Thin-layer chromatography linear

Thin-layer chromatography does not provide quantitative information of the highest precision and accuracy. Linear relationships between the mass of a substance and the logarithm or square-root of the spot area can sometimes be established under very closely controlled conditions. The optical absorbance of a spot determined by reflectance measurements can be similarly related to mass, or the substances can be scraped from the plate and dissolved in a suitable solvent for a spectrometric determination. The main difficulties with area and density measurements lie in defining the boundaries of spots and controlling chromogenic reactions in a reproducible manner. Relative precision can be as good as 1-2% but is more usually 5-10%. 

On the thermal cyclization of compound (806) in boiling Dowtherm A for 30 min, only the linear product (813) was obtained in 59% and 67% yields (75GEP2416519 77MI4). In these cases, however, the product was not investigated by the use of thin-layer chromatography (TLC) or NMR. 

Thin Layer Chromatography (TLC). Commercially available (Whatman LK6D, linear-K) silica gel (40S) plates of 250 ym thickness were used. These were developed in chloroform acetone formic acid (80 19 1). Spots were detected by UV light and iodine vapor. 

Polymer Separation and Characterization by Thin-Layer Chromatography Table 7. Characteristics of tetrachain-star-shaped and linear polystyrenes... 

Experimental and theoretical studies of the separation of 1,7- and 1,10-phenanthrolines and some substituted derivatives in linear elution adsorption chromatography,44> 145 thin-layer chromatography,146-148 and liquid-liquid partition chromatography149 have been described. 

Thin-layer chromatography (TLC) on silica gel is well known for its separation power for lipids and related compounds. The flame ionization detector (FID) is a universal analytical instrument that offers high sensitivity and linearity for carbon-containing organic compounds. The combination of TLC and FID led to the wide use of the Iatroscan TLC-FID for the analysis of lipid classes. The adoption of the Iatroscan TLC-FID in both academia and industry has generated sufficient data to indicate that TLC-FID is currently one of the most efficient tools for the quantitation of lipids classes (Ackman et al., 1990 Hammond, 1993). 

When comparing the above two methods to linear development, anticircular apparently is superior in terms of sensitivity, number of samples per plate, speed of analysis, and solvent consumption. Conventional linear TLC ranked second to the anticircular techniques [46], Also refer to the Handbook of Thin-Layer Chromatography [27] for additional details. 

Argekar and Sawant [55] developed simultaneous determination of paracetamol and mefenamic acid in tablets by high performance thin layer chromatography method (HPTLQ. The procedure was performed on silica gel using toluene-acetone-methanol (8 1 1) as the solvent system. Detection and quantification of the substance was assayed by densitometry at 263 nm. The linearity ranges were 120-360 ng/pL and the RSD were between 0.41 and 0.78%. Limit of detection and limit of quantification were found to be 1.80 and 5.5 ng/pL, respectively. Recoveries were in the range of 95.50-103.60%. 

Fluorophilic CD derivatives have been obtained as a result of combinations of CDs and a linear perlluorocarbon [73]. 2,3-Di-O-decafluorooctanoyl-y-CD was obtained with a protection-deprotection synthetic method and characterized further by thin-layer chromatography (TLC), Fourier transform infrared (FTIR) spectroscopy, differential scanning calorimetry (DSC), elemental analysis, and time-of-flight mass spectrometry (OF-MS). 

One milligram of microsomal protein is added to 0.1 M potassium phosphate buffer (pH 7.4) containing 50 mM NaF, 10 mM dithiothreitol, 1 mM EDTA, 20% glycerol (v/v), 150 iM 5-cholestene-3/3, 7a-diol, and 0.915% CHAPS. The reaction is initiated by 1 mM NAD+ to give a final reaction volume of 1.0 mL. After incubation at 37°C for 5 minutes, the reaction is terminated by adding 2 mL of 95% ethanol. An internal recovery standard, 4-cholesten-3-one (3 fig in methanol) is also added. The steroid products are extracted into 5 mL of petroleum ether (repeated twice). After the ether has been removed at 40°C under a stream of nitrogen, the products are dissolved in 100 fxL of mobile phase and 20 ju.L is injected into the column. The amount of product formed is linear with protein (to 1.5 mg) and with time (up to 10 min, 1 mg protein). The assay is much more sensitive than the direct spectrophotometric assay, and it avoids the use of thin-layer chromatography and radioisotopes described in other methods. 

This is similar to the linear relationship measured by thin-layer chromatography (TLC), given in Eq. (18) ... 

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