RESUMEN

New, simple, accurate, sensitive and validated high performance thin layer chromatographic (HPTLC) method coupled with UV absorbance mode and fluorescence (FL) detectors which were used for simultaneous determination of ivabradine (IVA) and metoprolol (MET) in their bulk and pharmaceutical dosage form using TLC silica 60 F254 plates and non-fluorescent TLC silica gel 60 plates. The developing system was chloroform: methanol: formic acid: ammonia (8.5:1.5:0.2:0.1, v/v). Desnitometric analysis in UV absorbance mode was set at λ = 275 nm. While, fluorescence mode was performed with excitation at 260 nm for quantitative simultaneous determination of IVA and MET using optical filter K320. The retention factors values were 0.45 ± 0.05 and 0.89 ± 0.01 of IVA and MET, respectively. UV absorbance mode, linearity was 50.0-600.0 ng/band for IVA and 50.0-900.0 ng/band for MET. For fluorescence mode, the linearity ranges were 18.0-400.0 ng/band and 50.0-550.0 ng/band for IVA and MET; respectively. ICH guidelines were followed in respect to linearity and range, accuracy, precision and selectivity, limit of detection (LOD), limit of quantitation (LOQ) and robustness. The analytical eco-scale, green analytical procedure index (GAPI) and analytical greenness metric tools were used to assess the suggested method. The quantitative proposed method results showed there was no statistically significant difference at 95% confidence when compared to the reported method of high performance liquid chromatography (HPLC).

RESUMEN

In this article, we report a simple approach to stacking micro- and nanoparticle zones by electrokinetically migrating them through moderately confined channels of uniform cross-section. Experiments show the reported pre-concentration process to initiate at the tail end of the zone following its electrokinetic injection, with the stacked region migrating faster than the rest of the sample band. This effect causes the particles traveling in front to merge into the stacked region making it grow both in size and concentration. Because the stacked zone also gradually loses particles from its trailing edge, it eventually disintegrates upon running out of particles at its front end. Nevertheless, enhancements in peak height by over 100-fold were recorded using the reported approach for polystyrene beads with diameters comparable to the channel depth. This enhancement however, exhibited a temporal variation as the particle band migrated through the analysis column reaching a maximum value that depended on the particle diameter, particle concentration, channel depth, electric field strength, electroosmotic mobility, etc. Interestingly, the peak area recorded by the detector remained relatively constant during this particle migration period allowing reliable sample quantitation. Moreover, upon incubating antibody-coated particles against an antigen sample, the peak area for the particle zone was seen to scale linearly with the antigen concentration establishing the utility of the reported focusing phenomenon for chemical/biochemical analysis. The noted stacking technique was further applied to enabling UV absorbance detection of particle zones on microchips which then allowed us to determine the colloidal content in actual natural water samples. .

Asunto(s)

Electroósmosis , Poliestirenos

RESUMEN

The aim of the current study was to optimise and validate the methodology for determination of γ-hydroxybutyric acid (GHB) in saliva by CE combined with a contactless conductivity detector (C(4)D) and indirect UV absorbance detection (λ(ABS) = 210 nm). The optimized BGE, consisting of 8.5 mM maleic acid, 17 mM arginine, 255 µM cetyltrimethylammonium bromide (CTAB), and 15% acetonitrile, was evaluated for the separation of GHB in saliva within 6 min. The performance characteristics of the CE-C(4)D-indirect UV methodology was validated. The instrument detection and quantification limits were 0.49 and 1.6 mg/L for C(4)D, and 5.1 mg/L and 17.0 mg/L for indirect UV, respectively. The linearity was obtained over the range from 2.5 to 400 mg/L for C(4)D and from 12.5 to 400 mg/L for indirect UV. The interday precisions were within 2.3-5.7% and intraday precisions were within 1.6-9.0% for C(4)D as well as 2.1-9.3%, 5.6-10.1% for indirect UV in spiked saliva, respectively. The recoveries were within 87.2-104.4%. The matrix effects were +53.2% for small concentrations up to 25 mg/L for C(4)D and +23.6% for concentrations up to 75 for mg/L for indirect UV detection. No matrix effects were observed for higher concentration levels. In conclusion, CE-C4D-indirect UV can offer a rapid, accurate, sensitive, and definitive method for the determination of GHB abuse in saliva samples as a forensic screening tool.

Asunto(s)

Electroforesis Capilar/métodos , Hidroxibutiratos/análisis , Saliva/química , Adulto , Anciano , Conductividad Eléctrica , Femenino , Humanos , Límite de Detección , Modelos Lineales , Masculino , Persona de Mediana Edad , Reproducibilidad de los Resultados , Espectrofotometría Ultravioleta

RESUMEN

Objective:To investigate the feasibility of fast assay of vitamin C (VC) in body fluids by iodometry with UV absorbance detection.Methods:The sample was pretreated with iodoacetic acid to block sulfhydryl group.Protein was precipitated by trichloroacetic acid,and chromogen was extracted with chloromethylene.The change of absorbance after 30 s reaction of the pretreated sample with iodine was measured.Results:The assay of absorbance before and after 30 s reaction of the pretreated sample with iodine showed the variation coefficient within 5%,and the recovery of VC was above 90%.There was linear response of the absorbance change to the amount of VC from body fluids with slope consistent to that for iodine.Conclusion:This method may be desirable for fast assay of VC in body fluids.