Skin advanced glycation end products as biomarkers of photosensitivity in schizophrenia.

OBJECTIVES: Photosensitivity to ultraviolet A (UVA) radiation from sunlight is an important side effect of treatment with antipsychotic agents. However, the pathophysiology of drug-induced photosensitivity remains unclear. Recent studies demonstrated the accumulation of advanced glycation end products (AGEs), annotated as carbonyl stress, to be associated with the pathophysiology of schizophrenia. In this study, we investigated the relationship among skin AGE levels, minimal response dose (MRD) with UVA for photosensitivity, and the daily dose of antipsychotic agents in patients with schizophrenia and healthy controls. METHODS: We enrolled 14 patients with schizophrenia and 14 healthy controls. Measurement of skin AGE levels was conducted with AGE scanner, a fluorometric method for assaying skin AGE levels. Measurement of MRD was conducted with UV irradiation device. RESULTS: Skin AGE levels and MRD at 24, 48, and 72 hr in patients with schizophrenia showed a higher tendency for photosensitivity than in the controls, but the difference was statistically insignificant. Multiple linear regression analysis using skin AGE levels failed to show any influence of independent variables. MRD did not affect skin AGE levels. CONCLUSIONS: Photosensitivity to UVA in patients with schizophrenia receiving treatment with antipsychotic agents might not be affected by skin AGE levels.

Rapid determination of the various native forms of vitamin B6 and B2 in cow's milk using ultra-high performance liquid chromatography.

As the formation of pyridoxal phosphate, the active cofactor of vitamin B6, is dependent on riboflavin 5-phosphate, we propose a fast and simple ultra-high performance liquid chromatography method for the simultaneous determination of the native B6 vitamers pyridoxal, pyridoxine, pyridoxamine, their mono phosphorus esters and 4-pyridoxic acid as well as vitamin B2 as riboflavin and its phosphorus ester riboflavin 5-phosphate in milk. Separation was achieved under 6.0min by reversed-phase and pH gradient elution. Sample preparation was optimized regarding various acids and pH levels. Changes in those parameters led to significant deviations of sample matrix breakdown efficiency. The optimized method was then validated regarding specificity, accuracy, precision, linearity, range, detection and quantification limits. As the method performed satisfactory, is was used to study commercial liquid cow's milk (n=31), regarding effects of the employed preservation technique (pasteurization, extended shelf-life, ultra-high temperature) on the composition and content of B6 and B2 vitamers. In cow's milk, vitamin B6 mostly consists of pyridoxal and its phosphate ester, with pyridoxal phosphate being the bulk component. The catabolite of the vitamin B6 metabolism, 4-pyridoxic acid was present in significant amounts in all studied samples, with up to 2.69µmolL-1. Vitamin B2 was present as riboflavin and its phosphate ester up to 12.86µmolL-1.

Evaluación multicéntrica del nuevo sistema analítico BioSystems BA 400 ® y comparación de procedimientos de medida / Multicentre evaluation of the new analytical system BioSystems BA 400 ® and comparison of measurement procedures

Objetivo. El objetivo de este trabajo fué evaluar, mediante un estudio multicéntrico, la imprecisión y la veracidad de un elevado número de procedimientos de medida en el nuevo sistema analítico BioSystems BA 400(R). Material y método. El estudio de la imprecisión se llevó a cabo siguiendo recomendaciones establecidas y utilizando sueros control con 2 concentraciones distintas. El estudio de la veracidad se ha realizado mediante la comparación de los procedimientos de medida del nuevo sistema con los utilizados habitualmente en los centros evaluadores. Resultados. Los resultados obtenidos para la imprecisión interdiaria con el nuevo analizador han sido en general excelentes en relación a los errores máximos permitidos. Se han encontrado algunas diferencias no despreciables y estadísticamente significativas entre los distintos procedimientos de medida, que son debidas a diferencias en el mensurando en algunos casos (transaminasas, inmunoanálisis) y a diferencias en los calibradores en otros. Conclusiones. La evaluación ha demostrado las excelentes prestaciones de precisión y veracidad del sistema. El nuevo analizador proporciona resultados en muestras de pacientes que son equivalentes a los obtenidos con otros analizadores (Olympus AU5400 y AU2700, Roche Cobas C711 y Siemens ADVIA 2400, 1800 y BNII) (AU)

Background. The purpose of the study was a multicentre evaluation of the imprecision and of the trueness of a wide variety of measurement procedures with the new analytical system BioSystems BA 400(R). Methods. The imprecision study was performed following established recommendations and using control sera with two different concentrations. The trueness was studied by means of a comparison of the measurement procedures of the new analyser with those of routine use in the evaluating centres. Results. The results obtained for the between-day imprecision with the new analyser have been in general excellent in relation to the maximum allowed errors. Several differences that are not worthless and that are statistically significant have been found between the measurement procedures. The differences are due to measurand differences in some cases (transaminases, immunoanalysis), and to the calibration in other. Conclusion. The evaluation study has demonstrated the excellent performance of the system regarding precision and trueness. The results obtained for patient samples with the new analyzer are equivalent to those obtained with other analyzers (Olympus AU5400 y AU2700, Roche Cobas C711 y Siemens ADVIA 2400, 1800 y BNII) (AU)

Contents of all forms of vitamin B6, pyridoxine-ß-glucoside and 4-pyridoxic acid in mature milk of Japanese women according to 4-pyridoxolactone-conversion high performance liquid chromatography.

The contents of six vitamin B6 forms, pyridoxine-ß-glucoside, and 4-pyridoxic acid in mature milk of 20 Japanese lactating women consuming ordinary Japanese foods were determined by a 4-pyridoxolactone-conversion HPLC method. These compounds were determined with the average recovery rate of 83.9% or more. The average total content of vitamin B6 forms was 1.01 ± 0.32 (µmol/L). Pyridoxal and pyridoxal 5'-phosphate were found in all of the samples, and their average contents were 0.71 ± 0.28 (µmol/L) and 0.16 ± 0.07 (µmol/L), respectively. Pyridoxamine, pyridoxine, pyridoxamine 5'-phosphate, pyridoxine 5'-phosphate, and pyridoxine-ß-glucoside were found in 15, 14, 13, 9, and 7 samples, respectively. The presence of pyridoxine 5'-phosphate was for the first time found in human milk. A method for the determination of 4-pyridoxic acid, which is the excretion form of vitamin B6, was modified to quantitate it by isocratic HPLC. 4-Pyridoxic acid was found in all samples, and its average content was 0.094 ± 0.040 (µmol/L), which was only 12% of its content in cow (Holstein) milk. The total content of vitamin B6 forms, and predominant presence of pyridoxal among other vitamin B6 forms in the Japanese women's milk samples shared similar characteristics with American women's milk samples.

Ultra-performance liquid chromatography tandem mass-spectrometry (UPLC-MS/MS) for the rapid, simultaneous analysis of thiamin, riboflavin, flavin adenine dinucleotide, nicotinamide and pyridoxal in human milk.

A novel, rapid and sensitive ultra-performance liquid-chromatography tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous determination of several B-vitamins in human milk was developed. Resolution by retention time or multiple reaction monitoring (MRM) for thiamin, riboflavin, flavin adenine dinucleotide (FAD), nicotinamide and pyridoxal (PL) has been optimized within 2 min using a gradient of 10 mM ammonium formate (aq) and acetonitrile. Thiamin-(4-methyl-¹³C-thiazol-5-yl-¹³C3) hydrochloride, riboflavin-dioxo-pyrimidine-¹³C4,¹5N2, and pyridoxal-methyl-d3 hydrochloride were used as internal standards. A sample-like matrix was found to be mandatory for the external standard curve preparation. ¹³C3-caffeine was added for direct assessment of analyte recovery. Intra- and inter-assay variability for all analytes ranged from 0.4 to 7.9% and from 2.2 to 5.2%, respectively. Samples were subjected to protein precipitation and removal of non-polar constituents by diethyl ether prior to analysis. Quantification was done by ratio response to the stable isotope labeled internal standards. The standard addition method determined recovery rates for each vitamin (73.0-100.2%). The limit of quantitation for all vitamins was between 0.05 and 5 ppb depending on the vitamin. Alternative approaches for sample preparation such as protein removal by centrifugal filter units, acetonitrile or trichloroacetic acid revealed low recovery and a greater coefficient of variation. Matrix effect studies indicated a significant influence by matrix constituents, showing the importance of stable isotope labeled internal standards for analyte quantitation in complex matrices.

Vitamins in the monkey brain: An immunocytochemical study.

Using highly specific antisera directed against vitamins, the distribution of pyridoxal-, pyridoxine-, vitamin C- and nicotinamide-immunoreactive structures in the monkey (Macaca fascicularis) brain was studied. Neither immunoreactive structures containing pyridoxine or nicotinamide, nor immunoreactive fibers containing vitamin C were found in the monkey brain. However, this work reports the first visualization and the morphological characteristics of pyridoxal- and vitamin C-immunoreactive cell bodies in the mammalian central nervous system using an indirect immunoperoxidase technique. A high density of pyridoxal-immunoreactive cell bodies was found in the paraventricular hypothalamic nucleus and in the supraoptic nucleus and a low density of the same was observed in the periventricular hypothalamic region, whereas a moderate density of vitamin C-immunoreactive cell bodies was observed in the somatosensorial cortex (precentral gyrus). Immunoreactive fibers containing pyridoxal were only visualized in the anterior commissure. The restricted distribution of pyridoxal and vitamin C in the monkey brain suggests that both vitamins could be involved in very specific physiological mechanisms.

HPLC methods for determination of two novel thiosemicarbazone anti-cancer drugs (N4mT and Dp44mT) in plasma and their application to in vitro plasma stability of these agents.

The aim of this study was to develop and validate HPLC methods for the determination in plasma of two novel thiosemicarbazone anti-tumour drugs developed in our laboratories (Dp44mT and N4mT). The appropriate separations were achieved using a HS F5 HPLC column with the mobile phase composed of a mixture of either acetate buffer/EDTA or EDTA and acetonitrile (62:38 and 50:50, v/v, respectively). The plasma samples were pretreated with SPE (phenyl and C18, respectively). Furthermore, these methods were successfully applied to in vitro plasma stability experiments. The investigation has clearly shown that both thiosemicarbazones are markedly more stable in plasma than their aroylhydrazone forerunners.

Spectrophotometric determination of ternary mixtures of thiamin, riboflavin and pyridoxal in pharmaceutical and human plasma by least-squares support vector machines.

Ternary mixtures of thiamin, riboflavin and pyridoxal have been simultaneously determined in synthetic and real samples by applications of spectrophotometric and least-squares support vector machines. The calibration graphs were linear in the ranges of 1.0 - 20.0, 1.0 - 10.0 and 1.0 - 20.0 microg ml(-1) with detection limits of 0.6, 0.5 and 0.7 microg ml(-1) for thiamin, riboflavin and pyridoxal, respectively. The experimental calibration matrix was designed with 21 mixtures of these chemicals. The concentrations were varied between calibration graph concentrations of vitamins. The simultaneous determination of these vitamin mixtures by using spectrophotometric methods is a difficult problem, due to spectral interferences. The partial least squares (PLS) modeling and least-squares support vector machines were used for the multivariate calibration of the spectrophotometric data. An excellent model was built using LS-SVM, with low prediction errors and superior performance in relation to PLS. The root mean square errors of prediction (RMSEP) for thiamin, riboflavin and pyridoxal with PLS and LS-SVM were 0.6926, 0.3755, 0.4322 and 0.0421, 0.0318, 0.0457, respectively. The proposed method was satisfactorily applied to the rapid simultaneous determination of thiamin, riboflavin and pyridoxal in commercial pharmaceutical preparations and human plasma samples.

Reversed-phase high-performance liquid chromatography method with coulometric electrochemical and ultraviolet detection for the quantification of vitamins B(1) (thiamine), B(6) (pyridoxamine, pyridoxal and pyridoxine) and B(12) in animal and plant foods.

A rapid and sensitive high-performance liquid chromatography (HPLC) method with coulometric electrochemical and ultraviolet detections for analysis of vitamin B (B(1), B(6) and B(12)) in animal and plant foods has been developed. A combination of acid digestion and enzymatic extraction to release protein bound and phosphorylated vitamins followed by HPLC analysis was applied. The analyses were carried out on a LC18 column 5 microm (25 cm x 4.6 mm), using the mobile phase consisting of methanol-phosphate buffer (10:90) and 0.018 M trimethylamine, pH 3.55, following at 1.0 ml min(-1). The method offers excellent linearity with regression coefficient r>0.998, good repeatability and reproducibility and relatively short analysis time (17 min). The relative standard deviation (RSD) of the intermediate precision was satisfactory for all the vitamins studied and amounted to <7.3%. The repeatability of the method was <4.7%. The limits of quantification (LOQ) for pyridoxamine, pyridoxal, pyridoxine, vitamins B(1) and B(12) in seafood products were as follows: 2.1, 2.01, 0.99, 62.0 and 0.11 ng ml(-1), respectively. The mean recovery values from a food products spiked with all five vitamins ranged from 92.3 to 101.3%, with a relative standard deviation less than 3.4%. The proposed separation and detection procedures were successfully applied for the simultaneous determination of vitamins B(1), B(6) and B(12) in fruit juices and vitamins B(6) and B(12) in seafood.

Simultaneous fluorometric resolution of pyridoxal, pyridoxamine and 4-pyridoxic acid using chemometric methods.

An alternatively minimizing covariant matrix error (AMCME) algorithm, newly proposed by the present authors, was applied to the simultaneous fluorometric determination of pyridoxal, pyridoxamine and 4-pyridoxic acid without loss of sensitivity. The experimental results illustrate that the profiles of spectra and concentration can be accurately resolved using the AMCME algorithm with a high sensitivity and stable repeatability. That is to say, the closely overlapping problem of the spectra could be resolved owing to the characteristic features of the AMCME algorithm.

HPLC study on stability of pyridoxal isonicotinoyl hydrazone.

Biocompatible iron chelators are currently under extensive investigation as promising drug candidates. Pyridoxal isonicotinoyl hydrazone (PIH) is a lead compound of the aroylhydrazone group of novel iron chelating agents. In this study, the precise and accurate HPLC analytical methods were used for the stability evaluation of water-soluble PIH salt (PIH x 2HCl) in aqueous media of different pH (2.0, 3.9, 7.0, 9.0 and 12.0) as well as in two selected pharmaceutical co-solvents at both laboratory and elevated (40 degrees C) temperatures. The susceptibility of PIH x 2HCl to oxidative decomposition was studied in the solutions of hydrogen peroxide (3 and 30%). Furthermore, the solid substance of PIH x 2HCl was exposed to UV, dry and wet heat. Our experiments revealed that PIH was considerably sensitive to hydrolytic decomposition in aqueous media, resulting in the splitting of the hydrazone bond. The elevated temperature significantly accelerated the hydrolytic reaction. The lowest rate of hydrolysis of PIH was observed in the phosphate buffer of pH 7.0 and in the pharmaceutical co-solvents (30% PEG-300 and 10% Cremophor EL). No special degradation products were detected in the samples exposed to either hydrogen peroxide or co-solvents. The solid substance of PIH x 2HCl was stable when exposed to UV, dry or wet heat for 33 h.

Micellar liquid chromatography in clinical chemistry: application to the monitorization of B6 vitamins.

BACKGROUND: A micellar reversed-phase liquid chromatographic procedure was developed for the determination of B6 group vitamins, i.e. pyridoxine, pyridoxal and pyridoxamine, in human serum. METHODS: Chromatographic conditions used were a C18 column, isocratic mode, flow-rate of 1 ml/min and UV-detection at 290 nm. Optimization of the composition of the mobile phase was performed using an interpretative strategy. RESULTS: After modeling, the composition of the selected mobile phase was 150 mM sodium dodecyl sulphate (SDS)--2% (v/v) pentanol-dihydrogenphosphate buffer 10 mM at pH 3. In this mobile phase, serum samples were injected without pretreatment and analysis time was below 14 min. Calibrations for the three vitamins were linear, with coefficient regression better than 0.999, and intra- and inter-day precision, achieved according to ICH, offering values below 4.3% and 3.2%, respectively. The method was applied to the determination of the B6 vitamins in spiked serum samples, with recoveries around 100%, and in the pharmacokinetic determination of pyridoxine half-life in serum, which was found to be 47.5 +/- 3.2 min (n = 5). The procedure was also applied for the analysis of pyridoxine in human serum spiked with several pharmaceutical preparations that contain other drugs which do not produce any kind of interference. Finally, solutions of B6 vitamins kept at -201 degrees C are stable for up to 3 months. CONCLUSIONS: Using the method proposed here, with an SDS-pentanol mobile phase, it is possible to carry out the fast sensitive determination of B6 vitamins in serum following direct injection, without sample pretreatment.

Uptake, hydrolysis, and metabolism of pyridoxine-5'-beta-D-glucoside in Caco-2 cells.

An important dietary source of vitamin B-6, pyridoxine-5'-beta-D-glucoside (PNG), exhibits only partial bioavailability, which is limited by the extent of enzymatic cleavage of the beta-glucosidic bond to release metabolically available pyridoxine (PN). This laboratory showed that the intestinal hydrolysis of PNG is catalyzed by cytosolic PNG hydrolase (PNGH) and brush border lactase-phlorizin hydrolase (LPH). LPH-catalyzed PNG hydrolysis in vitro is competitively inhibited by lactose. In the present study, the uptake and hydrolysis of PNG were examined in Caco-2 human colon carcinoma cells, which express a functional LPH but exhibit no PNGH activity. PNG uptake at 37 degrees C was linear over 5-500 micromol/L PNG. Uptake was not significantly reduced when Na(+) was substituted with K(+), Li(+), or Tris in the medium. Increasing PNG concentration in the medium did not change intracellular concentrations of PN, pyridoxamine (PM), pyridoxamine 5'-phosphate (PMP), or pyridoxal 5'-phosphate (PLP); however, intracellular pyridoxal (PL) concentration increased. Intracellular PNG concentration was not significantly reduced in the presence of lactose, but the concentration of PL declined in proportion to extracellular lactose (P = 0.01). These results indicate that PNG can be absorbed intact in a Na(+)-independent process and is taken up by passive diffusion. The presence of lactose in this in vitro model of intestinal uptake reduced the enzymatic hydrolysis of PNG by lactase.

Chromatographic methods for the separation of biocompatible iron chelators from their synthetic precursors and iron chelates.

Chromatographic methods have been developed for the separation of the three novel biocompatible iron chelators pyridoxal isonicotinoyl hydrazone (PIH), salicylaldehyde isonicotinoyl hydrazone (SIH), and pyridoxal 2-chlorobenzoyl hydrazone (o-108) from their synthetic precursors and iron chelates. The chromatographic analyses were achieved using analytical columns packed with 5 microm Nucleosil 120-5 C18. For the evaluation of all chelators in the presence of the synthetic precursors, EDTA was added to the mobile phase at a concentration of 2 mM. The best separation of PIH and its synthetic precursors was achieved using a mixture of phosphate buffer (0.01 M NaH2PO4, 5 mM 1-heptanesulfonic acid sodium salt; pH 3.0) and methanol (55:45, v/v). For separation of SIH and its synthetic precursors, the mobile phase was composed of 0.01 M phosphate buffer (pH 6.0) and methanol (60:40, v/v). o-108 was analyzed employing a mixture of 0.01 M phosphate buffer (pH 7.0), methanol, and acetonitrile (60:20:20, v/v/v). These mobile phases were slightly modified to separate each chelator from its iron chelate. Furthermore, a RP-TLC method has also been developed for fast separation of all compounds. The chromatographic methods described herein could be applied in the evaluation of purity and stability of these drug candidates.

Vitamin B-6 content of breast milk and neonatal behavioral functioning.

OBJECTIVE: To determine if vitamin B-6 intakes of mothers influence the B-6 vitamer content of transition milk and if correlations exist between the vitamin B-6 content of the milk and the infants' neurobehavioral functioning. DESIGN: Transition milk samples were collected from mothers 8 to 11 days after delivery for B-6 vitamer analysis. Neurobehavioral functioning of the neonates was determined at that time. A 24-hour recall was used in estimating vitamin B-6 intakes of the mothers. SUBJECTS: A convenience sample of low-income, lactating women (n = 25) who had normal pregnancies. MAIN OUTCOME MEASURES: B-6 vitamers were measured in the mothers' transition milk samples. Neurobehavioral functioning was assessed using the Brazelton Neonatal Behavioral Assessment Scale (NBAS), and the Center for Epidemiologic Studies Depression Scale was used to evaluate maternal depression. STATISTICAL ANALYSES PERFORMED: Pearson correlation coefficients were used to assess if statistically significant relationships existed between variables. The Mann-Whitney test was used to determine if median group values were significantly different. RESULTS: The major B-6 vitamer in transition milk was pyridoxal. Mothers with vitamin B-6 intake greater than the median value had a significantly higher median pyridoxal level in their breast milk than did the mothers with intakes below the median value. All except one mother had a dietary vitamin B-6 intake that exceeded the Recommended Dietary Allowance. Infant scores on habituation (r = .94, P < .05) and autonomic stability (r = .34, P < .05) subscales of the NBAS were positively correlated with milk pyridoxal values. APPLICATIONS/CONCLUSIONS: Vitamin B-6 is important for normal behavioral functioning of infants. The mothers' vitamin B-6 intake affects vitamin B-6 levels of breast milk and the need for consuming recommended levels of vitamin B-6 should be emphasized to all pregnant and lactating mothers.

Differential scanning calorimetry and scanning thermal microscopy analysis of pharmaceutical materials.

Micro-thermal analysis (microTA) by scanning thermal microscopy is being used increasingly for the analysis of pharmaceutical dosage forms. However, there is currently little evidence to show that microTA data can compare directly with that from the established approach of differential scanning calorimetry (DSC). This work compares DSC and microTA data from an active vitamin B6 analogue, pyridoxal hydrochloride, and two commonly used pharmaceutical excipients, Mannitol and Avicel which are used in its formulation. It is found that microTA provides precise and accurate micro-thermal analytical data with 0.1 K thermal sensitivity, which is comparable to that obtained by DSC measurements of bulk samples. It is also shown that microTA offers the opportunity to study single particles and the interfacial region between particles, data which is currently inaccessible through the DSC technique.

An enzymatic fluorometric assay for pyridoxal with high specificity and sensitivity.

An enzymatic fluorometric assay for pyridoxal with pyridoxal dehydrogenase was developed. The detection limit was about 10 pmol: the calibration curve of pyridoxal showed high linearity (r=0.993). The values obtained by this method correlated well with those by the HPLC method. The enzyme had a high specificity for pyridoxal, and thus animal samples could be directly analyzed without separation of pyridoxal 5'-phosphate by column chromatography.

Effect of phosphate on stability of pyridoxal in the presence of lysine.

The stability of the biologically active compound vitamin B(6) in aqueous solution was investigated. Schiff base formation is the major reaction between the epsilon-amino group of lysine and the aldehyde group of both pyridoxal and pyridoxal phosphate. Model systems composed of equal molar concentrations of lysine with either pyridoxal or pyridoxal phosphate were used to study the effect of proton transfer on Schiff base formation. Pyridoxylidenelysine was found to be the major product in both lysine/pyridoxal and lysine/pyridoxal phosphate systems. Quantitation of residual pyridoxal and pyridoxal phosphate was conducted using an HPLC to evaluate the degradation of pyridoxal and pyridoxal phosphate. The results indicate both the free phosphate ion in the buffer system and the bound phosphate on pyridoxal phosphate can enhance the formation of the Schiff base. The phosphate group serves as both proton donor and acceptor, which catalyzes the Schiff base formation. The aldehyde group on pyridoxal phosphate was found to be much more reactive than that on pyridoxal. The bound phosphate group on pyridoxal phosphate, with proton donating and accepting groups in close proximity, can simultaneously donate and accept protons, thus enhancing Schiff base formation between the aldehyde group and the epsilon-amino group. The deterioration rate of pyridoxal phosphate was faster than that of pyridoxal in an aqueous system.

Determination of vitamin B(6) in cooked sausages.

A reverse-phase high-performance liquid chromatography (HPLC) method has been described for the determination of various active forms of vitamin B(6) in meat products. Different extracting agents were tested to solubilize fully the analyte for quantification. The best data were obtained by extracting the samples with 5% (w/v) metaphosphoric acid. Separation by HPLC was performed with fluorescence detection (excitation, 290 nm; emission, 395 nm), on a 10 cm x 0.46 cm i.d. Hypersil BDS C(18) 5 microm column using a mixture of 50 mM phosphate buffer (pH 3.2) and acetonitrile (99:1, v/v) as mobile phase. Precision of the method was 0.5% (within a day) and 4.3% (between days). The detection limits were 0.020 mg/100 g for pyridoxal and pyridoxamine, 0.017 mg/100 g for pyridoxamine phosphate, 0.500 mg/100 g for pyridoxal phosphate, and 0.033 mg/100 g for pyridoxol, with a signal-to-noise ratio of 3. The recovery ranged from 92.0 to 100.0%.

Determination of vitamin B6 (pyridoxamine, pyridoxal and pyridoxine) in pork meat and pork meat products by liquid chromatography.

A liquid chromatographic method for determining vitamin B6 compounds in pork meat and pork meat products is examined. It uses the same extraction procedure as that applied for thiamin and riboflavin determination, followed by a liquid chromatographic separation on a reversed-phase C18 column with 0.01 M H2SO4 as mobile phase at 30 degrees C. 4-Deoxypyridoxine is used as internal standard. The analytical parameters linearity, precision of the method (R.S.D. = 7.3 and 6.9% for pyridoxamine and pyridoxal, respectively) and accuracy obtained by recovery assays (99 and 85.1% for pyridoxamine and pyridoxal, respectively) show that the studied method is useful to measure these compounds in pork meat.