TABLE 2.
Non-exhaustive list of organic acid assays and their enzymatic and detection systems.
| Analyte | Enzymes system used | Measurements | Detection limit |
| Acetic acid | Acetyl-coenzyme A synthetase Citrate synthase L-Malate dehydrogenase | Formation of NADH Measured at 340 nm | 0.14 mg/L (2.3 μM) |
| Acetic acid | Acetate kinase Phosphotransacetylase Pyruvate kinase D-Lactate dehydrogenase | Consumption of NADH Measured at 340 nm | 0.254 mg/L (4.2 μM) |
| Citric acid | Citrate lyase L-Malate dehydrogenase D-Lactate dehydrogenase | Consumption of NADH Measured at 340 nm | 0.491 mg/L (2.6 μM) |
| Citric acid | Citrate lyase Oxaloacetate decarboxylase D-Lactate dehydrogenase | Formation of NADH NADH reduces redox probe Abs measured at 570 nm (AB) | 0.002 mg/L (0.01 μM) |
| Formic acid | Formate dehydrogenase | Formation of NADH Measured at 340 nm | 0.0932 mg/L (0.2 μM) |
| D-gluconic | Gluconate kinase 6-Phosphogluconate dehydrogenase | Formation of NADH Measured at 340 nm | 0.792 mg/L (4.0 μM) |
| D-Lactic acid | D-Lactate dehydrogenase D-Glutamate-pyruvate transaminase | Formation of NADH Measured at 340 nm | 0.214 mg/L (2.4 μM) |
| D-Lactic acid | D-Lactate dehydrogenase | Formation of NADH NADH reduces redox probe Abs measured at 450 nm (WST) | 1.8 mg/L (20 μM) |
| D/L-Lactic acid | L-Lactate dehydrogenase D-Lactate dehydrogenase D-Glutamate-pyruvate transaminase | Formation of NADH Measured at 340 nm | 0.214 mg/L (2.4 μM) |
| D/L-Lactic acid | Lactate oxidase | Formation of H2O2 Fluorometric H2O2 probe | 0.135 mg/L (1.5 μM) |
| D-Malic acid | D-Malate dehydrogenase | Formation of NADH Measured at 340 nm | 0.26 mg/L |
| L-Malic acid | L-Malate dehydrogenase Glutamate-oxaloacetate transaminase | Formation of NADH Measured at 340 nm | 0.25 mg/L |
| Malic acid | Malate dehydrogenase | Formation of H2O2 NADH reduces redox probe Abs measured at 450 nm (WST) | (6.3 μM)** |
| Oxalic acid | Oxalate oxidase Peroxidase (+ MBTH+ DMAB) | Formation of H2O2 Indamine dye formed Measured at 590 nm E590 nm = 47,600 | NA |
| Pyruvic acid | D-Lactate dehydrogenase | Consumption of NADH Measured at 340 nm | 0.394 mg/L |
| Pyruvic acid | Pyruvate oxidase Peroxidase | Formation of H2O2 Peroxidase activated dye Abs measured at 540 nm (AB) | 3.0 μM |
| Succinic acid | Succinyl-CoA synthetase Pyruvate kinase L-Lactate-dehydrogenase | Consumption of NADH Measured at 340 nm | 0.256 mg/L |
Assays from providers that do not release the enzyme systems used or the nature of the redox or fluorimetric probe used for final detection were not included. Data compiled from the websites of the following providers: Megazyme, Abcam, Cell Biolabs Inc., Trinity Biotech, Libios, and Sciencell. AB, alamarBlue (resazurin); WST, tetrazolium-based dye; MBTH, 3-methyl-2-benzothi-azolinone hydrozone; DMAB, 3-(dimethylamino)benzoic acid. **First standard solution used for calibration in manufacturer booklet. NA, data not available.