# Fertilisers (Sampling and Analysis) Regulations (Northern Ireland) 1996, Paragraph 5: PROCEDURE


Calibration of the pH meter
5.1 Calibrate the pH meter (4) at a temperature of 20 (± 1)°C, using the buffer solutions (3.1), (3.2) or (3.3). Pass a slow stream of nitrogen onto the surface of the solution and maintain this throughout the test.
Determination
5.2 Pour 100.0 ml of water onto 10 (± 0.01) grams of the sample in a 250 ml beaker. Remove the insolubles by filtering, decanting or centrifuging the liquid.
Measure the pH value of the clear solution at a temperature of 20 (± 1)°C, according to the same procedure as for the calibration of the meter.

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Source: https://www.legislation.gov.uk/nisr/1996/513/schedule/2/part/I/chapter/14d./paragraph/5 (the official version)
Page: https://openlegislation.uk/fertilisers-sampling-and-analysis-regulations-northern-ireland-1996/schedule-2/part-I/chapter-14d./paragraph-5
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.