CYCLODEXTRIN MODIFIED MICELLAR LIQUID CHROMATOGRAPHY FOR DETERMINATION OF HYDROCHLOROTHIAZIDE AND CEFDITOREN PIVOXEL IN BIOLOGICAL FLUIDS AND TABLETS

Rapid and Sensitive Electrochemical Assay of Cefditoren with MWCNT/Chitosan NCs/Fe2O3 as a Nanosensor

In this research, a glassy carbon electrode (GCE) modified by MWCNT/chitosan NCs/Fe₂O₃ was prepared for the determination of the cephalosporin antibiotic cefditoren (CFT) using adsorptive stripping differential pulse and cyclic voltammetry techniques. The effects of pH, the scan rate, the deposition potential, the accumulation time, and modification agents on the determination of CFT were analyzed. The results showed that the modified electrode significantly increased the oxidation peak current of CFT. Under optimized conditions, the MWCNT/chitosan NCs/Fe₂O₃/GCE nanosensor exhibited a linear response between 0.2 µM and 10 µM toward CFT. The limit of detection and quantification were determined to be 1.65 nM and 5.50 nM, respectively. Model drugs (cefdinir, cefpodoxime, cephalexin, and ceftazidime compounds) were used to enlighten the CFT oxidation mechanism. Moreover, the nanosensor was used to analyze CFT in a pharmaceutical dosage form and commercial deproteinated human serum samples. The accuracy of these methods was proven in the recovery studies, with values of 96.98 and 98.62% for the pharmaceutical dosage form and commercial deproteinated human serum sample, respectively.

Quantitative analysis of nine isoflavones in traditional Chinese medicines using mixed micellar liquid chromatography containing sodium dodecylsulfate/β-cyclodextrin supramolecular amphiphiles

Isoflavone is one of the phytoestrogens that have estrogenic effects, so it is usually served as an active ingredient for quality control of traditional Chinese medicines rich in isoflavones. Nine isoflavones commonly found in traditional Chinese medicines were separated in 30 min using mixed micellar liquid chromatography. The mobile phase consisted of 0.08 M sodium dodecylsulfate and 6.05 mM β-cyclodextrin:methanol (87:13, v/v) at pH 3 and eluted isocratically at 1 mL/min through a C18 column. In this study, we systematically optimized the chromatographic conditions including the pH, the composition and concentration of surfactants, the type and ratio of organic solvents, and column temperature. The method was validated according to the International Council for Harmonization of Technical Requirements for Pharmaceuticals for Human Use guidelines. There is no report using micellar liquid chromatography to detect isoflavones, and the optimized method has been successfully applied to quantify isoflavones in red clover and Radix Puerariae. This method is efficient, cheap, and convenient. Finally, we verified the existence of supramolecular amphiphilic vesicles in the mobile phase by transmission electron microscopy to explain the increased chromatographic efficiency.

Cyclodextrin-Modified Micellar UPLC for Direct, Sensitive and Selective Determination of Water Soluble Vitamins in Milk

Cyclodextrin-modified micellar ultra pressure liquid chromatography (CD-MUPLC) was firstly developed and directly applied to the simultaneous determination of water-soluble vitamins thiamine hydrochloride (VB1), pyridoxine hydrochloride (VB6) and ascorbic acid (VC) in milk samples. A hybrid isocratic mobile phase consisting of β-cyclodextrin (β-CD, 5.0 mmol L-1) and cetyltrimethylammonium bromide (CTAB, 0.1 mol L-1) in the presence of acetic acid (0.1 mol L-1) at pH 2.9 on a RP-C18 column at 25.0°C was successfully used. The separation of vitamins was achieved in less than 10 min at a 0.2 mL min-1 flow rate showing adequate linearity at 245 nm in the ranges of 5.0-500.0 μg L-1 for VB1, 5.0-1000.0 μg L-1 for VB6 and 5.0-10000.0 μg L-1 for VC with coefficients of variation (r2) of 0.9999, 0.9987 and 0.9971, respectively. In addition, limits of detection obtained were 0.885, 1.352 and 1.358 μg L-1 and limits of quantification were 2.681, 4.096 and 4.115 μg L-1 for VB1, VB6 and VC, respectively. The high sensitivity of the proposed CD-MUPLC-UV method permitted its applications to the determination of water-soluble vitamins VB1 (32-488 μg L-1), VB6 (82-95 μg L-1) and VC (790-45000 μg L-1) in breast and bovine milk samples. The relative standard deviations and recoveries ranged between 0.07 and 2.14% and between 85.27 and 114.8%, respectively, indicating the accurate and precise measurements without any negative impact of matrix. The current analytical method illustrated several advantages including direct, sensitive, selective and non-consuming organic solvents over the hitherto published methods. These features could be attributed to the four-point competitive interactions among analytes, pseudostationary phases and modified C18 stationary phases.