem mass spectrometry method with derivatization and a modified quick, easy, cheap, effective, rugged, and safe (QuEChERS) sample preparation was developed for the determination of mancozeb in fruits. The target compound was determined in less than 4.0min with use of an electrospray ionization source in positive mode. The limits of detection and the limits of quantification ranged from 1.0 to 3.2μgkg-1 and from 10 to 15μgkg-1 in fruit respectively. The linearity was excellent for mancozeb (R 2 ≥ 0.9920). Recoveries in five matrices were obtained at three spiking levels (0.02, 0.1, and 1mgkg-1). For all concentrations, the mean recoveries ranged from 84.0% to 95.9%, with repeatability relative standard deviation (n = 5) of 0.6 - 7.0%. The interday reproducibility relative standard deviation (n = 3) ranged from 1.4% to 5.5%. This method could be used for the routine detection of mancozeb residues in fruit. Graphical abstract The derivation of mancozeb and the detection process of derivative product by UPLC-MS/MS.

An HPLC method for simultaneous quantitative determination of seven secoiridoid glucosides separated from the roots of Ilex pubescens.

A simple and specific high-performance liquid chromatographic method has been developed and validated to simultaneously determine seven secoiridoid glucosides for the first time. Three of them were separated from the ethanolic extract of the roots of Ilex pubescens for the first time, namely nuezhenide A, ligusides B and oleonuezhenide. In quantitative analysis, all of the calibration curves showed good linear regression (r> 0.999) within the tested ranges, and the mean recoveries of three different concentrations ranged from 97.6 to 101.2%. The limit of detection and limit of quantification were <4.18 and 11.63 ng mL-1 , respectively. The relative standard deviation for repeatability and the precision of seven analytes were <3.4 and 1.9%, respectively. The established method was successfully applied to simultaneous determination of seven secoiridoid glucosides in 11 batches of samples collected from different habitats in China.

Determination of total phosphorus content in bottom sediment samples using inductively coupled plasma optical emission spectrometry

This paper describes the methodology of inductively coupled plasma optical emission spectrometry for determining the total phosphorus content in bottom sediment samples. Homogenized samples subjected to a microwave-assisted aqua regia digestion, and next analyzed for total phosphorus content using the inductively coupled plasma optical emission spectrometer. The method was optimized and its validation parameters were determined. Assessing the selectivity of the method, found the spectral interferences of other elements (especially copper) on P can be partially eliminated by using the optimal operating conditions. The method exhibited excellent linearity (r&gt;0.999) in the entire measurement range (25-5000 mg Pkg-1) and very good recovery (99%). It was also characterized by high repeatability (relative standard deviation of 1%) and reproducibility (reproducibility standard deviation of 10%). The relative expanded uncertainty of the method was estimated at 21.2%.

Polydimethylsiloxane/MIL-100(Fe) coated stir bar sorptive extraction-high performance liquid chromatography for the determination of triazines in environmental water samples

Polydimethylsiloxane (PDMS)/MIL-100(Fe) coated stir bar was prepared by sol gel technique, and good preparation reproducibility was achieved with relative standard deviations (RSDs) ranging from 2.6% to 7.5% (n=7) and 3.6% to 10.8% (n=7) for bar-to-bar and batch-to-batch, respectively. Compared with commercial PDMS coated stir bar (Gerstel) and PEG coated stir bar (Gerstel), the prepared PDMS/MIL-100(Fe) stir bar showed better extraction efficiency for target triazines compounds. It also exhibited relatively fast extraction/desorption kinetics and long lifespan. Based on it, a method of PDMS/MIL-100(Fe) coated stir bar sorptive extraction (SBSE)-high performance liquid chromatography-ultraviolet detector (HPLC-UV) was developed for the determination of six triazines (simazine, atrazine, prometon, ametryn, prometryne and prebane) in environmental water samples. Several parameters affecting SBSE of six target triazines including extraction time, stirring rate, sample pH, ionic strength, desorption solvent and desorption time were investigated. Under the optimal experimental conditions, the limits of detection (LODs, S/N=3) were found to be in the range of 0.021–0.079μgL−1. The repeatability RSDs were in the range of 2.3–6.3% (n=7, c=0.5μgL−1) and the enrichment factors (EFs) ranged from 51.1 to 102-fold (theoretical EF was 200-fold). The proposed method was applied to the analysis of target triazines in environmental water samples, with recoveries of 98.0–118% and 94.0–107% for spiked East Lake water and local pond water samples, respectively.

Ion-Exchange Chromatographic Method for the Determination of the Free Amino Acid Composition of Cheese and Other Dairy Products: an Inter-Laboratory Validation Study

Although free amino acids (FAAs) represent a significant component of ripened cheeses and can provide useful information for their characterization, no inter-laboratory validated analytical method exists which allows a reliable comparison of data obtained by different laboratories and the adoption of quality control schemes based on FAA pattern. The objective of the present work was to test the effectiveness of an analytical protocol for the determination of the FAA composition of cheese and to verify the adequateness of this type of analysis for quality control procedures of Grana Padano PDO cheese as well as for research purposes. After an initial test to compare performances of ion-exchange chromatography (IEC) and HPLC techniques, an inter-laboratory collaborative study (seven laboratories, four samples) was organized to validate an IEC method with post-column ninhydrin derivatization and using l-norleucine as an internal standard. Determined amounts of individual FAA ranged from 8 to over 1380 mg/100 g cheese, with relative standard deviation of repeatability (RSDr) ranging from 0.5 to 4.6%, and relative standard deviation of reproducibility (RSDR) ranging from 1.3 to 9.9% for FAA concentrations over 100 mg/100 g. For lower concentrations, RSDr and RSDR were about thrice as high. On the basis of the results of this investigation, at present, the validated method is adopted as the official method for the determination of FAA patterns in the quality control of Grana Padano PDO cheese.