Handbook Of Solid Phase Microextraction Pdf File

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Look up additional information online by highlighting a word or phrase. The relatively new technique of solid phase microextraction (SPME) is an important tool to prepare samples both in the lab and on-site. SPME is a 'green' technology because it eliminates organic solvents from analytical laboratory and can be used in environmental, food and fragrance, and forensic and drug analysis. This handbook offers a thorough background of the theory and practical implementation of SPME.

SPME protocols are presented outlining each stage of the method and providing useful tips and potential pitfalls. In addition, devices and fiber coatings, automated SPME systems, SPME method development, and In Vivo applications are discussed.This handbook is essential for its discussion of the latest SPME developments as well as its in depth information on the history, theory, and practical application of the method.

Key Features. DedicationPrefaceList of Contributors1.

Solid-Phase Microextraction in Perspective1.1. Sample Preparation as Part of the Analytical Process1.2.

Classification of Extraction Techniques1.3. Perspective on Microextraction Techniques1.4.

Implementations of SPME1.5. Miniaturisation and Integration1.6. In Vivo Analysis1.7.

SPME Versus SPE2. Theory of Solid-Phase Microextraction2.1.

SPME Principle2.3. Extraction with Derivatisation2.6. Extraction of Sample Matrices Containing Solids2.7.

Solid Versus Liquid Sorbents2.8. Passive TWA Sampling2.9.

In-Tube SPME2.10. Experimental Verification3. Development of SPME Devices and Coatings3.1. Historical Perspective3.2.

Rational Design of SPME Devices3.3. On-Site Samplers3.4. Development of New SPME Coatings3.5.

Interfaces to Analytical Instrumentation4. SPME Commercial Devices and Fibre Coatings4.1. Description of SPME Fibre Assemblies and Holders4.3. Description of Fibre Cores, Coatings and the Coating Process4.4. A Guide for the Selection of the Appropriate SPME Fibre5.

Automated SPME Systems5.1. Automated Solid-Phase Microextraction–Gas Chromatography5.2.

Automated SPME–LC5.3. Other Automated Configurations Involving SPME6.

Traditional Calibration Methods for the Quantification of SPME6.3. Equilibrium Extraction6.4. Exhaustive Extraction6.5. Diffusion-Based Calibration6.6. Calibration of SPME by Liquid Injection6.7.

Solid-Phase Microextraction Method Development7.1. SPME Method Development – General7.3. SPME Method Development for GC Applications7.4. SPME Method Development for HPLC Applications7.5. Method Validation7.6.

Concluding Remarks8. SPME and Environmental Analysis8.1. Fibre SPME8.3. In-Tube SPME8.4. Applications of SPME in Various Environmental Sample Matrices8.6. Applications of SPME for Various Analytes in Environmental Samples8.7.

Concluding Remarks9. Application of Solid-Phase Microextraction in Food and Fragrance Analysis9.1. Introduction and Method Development Considerations9.2. Reviews and Case Studies Involving SPME as an Extraction Procedure9.3. Concluding Remarks10. Drug Analysis by SPME10.1. Fundamentals of Extraction10.3.

Fibre Selection: Adsorption Versus Absorption10.4. Considerations of Drug Properties10.5. Novel SPME Coatings for LC10.7.

Instrumental Configurations10.9. Ligand—Receptor Binding and Determination of Free Concentrations11.1. Analysis of Biological Samples11.3.

Determination of Free Concentrations and Binding Constants11.4. Calibration of SPME for Bioanalytical Applications11.5. In Vivo Sampling with Solid-Phase Microextraction12.1. In Vivo Method Development12.3. In Vivo Applications12.4. Solid-Phase Microextraction Protocols13.1. Protocol for Automated High-Throughput SPME-LC using the Concept 96 Robotic Sample Preparation Station13.2.

Protocol for Automation of Ligand-Receptor Binding Studies Using Concept 9613.3. In Vivo SPME Protocol for Direct Monitoring of Circulating Intravenous Blood Concentrations13.4. Protocol for Setting up Automated SPME-GC Methods. The primary focus of Professor Pawliszyn's research program is the design of highly automated and integrated instrumentation for the isolation of analytes from complex matrices and the subsequent separation, identification and determination of these species. The primary separation tools used by his group are Gas Chromatography, Liquid Chromatography and Capillary Electrophoresis coupled to variety of detections systems, including range of mass spectrometry techniques.

Currently his research is focusing on elimination of organic solvents from the sample preparation step to facilitate on-site monitoring and in-vivo analysis. Several alternative techniques to solvent extraction are investigated including use of coated fibers, packed needles, membranes and supercritical fluids. Pawliszyn is exploring application of the computational and modeling techniques to enhance performance of sample preparation, chromatographic separations and detection. The major area of his interest involves the development and application of imaging detection techniques for microcolumn chromatography, capillary electrophoresis and micro chip separation devices.He is an author of over 400 scientific publications and a book on Solid Phase Microextraction.

His Hirsch Index (H-index) is 69. He is a Fellow of Royal Society of Canada and Chemical Institute of Canada, editor of Analytica Chimica Acta, Trends in Analytical Chemistry and a member of the Editorial Board of Journal of Separation Science. He initiated a conference, 'ExTech', focusing on new advances in sample preparation and disseminates new scientific developments in the area, which meets every year in different part of the world. He received the 1995 McBryde Medal, the 1996 Tswett Medal, the 1996 Hyphenated Techniques in Chromatography Award, the 1996 Caledon Award, the Jubilee Medal 1998 from the Chromatographic Society, U.K., the 2000 Maxxam Award from Canadian Society for Chemistry, the 2000 Varian Lecture Award from Carleton University, the Alumni Achievement Award for 2000 from Southern Illinois University, the Humboldt Research Award for 2001, 2002 COLACRO Medal, 2003 Canada Research Chair, in 2006 he has been elected to the most cited chemists by ISI, in 2008 he received A.A. Benedetti-Pichler Award from Eastern Analytical Symposium, 2008 Andrzej Waksmundzki Medal from Polish Academy of Sciences, 2008 Manning Principal Award, 2010 Torbern Bergman Medal from the Swedish Chemical Society, 2010 Ontario Premier's Innovation Award, 2010 Marcel Golay Award, 2010 ACS Award in Separation Science and Technology and 2011 PittCon Dal Nogare Award.

He presently holds the Canada Research Chair and Natural Sciences and Engineering Research Council of Canada Industrial Research Chair in New Analytical Methods and Technologies. He presently holds the University Professor title, the Canada Research Chair and NSERC Industrial Research Chair in New Analytical Methods and Technologies.

His Hirsh Index ('H' Index) is 70.

Determination of time-weighted average (TWA) concentrations of volatile organic compounds (VOCs) in air using solid-phase microextraction (SPME) is advantageous over other sampling techniques, but is often characterized by insufficient accuracies, particularly at longer sampling times. Experimental investigation of this issue and disclosing the origin of the problem is problematic and often not practically feasible due to high uncertainties. This research is aimed at developing the model of the TWA extraction process and optimization of TWA air sampling by SPME using finite element analysis software (COMSOL Multiphysics, Burlington, MA, USA).

It was established that sampling by porous SPME coatings with high affinity to analytes is affected by slow diffusion of analytes inside the coating, an increase of their concentrations in the air near the fiber tip due to equilibration, and eventual lower sampling rate. The increase of a fiber retraction depth ( Z) resulted in better recoveries. Sampling of studied VOCs using 23 ga Carboxen/polydimethylsiloxane (Car/PDMS) assembly at maximum possible Z (40 mm) was proven to provide more accurate results. Alternative sampling configuration based on 78.5 × 0.75 mm internal diameter SPME liner was proven to provide similar accuracy at improved detection limits. Its modification with the decreased internal diameter from the sampling side should provide even better recoveries.

The results obtained can be used to develop a more accurate analytical method for determination of TWA concentrations of VOCs in air using SPME. The developed model can be used to simulate sampling of other environments (process gases, water) by retracted SPME fibers. IntroductionAnalysis of time-weighted average (TWA) concentrations of volatile organic compounds (VOCs) in outdoor and indoor (occupational) air is an important part of environmental monitoring programs aiming at chronic exposure or background concentrations. Such analysis is commonly conducted using gas chromatography (GC) in combination with various sampling and sample preparation approaches.

Handbook Of Solid Phase Microextraction Pdf File Online

Passive sampling is a common approach for determination of TWA concentrations because of its simplicity and low cost. However, most techniques require additional sample preparation and thermal desorption in a separate unit connected to a GC.Solid-phase microextraction (SPME) is the only TWA sampling technique, that does not require additional stages and/or equipment. It is based on sampling via the passive VOCs extraction by a fiber coating retracted inside a protecting needle followed by thermal desorption inside a GC injection port ,. Desorption of VOCs from the SPME coating is fast and does not require cryogenic or another type of focusing as is the case with whole air- or sorbent tube-based samples. In the TWA mode, the SPME device with retracted fiber is deployed into a sampling location for the desired period (e.g., 24 h for daily average sampling), then isolated from possible interferences during storage and transport to a laboratory and analyzed. The method can be considered “green” because it fulfills all the requirements of green analytical chemistry ,.

Time-Weighted Average (TWA) Sampling Profiles of Benzene from Air Using Different CoatingsA sampling of VOCs from the air via retracted SPME has been described using a simplified form of the Fick’s first law of diffusion (Equation (1)). However, this equation works only when a SPME fiber acts as a “zero sink” sorbent. Modeling using COMSOL Multiphysics software (methodology is provided in the Materials and Methods section) allowed obtaining sampling profiles for benzene. Closer inspection of illustrates that none of the studied coatings behave as “zero sink” sorbent adhering to Equation (1), an effect amplified by extended sampling time. After 100,000 s of sampling, Carboxen/polydimethylsiloxane (Car/PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB), and polydimethylsiloxane (PDMS) extracted 77, 38 and 2.7%, respectively, of the theoretically required for a passive sampling technique.

Even if sampling time is decreased to 10,000 s, recoveries for these three SPME fiber coatings were 91, 69 and 12.6%, respectively. At sampling time 1000 s, recoveries were 97, 88 and 32% for Car/PDMS, PDMS/DVB and PDMS, respectively.

Benzene sampling profiles from ambient air ( T = 298 K, Z = 10 mm, 24 ga needle, p = 1 atm, C benzene = 0.641 μmolm −3) obtained using different fiber coatings. The ideal case pertains to Equation (1).One possible explanation for the departure from Equation (1) is that it can be caused by the increase of the analyte concentration in the air near the fiber tip (a), which is directly proportional to the analyte concentration in the fiber tip continuously increasing during the sampling. The increase of analyte concentration in the air near the fiber tip results in the decrease of the analyte flux (i.e., the number of moles of analyte entering protecting needle per cross-sectional area and time) from the sampled air with time. This affects the sampling rate (i.e., number of moles of an analyte extracted by a coating per unit of time), which was previously assumed to be constant ,. Concentrations of benzene in diffusion path air ( a) and coating ( b) of the retracted solid-phase microextraction (SPME) device after 100,000 s of time-weighted average (TWA) air sampling at Z = 10 mm.SPME fiber coating can affect the apparent rate of sampling.

This was previously assumed to be negligible. According to, Car/PDMS is the most efficient coating for TWA sampling of benzene because it provides the highest benzene extraction effectiveness indicated by the highest distribution constant. However, sampling by this coating is limited by the slow diffusion of an analyte via pores of the adsorbent (b). At sampling time 100,000 s, the closest 1 mm of the Car/PDMS coating to the needle opening contains 41% of the total extracted analyte.

Benzene concentration in the fiber tip is about 500 times higher than in its other end (furthest from the needle opening). For PDMS/DVB coating, the concentration in the tip is only about 24% higher. Slower diffusion of benzene via pores of Car/PDMS fiber is caused by the higher affinity of benzene to the surface of the solid phase (higher distribution constant), and lower porosity. Such non-uniform distribution of analytes in the Car/PDMS may be the reason of their slow desorption after TWA sampling and highly tailing peaks, particularly for most volatile analytes, which cannot be cold-trapped and refocused in a column front without cryogens. This problem also decreases the accuracy of the method.The accuracy of the model was validated by increasing the pore diffusion coefficient of benzene inside Car/PDMS coating by three orders of magnitude.

In this case, the benzene sampling profile was the same as predicted by Equation (1). This also confirms that an analyte diffusion coefficient inside a coating affects sampling profile and the accuracy of its quantification using TWA SPME.

The model has also been validated in the 3D mode of COMSOL software, which is much slower compared to 2D. The difference between the results of 2D and 3D modeling were below 2%, which confirms the accuracy of the 2D model. Effect of the Diffusion Coefficient and Distribution Constant on Sampling of Analytes by 85-µm Carboxen/Polidimethylsiloxane CoatingThe Car/PDMS coating was used for simulating extraction of other common VOCs associated with a wide range of diffusion coefficients and distribution constants. During 100,000 s, 3.3, 3.9, 3.5 and 3.3 pmol of dichloromethane, acetone, toluene, and benzene, respectively, were extracted, which corresponds to 68, 65, 82 and 77% of the theoretical values predicted by Equation (1). The lowest value was observed for acetone having a distribution constant close to dichloromethane, and the highest diffusion coefficient among studied compounds. Highest recovery was observed for toluene having the lowest diffusion coefficient and the highest distribution constant.

Thus, both diffusion coefficient and distribution constant affect the recovery of sampled analytes. Highest recovery can be achieved at the lowest diffusion coefficient and highest distribution constant. At sampling times 1000 and 10,000 s, recoveries are greater (95–98 and 85–93%, respectively) and less affected by the analyte’s properties. Effect of a Protecting Needle Gauge SizeCommercial SPME fiber assemblies are available with two different sizes of a protecting needle 24 ga and 23 ga having an internal diameter (I.D.) 310 and 340 μm, respectively. A cross-section area of the 23 ga needle is 20.3% greater than that of 24 ga needle, which (according to Equation (1)) should result in the proportionally greater amount of an analyte extracted by a 23 ga SPME assembly. However, as shown above, faster extraction rates result in a faster saturation of the coating and lower recovery at longer sampling times. According to the results of COMSOL simulations, despite 19% greater amounts of extracted analytes compared to a 24 ga assembly, sampling with a 23 ga assembly provided similar recoveries of analytes.

Such results can be explained by considering the effect of a greater space between the coating and the internal wall of the protecting needle allowing faster diffusion of analytes to the side and rear sides of the coating. This is consistent with recent experimental observations where straight glass GC liners were used (actual measured I.D. Is 0.84 mm compared with the nominal 0.75 mm I.D.) instead of SPME needle for sampling with retracted fiber. Thus, TWA sampling using 23 ga SPME assembly is recommended over 24 ga for achieving lower detection limits without negative impact on the accuracy. All further modeling was conducted using a 23 ga SPME device.

Effect of Diffusion Path (Z) at Constant Analyte Concentration in Sampled AirDiffusion path length is one of the two parameters that can easily be adjusted by users for achieving the optimal sampling conditions (the other one being sampling time). The increase of Z decreases the rate of sampling. It slows down the saturation of the fiber tip and increases the recoveries of analytes at longer sampling times. For all studied analytes, at t = 100,000 s and Z = 40 mm, recovery was 86–93% compared to 66–82% at Z = 10 mm. The only major drawback of the increase of Z is the decrease of an analyte amount extracted by a coating and a lower analytical signal, which result in the increased detection limits.

At Z = 40 mm, C = 50 µgm −3 (0.641 μmolm −3) and t = 100,000 s, 23 ga Car/PDMS assembly extracts 100 pg of benzene. For GC-mass spectrometry (MS), the detection limit of benzene is less than 2 pg meaning that the detection limit will be 1 µgm −3, which is five times lower than the maximum permissible annual average concentration of benzene in ambient air in the European Union (5 µgm −3).

In other countries, permissible concentrations are even higher. Effect of Diffusion Path (Z) at Variable Analyte Concentration in Sampled Air (Worst-Case Scenario)Time-weighted average sampling is conducted during long time periods (e.g., 24 h), during which concentrations of analytes in the sampled air can vary significantly. The apparent worst-case scenario can be when in the first half of sampling, concentration is much higher than during the second half. When the concentration of an analyte in the sampled air becomes close to or lower than the concentration near the fiber tip, the flux of analytes inside a protecting needle can go to a reverse direction resulting in desorption of analytes from a coating. However, this violates the main principle of TWA sampling: the rate of sampling should depend only on the concentration of an analyte in a sampled air. It means that if an analyte concentration in sampled air is zero, a rate of extraction should also be equal to zero.

Thus, the aim of this part of the work was to model such a case and estimate the highest possible uncertainty of the TWA SPME sampling approach.As was assumed, desorption of dichloromethane, acetone, and benzene from a fiber started after concentrations of analytes dropped from 1.176 to 0.1176 μmolm −3 in the middle of the extraction process. Desorption of toluene was not observed because it has the highest distribution constant among all studied analytes. However, the toluene sampling rate after the drop of its concentration in sampled air was lower than theoretical. Recoveries of analytes at Z = 10 mm dropped from 65–82 to 52–70%, at Z = 20 mm from 78–90 to 67–79%, at Z = 30 mm from 85–93 to 73–82, at Z = 40 mm from 86–93 to 75–82%. Only at Z = 40 mm, it was possible to keep recovery of all analytes above 75%. Thus, if possible, for greater accuracy, sampling must be arranged so that no significant drop in concentration takes place. Such a drop can be observed, e.g., if the end of sampling is planned for the night when VOCs concentrations in ambient air are typically lower due to much lower road traffic and other human activities.

Also, using shorter sampling times can minimize the risk of the reverse diffusion when ambient concentrations are predicted to drop significantly. Alternative Geometries for TWA SPME SamplingAs was shown above , an increase of the internal diameter of a protecting needle provides more space for analytes to diffuse around the coating and better reach the side of the coating.

Solid Phase Microextraction Spme

It decreases the controlling role of the fiber coating tip and should lead to more accurate and reproducible results.Tursumbayeva proposed using SPME liner for TWA SPME to avoid sorption of analytes onto metallic walls of a protecting needle. The same approach can be used to avoid equilibration of analytes between the fiber tip and the surrounding space after sampling over longer time periods. At variable concentrations of analytes (as simulated in the previous section), calculated recoveries for VOCs using Z = 67 mm (a) are 73–84%, which are close to the values obtained using retracted fiber at Z = 40 mm. No improvement was observed because of 0.75-mm I.D. SPME liner has 4.9 times greater cross-sectional area than 23 ga protecting needle, which results in 2.9 times greater theoretical flux of analytes from sampled air to the coating under the set Z (67 and 40 mm, respectively). To decrease the flux of analytes, the liner can be manufactured with a lower I.D. (e.g., 0.34 mm as for 23 ga needle) from the sampling side almost to the expected location of the fiber as shown in b.

Under these conditions, recoveries increased to 88–91%. Effect of TWA SPME sampling geometry on recoveries ( t = 100,000 s, C 0–49,000 s = 1.176 μmolm −3, C 49,000–51,000 s = 1.176–0.1176 μmolm −3, C 49,000–100,000 s = 0.1176 μmolm −3).The use of alternative geometries resulted in a more uniform distribution of the analytes in the coating; for 0.75-mm I.D. SPME liner concentrations of analytes near the fiber tip were only 1.1–2.7 times greater than at another side of the coating. This should result in faster desorption of analytes, less pronounced peak tailing and greater accuracy of the method. A similar effect is achieved when using Radiello ® passive air sampler , which provide a greater surface area of an adsorbent available for the diffusive air sampling. (2)Benzene, a ubiquitous air pollutant, was used as a model analyte for most initial calculations. Diffusion coefficients of benzene in the air and PDMS coating were set to 8.8 × 10 −6 and 10 −10 m 2s −1, respectively.

Distribution constant ( K d) for benzene and common SPME coatings was set to 150,000 (85 µm Car/PDMS) , 8300 (65 µm PDMS/DVB) , and 301 (PDMS). For dichloromethane, acetone and toluene, distribution constants between 85 µm Car/PDMS coating and air were set to 72,000, 71,000 and 288,000, respectively.The geometry of a fiber assembly was built in as inputs based on the data provided by Pawliszyn. Simulations were conducted for Stableflex ® (Supelco, Bellefonte, PA, USA) fibers with a core diameter of 130 µm. For 85 µm Car/PDMS and 65 µm PDMS/DVB, total fiber diameters were set to 290 and 270 µm, respectively. Calculations were conducted for 24- and 23 ga coatings having internal diameter of 310 and 340 µm, respectively.The extra fine free triangular mesh was used for the modeling. To provide better meshing at the coating−air interface, the resolution of narrow regions was increased to “2”.

The computation was completed in the range between 0 and 100,000 s at the step of 1000 s. The concentration of an analyte at the tip of the protecting needle was set to 0.641 µmolm −3, which corresponds to 50 µgm −3 of benzene. Sampling Using Adsorptive CoatingsFor adsorptive coatings, the “Adsorption” mechanism was activated in the model.

The isotropic diffusion coefficient (in the air inside pores) was the same as for air (set to 8.8, 8.7, 12.4 and 10.1 mm 2s −1 for benzene, toluene, acetone, and dichloromethane, respectively). The approach proposed by Mocho and Desauziers involving Knudsen diffusion in micro-pores was also tested. However, it was later rejected for model simplification because the diffusion of analytes inside coating is mainly driven by molecular diffusion inside macro-pores. The presence of PDMS binder was not considered in the model because: (1) it has much weaker affinity to analytes than Carboxen; and (2) the layer of PDMS in the coating is very thin and should not affect the diffusion of analytes ; (3) there is not enough published information about the exact structure of the coating.Adsorption was set to “User defined” with a distribution constant ( K p, m 3kg −1) calculated as a dimensionless distribution constant divided by a coating density ( K d/ ρ).

Coating porosities ( ε = 0.685 for Car/PDMS and 0.775 for PDMS/DVB) were calculated using intra-particle porosities (0.37 for Car, and 0.55 for DVB ) and inter-particle porosity. The exact value of the latter is proprietary and not available in the open literature. Taking into account, the spherical shape of particles and available scanning electron microscope (SEM) photos, the inter-particle porosity of both coatings was set to the maximum possible value (0.50). A particle porosity ( ε) was calculated as the total volume of pores (0.78 mL for Car, and 1.54 mL for DVB) divided by the total volume of one gram of material (2.13 mL for Car, and 2.78 mL for DVB).

Densities of the coatings were calculated using free fall densities of the particles (470 kgm −3 for Car, and 360 kgm −3 for DVB) and inter-particle porosity. Effective diffusion coefficients were calculated during the calculations by the COMSOL software using the Tortuosity model. ConclusionsA finite element analysis-based model (based on COMSOL Multiphysics software) allowed efficient simulation of TWA air sampling of VOCs using retracted SPME fibers. It was possible to model the effects of sampling time, coating type (including adsorptive coatings for the first time) and composition, diffusion coefficient, the distribution constant, the internal diameter of a protecting needle and diffusion path on the recovery of analytes, their concentration profiles in the air inside protecting needle, and the coating.

The advantages of such a simulation compared to an experiment are: (1) time and cost savings; (2) lower uncertainty and the possibility to discover minor impacts of sampling parameters on its performance; and (3) the possibility to understand and optimize a sampling process in greater detail. The results of this research allowed disclosing potential sources of the apparent departure from Fick’s law of a diffusion-based model used for quantification of VOCs with retracted SPME.It was established that sampling by porous coatings with high affinity to the analyte (Car/PDMS) is affected by the saturation of the fiber tip and slow diffusion of analytes in the coating. Highest recoveries are achieved for analytes having lowest diffusion coefficients and highest affinities to a coating. The increase of an internal diameter of a protecting needle from 24 to 23 ga allows proportionally greater responses to be obtained at similar recoveries.The most important parameter of a sampling process that users can control is a retraction depth.

The increase of Z allows slowing down the sampling and achieving higher recoveries of analytes. In this study, at Z = 40 mm and constant analyte concentration in a sampled air, recoveries of studied analytes reached 86–93% compared to 65–82% at Z = 10 mm. The developed model allowed simulation of the worst sampling case when analyte concentrations significantly drop in the middle of sampling. For the first time, it has been proven that at such sampling conditions and Z = 40 mm, recoveries of analytes can drop by 10%, while at Z = 10 mm by 15%.According to the results of the simulation, it is optimal to conduct sampling of studied VOCs using a 23 ga Car/PDMS assembly at Z = 40 mm. Expected detection limits at these parameters are about 1 µgm −3.Alternative geometries of a protective TWA SPME sampling devices could be used to increase recoveries of analytes. Sampling using 0.75-mm I.D. SPME GC liner at Z = 67 mm provides similar recoveries compared to sampling using a protecting needle at Z = 40 mm, but it provides greater amounts of analytes extracted and lower detection limits.

To achieve greater recovery, part of the liner should have narrower I.D. (e.g., 0.34 mm). The increase of the diameter of the extraction zone where the coating is located results in a more uniform distribution of analytes, which should lead to faster desorption, less pronounced peak tailing and greater accuracy. Specific sampler parameters should be selected for particular sampling time and environmental conditions (temperature and atmospheric pressure) using the developed model.The methodology used in this study could also be used for more accurate and simpler calibration of the method.

Solid Phase Microextraction Fibers

It can be used to model the sampling of other environments (process gases, water) by retracted SPME fibers. Further modification of this model could allow simulation of soil and soil gas sampling.