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Evaluation Using a TLC Scanner

The TLC scanner was developed principally as a highly effective analytical tool to provide quantitative measurement results. However, its field of use will most likely increase. [Pg.154]


For the quantitative determination, the results of the metoclopramide determination should be checked before dipping the plate, and the measurement repeated if necessary. The plate is then dipped for 3 s also and dried for 15 min in a cold current of air. It is then covered with a clean glass plate and kept in a desiccator overnight. Further information on the measurement of this plate can be found in Section 7.2 Evaluation using a TLC Scanner . [Pg.138]

Cabon tetrachloride, n-hexane, chloroform, ACN, acetone, THF, pyridine, acetic acid, and their various mixtures were applied as mobile phases for adsorption TLC. Methanol, 1-propanol, ACN, acetone, THF, pyridine and dioxane served as organic modifiers for RP-TLC. Distilled water, buffers at various pH (solutions of and dipotassium hydrogen phosphate or potassium dihydrogen phosphate) and solutions of lithium chloride formed the aqueous phase. Carotenoids were extracted from a commercial paprika sample by acetone (lg paprika shaken with 3 ml of acetone for 30 min), the solution was spotted onto the plates. Development was carried out in a sandwich chamber in the dark and at ambient temperature. After development (15 cm for normal and 7cm for HPTLC plates) the plates were evaluated by a TLC scanner. The best separations were realized on impregnated diatomaceous earth stationary phases using water-acetone and water-THF-acetone mixtures as mobile phases. Some densitograms are shown in Fig.2.1. Calculations indicated that the selectivity of acetone and THF as organic modifiers in RP-TLC is different [14],... [Pg.64]

Unhke visual evaluation of a chromatograms before derivatization, which can only give quahtative or semiquantitative results, direct optical evaluation using instruments enables quantitative results to be obtained. For this, a traditional TLC scanner, diode-array scanner or video equipment, either alone or in combination with a flat-bed scanner, is used. Quantitative evaluation with these instruments is described in more detail in Sections 1.2-1 A. However, the limits of this book would be exceeded if we gave a detailed description of all the commercially available equipment that can be used to quantify substances on TLC plates. Training in the use of TLC scanners can be obtained in company seminars (e.g. CAMAG) and detailed instructions are provided by the manufacturer when the equipment is purchased. [Pg.116]

The well-known and widely applied TLC silica gel G plates 20 x 20 cm from Merck (Darmstadt, FRG) is used. Stock solutions from the compounds given in Table 1 were prepared. After corresponding dilution, a 1-/aL sample is applied and the plate is developed for a distance of 10 cm using n-propanol-water, 8 2 (v/v), as the mobile phase. Densitometric evaluation is performed at 365 nm with a Camag TLC Scanner II in absorbance reflection mode. The plate is first air-dried and then heated in an oven for 5 min at 100°C. Immediately after drying, the plate is inserted in a tank saturated with ammonia atmosphere (ammonia solution in... [Pg.310]

The first critical step in TLC is the sample application. It is well-known that circular chromatography phenomena may occur when manual spots are applied (6), especially if the volume is too large or if an unsuitable solvent for the layer adsorption has been used due to its choice for the dissolution of samples. Such phenomena induce spot diffusion. Location errors can then be observed when detection is performed by a classical scanner. For example, a systemic position error of 0.1 mm for each spot produces a final location error of 1.0 mm at the 10th spot. Such a variation is not acceptable for quantitative postchromatographic evaluation. To prevent this, the most suitable laboratory equipment should combine sample application and densitometry within the same mechanical system. The automatic spraying system for sample applications is equipped with a microprocessor (7), which ensures very reproducible repetitive applications, (Figure 1). It also allows the selection of the application speed and the form of application as a spot or a narrow band. [Pg.374]

Pesticides in drinking water were analyzed by automated multiple development (AMD). This gradient TLC development consisted of 20 steps starting with 30% methanol in dichloromethane. The solvent was changed in 5 steps to 1(X)% dichloromethane and that was altered to dichlorometh-ane-n-hexane (1 1) in the following 10 steps, and finally to n-hexane (100%) in the last 5 steps. Linuron, atrazine, and parathionmethyl were analyzed in the presence of other pollutants. Computer-controlled evaluation was carried out with a Camag TLC scanner n using software 86. The... [Pg.798]

Generally, the results of TLC separations are evaluated qualitatively or semi-quan-titatively. Thin layer scanners are available for quantitative work that measure the intensity of reflected light. Alternatively, spots containing a substance can be scratched off the plate, extracted into solution and quantitated. Radioactively-labelled compounds can be detected, and determined quantitatively, using autoradiography. [Pg.104]

If the starting material is a Sperry extract [202], 1 ml of extract is concentrated to 0.14 ml and the amount of this concentrated extract to be applied is calculated from the equation ml lipid concentrate = 1.67/mg-% ester cholesterol in the serum. Immediately after the TLC-separation, the 200 X 38 mm plate is sprayed evenly with antimony(ni)chloride reagent and then heated ca. 5 min at 110°C. The characteristic coloured reaction product changes from red to blue at a rate which varies from fraction to fraction correction factors must be thus determined for the particular technique used, with the help of standard substances. Table 123 contains such factors for the Beckmann spectrophotometer DU G 4700 at 575 nm. Some electrophoresis scanners with adequate light intensity are also suitable for photometric evaluation of the chromatograms (cf. also p. 139). [Pg.594]

Another major step forward for radio-TLC came in the early 1980s when the so-called linear analyzer was introduced. This instrument was easier to use and more sensitive than the old scanners and was automated to the extent that up to four plates could be run overnight. More details are given below. As a consequence, improved quantitative results were obtained and analysis time was shortened. However, resolution was still not as good as that obtained by using autoradiography, and two-dimensional plates could not be easily evaluated. [Pg.349]

CAM AG Scanner II (Figure 19) Automated scanning and densitometric evaluation of TLC up to 200 X 200 mm. Absorbance, transmittance, and fluorescence of wavelength between approximately 200-800 nm are measured. This program is generally used with a 386 processor or greater PC with CATS software, and is advertised by CAMAG as the most powerful currently available software. [Pg.962]


See other pages where Evaluation Using a TLC Scanner is mentioned: [Pg.154]    [Pg.154]    [Pg.155]    [Pg.159]    [Pg.161]    [Pg.165]    [Pg.169]    [Pg.171]    [Pg.154]    [Pg.154]    [Pg.155]    [Pg.159]    [Pg.161]    [Pg.165]    [Pg.169]    [Pg.171]    [Pg.320]    [Pg.321]    [Pg.199]    [Pg.41]    [Pg.4839]    [Pg.166]    [Pg.224]    [Pg.543]    [Pg.202]    [Pg.120]    [Pg.161]    [Pg.76]    [Pg.2322]    [Pg.1190]    [Pg.1022]    [Pg.130]    [Pg.522]    [Pg.522]    [Pg.166]    [Pg.622]    [Pg.342]    [Pg.209]    [Pg.292]    [Pg.633]    [Pg.292]    [Pg.962]   


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