Ascorbic tablets

The technique of hydrodynamic modulation voltammetry (HMV), in which the rate of stirring is pulsed between high and low values, is demonstrated in this experiment. The application of HMV for the quantitative analysis of ascorbic acid in vitamin C tablets using the method of standard additions also is outlined. 

L-Ascorbic acid is used as a micronutrient additive in pharmaceutical, food, feed, and beverage products, as weU as in cosmetic appHcations. The over-the-counter (OTC) vitamin market is strong, growing in demand, and vitamin C is available in the form of piUs and tablets to supplement the daily diet to maintain peak physical performance. 

C04-0144. Vitamin C (also called ascorbic acid) is an acid whose formula is HCg H7 Og. When treated with strong base, it undergoes the following reaction HCg H7 0(5 + OH H7 Og + H2 O A pharmacist suspects that the vitamin C tablets received in a recent shipment are not pure. When a single 500.0-mg tablet is dissolved in 200.0 mL of water and titrated with a standard base that is 0.1045 M, it takes 24.45 mL to reach the stoichiometric point. Are the tablets pure If not, what is the mass percentage of impurities (Assume no impurity is either an acid or a base.)... 

Analysis of ascorbic acid (vitamin C) in a vitamin C tablet. 

Other workers have used the tristimulus parameters to study the kinetics of decomposition reactions. The fading of tablet colorants was shown to follow first-order reaction kinetics, with the source of the illumination energy apparently not affecting the kinetics [49]. The effect of excipients on the discoloration of ascorbic acid in tablet formulations has also been followed through determination of color changes [50]. In this latter work, it was established that lactose and Emdex influenced color changes less than did sorbitol. 

The SP procedure of water-soluble vitamins from multivitamin tablets is particularly challenging due to the diverse analytes of varied hydrophobicities and pfC. Water-soluble vitamins (WSVs) include ascorbic acid (vitamin C), niacin, niacinamide, pyridoxine (vitamin B ), thiamine (vitamin Bj), folic acid, riboflavin (vitamin B2) and others. While most WSVs are highly water soluble, riboflavin is quite hydrophobic and insoluble in water. Folic acid is acidic while pyridoxine and thiamine are basic. In addition, ascorbic acid is light sensitive and easily oxidized. The extraction strategy employed was a two-step approach using mixed solvents of different polarity and acidity as follows ... 

Tablets 66 mg iron, 125 mg ascorbic acid (otc) Vitron-C (Heritage Consumer Products)...

Tablets, controlled-release 105 mg iron, 500 mg sodium ascorbate (otc) Fero-Grad-500 (Abbott)...

Water-soluble vitamins in formulations have been determined by use of ion-pair chromatography. The vitamins include several B vitamins as well as niacin, folic acid, and ascorbic acid (565). Vitamins D and Da were rapidly separated on reverse phase columns (247) as are vitamins A, D, and E in multivitamin tablets (564). Addition of silver ions to the mobile phase has been shown to increase the flexibility inherent in RPC by complexing with the unsaturated bonds and thereby decreasing the retention factor. This effect is also observed with other unsaturated drug molecules including steroids (247). Vitamin A and related compounds have... 

Method allows isolation of antagonistic components, like iron and ascorbic acid, in nutritional mixes in small tablets (Gibbs et al, 1999 Gouin, 2004)... 

Vitamin C (Ascorbic Acid + Ascorbate) Chewable Tablets (500 mg)... 

This experiment is flexible in that students may choose the samples they wish to analyze. It is suggested that several fruits and vegetables as well as an unknown ascorbic acid sample be available for analysis. The vitamin C content of raw and cooked vegetables can also be measured and compared. Commercially available vitamin C tablets or multivitamin pills provide interesting samples for analysis. The time required for this experiment can be adjusted by controlling the number and type of samples. 

Because of this apparent importance of ascorbate not only in artificial systems (for the OH-production by multivitamin tablets, see Maskos and Koppenol 1991) but also in the living cell where a concentration of ca. 10-2 mol dm-3 is typically maintained, it seems adequate to digress for a short moment on its chemistry. 

For the first biosensor shown in Table 17.2, L-ascorbic acid has been determined in fruit juices and vitamin tablet, by immobilizing a slice of cucumber (Cucumis sativus) onto an 02 electrode in the pH range 6.0-6.5 (phosphate buffer solution) [11] ... 

Rutin, Ascorbic acid Tablet MLR Non-destructive quantitation method. Errors (SEP) less than 0.7%. Method validated using ICH-adapted guidelines 129... 

Sun, S., Du, D., Zhou, Q., Leung, H.W. and Yeung, H.W. (2001) Quantitative analysis of rutin and ascorbic acid in compound rutin tablets by near-infrared spectroscopy Anal. Sci. 17, 455 58. 

R. Thomas, E. Roets, and J. Hoogmartens, Analysis of tablets containing aspirin, acetaminophen, and ascorbic acid by high-performance liquid chromatography, J. Pharm Sci., 73 1830 (1984). 

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