Pesticides in Water: Sampling, Sample Preparation, Preservation

Abstract

Listen

Translate article

AbstractContamination of water by pesticides is an important issue in many regions, posing problems in the environmental, water management and health sectors. To assess the extent of contamination of water, effective and properly designed analytical methods having sufficient sensitivity and accuracy are needed. However, no matter how excellent are the state‐of‐the‐art analytical instrumentation and techniques applied, the data on trace concentrations of pesticides provided by the analytical system will be useless unless sufficient attention is given to sampling and sample preparation.To collect a representative water sample for pesticide analysis, all sampling parameters must be selected properly. This refers predominantly to the selection of the appropriate sampling site, sampling technique and volume of the water sample. To prevent the sample matrix from any undesirable alterations during its transport from the sampling site to an analytical laboratory, physical (e.g. temperature, light intensity) and chemical/biochemical (e.g. pH, microbial growth) conditions must be under control, i.e. the sample must be preserved carefully. An efficient alternative to the transport of liquid water samples from the sampling point to the laboratory is on‐site sorption of analytes on a solid phase. This minimizes the weight of transported samples and increases the stability of analytes.The determination of trace concentrations of pesticides in water samples and the complexity of environmental matrices require the application of an efficient sample‐handling procedure prior to separation and detection of these analytes. At present, liquid–liquid extraction (LLE) and solid‐phase extraction (SPE) are the most frequently applied sample‐handling techniques in the determination of pesticides in water. LLE is a traditional method that is still widely used in standardized methods. The increasing popularity of SPE is a result of its versatility and effectiveness and SPE is also preferred owing to the lower health risks.The introduction of new sorbent materials, the development of automated sample‐handling systems allowing unattended operation and newly emerging sample‐handling techniques such as solid‐phase microextraction (SPME) and membrane separation methods guarantee that sample preparation in pesticide analysis will remain a fertile area of development in the future.