Abstract Binary admixtures of the poorly water-soluble chiral corticosteroid triamcinolone acetonide and chiral local anesthetics can be physically unstable in aqueous systems, posing challenges for the accurate stability monitoring. A robust HPLC method was developed to simultaneously evaluate drug stability and the reliability of triamcinolone acetonide quantification in binary admixtures. Under achiral (isotropic) separation conditions, the chromatographic behavior was strongly influenced by the final water–methanol composition. Increasing the methanol improved triamcinolone acetonide solubility and reduced retention. However, it also caused earlier elution of the local anesthetics, leading to overlap with the unretained solvent peak and diminished resolution. Conversely, higher water content impaired peak symmetry, baseline quality, and analyte recovery. Microscopic analysis revealed the onset of physical instability of triamcinolone acetonide within 1 h after bulk admixture preparation, whereas a significant decrease in analyte concentration was detected chromatographically only after 3 h. These findings indicate that physical instability precedes measurable chromatographic loss, supporting microscopy as an early indicator of admixture instability. The physicochemical behavior was elucidated using molecular descriptor analysis (pKa, logP, logS) and in silico docking (AutoDock Vina). Descriptor evaluation found a mismatch between the chromatographic pH (3.0) and the ionization states, while docking confirmed the absence of energetically favorable drug-drug interactions. These findings demonstrate that instability is primarily driven by solubility-mediated precipitation of triamcinolone acetonide rather than specific drug-drug interactions or chirality-related effects. Practically, methanol–water admixtures require to be analyzed immediately or within 1 h after preparation to ensure assay reliability. The integration of chromatographic, microscopic, and computational approaches provides a rational strategy for evaluating corticosteroid–chiral local anesthetic admixtures.
Abstract A simple, rapid, and reliable bioanalytical method based on protein precipitation coupled with LC-MS/MS was developed and validated for the quantification of omeprazole in human plasma. The method employs protein precipitation with acetonitrile for sample preparation, offering a fast and efficient extraction process. Chromatographic separation was achieved on a reverse-phase using an isocratic mobile phase composed of 2-mM ammonium formate and acetonitrile (30:70, v/v), at a flow rate of 0.2 mL min −1 , within a run time of 4 min. Mass parameters were optimized to monitor transitions at m/z [M+H] + 346.1→198 for omeprazole, and m/z [M+H] + 370→252 for lansoprazole as an internal standard (IS). The calibration curve ranged from 2 to 1,600 ng mL −1 , demonstrating excellent linearity ( R 2 = 0.998) with a lower limit of quantification of 2 ng mL −1 . The accuracy was acceptable with CV (%) < 15, matrix effect (%) < 15, and the hemolytic effect was negligible. Omeprazole was stable in human plasma for 24 h at room temperature (25 °C), for 114 days frozen at −25 °C, for 72 h in an auto-sampler at 6 °C, and for three freeze/thaw cycles. The method was further evaluated using the accuracy profile approach, a robust statistical tool that incorporates tolerance intervals to assess trueness and precision. This approach enables the construction of confidence intervals around measured concentrations, providing a quantitative measure of the method's reliability and the expected analytical performance. The validated method was applied in a pharmacokinetic study to determine the concentration of omeprazole in plasma samples. The study provides a fast and simple bioanalytical method for routine analysis and particularly useful for bioequivalence studies. The method was successfully applied to a pharmacokinetic study of fixed-dose omeprazole in ten healthy volunteers.
Abstract The objective of this study was to evaluate two extraction methods, accelerated solvent extraction (ASE) and Roese-Gottlieb (RG) method, for the analysis of dairy products. The extracted lipids were characterized by determining their fatty acid (FA) profile using gas chromatography with flame ionization detection (GC-FID), while the amino acid (AA) profiles were determined using ultra-high-performance liquid chromatography with photodiode array detection (UHLP-PDA). The analysis of AAs closely matched the certified AAs values provided by the National Institute of Standards and Technology (NIST). The extraction of FAs using the ASE method produced results that were the closest to the certified FAs values provided by NIST. Repeatability of FAs in dairy products was in the range of 0.03–2.96% calculated as relative standard deviations. Bias values were calculated for AAs (0.27–5.01%) and FAs (0.21–3.61%). The ratios of lipids content, as measured by ASE and RG methods, for milk and dairy products ranged from 99% to 102%, which makes the ASE method suitable for extracting lipids from dairy products. The lipid extraction procedures obtained with the ASE method were optimised to prepare dairy samples for instrumental determination of FAs composition by GC. Principal component analysis (PCA) was used as an exploratory tool to visualize trends and similarities among the analyzed samples. It was not used as a validated classification or authentication model. PCA of FAs resulted in a two-principal-component model that explained 75% of the total variance. The first principal component (PC1) accounted for 61.9% of the variance, while the second principal component (PC2) accounted for 13.1%. The results obtained by ASE were analysed using GC were promising, indicating that these techniques have great potential for detecting components in dairy products. The proposed methods were simple, safe, reproducible and suitable for determining dairy products.
Some drug combinations, also known as multi-component formulations, have shown promising results due to their combined mechanism of action in the body, which consists of a mixture of medications (paracetamol, tramadol, metoclopramide, and domperidone). In addition to providing greater therapeutic efficacy due to their cumulative or synergistic effects, these drug combinations are also characterized by their lower production cost and the possibility of administering them in a single dose. The aim of this work is to develop novel, simple, accurate, and selective chromatographic methods (reversed-phase high-performance liquid chromatography) for the determination/quantification of these drugs. These methods can be used as analytical tools in routine analyses in quality control laboratories. In this study, RP-HPLC method was used, where the separation was performed on an ULTISIL L10 column (250 mm & times; 4.6 mm, 5 & micro;m) using a mobile phase composed of a buffer solution and acetonitrile in a ratio of (80:20, v/v) at a flow rate of 1.5 mL min-1. Detection was performed at a wavelength of 283 nm. In the proposed RP-HPLC method, the peaks were sharp and well separated, with retention times of 2.11, 4.37, 5.72, and 8.77 min, respectively, for paracetamol (PARA), tramadol (TRA), metoclopramide (METO), and domperidone (DMO). Linearity was obtained within the concentration ranges of 25-150, 10-60, 10-30, and 10-30 mu g mL-1, respectively, for paracetamol, tramadol, metoclopramide, and domperidone. The method was validated according to ICH guidelines for linearity, accuracy, precision, selectivity and robustness. This improved method is used to identify drugs in lab-mixtures containing a combination of four drugs. This method is simple and accurate and can be used for routine drug analysis in compounded dosage forms in quality control laboratories.
Contents of yeast cell wall polysaccharides including mannan and beta -glucan derived from yeast cell wall in yeast cultures (YC) were assessed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) with the hydrolytic monosaccharides as markers. The sample hydrolyzed with hydrochloric acid solution in an autoclave and neutralized with sodium hydroxide solution and derivatized with 5-methyl-2-phenyl-1,2-dihydropyrazol-3-one (PMP). Then three main monosaccharides (mannose, glucose and galactose) derivatives were separated using a C18 column (50 mm & times; 2.1 mm, 1.8 mu m) with an isocratic elution of 0.02 mol L -1 ammonium acetate (82%) and acetonitrile (18%) as the mobile phases, and were detected using mass spectrometry with multiple reaction monitoring mode. Within the investigated concentration ranges (0.1-5 mu g mL -1 ), the monosaccharides exhibited good linearity with R 2 values greater than 0.99; the limit of detection (LOD) and limit of quantification (LOQ) was not more than 0.03 and 0.1 mu g mL -1 in the hydrolysate; Spike recoveries ranging from 82.56 to 105.58% were obtained with relative standard deviations (RSDs) between 1.42 and 10.30%. The quantitative results of mannose and glucose released from the yeast cell wall polysaccharides (YCWP) were corrected in the YC sample according to the mass ratios of mannose to galactose in the raw materials and that of glucose to mannose in the yeast respectively, and based on the corrected results the contents of YCWP, mannan and beta -glucan, in YC samples were assessed.
