<Li> In the case of lipids, the chromatogram may be transferred to a PVDF membrane and then subjected to further analysis, for example mass spectrometry, a technique known as Far - Eastern blotting . </Li> <P> Once visible, the R value, or retardation factor, of each spot can be determined by dividing the distance the product traveled by the distance the solvent front traveled using the initial spotting site as reference . These values depend on the solvent used and the type of TLC plate and are not physical constants . </P> <P> In organic chemistry, reactions are qualitatively monitored with TLC . Spots sampled with a capillary tube are placed on the plate: a spot of starting material, a spot from the reaction mixture, and a cross-spot with both . A small (3 by 7 cm) TLC plate takes a couple of minutes to run . The analysis is qualitative, and it will show if the starting material has disappeared, i.e. the reaction is complete, if any product has appeared, and how many products are generated (although this might be underestimated due to co-elution). Unfortunately, TLCs from low - temperature reactions may give misleading results, because the sample is warmed to room temperature in the capillary, which can alter the reaction--the warmed sample analyzed by TLC is not the same as what is in the low - temperature flask . One such reaction is the DIBALH reduction of ester to aldehyde . </P> <P> In one study TLC has been applied in the screening of organic reactions, for example in the fine - tuning of BINAP synthesis from 2 - naphthol . In this method, the alcohol and catalyst solution (for instance iron (III) chloride) are placed separately on the base line, then reacted, and then instantly analyzed . </P>

Where is thin layer chromatography used in industry