Spike (M.I.) Walker
Vitamin C Crystallites
English photomicrographer Spike (M.I.) Walker has been a consistent winner of the Nikon Small World competition for many years and has published many articles and a book about microscopy. Featured below is thin preparation of Vitamin C crystallites recovered from aqueous solution.
Ascorbic acid, also known by the chemical name L-ascorbic acid, is a water-soluble vitamin that functions as a powerful antioxidant. Although most animals can synthesize vitamin C, others -- such as humans, other primates, and guinea pigs -- obtain it only through their diets. Vitamin C is commonly found naturally in peppers, citrus fruits, tomatoes, melons, broccoli, and green leafy vegetables such as spinach, turnip, and mustard greens.
Vitamin C is known to be essential in a variety of metabolic functions, but the details of its mechanism aren't yet understood. It is necessary for synthesis of collagen (a protein important in the formation of healthy skin, tendons, bones, and supportive tissues and in wound healing); maintenance of the structural strength of the blood vessels; metabolism of certain amino acids; and the synthesis or release of hormones in the adrenal glands. Although some anecdotal evidence suggests that vitamin C plays a part in protecting the body against infection, that claim has not been scientifically proven yet.
Chemically, L-ascorbic acid occurs as a white or slightly yellow crystal or powder with a slight acidic taste and darkens on exposure to air and light. As a dry state, it is reasonably stable in air, but it rapidly oxidizes in solution. Ascorbic acid is freely soluble in water; sparingly soluble in alcohol; insoluble in chloroform, ether, and benzene.
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