Sorbic Acid (TLC) (Type-IV)
OIV-MA-AS313-14C Sorbic acid
Type IV method
- Principle of Methods
Identification of traces by thin-layer chromatography
Sorbic acid extracted in ethyl ether is separated by thin layer chromatography and its concentration is evaluated semi-quantitatively.
Sorbic Acid (GC) (Type-IV)
OIV-MA-AS313-14B Sorbic acid
Type IV method
- Principle of Methods
Determination by gas chromatography
Sorbic acid extracted in diethyl ether is determined by gas chromatography using an internal standard.
Sorbic Acid (spectrofluorimetry) (Type-IV)
OIV-MA-AS313-14A Sorbic acid
Type IV method
- Principle of Method
Determination using ultraviolet absorption spectrophotometry
L-ascorbic Acid (spectrofluorimetry) (Type-IV)
OIV-MA-AS313-13A L-Ascorbic acid
Type IV method
- Principle
The following methods enable the presence of L-ascorbic acid and dehydroascorbic acid in wines or musts to be determined.
D-malic Acid: enzymatic method low concentrations (Type-IV)
OIV-MA-AS313-12B Determination of d-malic acid in wines at low concentrations using the enzymatic method
Type IV method
- Field of application
The method described is applied to dosage, by the enzymatic means, of malic acid D of wines with contents under 50 mg/l.
D-malic Acid: enzymatic method (Type-II)
OIV-MA-AS313-12A D-Malic acid (Enzymatic method)
Type II method
- Principle
In the presence of D-malate-dehydrogenase (D-MDH), D-malic acid (D-malate) is oxidized to oxalo-acetate by nicotinamide-adenine-dinucleotide (NAD). The formed oxalo-acetate is transformed into pyruvate and carbon dioxide.
L-malic Acid: enzymatic method (Type-II)
OIV-MA-AS313-11 L-Malic acid
Type II method
- Principle of the method
L-malic acid (L-malate) is oxidized by nicotinamide adenine dinucleotide (NAD) to oxaloacetate in a reaction catalysed by L-malate dehydrogenase (L-MDH).
Total malic Acid: usual method (Type-IV)
OIV-MA-AS313-10 Total malic acid
Type IV method
Citric Acid - enzymatic method (Type-II)
OIV-MA-AS313-09 Citric acid
Type II method
- Principle
Citric acid is converted into oxaloacetate and acetate in a reaction catalyzed by citratelyase (CL):
Citric Acid - chemical method (Type-IV)
OIV-MA-AS313-08 Citric acid (Chemical method)
Type IV method
- Principle
Citric acid is fixed with other wine acids onto an anion exchange column. The citramalic acid is obtained by fractionating the elute.