The application of a manual operated solid-phase microextraction (SPME)-HPLC interface is discussed for the analysis of thermally labile analytes in aqueous matrices. The technique has been applied on-site at a flooded rice field to demonstrate its potential for real time extraction of the herbicide profoxydim. Thus, compounds which would otherwise easily degrade in the aqueous matrices within hours or days could be determined more accurately. The fibers were shipped back to the laboratory with express delivery where the target analyte was desorbed from the fiber and determined by HPLC-UV analysis. The SPME method was characterized by significant ruggedness where conventional techniques such as liquid-liquid extraction and solid-phase extraction require additional shipping and handling costs and time-consuming multiple sample preparation steps. In general, any delay in shipping the aqueous samples to the laboratory has the potential for sample degradation and a loss in accuracy when using non on-site extraction techniques. Fifty microm Carbowax-templated resin coatings were most suitable for coupling SPME to HPLC in order to achieve a high sensitivity for polar analytes. The SPME technique was characterized by a good sensitivity and a precision less than 10% RSD. The SPME-LC-UV method was linear over at least three orders of magnitude while achieving a limit of detection in the lower microg/l range. The on-site SPME method has shown significantly increased accuracy. Profoxydim was determined at concentrations of ca. 180 microg/l 3 h after an application on a flooded bare soil field.

In-tube solid-phase microextraction (SPME) is an automated version of SPME that can be easily coupled to a conventional HPLC autosampler for on-line sample preparation, separation and quantitation. It has been termed "in-tube" SPME because the extraction phase is coated inside a section of fused-silica tubing rather than coated on the surface of a fused-silica rod as in the conventional syringe-like SPME device. The new in-tube SPME technique has been demonstrated as a very efficient extraction method for the analysis of polar and thermally labile analytes. The in-tube SPME-HPLC method used with the FAMOS autosampler from LC Packings was developed for detecting polar carbamate pesticides in clean water samples. The main parameters relating to the extraction and desorption processes of in-tube SPME (selection of coatings, aspirate/dispense steps, selection of the desorption solvents, and the efficiency of desorption solvent, etc.) were investigated. The method was evaluated according to the reproducibility, linear range and limit of detection. This method is simple, effective, reproducible and sensitive. The relative standard deviation for all the carbamates investigated was between 1.7 and 5.3%. The method showed good linearity between 5 and 10000 microg/l with correlation coefficients between 0.9824 and 0.9995. For the carbamates studied, the limits of detection observed are lower than or similar to that of US Environmental Protection Agency or National Pesticide Survey methods. Detection of carbaryl present in clean water samples at 1 microg/l is possible.

The determination of carbamate and triazine pesticides from soil leachates and slurries was investigated using solid phase microextraction (SPME) coupled to high-performance liquid chromatography-electrospray/ mass spectrometry (HPLC-ESI/MS). SPME was carried out using fibres with a newly developed 50 μm Carbowax/ template coating which are suitable for relatively polar analytes. These fibers exhibit precisions better than 10% RSD, and are resistant against high contents of organic solvents during desorption. The technique shows a high sampling frequency resulting in an increasing sample throughput.

An automated solid-phase microextraction (SPME) unit coupled to gas chromatography was used to determine organic compounds in air. The target analyte was released from microcapsules into the air at ambient temperature. A fully automated system was designed to facilitate the monitoring of the organic analytes in the continuous air stream. A thin layer of the capsules was prepared by spraying an aqueous solution containing the microcapsules on one side of a glass slide. The slide was exposed to an air stream, which served as a carrier for the analyte vapors. The exposed air was passed through a flow-through cell that was mounted on the autosampler carousel, The SPME assembly, which was fitted with poly(dimethylsiloxane) fiber, was controlled by standard autosampler software. In the dynamic measurement mode, the fiber was inserted in the cell and the analytes partitoned onto the coating. The performance of the sampling device was characterized with respect to mass loading on the fiber, linearity, exposure time and precision. The primary objective of the study was to characterize the release of the pheromone Gossyplure [(Z)-7-(Z8)-11-hexadecadien-1-ol acetate] from microcapsules, The precision of the SPME method was, in general, less than 7% RSD using 18 repetitive extractions. The method was found to be linear over at least three orders of magnitude. The sampling interval was typically 30 min.

The evaluation of static absorption and three different agitation modes including magnetic stirring, fibre vibration method, and a self constructed flow-through extraction cell for solid-phase microextraction (SPME) of trace organics is presented in this study. A mixture of analytes which contained five pesticides: ametryn, parathion, prometryn, simetryn, and terbutryn was selected for direct absorption from aqueous samples using a 100 μm poly(dimethylsiloxane) fibre. The absorption–time profiles and precisions were studied under different conditions using spiked aqueous samples. A commercially available autosampler was investigated for static absorption and the fibre vibration method. The efficiency of the automated SPME analysis methods developed was compared to the classical extraction of magnetically stirred samples and on-line SPME using the recently developed flow-through cell concept. Besides the kinetic aspect of a fast absorption characterizing the efficiency of the absorption mode selected, the precision was studied for all systems investigated to estimate the analytical accuracy which could be achieved by using these absorption techniques. In general, all agitation modes showed a precision for most of the compounds below 5% R.S.D. The fibre vibration technique significantly increases the precision and sample output of the automated SPME–GC method for the analysis of semi-volatile compounds.

Recently, solid-phase microextraction (SPME) was successfully coupled to high-performance liquid chromatography, However, the efficiency of this analytical method, in terms of manpower, still suffers from its manual operation technique, Furthermore, the selectivity obtained for the analysis. of very polar compounds is still poor because of a limited selection of commercially available fiber coatings that can withstand the aggressive HPLC conditions (solvents). This paper describes the first approach to developing an automated SPME-HPLC system, A mixture of polar thermally labile analytes, phenylurea pesticides, was selected for microextraction directly from an aqueous sample, A piece of a ordinary capillary GC column with its coating (Omegawax 250) was used for the absorption of analytes from the aqueous sample (in-tube solid-phase microextraction), A needle hosts the capillary when it is pierced through the septum of the vial containing the spiked aqueous sample, The aqueous samples were stored in 2 mL, vials on the tray of a commercial autosampler, A sample of 25 mu L was aspirated and dispensed several times from the sample into the capillary using a syringe, After the extraction the absorbed analytes were released from the coating by aspiring methanol into the column and then dispensing the methanol into the HPLC injector loop, The absorption-time profiles, the amounts absorbed by different coatings, linearity, and precision were studied under different sampling conditions using spiked aqueous samples, SPME selectivity for polar compounds, which represent an important compound class for water analysis, can be improved by using more polar column coatings such as Carbowax instead of poly(dimethylsiloxane)coated columns, Compared to the manual version this automated SPME-HPLC system could increase productivity and reproducibility, Furthermore, the desorption step is quantitative; i.e., no carryover could be detected, This entire method for automated SPME sample preparation is simple and controlled by a commercial autosampler from LC Packings which was modified to operate in-tube SPME, The automated SPME-HPLC device obtains RSD for all investigated compounds below 6%, A simple mathematical model was used to calculate the concentrations vs length pro files in the column for any time, The model was in good agreement with experimental data which was obtained for benzene as a model compound, Thus, the main parameters affecting the partitioning process were determined and the amount absorbed by the coating could be predicted.

A multi-residue method was developed for the determination of nitrogen- and phosphoruscontaining compounds, mostly pesticides, by solid-phase microextraction (SPME). The limit of detection depends on the compound and is normally < 100 ng/l using a nitrogen-phosphorus detector (NPD). The method is linear over at least three orders of magnitude with correlation coefficients of correlation usually ≥ 0.996. In general, the coefficient of variation (precision) is < 10 %. The partitioning of the analyte between the aqueous phase and the polymeric phase depends on the hydrophobicity of the compound as expressed by the octanol/water partitioning coefficient K ow . The addition of sodium chloride has a strong effect on the extraction efficiency. This effect increases with decreasing hydrophobicity (increasing polarity) of the compound. The triazines atrazine, simazine and terbuthylazine were identified and quantified in water samples from the effluent of sewage plants by SPME-GC/NPD. For such a complex matrix GC/NPD is not sufficiently selective for an unambiguous identification at low levels (< 1 μg/l). Selectivity may be enhanced by using SMPE-GC/MS in the selective ion monitoring (SIM) mode with three characteristic ions for each pesticide. At a target limit of detection below 100 ng/l, SPME-GC/MS represents a very simple, fast, selective and solvent-free multi-method for the extraction and determination of these compounds in aqueous environmental samples.

Methods developed for the analysis of organic compounds from aqueous samples by solid-phase microextraction (SPME) coupled to gas chromatography (GC) are reviewed with special emphasis on the determination and monitoring in environmental samples contaminated by organic micropollutants, i.e., benzene, toluene, ethylbenzene and xylene isomers (BTEX), pesticides, phenols and polycyclic aromatic hydrocarbons (PAH).

In the present study, an efficient method for extraction, separation and determination of a limited number (30) of polar pesticides in aqueous matrices has been developed. Pesticides were extracted with high recoveries (usually >85%) from 1 L water samples, using the solid-phase extraction (SPE) technique. Affinities to different SPE materials (C-18 and XAD resins) have been studied for all pesticides. Special attention has been paid to the following 5 pesticides (which have classified by the EC as compounds which are particularly difficult to analyse): benazolin, bromofenoxim, ethofumesate, fenamiphos and phenmedipham. Thermally labile compounds have been determined with high pressure liquid chromatography (HPLC) and UV detection in comparison to TSP-LC-MS. Absolute limits of detection (LODs) for the HPLC technique are usually below 1 ng at 220 nm. Thermospray LC-MS determination shows usually limits of detection of 1-10 ng (SCAN) and 60-800 pg (SIM). All pesticides, which are amenable to GC have been detected in a comparative study with the following detectors: flame ionization detector (FID), nitrogen-phosphorus detector (NPD), electron capture detector (ECD) and atomic emission detector (AED). Element-specific detection of various functional groups of these pesticides has been achieved using GC-AED. Thus, while the FID has the lowest specificity, the AED is the most specific detector. LODs are usually <300 pg (FID < 20 pg, NPD < 1 pg, ECD < 1 pg, AED < 300 pg). Spiked river water samples (from the River Leine and River Weser in Lower Saxony, Germany) have been used to test the employed method. With the spiked surface water samples recoveries were usually >80%.

Methods for the determination of three compound classes, i.e. diaminotoluenes, nitrophenols, and chloroaromatics in groundwater of a former ammunition plant are reported. Diaminotoluenes were extracted by discontinuous liquid/liquid-, nitrophenols by continuous liquid/liquid-extraction using dichloromethane, and chloroaromatics by solid-phase extraction. These compound classes may be analyzed by gas chromatography (GC) or gas chromatography coupled to mass spectrometry (GC/MS) without derivatization or after derivatization with N-methyl-bis(trifluoroacetamide) (MBTFA) or heptafluorobutyric anhydride (HFBA) in the case of diaminotoluenes and HFBA or acetic anhydride in the case of nitrophenols. An atomic emission detector (AED) coupled to a gas chromatograph may be employed for the analysis of chloroaromatics. High selectivity can be achieved using the characteristic wavelengths of chlorine. A variety of these compounds were identified and quantified in a groundwater sample from the former ammunition plant Elsnig (Saxony, Germany). Concentrations were in the lower ppb range. Thus, dichlorobenzenes which may have been used as substituents at the end of World War II could be identified in groundwater samples at this site.

The paper describes three new approaches to the analysis of pesticides in aqueous samples: (1) coupling of high performance liquid chromatography (HPLC) to mass spectrometry (MS) using thermospray ionization (TSP); (2) on-line-solid phase extraction (SPE) coupled to HPLC/MS; and (3) in-line coupling of solid phase microextraction (SPME) to gas chromatography (GC) and GC/MS. These methods can be readily automated and allow a rapid analysis of pesticides in aqueous samples at the low ppt-level.

The analysis of samples contaminated by organic compounds, especially pesticides, is an important tool of environmental monitoring. A new isolation method has been developed for the determination of pesticides in environmental water samples using solid-phase microextraction (SPME). Thus, the extraction and preconcentration steps of sample preparation are focused in a single process step. For the determination of organophosphorus pesticides using SPME extraction and preconcentration steps a GC—atomic emission detection coupling system was used. This coupling technique is a very selective analytical tool. Element-characteristics chromatograms acquired by using different element emission lines can be obtained, enhancing the selectivity of the method in environmental monitoring, and they can be used to identify even unknown compounds in environmental samples. A fused-silica fiber coated with a polymer (polydimethylsiloxane) phase is used to extract organic compounds and transfer them into a GC injector for thermal desorption and analysis. Volatile pesticides can be efficiently isolated from aqueous environmental samples, as demonstrated for organophosphorus pesticides. This method shows a precision of 8–12% (R.S.D.), depending on the compound. Furthermore, it is capable of limits of detection in the ppb and sub-ppb range. The adsorption and desorption times to carry out the optimum equilibrium and thermodesorption conditions, have been optimized. Determination of pesticides in spiked river water samples with this technique is reported and a comparison of SPME to established extraction techniques, i.e. solid-phase extraction is also carried out. The results demonstrate the suitability of the SPME approach for analysis of these polar compounds.