Determination of the concentration of the anions bromide, chloride, fluoride, nitrate, nitrite, oxalate, phosphate and sulfate through ion chromatography
Water, wort, beer, NAB and beverages as well as malt and hops
Separation of bromide, chloride, fluoride, nitrate, nitrite, oxalate, phosphate and sulfate through ion chromatography followed by conductivity detection
Determination of oxalic acid by enzymatic means
Suitable for malt, wort, beer, beer-based beverages and soft drinks
Oxalic acid is primarily derived from malt. By reacting with the calcium ions in the brewing liquor, haze caused by calcium oxalate can form. These crystals also serve as nucleation sites for the spontaneous and rapid release of carbon dioxide (gushing). The precise determination of oxalic acid is therefore of great importance in brewing technology.
Oxalic acid (oxalate) is oxidized to carbon dioxide and hydrogen peroxide by the enzyme oxalate oxidase.
\(\text{ Oxalate} \hspace{0.5em}^{\underrightarrow{oxalatoxidase}}\hspace{0.5em} H_2O_2\hspace{0.3em}{+}\hspace{0.3em}CO_2\)
In the presence of the enzyme peroxidase (POD), hydrogen peroxide reacts with MTBH (3-methyl-2-benzo thiazolinone hydrazone) and DMAB (3-dimethyl amino benzoic acid to form a blue quinone complex.
\(H_2O_2+MTBH+DMAB\hspace{0.8em}^{\underrightarrow{POD}} \hspace{0.8em} \text{quinone complex} \space + \space H_2O\)
The intensity of the color is proportional to the concentration of the oxalate in the sample and is measured at 590 nm.
Suitable for analysis of all (laboratory) wort samples.
Calcium in wort is measured using AAS by directly aspirating the diluted sample into a nitrous oxide-acetylene flame; the measurement is made at 423 nm.
Lanthanum chloride reduces interference.