Water for Preparation of Extracts

(Ph. Eur. monograph 2249)

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DEFINITION

Water intended for the preparation of Herbal drug extracts (0765) complies with the sections Purified water in bulk or Purified water in containers in the monograph Purified water (0008), or is water intended for human consumption of a quality equivalent to that defined in Directive 98/83/EC which is monitored according to the Production section described below.

PRODUCTION

When water intended for human consumption is used as water for preparation of extracts it is a clear, colourless liquid. It is stored (where necessary) and distributed under conditions designed to prevent growth of micro-organisms and to avoid other contamination.

For monitoring purposes, the following tests are carried out at regular intervals to demonstrate consistency in the quality of the water used for the preparation of extracts.

Conductivity (2.2.38)

Maximum 2500 µS⋅cm^-¹, measured at 20 °C.

Nitrate

Liquid chromatography (2.2.29).

Test solution The substance to be examined.

Reference solution Dissolve 0.163 g of potassium nitrate R and 0.149 g of potassium bromide R in water R and dilute to 100.0 mL with the same solvent. Dilute 5.0 mL of the solution to 100.0 mL with water R.

Column:

— size: l = 0.25 m, Ø = 4 mm;

— stationary phase: anion-exchange resin R3.

Mobile phase Dissolve 0.265 g of anhydrous sodium carbonate R and 0.210 g of sodium hydrogen carbonate R in water R and dilute to 1000.0 mL with the same solvent.

Flow rate 1.2 mL/min.

Detection Conductivity detector, using a self-regenerating anion suppressor.

Injection 25 µL.

Run time Twice the retention time of nitrate.

Relative retention With reference to nitrate (retention time = about 7 min): bromide = about 0.9.

System suitability: reference solution:

— resolution: minimum 2.0 between the peaks due to bromide and nitrate.

Limit:

— nitrate: maximum 50 ppm.

Microbiological monitoring

Appropriate measures are taken to ensure that the microbial count is adequately controlled and monitored. Appropriate alert and action levels are set so as to detect adverse trends.

Under normal conditions, an appropriate action level is a microbial count of 100 CFU/mL, determined by filtration through a membrane with a nominal pore size not greater than 0.45 µm, using casein soya bean digest agar and incubating at 30-35 °C for not less than 5 days.

The size of the sample is to be chosen in relation to the expected result.

Casein soya bean digest agar

Adjust the pH so that after sterilisation it is 7.3 ± 0.2. Sterilise in an autoclave using a validated cycle.

Growth promotion of casein soya bean digest agar

— Preparation of test strains. Use standardised stable suspensions of test strains or prepare them as stated in Table 2249.-1. Seed lot culture maintenance techniques (seed-lot systems) are used so that the viable micro-organisms used for inoculation are not more than 5 passages removed from the original master seed-lot. Grow each of the bacterial strains separately as described in Table 2249.-1. Use buffered sodium chloride-peptone solution pH 7.0 or phosphate buffer solution pH 7.2 to make test suspensions. Use the suspensions within 2 h, or within 24 h if stored at 2-8 °C. As an alternative to preparing and then diluting a fresh suspension of vegetative cells of Bacillus subtilis, a stable spore suspension is prepared and then an appropriate volume of the spore suspension is used for test inoculation. The stable spore suspension may be maintained at 2-8 °C for a validated period of time.

— Growth promotion. Test each batch of ready-prepared medium and each batch of medium, prepared either from dehydrated medium or from the ingredients described. Inoculate plates of casein soya bean digest agar separately with a small number (not more than 100 CFU) of the micro-organisms indicated in Table 2249.-1. Incubate under the conditions described in this table. Growth obtained must not differ by a factor greater than 2 from the calculated value for a standardised inoculum. For a freshly prepared inoculum, growth of the micro-organisms must be comparable to that obtained with a previously tested and approved batch of medium.

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