TLC Silica Gel 60 G Plates with Gypsum

The TLC silica gel 60 G plates consist of silica gel having a pore size of 60 Å as the adsorption formulation, with gypsum as a binder material. Gypsum is incorporated in the silica gel in the form of calcium sulfate hemihydrate (1/2CaSO₄).

Our highly robust TLC silica gel plates with gypsum as binder, are recommended for customers working in QA/QC labs using European Pharmacopoeia (Ph. Eu.) monograph methods. As these customers specifically require TLC plates with gypsum and do not wish to use classical TLC plates, having organic binders for their analysis.

The plates exhibit complete compliance with the International Pharmacopoeia and have been mentioned in about 200 monograph methods described in the European Pharmacopoeia (Ph. Eu.). These TLC silica gel 60 G plates satisfy the TLC performance test requirements of European Pharmacopoeia, in addition to our in-house standard QC tests, proving their premium quality.

The TLC performance test is a chromatographic separation, which involves the application of an appropriate (10 μL for a normal TLC plate and 1 μL to 2 μL for a fine particle size plate) volume of TLC performance test solution R (Reagent 1116600) to the plate. The plate is then left for development to a length equal to two thirds of the plate height, in the mobile phase consisting of 20 volumes of methanol R and 80 volumes of toluene R. Successful development of four clearly separated spots, indicates a positive result. The spot of bromocresol green with an Rf value less than 0.15, the spot of methyl orange with an Rf value in the range of 0.1-0.25, the spot of methyl red with an Rf value in the range of 0.35-0.55, and finally the spot of Sudan red G with an Rf value in the range of 0.75-0.98.

Parameter	Specification	Typical value
	hRf, values
Separation	4 clearly separated spots	passed
Bromocresol green	<15	5
Methyl orange	10 - 25	10
Methyl red	35 - 55	38
Sudan red	75 - 98	82

Figure 1. Chromatogram of TLC Silica Gel 60 G plates in the Ph. Eur. performance test

The development of four clearly separated spots, with Rf values within the prescribed range indicate the promised quality of our silica gel G TLC plates.

Identification Test for Atenolol and Chlorthalidone in Tablets Following European Pharmacopeia Monograph

Atenolol is a selective β1 receptor antagonist, belonging to the group of beta blockers, a class of drugs used primarily in cardiovascular diseases.

Chlorthalidone is a diuretic drug used to treat hypertension, originally marketed as Hygroton in the USA. It is described as a thiazide diuretic, and often used in the management of hypertension and edema.

With this application note we illustrate how silica gel G F₂₅₄ plates are suitable for analysis of Atenolol and Chlorthalidone in a combination drug following the experimental conditions per the European Pharmacopeia identification TLC test for Atenolol (version 9.0).

Experimental Condition
TLC Plate	Silica Gel 60 G F254, 20 x 20 cm
Application volume	5 μL of each solution
Detection	UV @ 254 nm
Mobile phase	18 M Ammonia and n-butanol 30:150 (v/v)
Plate development	Line the walls of chromatographic tank with filter paper. Pour a sufficient quantity of mobile phase into the chromatographic tank. Saturate the chromatographic tank, replace the lid and allow to stand at 20-25°C for 1 hr. Apply the prescribed volume of the solutions in sufficiently small portions to obtain bands at an appropriate distance from the lower edge.
Migration distance	15 cm
Drying	in air
Standard	1.0 % (w/v) of atenolol in 0.25 % (w/v) of Chlorthalidone in methanol
Sample	Remove any film coating on the tablet powder and shake the quantity of powered tablet containing 0.1 g of atenolol with 10 mL of methanol for 15 minutes and filter.

Figure 2. TLC chromatogram for the identification of Atenolol and Chlorthalidone in combined tablets