Analytical Method: Surfactants (nonionic) in Extran®; rinse solutions

Instruments and Reagents:

Cat.No. 173016  Spectroquant® VIS Spectrophotometer Prove 100 or

Cat.No. 173017  Spectroquant® UV/VIS Spectrophotometer Prove 300 or

Cat.No. 173018  Spectroquant® UV/VIS Spectrophotometer Prove 600 or

Cat.No. 109748  Spectroquant® Photometer NOVA 30 or

Cat.No. 109751  Spectroquant® Photometer NOVA 60 or
Cat.No. 173632  Spectroquant® Colorimeter Move 100
Cat.No. 101787  Spectroquant® Surfactants (nonionic) Cell Test
Cat.No. 116754  Water for analysis
Swabs for taking samples from planar surfaces (like e.g. large Alpha® Swab TX 417 A from ITW Texwipe®)



This application gives an example of a possible procedure for cleaning validation. Nonionic surfactants adhere at the most surfaces relatively good. This is the reason that it is essential to assure the absence of those substances. Ionic surfactants and also phosphates are much easier to remove from the cleaning system by rinsing with water for analysis. Therefore the absence of those substances doesn’t indicate the conclusion that the nonionic surfactants are not present. Therefore it is essential to implement the sample preparation step before analysis. For the analysis system used, the method must be validated against a reference system in accordance with the current regulatory requirements (e.g. GMP, cGMP).
Sample Preparation:
The sample procedure depends on the material of the surface that is to be analyzed for residues:
) Non-planar surfaces (e.g. sieves or process seals) are rinsed with water for analysis and the rinse solution is collected. This solution can be analyzed directly.
(b) Swabs are used for taking samples from planar surfaces. Both adsorptive sides of the swab are soaked with 0.25 ml of water for analysis and the surface that is to be analyzed is wiped using both sides of the swab. The direction of wiping is changed at least once by wiping perpendicular to the previous direction. The swabs are then extracted with water for analysis. The surface area analysed and the volume of water used for swab extraction are defined by the desired limit of detection (large surface area + small volume of water = high detectability). Typical is a surface area of 400 cm2 and swab extraction with 10 ml of water for analysis. The thus received solution (sample) can be analysed with the above Spectroquant® Cell Test.
The obtained sample must be free of organic solvents (e.g. ethanol) as these may interfere with the Spectroquant® Cell Test. The sample must be clear. If necessary, filter through a paper or a membrane filter. Dilute the sample, if needed into the measuring range (0.10 - 7.50 mg/l) of the Spectroquant® Cell Test with water for analysis. If needed, adjust pH into the range 3 – 9.

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The method for analysing surfactants (nonionic) is precalibrated in the Merck photometers NOVA 30, NOVA 60, NOVA 400, Pharo 100, Pharo 300, Prove 100, Prove 100, Prove 300, Prove 600, Move 100 and in the Multy colorimeter. For the analysis of nonionic surfactants a 16-mm round cells must be useable.
For the verification of the handling the use of a Triton® X-100 Standard (reference substance for nonionic surfactants) is recommended. The details information how to prepare the standard solution can be found in the application "AQA Standard nonionic surfactants". Alternatively this information can be found also in the manual of the above photometers.
Measuring range:
0.10 – 7.50 mg/l as Triton® X-100
Follow the instructions sheet of the cell test. A clear phase separation must occur within the reaction time; an emulsion indicates too high Extran® concentrations in the tested sample.

Nonionic surfactants [mg/cm2] = (value measured [mg/l] x volume of water used [l]) / surface area analyzed [cm2]



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