1996•Journal of AOAC InternationalRequires access
Determination of D-Malic Acid in Apple Juice by Liquid Chromatography: Collaborative Study
THOMAS A. EISELE, Collaborators:, K Adadevoh, G Anderson, A Brause, D Briesmeister, J Burke, G Cherix, C Ellis, S Hendricks, C T Ho, C J Huang, T Iuliano, L Kline, C Knapp, Dirk Krueger, L Terwel
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Abstract
Eleven laboratories collaboratively studied a liquid chromatographic (LC) method for determination of D-malic acid in apple juice. The mobile phase consisted of mM L-valine and 8 mM copper acetate adjusted to pH 5.5 with NaOH. The UV detector was set at 330 nm, and a single reversed-phase LC column was used. Seven paired samples containing various amounts of D-malic acid ranging from 0 to 188 mg/100 mL of 12 Brix pasteurized apple juice were tested by each collaborator. Repeatability and reproducibility coefficients of variation ranged from 1.0 to 3.5% and 7.7 to 11.7%, respectively, within the range of 26 to 188 mg D-malic acid/100 mL of 12 Brix apple juice. The collaborative study results demonstrated that the method could quantitate the economic adulteration of apple juice with DL-malic acid at lower levels than those reported with previous methods. The LC method for determination of D-malic acid in apple juice has been adopted first action by AOAC INTERNATIONAL.