Improved 2,4-dinitrophenylhydrazine, thin layer chromatography methods for the determination of micro- and macroamounts of ascorbic acid.

Ascorbate Determination, 2,4-Dinitrophenylhydrazine Microamounts of vitamin C could be readily determined in 20 ul-samples using the 2,4-dinitrophenylhydrazine method together with separation by thin layer chromato­ graphy. The condensation reaction was carried out for 5 min at 100 °C on a glass fibre disc. Purification of vitamin C hydrazones was accomplished by repeated separation on TLC plates. An aqueous solution of 65% acetic acid was em ­ ployed to dissolve the vitamin C hydrazones, providing m axi­ mal absorbance at 500 nm. The minimum amount detectable by this method is 0.4 i/g of dehydroascorbic acid. The macrodetermination of vitamin C was improved by sim pli­ fying a previous method and employing 65% aqueous acetic acid as a solvent for the hydrazones.