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

Benzalkonium chloride (BAK) can be readily concentrated prior to chromatographic analysis by the addition of appropriate amounts of sodium chloride and acetonitrile to the sample. This affords a two-phase system the upper of which contains the BAK and which can be directly injected onto the chromatographic column. Using this approach analytical methods with and without an internal standard, have been developed and validated that reproducibly afford an approximately ten-fold pre-concentration of the sample to be analysed thereby improving analytical sensitivity.