Lawan Sriphong

Chiral separation of bioactive cyclic Mannich ketones by HPLC and CE using cellulose derivatives and cyclodextrins as chiral selectors

The chiral separation of cyclic Mannich ketones of potential pharmaceutical interest is investigated using HPLC and CE. These Mannich ketones show a marked antibacterial and antifungal activity. In HPLC, stationary phases containing cellulose derivatives or beta-cyclodextrin were used and in CE different cyclodextrins, such as beta-CD, gamma-CD, carboxymethyl-beta-CD and succinyl-beta-CD were added to the background electrolyte as chiral selectors.

Application of Scion image software to the simultaneous determination of curcuminoids in turmeric (Curcuma longa)

INTRODUCTION Curcumin, desmethoxycurcumin and bisdesmethoxycurcumin are bioactive constituents of turmeric (Curcuma longa). Owing to their different potency, quality control of turmeric based on the content of each curcuminoid is more reliable than that based on total curcuminoids. However, to perform such an assay, high-cost instrument is needed. OBJECTIVE To develop a simple and low-cost method for the simultaneous quantification of three curcuminoids in turmeric using TLC and the public-domain software Scion Image. METHODOLOGY The image of a TLC chromatogram of turmeric extract was recorded using a digital scanner. The density of the TLC spot of each curcuminoid was analysed by the Scion Image software. The density value was transformed to concentration by comparison with the calibration curve of standard curcuminoids developed on the same TLC plate. RESULTS The polynomial regression data for all curcuminoids showed good linear relationship with R(2) > 0.99 in the concentration range of 0.375-6 microg/spot. The limits of detection and quantitation were 43-73 and 143-242 ng/spot, respectively. The method gave adequate precision, accuracy and recovery. The contents of each curcuminoid determined using this method were not significantly different from those determined using the TLC densitometric method. CONCLUSION TLC image analysis using Scion Image is shown to be a reliable method for the simultaneous analysis of the content of each curcuminoid in turmeric.

Stability-Indicating TLC-Image Analysis Method for Quantification of Ceftriaxone Sodium in Pharmaceutical Dosage Forms

A simple and rapid thin-layer chromatographic (TLC)-image analysis method has been established for stability-indicating studies and quantification of ceftriaxone sodium (CFX) in bulk and in pharmaceutical dosage forms. Chromatographic separation was achieved on RP-18 F254S plates with 15% (w/v) ammonium acetate buffer (pH 6.2)-methanol-acetonitrile 12:0.5:0.25 (v/v) as mobile phase. The method was validated in accordance with International Conference on Harmonization (ICH) guidelines. Polynomial regression data for the calibration plot were indicative of a good linear relationship between response and amount in the range 1–8 µg per spot. The limits of detection and quantitation were 228 and 759 ng per spot, respectively. The precision, accuracy, and robustness of the method were satisfactory. Good separation was achieved between CFX and the degradation products obtained under different stress conditions, suggesting the method is stability-indicating. The CFX content of dosage forms determined by use of TLC-image analysis, TLC-densitometry, and the official HPLC method was not significantly different. The proposed TLC method was found to enable reliable and convenient analysis of CFX and can be used as a stability- indicating assay.

Axially perpendicular offset Raman scheme for reproducible measurement of housed samples in a noncircular container under variation of container orientation.

An axially perpendicular offset (APO) scheme that is able to directly acquire reproducible Raman spectra of samples contained in an oval container under variation of container orientation has been demonstrated. This scheme utilized an axially perpendicular geometry between the laser illumination and the Raman photon detection, namely, irradiation through a sidewall of the container and gathering of the Raman photon just beneath the container. In the case of either backscattering or transmission measurements, Raman sampling volumes for an internal sample vary when the orientation of an oval container changes; therefore, the Raman intensities of acquired spectra are inconsistent. The generated Raman photons traverse the same bottom of the container in the APO scheme; the Raman sampling volumes can be relatively more consistent under the same situation. For evaluation, the backscattering, transmission, and APO schemes were simultaneously employed to measure alcohol gel samples contained in an oval polypropylene container at five different orientations and then the accuracies of the determination of the alcohol concentrations were compared. The APO scheme provided the most reproducible spectra, yielding the best accuracy when the axial offset distance was 10 mm. Monte Carlo simulations were performed to study the characteristics of photon propagation in the APO scheme and to explain the origin of the optimal offset distance that was observed. In addition, the utility of the APO scheme was further demonstrated by analyzing samples in a circular glass container.