Determination of polycyclic aromatic hydrocarbons in surface water by column liquid chromatography with fluorescence detection, using on-line micelle-mediated sample preparation

Screening and analysis of polar pesticides in environmental monitoring programmes by coupled-column liquid chromatography and gas chromatography-mass spectrometry

Screening and analysis of polar pesticides based on coupled-column reversed-phase liquid chromatography (LC-LC) and GC- or LC-MS is a powerful tool in the execution of environmental monitoring programmes. This paper presents a unified approach utilising LC-LC screening followed by GC-MS confirmation. As polar pesticides are not generally amenable to GC a widely applicable derivation technique is used. The results demonstrate that the proposed LC and MS techniques are capable of analysing a wide range of polar pesticides down to levels of 0.1 microgram/l (EU limit for drinking water). LC switching techniques for group analysis or individual compounds rely on the reversed-phase retention and the UV detectability of the pesticides in combination with the choice of the LC columns. Fast miniaturised derivatization prior to GC-MS forms an integral part in the proposed strategy. In order to avoid extraction losses, derivation in the aqueous sample, preferably with electrophoric reagents with enhanced sensitivity in GC-NICI-MS are employed where possible. In this communication, method development and validation fitting in the strategy are evaluated and the results of the combined approach are discussed.

Determination of benzo[a]pyrene in lipid-soluble liquid smoke (LSLS) by HPLC-FL

We developed a method for the determination of low levels of the carcinogen benzo[a]pyrene (BaP) in lipid-soluble liquid smoke (LSLS). The method consists of partitioning the LSLS (2 g) between n-hexane and DMSO, purification of the DMSO extracts on Sep-Pak C18 Plus and then Silica Plus cartridges, and determination of the BaP in the isolated extract by HPLC with fluorescence detection. Detection and quantification limits were 0.049 microgram/l (0.024 microgram/kg of LSLS) and 0.089 microgram/l (0.045 mg/kg), respectively. Recovery (87%) and CV% (< or = 1.5) were satisfactory.

Preliminary experiments for the analysis of tetrahydrotetrols of benz[a]anthracene and benzo[a]pyrene derived from their hemoglobin adducts using a coupled-column high-performance liquid chromatographic system

Improved technologies for the detection of polycyclic aromatic hydrocarbon adducts are required for human biomonitoring. Therefore, a coupled-column high-performance liquid chromatographic method, with system-integrated sample processing, has been developed and its applicability for determination of tetrahydrotetrols of polycyclic aromatic hydrocarbons in acid hydrolysates of human hemoglobin has been investigated. A novel column-switching technique applying "thermotransfer' is used to separate tetrahydrotetrols of benzo[a]pyrene and benz[a]anthracene more efficiently. Derivatives of polycyclic aromatic hydrocarbons from blood hydrolysates are concentrated on a pre-column and then transferred to the analytical column by applying an electrical current to heat the solvent eluting the pre-column. This method allows for rapid and quantitative transfer of the analytes from the pre-column to the analytical column, after HPLC-integrated sample processing.

Automated solid-phase extraction coupled to gas chromatography with electron-capture detection: a combination of extraction and clean-up of pyrethroids in the analysis of surface water

The combination of automated solid-phase extraction (SPE) and large-volume introduction gas chromatography electron-capture detection (GC-ECD) is used for the determination of synthetic pyrethroids in surface and drinking water. The selectivity that is needed for the use of GC-ECD of environmental samples is achieved by addition of a polarity modifier to the sample. In this study, sufficient methanol was added to 19 ml of sample to obtain a level of 30% of modifier prior to SPE. The cartridge is washed with one additional ml of 30% methanol in water. After drying, the cartridge is eluted with toluene. GC-ECD analysis is performed by on-column introduction of 100 microliters of the toluene extract. The whole procedure was automated by using an automated solid-phase extraction apparatus. Limits of detection (LODs) for the pyrethroids in surface water are in the range of 1 to 8 ng/1 (signal-to-noise ratio = 3); even lower limits of detection are possible for drinking water.