This method describes the spectrophotometric determination of the color of roasted malt beer/extract.
Roasted malt beer/extract intended for use in beer brewing or elsewhere in the food industry.
This method describes the visual determination of the color of roasted malt beer/extract.
Roasted malt beer/extract intended for use in beer brewing or elsewhere in the food industry.
The method describes how to determine the phosphate content of water photometrically with a cuvette test.
Phosphate ions form a yellow color in the presence of the molybdovanadate reagent. The color is determined using a photometer.
The PAH compounds are concentrated through extraction with cyclohexane and evaporation. The separation is carried out by means of high-performance thin-layer chromatography. The results are evaluated through examination under UV light, followed by comparison of the Rf values with the reference substances.
Determination of the concentration of alkaline cleaners on quicklime (CaO) and sodium hydroxide (NaOH) without soda (Na2CO3).
Determination of the quicklime (CaO) or sodium hydroxide (NaOH) content of the detergent solution with an acid solution (HCl or H2SO4) with corresponding equivalent concentration (normality) up to the color change of phenolphthalein (pH 8.2).
Quicklime
|
CaO + H2O |
→ Ca(OH)2 |
|
|
Ca(OH)2 + 2 HCl |
→ CaCl2 + H2O |
colorless against phenolphthalein |
|
Ca(OH)2 + H2SO4 |
→ CaSO4 + 2 H2O |
colorless against phenolphthalein |
Sodium hydroxide
|
NaOH + HCl |
→ NaCl + H2O |
colorless against phenolphthalein |
|
2 NaOH + H2SO4 |
→ Na2SO4 + 2 H2O |
colorless against phenolphthalein |
Determination of the concentration of alkaline cleaners in sodium hydroxide (NaOH) and soda (Na2CO3).
All alkaline cleaning solutions or "batch solutions" that contain soda (Na2CO3) as a cleaning component in addition to sodium hydroxide (NaOH).
If the alkaline solution is likely to be strongly influenced by carbonic acid or if the cleaning solutions are used over a longer period of time ('batch cleaning'), the degree of carbonation must be taken into account to determine the exact concentration or pH value, as the resulting soda has a greatly reduced cleaning effect, but simulates an excessively high concentration of the active cleaning agent.
Determine the sodium hydroxide (NaOH) content of the detergent solution with an acid solution (HCl or H2SO4) with corresponding normality up to the color change of phenolphthalein (pH 8.2).
NaOH + HCl → NaCl + H2O colorless against phenolphthalein
2 NaOH + H2SO4 → Na2SO4 + 2 H2O
Determination of the soda ash (Na2CO3) content of the detergent solution with an acid solution (HCl or H2SO4) with corresponding normality up to the color change from methyl orange (pH 4.3).
Na2CO3 + HCl → NaHCO3 + NaCl
NaHCO3 + HCl → NaCl + H2O + CO2 yellowish brown against methyl orange
2 Na2CO3 + H2SO4 → 2 NaHCO3 + Na2SO4
2 NaHCO3 + H2SO4 → 2 Na2SO4 + H2O + 2 CO2