UV-1200 UV-visible spectrophotometric determination of vitamin B12 content - Database & Sql Blog Articles

Determination of Vitamin B12 by UV-Vis Spectrophotometry

UV-1800PC UV-visible spectrophotometric determination of vitamin B12 vitamin [U1] B12 is a cobalt-containing organic drug, which is dark red crystal, also known as red vitamin B12 or cyanocobalamin, is the only vitamin containing major minerals. The traditional method for determining the content of vitamin B12 tablets is to use an ultraviolet-visible spectrophotometer to determine the content basis by the absorption coefficient method, but the method requires high precision of the instrument. The standard curve method is the most classic method in the ultraviolet-visible spectrophotometry. If an instrument is identified and its working state and measurement conditions are fixed, the method can eliminate some errors caused by the instrument, and the operation is simple and easy.

1 Instrument and reagent 1.1 Instrument UV-1800PC UV-visible spectrophotometer (America China Instrument Co., Ltd.).
1.2 Test drug vitamin B12 reference substance (China National Institute for the Control of Pharmaceutical and Biological Products); vitamin B12 tablets (Herrida Pharmaceutical Co., Ltd., batch number 060801, 060701, 061002, 060902, 070303). 0.8 filter [AUTOMATIC SCIENCE (TIANJIN) INSTRUMENT CO; LTD].
2 Methods and Results 2.1 Determination of wavelength selection There are three absorption peaks on the absorption spectrum of vitamin B12: 278 nm, 361 nm, 550 nm. The absorption peak of vitamin B12 at 361 nm has less interference factors and the strongest absorption. The Chinese Pharmacopoeia stipulates that the specific absorption coefficient of E1%1 cm (207) of the absorption peak at 361 nm is the basis for calculation. In this experiment, 361 nm was selected as the measurement wavelength, and the standard curve method was used as the basis for calculation.
2.2 Preparation of the solution 2.2.1 Preparation of the reference solution: Precisely weigh the reference substance vitamin B12 0.0025 g, place it in a 25 mL volumetric flask, add water to the mark, and shake well. Place the dissolved solution in the refrigerator and store it for later use.
2.2.2 Preparation of the test solution: Vitamin B12 tablets are sugar-coated tablets, take 50 tablets of this product, remove the sugar coating, make it pink, grind fine, accurately weigh the grinding sample, about equivalent to vitamin B12 1.25 mg ( The labeled amount of each piece is 25.0 μg), placed in a 50 mL volumetric flask, add 35 mL of water, shake well for 30 min to dissolve, add water to dilute to the mark, close the plug, then shake vigorously for 10 min, let stand, take The supernatant was filtered through a 0.8 μm microporous membrane, and the filtrate was placed in a refrigerator for storage.
2.3 Linear relationship standard curve drawing: Take the stock solution under 2.2.1, dilute with water, 1.5, 2, 4, 6, 8, 10, 15, 20 times, shake well. The absorbance was measured at a wavelength of 361 nm.
A standard curve was drawn with absorbance A and mass concentration c, and the regression equation Y=0.0193X+0.048, r=0.9937. The results showed that the concentration of vitamin B12 reference solution in the range of 5.00 μg / mL ~ 100.00 μg / mL showed a good linear relationship with the degree of absorption.
2.4 Precision test The reference solution with a concentration of 100 μg/mL was continuously measured 5 times at 361 nm. The average absorbance of vitamin B12 was 2.087 and the RSD was 0.7% (n=5). The RSD value is small, indicating that the method has good precision.
2.5 Stability test The same test solution was taken and stored in the refrigerator for 2 h, 4 h, 8 h, 12 h, 24 h, and determined by the content measurement method under 2.7. The average absorbance was calculated to be 0.468, and the RSD was 0.99. %(n=5). The results show that the test solution is basically stable within 24 h at refrigerated temperature.
2.6 Repeatability test: Take the same batch of samples and prepare 5 samples of the test solution according to the method of 2.2.2, and determine the average content of vitamin B12 by 22.6 μg/mL according to the content determination method under 2.7. The batch number is 070303) and the RSD is 1.08% (n=5), indicating that the method has good repeatability.
2.7 Determination of content Take water as a blank, take the filtrate under 2.2.2, shake well, set the absorption wavelength to 361 nm to determine the absorbance, according to the standard curve method to calculate the content basis.
The labeled amount of vitamin B12 tablets was 25.0 μg. From the above results, the content of vitamin B12 tablets produced by Shanxi Hengruida Pharmaceutical Co., Ltd. was within the range of 90.0% to 110.0%. The RSD is small, indicating that the drug produced by the plant is stable.