J. Chinese Trad. Patent Med. (Zhongchengyao) 25 (9), 719-720 (2004). TLC on silica gel with 1) chloroform - methanol - water 13:7:2, 2) chloroform - acetone - formic acid 10:5:2, 3) petroleum ether - ethyl formate - formic acid 15:5:1. Detection 1) by spraying with 10 % H2SO4 in ethanol and heating and under UV 365 nm, 2) by ammonia vapor and under UV 365 nm. Identification by fingerprint techniques. Quantitation of danshensu by HPLC. Discussion of use of the procedures for the quality control of the medicine.

J. Pharm. Biomed. Anal. 34, 525-530 (2004). HPTLC of busulfan, an alkylating agent in pharmaceutical preparations, on Lichrospher silica gel with ethyl acetate - chloroform - methanol 13:4:3 in horizontal sandwich chamber. After development the plate was soaked in 2 % ethanolic solution of 4-nitro benzyl pyridine, followed by heating at 193 °C for 10 min. Quantitative determination by absorbance measurement at 600 nm. The method was validated for accuracy, precision, linearity (100-500 µg/mL), and specificity. The method was suitable for stability studies of busalfan in pharmaceutical preparations.

Indian Drugs 41 (6), 354-357 (2004). HPTLC on silica gel with toluene - methanol - acetone - 10 % ammonia 80:40:20:1. Quantitative determination by absorbance measurement at 254 nm. The Rf value of pioglitazone hydrochloride was found to lie between 0.49-0.55. The linear dynamic response was found to be 2.0-4.0 µg/spot for pioglitazone hydrochloride. The results of the analysis have been validated statistically and by recovery studies. A simple, fast, specific and precise HPTLC method has been developed for the estimation of pioglitazone hydrochloride in its tablet dosage form.

Trad. Patent Med. (Zhongchengyao) 26 (6), 463-465 (2004). TLC of Xiatare Baixuan tablet extracts on silica gel with 1) toluene - chloroform - acetone - formic acid 8:5:7:1; chloroform - methanol - formic acid 38:2:1. Detection 1) by spraying with 1 % AlCl3 in ethanol and under UV 365 nm; 2) under UV light. Identification by fingerprint techniques. Quantification of aloin by HPLC with method validation.

J. Planar Chromatogr. 17, 355-359 (2004). HPTLC of aristolochic acid A, B, and C and numerous plant extracts on silica gel in a saturated twin-trough chamber using the upper phase of the mixture toluene - ethyl acetate - water - formic acid 20:10:1:1. Quantitative determination by fluorescence measurement at 366 nm after derivatization with tin(II) chloride reagent. The working range and linearity, LOD and LOQ (based on the calibration plot), and precision (n = 6), were validated with methods described by K. Ferenczi-Fodor et al., J. AOAC Int. 84 (2001) 1265-1276. The stability of the analyte during chromatography was established by two dimensional chromatography. The new method enables visual detection of the acids with certainty at very low levels (400 pg absolute of aristolochic acid A) in plant material and can therefore be used for screening Chinese drugs to ensure their safety on the basis of absence of aristolochic acid.

IPC 56th 2004, Abstract No. G-5. HPTLC of conessine in Holarrhena antidysentrica, an important ayurvedic drug, on silica gel with toluene - ethyl acetate - diethyl amine 13:5:2. Detection by spraying with Dragendroff’s reagent. Quantitative determination by densitometric scanning at 520 nm. Different market samples of the drug were found to contain 0.30 - 1.46 % of conessine with recovery of 95.18 - 102.70 %

J. Planar Chromatogr. 17, 224-228 (2004). TLC of fluvoxamine and moclobemide on silica gel in horizontal chambers with benzene - acetone - ethanol - 25 % ammonia 9:7:2:1. Densitometric detection and quantification were performed at 249 nm and 236 nm, respectively. The range of linearity was 1 - 10 µg per spot; the RSD was less than 2.5 % for densitometry and less than 5.1 % for videodensitometry.

J. Chromatogr. A 1090 (1-2), 165-171 (2005). This paper presents the first study of imaging of spots on thin-layer chromatographic plates whilst still wet with solvent. Imaging and quantification of Sudan II after development with dichloromethane was carried out in both reflectance and transmission modes, using a charge coupled device (CCD) camera. The relationship between peak area and sample loading was established at low sample loading, and found to be linear over an order of magnitude for both wet and dry modes with r2-values > 0.99. All data processing was carried out using the Beer-Lambert equation. Curvature at high loadings in the plots of integrated absorbance as a function of sample loading was accounted for using an empirical expression designed for use with the Kubelka-Munk treatment and apparent absorbance of the stationary phase due to scattering. Results are consistent with an effective pathlength significantly longer than the thickness of the sorbent layer. The limit of detection on a dry plate (0.5 ng) was found to be lower than on a wetted plate (2 ng). Precision was found to be 1-4 % RSD intra-plate and 8-14 % RSD inter-plate. Results are compared with quantification of the same analyte on dried plates.