Abstract
In the present work a sequential injection system for the enzymatic determination of L(-)malic acid in wines is described. The determination was based on the detection of NADH, formed by oxidation of L-malate to oxaloacetate, catalysed by L-malate dehydrogenase. A kinetic method was implemented by stopping the flow when a solution plug containing sample, NAD+ and enzyme reached the detector. The rate of reaction was measured by monitoring absorbance changes at 340nm during a fixed period of time. A linear calibration curve (rate of reaction versus concentration) was obtained for concentrations of L(-)malic acid between 0.01 and 0.15gl-1. The determination rate was about 22h-1 and samples were diluted 25 or 50 times before introduction to the system. Results obtained from 16 wine samples were comparable to those obtained by the reference method.
| Original language | English |
|---|---|
| Pages (from-to) | 99-106 |
| Number of pages | 8 |
| Journal | Analytica Chimica Acta |
| Volume | 499 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - 4 Dec 2003 |
| Event | 9th International Conference on Flow Analysis - Geelong, Australia Duration: 10 Feb 2003 → 14 Feb 2003 Conference number: 9 |
Keywords
- Kinetic enzymatic determination
- Malic acid
- Sequential injection analysis
- Wines