SALTING-OUT SOLVENT-EXTRACTION FOR PRECONCENTRATION OF BENZALKONIUM CHLORIDE PRIOR TO HIGH-PERFORMANCE LIQUID-CHROMATOGRAPHY

Benzalkonium chloride (BAK) can be readily concentrated prior to chrom atographic analysis by the addition of appropriate amounts of sodium c hloride and acetonitrile to the sample. This affords a two-phase syste m the upper of which contains the BAK and which can be directly inject ed onto the chromatographic column. Using this approach analytical met hods with and without an internal standard, have been developed and va lidated that reproducibly afford an approximately ten-fold pre-concent ration of the sample to be analysed thereby improving analytical sensi tivity.