Analysis by HPTLC

Ripphahn, J. Advances in Quantitative Analysis by HPTLC, Danube Symp. Chromatogr., 1st, Szeged (Hungary) 1976. 

Mouratidis, S., and Thier, H.-P. (1995). Solid phase extraction for the confirmation of results in polar pesticides residue analysis by HPTLC. Z. Lebensm.-Unter.s.-Forsch. 201 327-330. 

J. C. Spell and J. T. Stewart, Quantitative analysis of chloroprocaine and its major impurity 4-amino-2-chlorobenzoic acid in drug substance and injection dosage form by HPTLC and scanning densitometry, JP C, 8 12 (1995). 

HPTLC analysis by dansyl derivatization [247] as opium in plant extract by TLC [565. p. 

The HPTLC pre-coated layers examined in this paper, namely silica gel 60, RP, cellulose and silica gel 60 with concentrating zone, are new developments or modifications of existing TLC pre-coated layers offering new potential for pesticide analysis by thin-layer chromatography. 

D. J. White, J. T. Stewart, and I. L. Honigberg, Quantitative analysis of chlordiazepoxide hydrochloride and related compounds in drug substance and tablet dosage forms by HPTLC and scanning densitometry, 7 PC, 4 330 (1991). 

Beside HPLC, TLC is also commonly used in pharmaceutical analysis. Although it is less selective and less precise than other chromatographic methods, its versatility, rapidity, and low cost make it a popular method. The traditional TLC method is gradually being replaced by HPTLC, which uses new stationary phases and automatic densitometric detection. HPTLC is a method competitive with HPLC in the analysis of drug impurities [19, 20]. 

DiGregorio, D. Sherma, J. Analysis of the active ingredient magnesium salicylate in analgesic tablets by HPTLC with ultraviolet absorption densitometry. J. Planar Chromatogr.-Mod. TLC 1999,12, 230-232. 

Chandrashekhar, T.G. Rao, P.S.N. Smrita, K. Vyas, S.K. Dutt, C. Analysis of amlodipine besylate by HPTLC with fluorimetric detection a sensitive method for assay of tablets. J. Planar Chromatogr.-Mod. TLC 1994, 7, 458-460. 

The PYML-3 thus obtained seemed to be a mixture of two inseparable diastereoisomers because the synthetic precursor (33) consists of two components as indicated by HPTLC analysis [55]. In an attempt to separate the isomers, we carried out the following transformations. Diester (33) was treated with NaOH in aqueous MeOH to afford diacid (34), which was converted into the corresponding Cu(II) complex by treatment with Cu(OAc)2 (Fig. 18) [56]. HPLC analysis of (34)-Cu(II) complex indicated that this material is a 1 1 mixture of two components (retention time 8 12" and 9 00" Hibar RT-250-4 4mm X 250mm flow rate l.Oml/min 10% MeOH - 0.1 M phosphate buffer, pH 6.0). The thermodynamically unstable isomer in this mixture was found to be epimerized to the more stable isomer during the attempted separation by... 

Klaus, R., Fischer, W., and Hauck, H.E. 1991. Qualitative and quantitative analysis of uric acid, creatine, and creatinine together with carbohydrates in biological material by HPTLC, Chromatographia, 32 307-316. 

Lippstone, M. B., Grath, E. K., and Sherma, J. (1996). Analysis of decongestant pharmaceutical tablets containing pseudoephedrine hydrochloride and guaifenesin by HPTLC with UV absorption densitometry. J. Planar Chromatogr.—Mod. TLC 9 456-458. 

Commercial glass-backed TLC and HPTLC plates, which contain flat, uniform layers, are best to use for instrumental TLRC. Plates with plastic or aluminum backing can be cut into sections, thereby facilitating zonal analysis by scintillation counting or preparative isolation of compounds. Layers must be clean and free from dust and other particles in order to measure radioactivity accurately. Samples should be spotted manually or automatically with an instrument (see Chapter 5) as small spots or narrow bands sufficiently far apart (minimum of 1.5 cm) to avoid measurement of radioactivity from adjacent lanes. Complete resolution of sample components is required for accurate quantification there-... 

Nielsen (1992) reviewed the chromatographic methods used for the analysis of flavins. He noted that HPTLC combined with densitometry has some advantages in the field of flavin analysis even when compared with analysis by HPLC. He stated that TLC is still a valuable tool for the isolation and purification of flavin compounds. Nielsen (1992) provided extensive tabular data on the determination of flavins and riboflavin by TLC. 

Patil and Shingare (1993) reported on TLC detection of certain benzodiazepines. Otsubo et al. (1995) detected benzodiazepines and zopiclone in human serum at 0.1-0.4 pg/ml by HPTLC Rf values and spot colors in three systems. Sarbu and Cimpan (1996) developed a quantitative TLC method using plates with a fluorescent indicator to determine certain 1,4-benzodiazepines in pharmaceuticals. They provided calibration curves for the quantitative analysis of diazepam, oxazepam, and chlordiazepoxide. 

Spell, J. C., and Stewart, J, T. (1994). Quantitative analysis of p-aminosalicylic acid and its major impurity m-aminophenol in p-aminosalicylic acid drug substance by HPTLC and scanning densitometry. J. Planar Chromatogr.—Mod. TLC 7 472-473. 

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