In recent years, ground water contamination as well as surface water contamination by pesticides has become a matter of public concern. Identification and quantification of pesticides at trace level concentrations often require both high sensitive chromatographic equipment and effective enrichment steps. In the analysis of aqueous samples, sample preparation techniques including solid-phase extraction (SPE) are frequently the most time-consuming steps and in many cases can be effectively replaced by solid-phase microextraction (SPME). This International Standard specifies a method of chemical analysis for the determination of selected plant treatment agents, biocides and biocide products in drinking water, ground water and surface water by solid-phase microextraction (SPME) followed by gas chromatography-mass spectrometry (GC-MS). The scope of this standard follows the legal requirements of Council Directive 98/83/EC of 3 November 1998 on the quality of water intended for human consumption and the Decree for the Amendment to the Drinking Water Ordinance. The enrichment technique can be easily and quickly performed and is suitable for the analysis of a variety of volatile, semi-volatile or low volatile components without organic solvents being necessary. The underlying International Standard has been prepared by Technical Committee ISO/TC 147/SC 2/WG 57 "SPME" and taken over by Technical Committee CEN/TC 230 "Water analysis", the secretariat of which is held by DIN. The responsible German committee is NA 119-01-03-02-05 AK "Pflanzenbehandlungsmittel und leichtflüchtige Verbindungen, SPME-GC-Verfahren" ("Plant protection substances and easily volatile compounds, SPME-GC methods") at the NA 119-01-03 AA "Wasseruntersuchung" ("Water examination") at the NAW at DIN. On the national level, the revision of the project was funded by the Länderfinanzierungsprogramm "Wasser, Boden und Abfall" (federal funding programme "Water, soil and waste"). This standard differs from DIN 38407-34:2006-05 as follows: a) the title has been changed; b) "Interferences" has been rendered more precise to avoid any interference during the procedure: - reference to International Standards on sampling has been included; - the extraction times are to be held constant within a sample sequence for all samples; c) in "Sampling and sample pretreatment", new storage conditions have been specified with regard to sample temperatures and stability; d) in the clause concerning "Procedure", it is emphasized that the correct level of the liquid is particularly important in automatic systems; e) in the clause concerning "Calibration", only the calibration with an internal standard covering the total procedure is described; f) the standard has been editorially revised.