Dear Sir. Concerning your issue about the measurement of Cetylpyridinium chloride (CPC) anionic surfactant concentration in water using HS-3300 series water analyzer . I think the following below links may help you in your analysis:

http://issstindian.org/pubpdf/voiume21/1/issst_journal_vol21_3_4_Art1.pdf

http://www.chalcogen.ro/115_KarikalanV.pdf

http://shodhganga.inflibnet.ac.in/bitstream/10603/4811/11/11_chapter%204.pdf

Thanks

Thank you sir for your valued response. That data is mainly about CMC measurement of CPC but actually I want to measure different unknown concentration in water sample. Can we measure CPC concentration using spectrophotmeter ???

Dear Muhammad,

As you may have seen I have worked on Dye-surfactant interactions and I think you could use the CPC-Methyl orange ion-complex as a means of determining CPC in aqueous solutions. The article below shows the ion-pair formation and its properties:Article Spectrophotometric and Conductometric Study of Methyl Orange...

Another article that also uses a stoichiometric complex with clear spectral changes is this one:

Article Spectrophotometric determination of cetylpyridinium chloride...

Personally I would use titration using SDS as a titrant, you could use turbidity, conductometry, ion-selective electrodes, or visual using a anionic dye as a detection method. I hope this helps.

Kind regards, Leo