IN-VIAL C-18 EMPORE DISK ELUTION COUPLED WITH INJECTION PORT DERIVATIZATION FOR THE QUANTITATIVE DETERMINATION OF LINEAR ALKYLBENZENESULFONATES BY GC-FID

摘要

An ''in-vial elution'' technique was developed to elute C-18 Empore solid-phase extraction disks by placing them directly into gas chromatograph autosampler vials, Small (13 mm) C-18 Empore disks were used to isolate linear alkylbenzenesulfonates (LAS) from samples of liquid detergent formulations and primary sewage effluent. Instead of eluting the disks in a conventional manner, the C-18 disks were removed from their supports and transferred directly to a 2 mL autosampler vial containing 0.005 M tetrabutylammonium hydrogen sulfate in chloroform. The vials are then placed in an autosampler tray for a 40 min minimum equilibration period in which LAS is eluted from the disk as its tetrabutylammonium ion pair. Upon injection, LAS is derivatized to its butyl esters. Quantitative recovery of IAS was obtained from samples of deionized water (99 +/- 2%) and primary sewage effluent (95 +/- 5%). The precision of the C-18 Empore disk extraction and in-vial elution method, indicated by the relative standard deviation, was +/-5% for liquid detergent products and primary sewage effluent. The in-vial elution method is rapid and semiautomated since the autosampler and GC instrumentation manage disk elution, sample injection, and LAS derivatization.