### A Spectrophotometric Procedure for Malic Acid Determination in Wines Employing a Multicommutation ApproachA Spectrophotometric Procedure for Malic Acid Determination in Wines Employing a Multicommutation Approach

Access Restriction
Open

 Author Santana, Joyce F. S. De ♦ Belian, Mônica F. ♦ Lavorante, André F. Source J-STAGE Content type Text Publisher The Japan Society for Analytical Chemistry Language English
 Subject Keyword Multicommutation ♦ flow injections analysis ♦ wine ♦ malic acid ♦ spectrophotometry Abstract This work describes an automated procedure to determine L-malic acid (MA) in wine samples using a multicommuted flow analysis. The MA quantification was based on an enzymatic reaction between MA and L-malate dehydrogenase (L-MDH) in the presence of nicotinamide adenine dinucleotide $(NAD^{+}),$ producing nicotinamide adenine dinucleotide dehydrogenase (NADH), which was monitored at 340 nm. The L-MDH was immobilized on a surface of modified silica with amino groups in the presence of glutaraldehyde. For studying optimization, the system was maintained with 200 μL (288 U) of the L-MDH in 0.5 g of modified silica. Under the optimum experimental conditions, a linear response ranging from 0.1 to 1.5 g $L^{−1}$ MA (R = 0.997 and n = 7), a detection (3σ criterion) and quantification (10σ criterion) limit estimated at 0.02 and 0.06 g $L^{−1},$ respectively, a standard deviation relative of 1.8% (n = 7) for a sample of 0.5 g $L^{−1}$ MA, a sampling rate of 67 samples per hour were achieved. Analyzing ten wines samples and applying the t-test to the results found and those obtained using reference procedures (HPLC) provided no significant differences at the 95% confidence level. ISSN 09106340 Learning Resource Type Article Publisher Date 2014-06-10 e-ISSN 13482246 Journal Analytical Sciences(analsci) Volume Number 30 Issue Number 6 Page Count 5 Starting Page 657 Ending Page 661