First interlaboratory exercise on non-steroidal anti-inflammatory drugs analysis in environmental samples.

Comparability of monitoring data are essential for any meaningful assessment and for the management of environmental risks of emerging pollutants. The reliability and comparability of data at European level is often limited, because analytical methods for emerging pollutants are often not fully validated, not harmonized or not suitable for all relevant matrices. This paper describes a collaborative interlaboratory exercise for the analysis of non-steroidal anti-inflammatory drugs (NSAIDs) residues in freshwater and wastewater, held in the framework of the EU project "Network of reference laboratories for monitoring of emerging environmental pollutants" (NORMAN). The NSAID compounds selected in this study were ketoprofen, naproxen, ibuprofen and diclofenac. Thirteen laboratories distributed along nine European Countries (Austria, France, Germany, Greece, Italy, Slovak Republic, Slovenia, Spain, and Switzerland) took part in this exercise, 126 samples were analyzed and a total number of 473 values in duplicate were collected. Samples selected in this study include environmental water (river water and waste water) and artificial water (fortified environmental and distilled water) with different ranges of complexity. Two analytical methods were proposed by the organiser; one is based on the use of solid phase extraction (SPE) followed by liquid chromatography-tandem mass spectrometry (LC-MS/MS) and the second one is based on SPE followed by gas-chromatography-mass spectrometry (GC-MS), however, in the first round some different approaches were also admitted. The main goals of this interlaboratory comparison were to evaluate the available analytical schemes for NSAID analysis in natural waters, to evaluate the repeatability (r) and reproducibility (R) between participating laboratories, and to evaluate the influence of the analytical method and sample matrices on the results.

Development and validation of a new analytical method for the determination of 1,4-dichlorobenzene in honey by gas chromatography-isotope dilution mass spectrometry after steam-distillation.

A simple, fast, sensitive and robust analytical method using gas chromatography (GC)-isotope dilution mass spectrometry (MS) was developed and validated for the identification and quantification of 1,4-dichlorobenzene (p-DCB) residues in honey samples. The proposed methodology is based on steam-distillation using a Clevenger-type apparatus followed by gas chromatography-mass spectrometry (GC-MS) in the selected ion monitoring (SIM) mode employing the isotopically labeled analogue d4-1,4-dichlorobenzene (d4-p-DCB) as internal standard (IS). Validation of the method was performed in two different GC-MS systems, using quadrupole MS (QMS) and ion-trap MS (ITMS) detectors, with no statistically significant differences between two. Recoveries were better than 91% with percent relative standard deviations lower than 12%. The instrumental limits of detection were 1 microg kg(-1) in the GC-ITMS system and 0.6 microg kg(-1) in the GC-QMS system. The expanded uncertainty was estimated as 17% at the currently accepted "action level" of 10 microg kg(-1). The method was applied to the analysis of 310 honey samples in an extensive national monitoring study. A quality control (QC) system applied during the assays has demonstrated a good performance and long-term stability over a period of more than 8 months of continuous operation.