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The current study developed a method for quantifying four drugs—Sulfamethoxazole, Trimethoprim, Isoniazid, and Pyridoxine—in rabbit plasma. The method uses gradient liquid chromatography based on analytical quality by design. To achieve separation, a Eclip Plus C18 (250 mm × 5 mm, 4.6 µm) column with L1 packing was used, and analytes were detected at 254 nm at ambient temperature. The optimized mobile phase consisted of 50 mM potassium dihydrogen phosphate buffer (pH 6.5) and Methanol. The concentration of Methanol was 3% (0–5 min), 15% (5–15 min), 55% (15–27 min), and 3% Methanol until the end of the 30-min runtime, and the flow rate was set at 0.95 mL/min. Control Noise Experimentation was used to screen studies, revealing that flow rate, pH, and Methanol concentration significantly affected the analytical attributes. The study identified critical attributes (resolution and asymmetric factor) and developed a quality target method profile. A central composition design was used to optimize the essential parameters. The method developed for the drugs showed peaks at retention times of 6.990 min for Isoniazid, 7.880 min for Pyridoxine, 15.530 min for Sulfamethoxazole, and 26.890 min for Trimethoprim, respectively. The method was validated with linearity in the range of 10–640 ng ml −1 , with R 2 of 0.9993, 0.9987, 0.9993, and 0.9992 for Sulfamethoxazole, Trimethoprim, Isoniazid, and Pyridoxine, respectively.

A culture-specific web-based food frequency questionnaire (FFQ) to assess dietary intake in the United Arab Emirates (UAE) adult population was developed using data from the 2009-2010 national nutrition survey. The objective of this study was to assess the relative validity of the newly developed FFQ for use in the adult Emirati population (AE-FFQ), which contained a list of 139 food lines. A convenient sample of 60 (36 females and 24 males) adult Emiratis completed 3 non-consecutive 24HRs over a period of one month, followed by the AE-FFQ, which assessed the intake over the previous month. Relative validity was evaluated by comparing nutrient and food group intakes from the AE-FFQ with the average three 24HRs using Wilcoxon signed-rank tests, Spearman's correlation coefficients (CC), Bland-Altman analysis, and cross-classification. The AE-FFQ overestimated energy and most nutrients and food groups. Bland-Altman analysis showed significant proportional bias between the 2 methods. Deattenuated energy-adjusted Spearman correlation coefficients were poor to good ranging from 0.06 (iron) to 0.62 (fiber) for nutrients, 0.39 median value, and from -0.01 (cruciferous vegetables) to 0.64 (eggs) for food groups, 0.41 median value. A fairly acceptable agreement was obtained, with correct classification into the same or adjacent quartile ranging from 34% (vitamin B12) to 78% (pyridoxine), median 69% for nutrients and from 55% (diet soft drinks) to 87% (soft drinks), median 67% for food groups. The AE-FFQ is an acceptable tool for ranking UAE adults (aged 18 to 50) according to their dietary intake to investigate the role of Emirati dietary patterns on health and disease. Caution is needed for assessing absolute intake, however, given the bias observed in assessing group-level agreement.

The recent investigation targets to use adapted carbon paste (CP) with copper nanoparticles (CuNs) operating in a phosphate buffer (PBS) medium with a pH range of 5.0-8.0, to synthesize a novel, susceptible, and simple electrochemical sensor for the detection of one of the most important drugs, vitamin B . Copper (Cu) is one of the most three common essential trace elements found in the bodies of both humans and animals, along with iron and zinc for all crucial physiological and biochemical functions. Its properties, which are assessed using a variety of methods including scanning electron microscopy (SEM), cyclic voltammetry (CV), differential pulse voltammetry (DPV), and electrochemical impedance spectroscopy (EIS), have also drawn a lot of attention recently. We considered the effects of pH, buffer, scan rate, interference, and calibration curve. The susceptible electrode's linear calibration curve encompassed concentration values between 8.88 and 1000.0 µM. The calculated limits of detection and quantification were 32.12 and 107.0 µM, respectively. Furthermore, this method was established in real human urine samples and drug validation which have been shown satisfactory results for vitamin B detection.

This study aimed to assess the extent of vitamin B and B vitamer loss during a single peritoneal dialysis (PD) session using a combination of chromatographic techniques and chemometric analysis. Dialysis effluent samples were collected from 41 PD patients (22 on continuous ambulatory peritoneal dialysis (CAPD) and 19 on automated peritoneal dialysis (APD)) during a standardised peritoneal equilibration test. Concentrations of thiamine monophosphate, thiamine diphosphate (ThDP), pyridoxine, pyridoxal (PL), and pyridoxamine were determined using high-performance liquid chromatography with a fluorescence detector. The analytical method was validated in terms of sensitivity, linearity, accuracy, and recovery. Multiple regression analysis was employed to identify potential clinical and demographic predictors of vitamin washout. All vitamers except pyridoxal 5-phosphate (PLP) were detectable in dialysis effluents. ThDP exhibited the greatest loss among the B forms (ca. 0.05-0.57 mg/24 h), while PL exhibited the most significant loss among the B forms (ca. 0.01-0.19 mg/24 h). Vitamin losses varied depending on the dialysis modality (continuous ambulatory peritoneal dialysis, or CAPD, versus automated peritoneal dialysis, or APD) and the peritoneal transport category. Regression analysis identified body weight, haemoglobin, and haematocrit as independent predictors of ThDP washout (R = 0.58). No statistically robust models were established for the other vitamers. Even short medical procedures (such as single PD) can result in measurable losses of water-soluble vitamins, particularly ThDP and PL. The results emphasise the importance of personalised vitamin supplementation for PD patients and suggest that body composition and haematological parameters significantly influence the loss of thiamine.

Background Individual B vitamins have many favorable effects on the skin and are common cosmetic ingredients. However, their formulation is demanding due to stability issues, which consequently affect the products’ quality. Aims We aimed to determine the quality (labeling accuracy, content determination, and content‐related quality control) and stability under long‐term and accelerated storage conditions of a representative sample of commercial cosmetics containing the most common B vitamins – nicotinamide, dexpanthenol, pyridoxine, and cyanocobalamin. Methods Cyanocobalamin was determined by a previously published stability‐indicating HPLC– diode array detector (DAD) method for the simultaneous determination of all hydrophilic vitamins. This method was additionally simplified and adjusted for the time‐effective analysis of nicotinamide, dexpanthenol, and pyridoxine. Both methods were properly validated. Results All labeled B vitamins were present in the 36 tested products, mostly in contents, reported effective on the skin. Thus, a straightforward correlation between vitamin contents and product prices were not observed. The content‐related quality control of eight products, which quantitively specify their content, revealed significantly lower nicotinamide contents (47% and 57%) in two products and appropriate or higher nicotinamide (102%–112%) and dexpanthenol (100%–104%) contents than declared in the remaining products. The 6‐month long‐term and accelerated stability studies demonstrated the products’ physical stability, but also revealed dexpanthenol, pyridoxine, and cyanocobalamin degradation, while nicotinamide was mostly stable in the tested products. Conclusions The obtained results provide an inside into the quality of commercial vitamin B cosmetics and highlight the importance of stability testing in the formulation of quality, efficient, and safe cosmetics.

In this work, the electrochemical behavior of hydrochlorothiazide and pyridoxine on the ethylenediamine-modified glassy carbon electrode were investigated by differential pulse voltammetry. In pH 3.4 Britton-Robinson (B-R) buffer solution, both hydrochlorothiazide and pyridoxine had a pair of sensitive irreversible oxidation peaks, that overlapped in the 1.10 V to 1.20 V potential range. Under the optimum experimental conditions, the peak current was linearly related to hydrochlorothiazide and pyridoxine in the concentration range of 0.10–2.0 μg/mL and 0.02–0.40 μg/mL, respectively. Chemometrics methods, including classical least squares (CLS), principal component regression (PCR) and partial least squares (PLS), were introduced to resolve the overlapped signals and determine the two components in mixtures, which avoided the troublesome steps of separation and purification. Finally, the simultaneous determination of the two components in commercial pharmaceuticals was performed with satisfactory results.

The unintentional ingestion of toxic compounds in herbs is not uncommon in many parts of the world. To provide timely and life-saving care in the emergency department, it is essential to develop a point-of-care analytical method that can rapidly identify these toxins in herbs. Since electrospray laser desorption ionization mass spectrometry (ELDI/MS) has been successfully used to characterize non-volatile chemical compounds without sample preparation, it was used to identify toxic herbal compounds in this study. The herbal toxins were collected either by sweeping a metallic probe across the surface of a freshly cut herb section or by directly sampling extracts of ground herbal powder. The analytes on the probe were then desorbed, ionized and detected using ELDI/MS, wherein analysis of the herbal toxins was completed within 30 s. This approach allows for the rapid morphological recognition of herbs and early point-of-care identification of herbal toxins for emergency management and is promising in providing important toxicological information to ensure appropriate medical treatment. [Display omitted] •Various herbal toxins were identified within 30 s by ELDI/MS.•Limit-of-detection for the tested herbal toxins by ELDI/MS is at the ppm level.•Toxic ingredients identification bypasses morphological recognition of herbs.•Linearity tests for the tested toxic herbal ingredients were established.•Principal component analysis for mass spectrometric data of herbal toxins was performed.

Background The objective of this work was to study the vitamins B 1 , B 2 , B 6 and C stability in a pediatric formulation containing high amounts of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulfate, pediatric vitamins and trace elements under different conditions using developed and validated analytical methods. Methods The study was carried out during 72 h with formulations packaged in recommended storage temperature (4°C) and 25°C, with and without photoprotection. Results The results showed that the methodologies used for assessing the chemical stability of vitamins B 1 , B 2 , B 6 and C in the formulation were selective, linear, precise and accurate. The vitamins could be considered stable in the formulation during the three days of study if stored at 4°C. When stored at 25°C vitamin C presented instability after 48 h. Conclusion The pediatric formulation containing high amount of calcium in the presence of organic phosphate, amino acids, glucose, sodium chloride, magnesium sulphate, pediatric vitamins and trace elements packaged in bag-type trilaminate presented a shelf life of the 72 h, when maintained under refrigeration, between 2°C and 8°C. This shelf life was measured considering the vitamins studied. Further studies are needed including all the vitamins present in this formulation.

Melatonin (MLT) has many health implications, therefore it is important to develop specific analytical methods for the determination of MLT in the presence of its main impurity, N-2-[1-(3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-ylmethyl)-5-methoxy-1H-indol-3-yl]ethylacetaamide (DMLT) and pyridoxine HCl (PNH) as a co-formulated drug. This work describes simple, sensitive, and reliable four multivariate calibration methods, namely artificial neural network preceded by genetic algorithm (GA-ANN), principal component analysis (PCA-ANN) and wavelet transform procedures (WT-ANN) as well as partial least squares preceded by genetic algorithm (GA-PLS) for the spectrofluorimetric determination of MLT and PNH in the presence of DMLT. Analytical performance of the proposed methods was statistically validated with respect to linearity, accuracy, precision and specificity. The proposed methods were successfully applied for the assay of MLT in laboratory prepared mixtures containing up to 15% of DMLT and in commercial MLT tablets with recoveries of no less than 99.00%. No interference was observed from common pharmaceutical additives and the results compared favorably with those obtained by a reference method.

In this paper, a time-based multicommutated flow system is proposed for appropriate selection and modulation of mobile phase composition in flow-injection (FI)/sequential-injection (SI) chromatography. The novel flow assembly involves the on-line coupling of a short monolithic reversed-phase chromatographic column with a multisyringe flow injection set-up furnished with a set of solenoid valves. The proposed hyphenated technique was applied to the simultaneous spectrophotometric determination of thiamine (B₁), pyridoxine (B₆) and cyanocobalamin (B₁₂) which were taken as model analytes. The separation method capitalizes on a dual isocratic elution protocol involving the use of a single forward stroke of the multisyringe pump for initial delivery of 50 mmol L⁻¹ ammonium acetate (pH 7.0) for 2.4 min followed by 50 mmol L⁻¹ ammonium acetate-methanol (80:20, v/v) for 6.4 min at 0.5 mL min⁻¹ and room temperature. Detection was performed at the maximum wavelength for each target vitamin--280 nm for B₁, 325 nm for B₆, and 360 nm for B₁₂. A first-order, two-level full-factorial design was utilized to ascertain the significant variables influencing the chromatographic separation and the magnitude of the interaction effects. The experimental design method revealed that resolution of the target vitamins is highly dependent on the pH, percentage of organic modifier, and their second-order interaction. The multisyringe flow-injection-based monolithic column separation method, which should be viewed as an expeditious and cost-effective alternative to the high-performance liquid chromatography counterpart, was applied to the separation and determination of B₁, B₆, and B₁₂ in different pharmaceutical dosage forms in less than 9 min. Statistical comparison of the results from the proposed procedure with those from the HPLC method endorsed by the US Pharmacopeia revealed there were no significant differences at the 95 % confidence level.