# Commission Regulation (EEC) No 1764/86 of 27 May 1986 laying down minimum quality requirements for products processed from tomatoes under the production aid scheme, Division 4.1: Introductory remarks

Extent: E+W+S+N.I.

Special care must be taken to ensure cleanliness of the vessels used. Glassware must be rinsed beforehand with double-distilled water.
All solutions and all dilutions must be prepared with double-distilled water.
For dilution, samples must be at least 1 ml.
In each series of measurements, establish the calibration values with appropriate solutions.
For quantity determination by absorption spectrometry, carefully adjust the apparatus to the optimum wavelength.
If the various stages of the procedure to be followed are carried out in different laboratories (e.g. preparation laboratory and measurement laboratory), it is vital that the same batch of double-distilled water is used to dilute the solutions for analysis and standard solutions.

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Source: https://www.legislation.gov.uk/eur/1986/1764/annex/division/9/division/4/division/4.1 (the official version)
Page: https://openlegislation.uk/eu-regulation-1986-1764/annex/division-9/division-4/division-4.1
Contains public sector information licensed under the Open Government Licence v3.0. Source: legislation.gov.uk, The National Archives.