Fully automated water analyzer based on on‐line solid phase extraction‐gas chromatography

Abstract

Abstract. An automated procedure for the analysis of aqueous samples by membrane disk extraction coupled on-line to capillary gas chromatography (GC) is presented. Organophosphorus pesticides are preconcentrated from aqueous samples on three 0.5 mm thick, 4.0 mm diameter XAD-2 membrane extraction disks which are mounted in a polymer holder for use in a PROSPEKT sample processor. The layers are dried by a stream of nitrogen (30 min at ambient temperature). Desorption of the analytes is carried out with ethyl acetate which is directly introduced into a retention gap under partially concurrent solvent evaporation conditions, using an early solvent vapor exit. The method is a fully software-controlled automated system, and includes sample preparation, sample transfer and GC analysis. The final analysis is carried out by GC with nitrogen-phosphorus (NPD) or mass-selective detection. The technique is applied to the determination of a series of organophosphorus pesticides in tap water and water from European rivers. With a sample volume of only 2.5 mL, the detection limits achieved with the NPD were 20-50 ng L-' in tap water and 20-100 ng L-' in river water.

On-Line Solid Phase Extraction-Gas Chromatography-Cryotrapping-Infrared Spectrometry for the Trace-Level Determination of Microcontaminants in Aqueous Samples

“…cartridges packed with 20 lm, 100 Å PLRP-S styrene -divinylbenzene copolymer (Spark Holland, Emmen, The Netherlands). The SPE preconcentration of the aqueous samples was automated by using a Prospekt sample preparation system (Spark Holland) as described earlier [8]. After conditioning the SPE cartridge with 2 ml of methanol and 2.5 ml of HPLC-grade water, 20 ml of sample were loaded at 2.5 ml/min.…”

“…In the most efficient set-up, the total extract is transferred to the GC system. To quote an example, in on-line SPE -GC (SPE, solidphase extraction) the complete SPE desorption solvent volume of about 100 ll is transferred to the GC system [8,9].…”

Trace level analysis of micropollutants in aqueous samples using gas chromatography with on-line sample enrichment and large volume injection

“…The benchtop instrument used a PRogrammable On-line Solid-Phase E(K)straction Technique (PROSPEKT) for trace enrichment, and a GC-MS system for separation and detection/identification [82]. Analysis of 10 ml of river Rhine water under Fig.…”

Data correlation in on-line solid-phase extraction-gas chromatography-atomic emission/mass spectrometric detection of unknown microcontaminants

“…In this context, it will of course be highly desirable to focus attention on peaks representing compounds present in the samples at or above a predetermined threshold level of, typically, 0.1 or 1 pg L -1. This will require the application of SPE-GC procedures [15,16] to achieve analyte trace enrichment and, on a quite different level, experimental verification of the validity of the universal calibration concept. Our aim was to develop and apply a concept for the screening for relevant compounds by systematic and unambiguous AED-to-MS correlation of relevant peaks in aqueous samples like tap, surface and waste water and subsequent (approximate) quantification.…”