High-performance liquid chromatography - analysis of various vitamins in multivitamin tablets

Effective August 24, 2007, the US Food and Drug Administration (FDA) issued a regulation (21 CFR Part 111) that established the minimum current Good Manufacturing Practices (cGMPs) required for activities in manufacturing, packaging, labelling and holding Dietary Supplements to ensure the identity, purity, quality, strength and composition of these products.

Depending on the business size determined by the number of employees, FDA set 3 different timelines by which the companies must comply with the new requirements. For businesses with 500 or more employees, the compliance date was June 25, 2008. For businesses with 20 to 499 employees, the compliance date was June 25, 2009. For businesses with 19 or fewer employees, the compliance date is June 25, 2010. The new regulation means more testing needs to be performed by companies that manufacture Dietary Supplements.

The United States Pharmacopeia (USP) is an official authority that sets standards for all prescription and over-the-counter drugs, dietary supplements and food ingredients that are intended for sale in the United States. USP develops standards for the quality, purity, strength, and consistency of these products. In its annual book, the United States Pharmacopeia-National Formulary (USP-NF), USP publishes pharmacopeial standards along with validated analytical methods that have been the choice of many commercial laboratories. The pharmacopeial forum (USP-PF) discusses proposed method revisions. Table 1 shows examples of USP techniques for the analysis of some dietary supplements.

Analysis of Vitamin B12 in Multivitamin Tablets

Here we used an LC-UV to conduct analysis of Cyanocobalamin in multivitamin tablets from a popular brand. Sample preparation and analysis followed the USP32-NF27 procedure.

[Sample Preparation]

30 tablets corresponding to approximately 48 g were finely powdered. 6.1 g of the powder was transferred to a flask and 100 mL of water was added volumetrically. The mixture was carefully extracted for 2 minutes. 10 mL of the extract was filtered and the filtrate used for analysis.

Analysis of Vitamin D in Multivitamin Tablets

Here we used an LC-UV to conduct analysis of Cholecalciferol (Vitamin D3) and Ergocalciferol (Vitamin D2) in multivitamin tablets from a popular brand. Sample preparation and analysis followed the USP32-NF27 procedure.

[Sample Preparation] common procedure for Vitamins D, A and E.

20 Tablets were finely powdered and a weighed portion of the powder, equivalent to 5 tablets, was transferred to a container with a POLYTEF-lined screw cap. 10 mL of dimethyl sulfoxide and 15 mL of n-hexane were added, and the mixture was shaken for 45 minutes on a wrist-action shaker in a water bath maintained at 60°C followed by centrifugation for 10 minutes at 3000 rpm. The hexane layer was transferred to a 100 mL volumetric flask. 15 mL of n-hexane was added to the dimethyl sulfoxide layer, shaken thoroughly for 5 minutes, and the hexane layer was transferred to the 100 mL volumetric flask. This extraction was repeated with 3 additional 15 mL portions of n-hexane. The extracts were brought to 100 mL volume with n-hexane. 10 mL of the resulting solution was diluted quantitatively with n-hexane to a final concentration of about 15 µg/mL of vitamin A.

Analysis of Vitamin A in Multivitamin Tablets

Here we used an LC-UV to conduct analysis of Retinyl Acetate and Retinyl Palmitate (Vitamin A) in multivitamin tablets from a popular brand. Sample preparation and analysis followed the USP32-NF27 procedure.

[Sample Preparation] common procedure for Vitamins D, A and E (see Vitamin D section above)

Analysis of Vitamin E in Multivitamin Tablets

Here we used an LC-UV to conduct analysis of Alpha Tocopheryl Acetate (Vitamin E) in multivitamin tablets from a popular brand. Sample preparation and analysis followed the USP32-NF27 procedure.

[Sample Preparation] common procedure for Vitamins D, A and E (see Vitamin D section above)

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