TLC-Densitometric Determination of Vitamins B1, B6 and B12 in Pure and Pharmaceutical Formulations Using Treated Aleppo Bentonite

Abstract

Determination of vitamins B₁, B₆ and B₁₂ in pure and in pharmaceutical formulations by thin layer chromatography (0.30 mm thickness) using acid treated Aleppo bentonite and mobile phase consisted of isobutyl alcohol:methanol:chloroform:acetic acid:ammonia (7.5:1:3.5: 0.4:0.5, v/v/v/v/v)has been applied. The specific surface area of bentonite was 168.25 m²/g and mean pore size was 52.3 Å determined using nitrogen adsorption (BET). Quantification was carried out densitometerically at λ = 275 nm for vitamins B₁, B₆ and B₁₂ ( if their concentrations are in close proximity) and at λ = 525 nm for vitamin B₁₂ (when CB₆ ≈ CB₁ >> CB₁₂ as in pharmaceutical products). This method is successful for vitamin B₁, B₆ and B₁₂ formulation even in the ratios between vitamin B₁₂ and others 1:100. The retardation factors (R_f) of B₁, B₆ and B₁₂ were 0.37, 0.68 and 0.26, respectively. Calibration curves were obtained in the range of 5.0-40.0 μg/ spot for vitamins B₁, B₆ and B₁₂ (at λ = 275 nm) for standard solutions, while for pharmaceutical products, vitamins B₁, B₆  were determined at λ = 275 nm and vitamin B₁₂ was determined at λ = 525 nm in the range of 0.5- 4.0 μg/spot.