Thin-layer chromatography validation procedures

Baer et al. during 1986 to 1988. Urine was screened by methods in effect in the federal probation system THC metabolite and opiates were screened by EMIT and confirmed by high performance liquid chromatography (HPLC) at cutoffs of 100 and 500 ng/mL, respectively. Cocaine metabolites and PCP were screened by thin-layer chromatography (TLC) at cutoffs of 2000 and 500 ng/mL, respectively, and confirmed by GC. Hair testing was by RIA. The RIA procedures, validated by GC/MS, showed no false positives due to cross-reactivity effects. 

Years of doing things the same way does not validate correctness. Many chemical tests have been proven incorrect over a period of time. Newer techniques like thin layer chromatography (TLC), high performance liquid chromatography (HPLC), capillary electrophoresis (CE) and mass spectrometry (MS) have revolutionized our standards of purity. So, too, should this testing procedure prove to be. 

In conclusion, CE is a valuable analytical tool that offers a number of possibilities for the analysis of a wide spectrum of forensicaUy interesting compounds. Practically all compounds which have been traditionally analyzed by GC, high-performance Uquid chromatography, thin-layer chromatography, or slab-gel electrophoresis, can be assayed by capillary electrophoretic procedures. AU methods of capillary electrophoresis can be validated and can meet the demands of good laboratory practice. 

A registration application should include documented evidence that the analytical procedures are validated and suitable for the detection and quantification of impurities (see ICH Q2A and Q2B on Analytical Validation). Technical factors (e.g., manufacturing capability and control methodology) can be considered as part of the justification for selection of alternative thresholds based on manufacturing experience with the proposed commercial process. The use of two decimal places for thresholds does not necessarily reflect the precision of the analytical procedure used for routine quality control purposes. Thus, the use of lower precision techniques (e.g., thin-layer chromatography) can be appropriate where justified and appropriately validated. Differences in the analytical procedures used during development and those proposed for the commercial product should be discussed... 

Assay of theophylline in effervesoerit tablets using high performance thin-layer chromatography and further densitometrio measurement. This preliminary testing procedure was worked out acc. to literature [144] "Validation of analytical procedures in pharmaceutical quality control" from B, Renger, H. Jehle, M. Fischer und W, Funk. 

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