ABSTRACT
In this study, an improved analytical method for the detection of the colorant Brown FK in foods using high-performance liquid chromatography was developed. The method, which employed an RC-C18 column and diode array detection at 254 nm with sodium acetate solution and methanol as mobile phases, exhibited good linearity (R2 = 1.0), and its limits of detection and quantification were determined to be 0.06 and 0.19 µg/mL, respectively. The precision was found to be 0-1.2% and the accuracy was between 86.5% and 94.8%. Liquid chromatography-tandem mass spectrometry was also performed to identify Brown FK in peaks. The pretreatment method was optimized for three different food sample groups, i.e., seafood, noodles and other, affording recoveries of 86.5-92.8%, 90.8-94.8% and 90.0-92.3%, respectively. In addition, inter-laboratory testing was also conducted to check the precision.
Subject(s)
Azo Compounds/analysis , Chromatography, High Pressure Liquid/methods , Food Analysis/methods , Azo Compounds/chemistry , Limit of Detection , Linear Models , Reproducibility of ResultsABSTRACT
This study investigated a method for the validation and determination of measurement uncertainty for the simultaneous determination of synthetic phenolic antioxidants (SPAs) such as propyl gallate (PG), octyl gallate (OG), dodecyl gallate (DG), 2,4,5-trihydroxy butyrophenone (THBP), tert-butylhydroquinone (TBHQ), butylated hydroxyanisole (BHA), and butylated hydroxytoluene (BHT) in edible oils commonly consumed in Korea. The validated method was able to extract SPA residues under the optimized HPLC-UV and LC-MS/MS conditions. Furthermore, the measurement of uncertainty was evaluated based on the precision study. For HPLC-UV analysis, the recoveries of SPAs ranged from 91.4% to 115.9% with relative standard deviations between 0.3% and 11.4%. In addition, the expanded uncertainties of the SPAs ranged from 0.15 to 5.91. These results indicate that the validated method is appropriate for the extraction and determination of SPAs and can be used to verify the safety of edible oil products containing SPAs residues.
Subject(s)
Antioxidants/chemistry , Food Analysis/methods , Phenols/chemistry , Plant Oils/chemistry , Butylated Hydroxyanisole/chemistry , Butylated Hydroxytoluene/chemistry , Calibration , Chromatography, High Pressure Liquid , Chromatography, Liquid , Gallic Acid/analogs & derivatives , Gallic Acid/chemistry , Hydroquinones/chemistry , Propyl Gallate/chemistry , Reproducibility of Results , Republic of Korea , Spectrophotometry, Ultraviolet , Tandem Mass Spectrometry , UncertaintyABSTRACT
This study presents a method validation for extraction and quantitative analysis of 4-hexylresorcinol residues in shrimp and crab meat using HPLC-FLD. We were focused on the collaboratively analysis of each shrimp and crab meat samples, and developed LC-MS/MS method for the correct confirmation of the identity of compound. Validation parameters; selectivity, linearity, LOD, LOQ, accuracy, precision, and measurement of uncertainty were attained. The measurement of uncertainty was based on the precision study, data related to the performance of the analytical process and quantification of 4-hexylresorcinol. For HPLC-FLD analysis, the recoveries of 4-hexylresorcinol from spiked samples at levels of 0.2-10.0 ppm ranged from 92.54% to 97.67% with RSDs between 0.07% and 1.88%. According to these results, the method has been proven to be appropriate for extraction and determination of 4-hexylresorcinol, and can be used to maintain the safety of shrimp and crab products containing 4-hexylresorcinol residues.
Subject(s)
Chromatography, High Pressure Liquid/methods , Hexylresorcinol/chemistry , Shellfish/analysis , Tandem Mass Spectrometry/methods , AnimalsABSTRACT
A simple and rapid method was developed and validated for the determination of hexamethylenetetramine (HMT) in foods. Samples were homogenised and extracted with methanol, followed by centrifugation. The resulting solution was filtered and injected into the high-performance liquid chromatograph (HPLC). HMT was separated using a Zorbax SCX-300 column coupled to a photodiode array detector. The calibration curve was linear in the range of 1.0-100 µg ml(-1), with good correlation coefficients (r(2) = 0.9992). The recoveries of HMT from foods spiked at levels of 10, 50 and 100 mg kg(-1) ranged from 91.6% to 103.8%, with relative standard deviations (RSDs) between 0.9% and 5.3%. The limit of detection and the limit of quantification of HMT were 0.3 and 1.0 mg kg(-1) based on three food matrixes (provolone cheese, glass noodle and tofu snack), respectively. Uncertainty associated with accuracy contributed mostly to the expanded uncertainty. No detectable levels of HMT were found in any of the samples retailed in Korea. The method was successful in determining HMT in foods.
Subject(s)
Chromatography, Liquid/methods , Food Analysis/methods , Methenamine/chemistry , Reproducibility of Results , Sensitivity and Specificity , Solvents , UncertaintyABSTRACT
A simple and rapid method has been developed and validated for the determination of carmine in foods. Samples were homogenised and extracted with 0.05 M NaOH, followed by centrifugation. The resulting solution was filtered and injected to HPLC. Carmine was separated by HPLC using an NovaPak C18 column coupled to a photodiode array detector. The contents of carmine were finally quantified using corresponding calibration curves over ranges of 1.0-100 µg ml(-1), with good correlation coefficients (r(2)=0.9999). The recoveries of carmine from foods spiked at levels of 10, 50, and 100 µg g(-1) which ranged from 90.4% to 96.2% with relative standard deviations between 2.8% and 6.8%. Limit of detection and limit of quantification of carmine were 0.4 and 1.0 µg ml(-1), respectively. This method was found to be useful to distinguish carmine from carminic acid, a major component of cochineal extract. The method has been successfully applied to various foods.
Subject(s)
Carmine/analysis , Food Additives/analysis , Food Analysis/methods , Calibration , Centrifugation , Chromatography, High Pressure Liquid , Coloring Agents/analysis , Food , Hydrogen-Ion Concentration , Limit of Detection , Reproducibility of Results , Solvents/chemistryABSTRACT
Sulfites in foods were analysed using four methods: optimised Monier-Williams (official method), modified Rankine, HPLC and ion-exchange chromatography (IEC). The modified Rankine and HPLC methods were performed according to the previously reported methods but with some modifications. The IEC method was carried out through a combination of a modified Rankine apparatus and an anion-exchange column for the first time. In false-positive response tests, false-positive results with acetic acid and propionic acid were not observed in the modified Rankine, HPLC or IEC methods, unlike the optimised Monier-Williams method. All methods were evaluated for accuracy, precision and simple correlations. Modified Rankine, HPLC and IEC methods were determined to be suitable for foods with less than 10 mg kg(-1) of sulfur dioxide (SO2). The modified Rankine and HPLC methods were suggested to be the most appropriate for the determination of sulfites in foods due to their high correlation coefficient with the optimised Monier-Williams method (R(2) = 0.9138 and 0.9011, respectively).
Subject(s)
Food Analysis/methods , Food Contamination/analysis , Sulfites/chemistry , Commerce , Republic of KoreaABSTRACT
The hepatitis C virus (HCV) NS5B protein is the viral RNA-dependent RNA polymerase required for replication of the HCV RNA genome. We have identified a peptide that most closely resembles a short region of the protein kinase C-related kinase 2 (PRK2) by screening of a random 12-mer peptide library displayed on the surface of the M13 bacteriophage with NS5B proteins immobilized on microwell plates. Competitive phage enzyme-linked immunosorbent assay with a synthetic peptide showed that the phage clone displaying this peptide could bind HCV RNA polymerase with a high affinity. Coimmunoprecipitation and colocalization studies demonstrated in vivo interaction of NS5B with PRK2. In vitro kinase assays demonstrated that PRK2 specifically phosphorylates NS5B by interaction with the N-terminal finger domain of NS5B (amino acids 1-187). Consistent with the in vitro NS5B-phosphorylating activity of PRK2, we detected the phosphorylated form of NS5B by metabolic cell labeling. Furthermore, HCV NS5B immunoprecipitated from HCV subgenomic replicon cells was specifically recognized by an antiphosphoserine antibody. Knock-down of the endogenous PRK2 expression using a PRK2-specific small interfering RNA inhibited HCV RNA replication. In contrast, PRK2 overexpression, which was accompanied by an increase of in the level of its active form, dramatically enhanced HCV RNA replication. Altogether, our results indicate that HCV RNA replication is regulated by NS5B phosphorylation by PRK2.
