Search: low capacity for water uptake

Barley is steeped according to a defined scheme, and the absorption of the steeping liquor by the kernels at defined times is determined by calculating the moisture content. The moisture content after 72 h steeping time is used to assess the absorption of steeping liquor or the capacity for water imbibition in barley.

Potassium permanganate oxidizes many organic and certain inorganic substances more or less completely in acidic, neutral or alkaline solutions. The volume of potassium permanganate required in the analysis is determined potentiometrically. Since oxidation depends on the type of solution, on its temperature and on the reaction time, the procedure described below must be followed precisely.

In acidic solutions, permanganate ions are typically reduced to manganese(II) ions:

MnO₄^- + 5 e- + 8 H₃O⁺ → Mn²⁺ + 12 H₂O

In alkaline solutions, the reduction results in tetravalent manganese only:

MnO₄^- + 3 e- + 4 H₃O⁺ → MnO₂ + 6 H₂O

Since in both cases the titration takes place in an acidic solution, this is irrelevant for the calculation. By adding oxalic acid, both the excess permanganate ions as well as the tetravalent manganese are reduced to manganese(II) ions:

2 MnO₄^- + 5 C₂O₄^2- + 16 H₃O⁺ → 2 Mn²⁺ + 24 H₂O + 10 CO₂

MnO₂ + C₂O₄²- + 4 H₃O⁺ → Mn²⁺ + 6 H₂O + 2 CO₂  

Analogous to the p and m values obtained in the determination of acid capacity (pH 8.2 and 4.3), this analysis is performed according to W-000.13.031 Acid Consumption (Alkalinity, p-Value and m-Value)/Acid Capacity to pH of 8.2 and/or 4.3 for Water. The alkaline capacity of the boiler water is determined through titration of the sample with 0.1 N sodium hydroxide (instead of hydrochloric acid) to a pH of 4.3 and/or 8.2.

Qualitative detection of sulphite-reducing, spore-forming anaerobes in mineral water, spring water, table water, and other drinking water bottled for distribution to the consumer, by means of membrane filtration and immersion of the filter in single-concentrate dextrose-iron citrate-sodium sulphite broth (DRCM broth).

Note 1: If only the spores of sulphite-reducing anaerobes are to be analysed, the prescribed sample volume must be heated at 75 °C ± 1 °C for 10 minutes in order to inactivate the vegetative cells. Then cool quickly with cold water.

Important: Carry out a comparative test with the same volume of tap water to determine the total heating time required in the water bath.

Qualitative detection of sulphite-reducing, spore-forming anaerobes in mineral water, spring water, table water, and other drinking water bottled for distribution to the consumer, by means of membrane filtration and placing the filter on a solid culture medium.

Note 1: If only the spores of sulphite-reducing anaerobes are to be analysed, the prescribed sample volume must be heated at 75 °C ± 1 °C for 10 minutes in order to inactivate the vegetative cells. Then cool quickly with cold water.

Important: Carry out a comparative test with the same volume of tap water to determine the total heating time required in the water bath.

Membrane filtration (MF) and placing the filter on dextrose-iron sulphate-sodium sulphite agar (DRCM agar) (corresponds to method Annex 2, point 4 a of § 4 para. 3 of the German Mineral and Table Water Ordinance, MTV) [1].

Qualitative detection of sulphite-reducing, spore-forming anaerobes in mineral water, spring water, table water, and other drinking water bottled for distribution to the consumer, by means of enrichment culture in double-concentrated dextrose-iron citrate-sodium sulphite broth (DRCM broth) [1].

Note 1: If only the spores of sulphite-reducing anaerobes are to be analysed, the prescribed sample volume must be heated at 75 °C ± 1 °C for 10 minutes in order to inactivate the vegetative cells. Then cool quickly with cold water.

Important: Carry out a comparative test with the same volume of tap water to determine the total heating time required in the water bath.