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A fine, white, homogeneous powder of an average particle size of about 15 µm containing about 13% of calcium sulphate hemihydrate and complying with the following requirements.
Content of calciumsulphate To 0.25 g add 3 ml of 2M hydrochloric acid and 100 ml of water and shake vigorously for 30 minutes. Filter, wash the residue with water and carry out the complexometric titration of calcium, Appendix VIII D, on the combined filtrate and washings. Eachml of 0.1M disodium edetate VSis equivalent to 14.51 mg of CaSO4,½H2O.
Introduce the prescribed solutionin to a 500 ml conical flask, and dilute to 300 ml with water R. Add 6.0 ml of strongsodium hydroxide solution R and about 15 mg of calconecarboxylic acid triturate R.Titrate with 0.1 M sodium edetate until the colour changes from violet to full blue.
1 ml of 0.1 M sodium edetate is equivalent to 4.008 mg of Ca.
Acidity or alkalinity pH of a suspension prepared by shaking 1 g with 10 ml of carbon dioxide-free water for 5 minutes, about 7, Appendix V L.
A fine, white, homogeneous powder of anaverage particle size of about 15 µmcontaining about 13% of calcium sulphate hemihydrate and about 1.5% of a fluorescent indicator having a maximumintensity at 254 nm. It complies with the tests for content of calcium sulphate and Acidity or alkalinitydescribed under silica gel G and with the following requirement.
Fluorescence carry out the method for thin-layer chromatographyusing a mixture of 10 volumes of anhydrousformic acid and 90 volumes of propan-2-ol as the mobile phase, but allowing the solvent front to ascend 10 cm above the line of application. Apply separately to the plate 10 quantities from 1 to 10 µl of a 0.1% w/v solution of benzoic acid in the mobile phase.After removal of the plate, dry it in a current of warm air and examine under ultravioletlight (254 nm). The benzoic acid appears as dark spots on a fluorescent background in the upper third of the chromatogram at levels of 2 µg andgreater.
A fine, white, homogeneous powder of an average particle size of about 15 µm. It complies with the test for Acidity or alkalinity described under silica gel G.
A fine, white homogeneous powder which, after shaking with water, floats on the surface because of its water-repellent properties. It complies with the test for Acidity or alkalinitydescribed under silica gel G.
Use a suspension prepared by vigorously shaking 30 g of the silica gel for 2 minutes with 60 ml of methanol (33%) and spreading it to form a uniformlayer about 0.25 mm thick on a series of carefully cleaned glass plates (200 mm × 50 mm). Allow the coated plates to dry in air and heat in anoven at 105° to 110° for 30 minutes.
Complies with the test for Separating power prescribed under silanised silica gel HF254.
A fine, white homogeneous powder of an average particle size of about 15 µmcontaining about 1.5% of a fluorescent indicator having a maximum intensity at 254 nm. It complies with the test for Acidity or alkalinity described under silica gel G and with the test for Fluorescence described under silicagel GF254.
A fine, white, homogeneous powder which, after shaking with water, floats on the surface because of its water-repellent properties. It contains about 1.5% of a fluorescentindicator having a maximum intensity at 254 nm.
Use a suspension prepared by vigorously shaking 30 g of the silica gel for 2 minutes with 60 ml of methanol (33%) and spreading it to form a uniformlayer about 0.25 mm thick on a series of carefully cleaned glass plates (200 mm × 50 mm). Allow the coated plates to dry in air and heat in anoven at 105° to 110° for 30 minutes.
Complies with the following test.
Separating power carry out the method for thin-layerchromatography using a plate prepared as described above and a mixture of 10 volumes of glacial aceticacid, 25 volumes of water and 65 volumes of 1,4-dioxan as themobile phase. Apply separately to the plate three 10-µl quantities of a solution prepared in the following manner. To a mixture of 0.1 g each of methyllaurate, methyl myristate, methyl palmitate and methyl stearate add 40 ml of alcoholicpotassium hydroxide solution andheat under a reflux condenser on a water bath for 1 hour. Allow to cool, add 100 ml of water, acidify the mixture with 2M hydrochloric acid and extract with three 10-ml quantities of chloroform. Dry the combined chloroform extracts over anhydrous sodium sulphate, filter and evaporate to dryness on a water bath. Dissolve the residue in 50 ml of chloroform. After removal of the plate, heat it at 120° for 30 minutes. Allow to cool, spray with a 3.5% w/vsolution of phosphomolybdic acid in propan-2-ol and heat at 150° until spots become visible. Expose the plate to ammonia vapour until the background turns white. Each chromatogram shows four clearly separated, well-defined spots.
Support of glass, metal or plastic, coated with a layer of silica gel of a suitable thickness and particle size (usually 2 µm to 10 µm for fine particlesize (high performance thin layerchromatography, HPTLC, plates) and 5 µm to 40 µm for normal plates). If necessary, the particle size is indicated after the name of the reagent in the tests where it is used. An organic binder may beincluded.
Chromatographic separation apply to the plate an appropriate volume (10 µl for a normal plate and 1 µl to 2 µl for a fine particle size plate) of TLC performance test solution and develop over a pathlength of two thirds the height ofthe plate using a mixture of 20 volumesof methanol and 80 volumes of to lueneas the mobile phase. The plate is notsatisfactory unless the chromatogram shows four clearly separated spots, bromocresol green with an Rf value ofless than 0.15, methyl orange with an Rfvalue in the range 0.1 to 0.25, methyl red with an Rf value in the range 0.35to 0.55 and Sudan red G with an Rf valuein the range 0.75 to 0.98.
Complies with the requirements prescribed for TLC silica gel plate with the following modifications.
It contains a fluorescent indicatorhaving a maximum absorbance at 254 nm.
Fluorescencesuppression apply separately to the plate atfive points increasing volumes (1 µl to10 µl for normal plates and 0.2 µl to 2 µl for fine particle size plates) of a 0.1% w/v solution of benzoic acidin a mixture of 15 volumes of absolute ethanol and 85volumes of cyclohexane. Develop over a pathlength of half the plate height using the same mixture of solvents as the mobile phase. After removal of the plate, allow the solvents to evaporate and examinethe chromatograms in ultraviolet light (254 nm). For normal TLC plates benzoic acid appears as dark spotson a fluorescent back ground approximately in the middle of the chromatogram for quantities of 2 µg or greater. For fine particle size plates benzoic acid appears as dark spots on a fluorescent background approximately in the middle ofthe chromatogram for quantities of 0.2µg or greater.
