Rapid sample handling in microcolumn-liquid chromatography using selectiveon-line immunoaffinity extraction

On-line coupling of solid-phase extraction (SPE) and microcolumn-liquid chr omatography (micro-LC) was developed requiring minimal sample preparation a nd providing maximal sensitivity. The selectivity was greatly enhanced by u sing a 10 x 1-mm precolumn packed with a silica-based immunoaffinity extrac tion sorbent obtained by bonding antichlortoluron antibodies. The cross-rea ctivity of the antibodies allows the extraction of a mixture of seven pheny lureas with recoveries above 75% for sample volume up to 10 mL. Calibration curves were linear in the range 0.03-0.7 mu g/L for each analyte in the mi xture with a 5-mL sample. The high selectivity provided by the immunoextrac tion was shown by comparing the analysis of the River Seine water using bot h C-18 and immunoaffinity SPE sorbents. Quantification limits were as low a s 10 ng/L in drinking water and in seawater from 5-mL samples. Since no int erfering peaks from the matrix of samples are showing up, the analysis can be very rapid. In addition, the use of 40-mu m silica particles for prepari ng the immunosorbent allows rapid sample percolation and high sample throug hput. Applications to real samples illustrate the main features of the on-l ine procedure, (C) 2000 John Wiley & Sons, Inc.