J. AOAC Int. 95, 1371-1377 (2012). HPTLC of organophosphate and carbamate pesticides such as chlorpyrifos (1), paraoxon (2), parathion (3) and pirimicarb (4) in fresh fruits and vegetables on silica gel in an automatic development chamber with methanol – dichloromethane 1:9 and n-hexane – ethyl acetate - dichlormethane 13:4:3. Matrix interferences were visualized at 366 nm after dipping in primuline reagent (0.5 g/L in acetone – water 4:1). Detection by immersion in a solution of rabbit liver esterase or cutinase, followed by horizontal incubation for 30 min at 37 °C. The enzymatic reaction was stopped by heating the plate at 50 °C for 5-7 min. Staining was performed with a mixture of 60 mL Fast Blue Salt B (2.5 g/L in water) and 30 mL alpha-naphythyl acetate (2.5 g/L in ethanol). Recoveries were in the ranges of 86-109, 95-129, 96-114 and 90-111 % for pesticides (1) to (4), respectively. Mean %RSD was 8.5 for all samples.

J. Planar Chromatogr. 25, 420-425 (2012). HPTLC of juglone (1), quercetin (2), myricetin (3), rutin (4), caffeic acid (5), and gallic acid (6) in the stem bark of Juglans regia L. on RP-18 with methanol - water - formic acid - acetic acid 61:58:3:3. Quantitative determination by absorbance measurement at 254 nm. The hRf values of compounds (1) to (6) were 16, 20, 31, 42, 55 and 78, respectively. Linearity was in the range of 13-800 ng/zone for (1) and (5), 100-1000 ng/zone for (2) and (6) and 50-800 ng/zone for (3) and (4). Limits of detection and quantification were 4 and 13 ng/zone for (1) and (5), 30 and 100 ng/zone for (2), 15 and 50 ng/zone for (3), (4) and (5), respectively. The intra-day and inter-day precisions for compounds (1) to (6) were in the range of 0.6-1.3 % and 0.5-1.9 %, respectively. Average recovery was between 98.6 and 101.1 %.

J. Liq. Chromatogr. Relat. Technol. 35, 1459-1480 (2012). HPTLC of itraconazole on silica gel with toluene - ethyl acetate 1:5 + 1 drop ammonia. Quantitative determination by absorbance measurement at 266 nm. The hRf value of itraconazole was 77 and selectivity regarding matrix was given. Linearity was in the range of 50-2000 ng/zone. The intra-day and inter-day accuracy were in the range of 81.9-97.8 and 89.2-97.1 %, respectively. The limits of detection and quantification were 14 and 43 ng/zone, respectively. Recovery (by standard addition) was between 99.6 and 100.2 %.

J. Planar Chromatogr. 25, 409-414 (2012). HPTLC of two anthocyanins, cyanidin-3-O-rutinoside (1) and cyanidin-3-O-glucoside (2), in the berries of Euterpe oleracea Mart. on silica gel with ethyl acetate - formic acid - acetic acid - water 100:11:11:26. Quantification by absorbance measurement at 520 nm. The hRf of compounds (1) and (2) were 29 and 37, respectively. Linearity was in the range of 100-500 ng/zone. The limit of detection was 30 ng/zone for (1) and 40 ng/zone for (2) and the limit of quantification was 100 ng/zone for both (1) and (2). The intermediate/inter-day/intra-day precision was below 2.8 % (n=3). The average recovery was between 99.8-101.8 %.

J. Planar Chromatogr. 25, 208-213 (2012). The phenomenom of lateral relocation in the migration tracks of chiral analytes was reviewed as a retention fundamentals in TLC. By employing silica gel plates and others impregnated with L-arginine and DL-arginine, the non-linear motion of (±)-2-phenylpropionic acid was studied. TLC on impregnated or non-impregnated silica gel (pre-washed by development with methanol – water 9:1) with acetonitrile - methanol - water 20:4:3. For plates impregnated with arginine, the mobile phase additionally contained 0.5 % (v/v) glacial acetic acid to set the pH to < 5.

CBS 108, 9-11 (2012). HPTLC of fructose, galacturonic acid, rhamnose, xylose, and galactose in samples of agar agar, arabic gum, carubin, guaran, traganth, xanthan, pectin, alginic acid, alginates and carrageen on silica gel with i-propyl acetate - ethyl acetate - methanol - water 50:40:10:1 to a migration distance of 60 mm. Densitometric absorption measurement at 370 and 630 nm and peak area evaluation by linear or polynomial regression. Detection by immersion in aniline diphenylamine o-phosphoric acid reagent (20 % o-phosphoric acid (85 %) added to 1:1 mixtures of 2 % solutions of diphenylamine and aniline in acetone) and heating at 110 °C for 5 min. Comparison of HPTLC with GC gave comparable results, however, the HPTLC method is more effective in terms of sample throughput, robustness, costs and analysis time (8 times faster than GC).

Food Control. 34, 138-148 (2013). TLC was reviewed as a fast screening methodology for the determination of deoxynivalenol (DON) showing LOD in rice of 100 mg/kg. 2D-TLC on silica gel with dichloromethane - ethyl acetate - propan-2-ol 18:1:1 and toluene - ethyl acetate - formic acid 6:3:1 for the first and second runs, respectively. Detection by spraying with chromotropic acid, followed by heating at 110 °C for 5 min. Quantitative determination by absorbance measurement at 366 nm. The hRf values of DON were 13 and 20. Advantages and disadvantages of current methods as well as comparison with other techniques were also described for the effective monitoring and surveillance of DON and its derivatives.

J. Liq. Chromatogr. Relat. Technol. 36, 1231-1242 (2013). HPTLC of melitracen (1) and flupentixol (2) in combined dosage form on silica gel with methanol - toluene 4:1+1 drop ammonia. Quantitative determination by absorbance measurement at 270 nm. The hRf values of (1) and (2) were 79 and 88, respectively. Linearity was in the range of 1000-8000 ng/zone for (1) and 50-400 ng/zone for (2). LOD and LOQ were 225 and 683 ng/zone for (1) and 4.7 and 14.1 ng/zone for (2). Intermediate precision was below 3.6 %. Recovery (by standard addition) for (1) and (2) was in the range of 98.6-102.1 % and 97.8-101.8 %, respectively.