International Laboratory News, February, 8A-8B (1994). HPTLC of clenbuterol in various matrices on silica in horizontal developing chamber from both sides with ethyl acetate - methanol - acetic acid 8:1:1 with chamber saturation. Derivatization by spraying with Bratton-Marshall reagent (first 1% sodium nitrite in 1 N HCl, then 0.4% N-(1-naphthyl)-ethylenediamine dihydrochloride in methanol). Quantification by densitometry (absorbance) at 525 nm. Detection limit 2.5 ng; determination limit 10 ng. Further betablockers can be detected with this method, like atenolol at hRf 8, salbutamol at 14, propranolol at 25, clenbuterol at 40 and labetalol at 44. Sample preparation includes deproteinization, defattening and final extraction from an alkaline aqueous phase. Very fast method - chromatography of 18 resp. 36 samples within 10 min.

J. West China Med. (Huaxi Yaoxue Zazhi) 10, 166-167 (1995). TLC on silica with chloroform - methanol 4:1. Detection by spraying with 5 % vanillic aldehyde sulfuric acid reagent. Quantification by densitometry.

J. Chinese Herb Med. (Zhongcaoyao) 27, 463-464 (1996). TLC on silica with chloroform - ethyl ether - acetic acid 2:2:1. Detection by spraying with 10 % phosphomolybdic acid in ethanol. Quantification by densitometry at 700 nm.

J. Planar Chromatogr. 9, 269-272 (1996). TLC of Pb(II), Cd(II), and Cu(II) on carboxymethylcellulose with 0.60 M acetic acid - 0.60 M sodium acetate. Detection with a 1 mm glassy carbon ultramicroelectrode (described in detail). Detection limits for cadmium and lead using a 120 s deposition time were 1 and 4 ng, respectively.

Chromatographia 47, 215-218 (1998). HPTLC on silica gel with toluene - ethyl acetate - formic acid 6:2:1. Quantitation by fluorodensitometry at 313 nm. Validation of the method by spiking uncontaminated extracts of maize with zearalenone over the range 10 to 320 mg/kg, with a linearity range between 10 and 80 mg/kg. Detection limit 2.6 mg/kg. Recovery > 62.8% (n=5).

J. Chinese Herb. Med. (Zhongcaoyao) 28, 723-725 (1997). TLC on silica gel by double development with hexane - ethyl acetate - ether - formic acid 100:80:20:1. Detection under UV 254 nm. Precision within plate 1.92% (n=5), plate-to-plate 2.64% (n=5). Recovery 98.10 ± 2.25% (n=5).

J. Chinese Trad. Patent Med. (Zhongchengyao) 20 (4), 12-14 (1998). TLC on silica gel with 1) petroleum ether - methyl acetate - formic acid 10:5:1, 2) chloroform - methanol - NH3 30:4:1, 3) chloroform - ethyl acetate - methanol - water 15:40:22:10, 4) petroleum ether - ethyl acetate - formic acid 10:5:1. Detection 1) under UV 365 nm, 2) spraying with KJ solution in ethanol, 3) spraying with 10% sulfuric acid in ethanol. Quantitation of emodin by densitometry at 440 nm. Precision = 3.4% (n=5) plate-to-plate and 2.7% (n=5) within plate. Recovery 98.1 ± 1.27% (n=4).

Acta Chromatographica 14, 60-69 (2004). TLC on silica gel with 1-butanol - glacial acetic acid - water 3:1:1 with chamber saturation. Detection by spraying with ninhydrin reagent (0.3 g ninhydrin in 100 mL 1-butanol plus 2 mL glacial acetic acid), followed by heating at 110 ºC for several min. Quantification by densitometry at 495 nm. Validation of the accuracy by analysis of spiked blank and standard addition samples and precision by performing replicate analysis on a single day and on different days. Recoveries and RSD for spiked blank and standard addition samples were 98.8 % and 98.5 %, 1.92 % and 0.67 %, respectively. Discussion of use of the method for the routine quality control of nutritional supplements.