A Liquid Membrane Enrichment Technique for Integrating Field Sampling in Water Applied to MCPA

Abstract

An integrating field sampling method for MCPA has been developed. Continuous sampling from a water stream for a desired period of time is achieved using a peristaltic pump and a liquid membrane device. The substance of interest is transferred as an uncharged species from a donor phase to a stagnant acceptor phase, where it is trapped in a buffer, permitting a high degree of enrichment. The final determination is made by reversed-phase liquid chromatography utilizing a pre-column instead of a sample loop in the injector. The method has been found to give values in good agreement with a technique based on batch extraction and gas chromatography. The precision at a recipient concentration of 1 ppb of MCPA is ca. 9% and the detection limit using a 24 h sampling period ca. 0.03 ppb.

Key Words:

• 2-methyl-4-chlorophenoxyacetic acid (MCPA)
• integrating field sampling
• recipient water
• liquid membrane technique