Lipophilic group analysis of a Nekal-type anionic surfactant was investigated. Highly purified potassium 1, 4-diisopropyl-6-naphthalenesulfonate (KDNS) (purity : >99mol%), prepared as a sample, was desulfonated with concentrated phosphoric acid, or fused with solid alkali hydroxides, and their reaction products were undertaken to GLC analysis.
As a result, the desulfonation with concentrated phosphoric acid was recognized unsuitable for the lipophilic group analysis of such Nekal-type surfactants because of various side reaction products. On the contrary, the alkali fusion method with potassium hydroxide, carried out in a nickel crucible under nitrogen for 1h at 270280°C, produced only 1, 4-diisopropyl-6-naphthol from KDNS in good yield, as a reaction product, and moreover no side reaction products were found by GLC.
Consequently, it was appreciated that the present method connected with GLC was adoptable for the lipophilic group analysis of the Nekal-type surfactants.