Commercial SPME Fibers Research Articles

Preparation of a new coating of graphene oxide/nickel complex on a nickelized metal surface for direct immersion solid phase microextraction of some polycyclic aromatic hydrocarbons

BackgroundSolid-phase microextraction (SPME) is a versatile sampling and sample preparation technology that possess a significant application in the extraction and pre-concentration of a broad range of micro-pollutants from different kind of matrices. Selection and preparation of an appropriate fiber substrate and coating materials have always been the main challenges of the SPME procedure. This paper introduces a high-efficiency metal-based SPME fiber with a new chemical coating of nickel/graphene oxide/nickel tetraazamacrocyclic complex (Ni/GO/NiTAM).ResultThe Ni/GO/NiTAM sorbent was electroless deposited onto the surface of an aluchrom (Alu) wire, and then the prepared fiber was employed for the extraction and pre-concentration of some PAHs before their HPLC–UV analysis. The prepared fiber characterization data were assessed using FE-SEM, EDX, XRD, FT-IR, and BET techniques. The method validation parameters, including the linearity range (LRs: 0.10 to 200.0 µg L−1), the limit of detection (LODs: 0.03‒0.30 µg L−1), and the limit of quantification (LOQs: 0.10–1.00 µg L−1), under optimal conditions. The relative standard deviations (RSDs) of intra-day, inter-day, and single fiber repeatability (for the samples spiked at 25 µg L‒1) were in the range of 0.32–2.94, 1.20–4.09, and 1.42‒4.39%, respectively. In addition, the technique recoveries (RR %) and enrichment factors (EF) were in the range of 83.10‒107.80% and 83–164, respectively.ConclusionThe fiber fabrication was simple, and the applied materials were also economical and easily accessible. Alu metal has high physicochemical and mechanical stability and thus can be a good alternative for the substrate of the fragile commercial SPME fibers. High rigidity and durability, long service life, and high extraction capability are some of the other advantages of the offered fiber.

Development of ZIF-67 derived hollow multishelled structures Co3O4/carbon nanomaterials as spiral solid-phase microextraction fiber for superior capture of fifteen PAHs

Here, a unique spiral-solid phase microextraction (S-SPME) fiber using ZIF-67 derived hollow multishelled structures Co3O4/carbon nanomaterials (HoMS-Co3O4/C) as the coating was designed for superior capture of trace polycyclic aromatic hydrocarbons (PAHs). The ligand 2-methylimidazole of ZIF-67 was replaced twice with 2,5-dihydroxyterephthalic acid and followed by pyrolysis to obtain the material with an unique hollow double-shelled structure. The formation of the hollow structure can be explained by the Ostwald ripening. Fifteen PAHs, four brominated flame retardants (BFRs), and seven endocrine chemicals (EDCs) were used to investigate the extraction performance of HoMS-Co3O4/C coated S-SPME fiber. The spiral fiber displayed higher selectivity for PAHs compared with BFRs and EDCs. The methods had low detection limits (0.002–2.680 μg L−1), wide linear ranges (0.005–1000 μg L−1), and good reproducibility (0.7–10.7%, fiber to fiber). In addition, the S-SPME fiber demonstrated excellent enrichment ability and extraction efficiency for PAHs compared with commercial SPME fibers, it might since there were strong π-π stacking force, hydrophobic interaction between analytes and HoMS-Co3O4/C coating, also the HoMS coating and the spiral fiber could greatly increase the contact area between adsorbent and target compounds. Finally, the HoMS-Co3O4/C coated S-SPME fiber had been further adopted to detect fifteen PAHs in environmental water samples successfully.

Solid-Phase Microextraction of Phthalate Esters from Aqueous Media by Functionalized Carbon Nanotubes (Graphene Oxide Nanoribbons) and Determination by GC–FID

Multiwalled carbon nanotubes were exposed to hydrothermal treatment for obtaining graphene oxide nanoribbons (GONRs). The fabricated graphene oxide nanoribbons have been morphologically and compositionally characterized via FE-SEM, XRD, and FT-IR techniques. The as-synthesized GONRs have been used as sorbent phase for headspace solid-phase microextraction of phthalate esters (PEs) from aqueous solutions. In this regard, the GC–FID analysis route has been used for quantification of PEs. The new SPME fiber shows remarkable analytical figures of merit including broad dynamic linear ranges, low limits of detection, as well as good stability and reasonable relative standard deviations for evaluation of PEs. The linearity of the method for analysis of PEs including DnBP, DnPP, DEHP, DEHA, BBP, and DMP was between the range of 0.05–100, 0.05–100, 0.1–100, 0.1–100, 0.2–100, and 0.5–100 μg L−1, respectively. The limits of detection (based on S/N = 3) and correlation coefficients were found to be in the range of 0.02–0.2 μg L−1 and 0.9907–0.9952, correspondingly. The prepared GONR-coated SPME fiber shows larger extraction yield in comparison to pristine MWNTs and commercial PDMS SPME fibers. Furthermore, real sample analysis showed that there is no significant matrix effect for evaluation of PEs from environmental water samples and proposed method could be used for evaluation and determination of PEs from aqueous samples in a precise and accurate manner. The existence of functional groups, π–π interactions, as well as hydrogen bonding between adsorbent phase and PE analytes could be the reason for observing such a high extraction yield.

Multiple solid phase microextraction combined with ambient mass spectrometry for rapid and sensitive detection of trace chemical compounds in aqueous solution

Multiple solid phase microextraction (mSPME) combined with thermal desorption-electrospray ionization/mass spectrometry (TD-ESI/MS) was developed to rapidly characterize trace analytes in aqueous solution. A number of commercial available SPME fibers (from 2 to 10 fibers) were simultaneously used for extracting the analytes in solution. The fibers were then bundled together on a holder and subjected for the ambient mass spectrometric analysis. Good linearity for calibration (R2 = 0.9995) and low limit of quantification (<1 ppb) were achieved by using 10 SPME fibers coated with polyacrylate (PA) to extract bisphenol A. It was also found that the analyte signals increased with the number of SPME fibers for extraction. Uncontroversial, a shorter extraction time was required by using mSPME to reach the same level of analyte signal as that by using single SPME fiber for a longer extraction time. Trace bisphenol A (4–20 ppb) in the polycarbonate (PC) baby milk bottles was rapidly detected using mSPME-TD-ESI/MS and the analysis was completed within 1 min. The use of multiple SPME fibers coated with different materials enable the concentration of different type of analytes in the solution. Ibuprofen, bisphenol A (BPA), and 4-n-nonylphenol (4-n-NP) were simultaneously detected by using PA and polydimethylsiloxane (PDMS) coated fibers for extraction.

In vivo investigation of pesticide residues in garlic using solid phase microextraction-gas chromatography-mass spectrometry

In this study, a novel multiwalled carbon nanotubes/polyaniline-polypyrrole@polydimethylsiloxane (MWCNTs/PANI-PPy@PDMS) fiber was prepared by a facile electrodeposition strategy followed by polymer surface modification, and used as the sorbent of in vivo solid phase microextraction (in vivo SPME). The custom-made fiber exhibits better enrichment capacity than three commercial SPME fibers. Ultra-high enrichment factor (438–2659), satisfactory thermal and mechanical stability, excellent matrix-compatibility and anti-biofouling ability render the fiber attractive as in vivo sampling probe. Combining in vivo SPME with gas chromatography-mass spectrometry (GC-MS), a convenient and sensitive method was successfully developed for the rapid determination of pesticides (hexachlorobenzene, chlorothalonil, fipronil, chlorfenapyr) in garlic. Under the optimal conditions, the proposed method displays relatively wide linear range (three or four orders of magnitude) with a coefficient of determination above 0.9944 both in the standard solution and spiked homogenized garlic samples, respectively. Low detection limits from 0.38 to 1.90 ng g−1 were obtained in homogenized garlic samples. Relative standard deviations (RSDs) less than 15.5% and recovery between 84.0% and 108.2% indicate satisfactory precision and accuracy of the method. In summary, a promising non-lethal method based on in vivo SPME-GC-MS is developed in this study, which provides a green, efficient, economic and rapid strategy for the determination of trace pesticide residues in edible plants.

Analysis of Echinacea flower volatile constituents by HS-SPME-GC/MS using laboratory-prepared and commercial SPME fibers

ABSTRACTHS-SPME-GC/MS has been widely used in herbs and spices for essential oil analysis. This paper reports on the utility of HS-SPME method for profiling of volatile compounds from Echinacea flower using commercial and laboratory-prepared SPME fibers, and additionally comparing the volatiles extracted from HD. For achieving optimum recovery of volatiles, SPME conditions (equilibrium time, extraction temperature and extraction time) were examined. The use of SPME method enhanced the detected volatiles (161 peaks) in comparison to HD method (90 peaks). The identified volatile in Echinacea as total was 92 whether identified by SPME or HD methods. The total of tentatively identified compounds including monoterpenes, monoterpenoids, sesquiterpenes, sesquiterpenoids and other hydrocarbons with HS-SPME method (83) was higher than HD method (59). Sesquiterpenic hydrocarbons were shown to be the main group within Echinacea by both methods. It is shown that the extraction efficiencies of polymeric ionic liquid based SPME fibers are comparable with commercial ones.

Comparison of two commercial solid‐phase microextraction fibers for the headspace analysis of volatile compounds in different pork and beef cuts

The performance of carboxen/polydimethylsiloxane (Car/PDMS) and divinylbenzene/Car/PDMS (DVB/Car/PDMS) fibers in extracting volatile organic compounds (VOCs) from different pork and beef cuts by headspace solid-phase microextraction (HS-SPME) was compared. A principal component analysis (PCA), cluster analysis (CA), and an analysis of variance were employed subsequently to evaluate the extraction performance. DVB/Car/PDMS fibers exhibited similar VOC profiles, but were less effective than Car/PDMS fibers which showed significantly (p < 0.05) higher extraction yields of major volatile groups including acids, alcohols, aldehydes, amines, and ketones in most of the tested meat cuts. There were no significant (p > 0.05) differences in the amount of aliphatic hydrocarbon, aromatic hydrocarbon, esters, and sulfur compounds extracted by both fibers. Car/PDMS exhibited significant (p < 0.05) differences in the amount of VOCs extracted from different meat cuts, while DVB/Car/PDMS fiber did not. These findings might provide insights into HS-SPME of VOCs from different meat cuts. Practical applications The application of HS-SPME for the determination of VOCs in raw or processed meats, particularly pork and beef cuts, has been extensively studied in recent years. Among the commercial SPME fibers available, Car/PDMS and DVB/Car/PDMS fibers are the most frequently employed. However, no adequate information regarding the selection process and comparison of the fibers has been provided. The results of this study demonstrate that the profile of VOCs in different cuts of pork and beef was strongly influenced by the type of fiber used for extraction. Thus, these findings might provide new insights into the HS-SPME analysis of VOCs in different meat cuts, especially the selection of fibers for the extraction of specific VOC analytes.

A poly-dopamine based metal-organic framework coating of the type PDA-MIL-53(Fe) for ultrasound-assisted solid-phase microextraction of polychlorinated biphenyls prior to their determination by GC-MS

The authors describe an ultrasonic-assisted headspace method for solid phase micro-extraction (UA-HS-SPME) of 7 polychlorinated biphenyls (PCBs) with codes PCB28, PCB52, PCB101, PCB118, PCB138, PCB153 and PCB180. The coating is based on a poly-dopamine metal-organic framework [PDA-MIL-53(Fe)] on a stainless steel wire. The coating can be prepared and evenly deposited on the stainless fiber by dipping the PDA fiber into a solution of MIL-53(Fe). The assay is also environmentally friendly because water is used as the solvent. The effects of extraction time, addition of salts, pH value and power of ultrasonic power were optimized. The coating is found to possess a high selectivity and adsorption capacity for PCBs compared to commercial SPME fibers such as the divinylbenzene/carboxen/polydimethylsiloxane fibers. Following desorption, the PCBs were quantified by GC-MS. The detection limits are between 50 and 90 pg⋅g−1 of PCBs in soil. The fibers can be easily prepared, and the batch-to-batch reproducibility (RDS) is <10% (for n = 6). The fibers are inexpensive, re-usable and can be easily manipulated, and particularly well suited for screening polychlorinated biphenyls in soil.

Vacuum-assisted headspace-solid phase microextraction for determining volatile free fatty acids and phenols. Investigations on the effect of pressure on competitive adsorption phenomena in a multicomponent system

This work proposes a new vacuum headspace solid-phase microextraction (Vac-HSSPME) method combined to gas chromatography-flame ionization detection for the determination of free fatty acids (FFAs) and phenols. All target analytes of the multicomponent solution were volatiles but their low Henry's Law constants rendered them amenable to Vac-HSSPME. The ability of a new and easy to construct Vac-HSSPME sampler to maintain low-pressure conditions for extended sampling times was concurrently demonstrated. Vac-HSSPME and regular HSSPME methods were independently optimized and the results were compared at all times. The performances of four commercial SPME fibers and two polymeric ionic liquid (PIL)-based SPME fibers were evaluated and the best overall results were obtained with the adsorbent-type CAR/PDMS fiber. For the concentrations used here, competitive displacement became more intense for the smaller and more volatile analytes of the multi-component solution when lowering the sampling pressure. The extraction time profiles showed that Vac-HSSPME had a dramatic positive effect on extraction kinetics. The local maxima of adsorbed analytes recorded with Vac-HSSPME occurred faster, but were always lower than that with regular HSSPME due to the faster analyte-loading from the multicomponent solution. Increasing the sampling temperature during Vac-HSSPME reduced the extraction efficiency of smaller analytes due to the enhancement in water molecule collisions with the fiber. This effect was not recorded for the larger phenolic compounds. Based on the optimum values selected, Vac-HSSPME required a shorter extraction time and milder sampling conditions than regular HSSPME: 20 min and 35 °C for Vac-HSSPME versus 40 min and 45 °C for regular HSSPME. The performance of the optimized Vac-HSSPME and regular HSSPME procedures were assessed and Vac-HSSPME method proved to be more sensitive, with lower limits of detection (from 0.14 to 13 μg L−1), and better intra-day precision (relative standard deviations values < 10% at the lowest spiked level) than regular HSSPME for almost all target analytes. The proposed Vac-HSSPME method was successfully applied to quantify FFAs and phenols in milk and milk derivatives samples.

Utilization of highly robust and selective crosslinked polymeric ionic liquid-based sorbent coatings in direct-immersion solid-phase microextraction and high-performance liquid chromatography for determining polar organic pollutants in waters

Several crosslinked polymeric ionic liquid (PIL)-based sorbent coatings of different nature were prepared by UV polymerization onto nitinol wires. They were evaluated in a direct-immersion solid-phase microextraction (DI-SPME) method in combination with high-performance liquid chromatography (HPLC) and diode array detection (DAD). The studied PIL coatings contained either vinyl alkyl or vinylbenzyl imidazolium-based (ViCnIm- or ViBCnIm-) IL monomers with different anions, as well as different dicationic IL crosslinkers. The analytical performance of these PIL-based SPME coatings was firstly evaluated for the extraction of a group of 10 different model analytes, including hydrocarbons and phenols, while exhaustively comparing the performance with commercial SPME fibers such as polydimethylsyloxane (PDMS), polyacrylate (PA) and polydimethylsiloxane/divinylbenzene (PDMS/DVB), and using all fibers under optimized conditions. Those fibers exhibiting a high selectivity for polar compounds were selected to carry out an analytical method for a group of 5 alkylphenols, including bisphenol-A (BPA) and nonylphenol (n-NP). Under optimum conditions, average relative recoveries of 108% and inter-day precision values (3 non-consecutive days) lower than 19% were obtained for a spiked level of 10µgL−1. Correlations coefficients for the overall method ranged between 0.990 and 0.999, and limits of detection were down to 1µgL−1. Tap water, river water, and bottled water were analyzed to evaluate matrix effects. Comparison with the PA fiber was also performed in terms of analytical performance. Partition coefficients (logKfs) of the alkylphenols to the SPME coating varied from 1.69 to 2.45 for the most efficient PIL-based fiber, and from 1.58 to 2.30 for the PA fiber. These results agree with those obtained by the normalized calibration slopes, pointing out the affinity of these PILs-based coatings.

Flow-Assisted Electro-Enhanced Solid-Phase Microextraction for the Determination of Haloethers in Water Samples

Haloethers represent a special class of disinfection byproducts which pose serious harms to humans and are carcinogenic at parts per billion levels. Flow-assisted electro-enhanced solid-phase microextraction (FA-EE-SPME) method was developed for the determination of 4-chlorophenyl phenyl ether (CPPE) and 4-bromophenyl phenyl ether (BPPE) in large volumes of water samples. Within the extraction system, different commercial SPME fibers were exposed into a 100 mL sample flowing at a rate of 50 mL min−1 via direct immersion mode for extraction of target analytes. The major factors affecting the extraction efficiency such as absorption time, pump flow rate, ionic strength, applied potential, sample pH and SPME fiber type were optimized using one factor at-a-time approach. After extraction, the SPME fiber was desorbed in the injector port of gas chromatography–mass spectrometry (GC–MS). The proposed method combines advantages of electrical potential and flow system together to enhance extraction efficiency of SPME. Quantification was carried out over a concentration range of 0.5–100 µg L−1 and good linearity was obtained with detection limits of 0.05 and 0.07 µg L−1, respectively, for CPPE and BPPE. The relative standard deviation of the calibrations was in the range of 1.1 and 3.6 %. Application of FA-EE-SPME was tested for various drinking and tap water samples collected from Eastern Province of Saudi Arabia and the method performance was compared with reported literature values.

Automated direct-immersion solid-phase microextraction using crosslinked polymeric ionic liquid sorbent coatings for the determination of water pollutants by gas chromatography.

Four different crosslinked polymeric ionic liquid (PIL)-based sorbent coatings were evaluated in an automated direct-immersion solid-phase microextraction method (automated DI-SPME) in combination with gas chromatography (GC). The crosslinked PIL coatings were based on vinyl-alkylimidazolium- (ViCnIm-) or vinylbenzyl-alkylimidazolium- (ViBzCnIm-) IL monomers, and di-(vinylimidazolium)dodecane ((ViIm)2C12-) or di-(vinylbenzylimidazolium)dodecane ((ViBzIm)2C12-) dicationic IL crosslinkers. In addition, a PIL-based hybrid coating containing multi-walled carbon nanotubes (MWCNTs) was also studied. The studied PIL coatings were covalently attached to derivatized nitinol wires and mounted onto the Supelco assembly to ensure automation when acting as SPME coatings. Their behavior was evaluated in the determination of a group of water pollutants, after proper optimization. A comparison was carried out with three common commercial SPME fibers. It was observed that those PILs containing a benzyl group in their structures, either in the IL monomer and crosslinker (PIL-1-1) or only in the crosslinker (PIL-0-1), were the most efficient sorbents for the selected analytes. The validation of the overall automated DI-SPME-GC-flame ionization detector (FID) method gave limits of detection down to 135 μg · L(-1) for p-cresol when using the PIL-1-1 and down to 270 μg · L(-1) when using the PIL-0-1; despite their coating thickness: ~2 and ~5 μm, respectively. Average relative recoveries with waters were of 85 ± 14 % and 87 ± 15 % for PIL-1-1 and PIL-0-1, respectively. Precision values as relative standard deviation were always lower than 4.9 and 7.6 % (spiked level between 10 and 750 μg · L(-1), as intra-day precision). Graphical Abstract Automated DI-SPME-GC-FID using crosslinked-PILs sorbent coatings for the determination of waterpollutants.

HS-SPME-GC-MS ANALYSIS OF VOLATILE AND SEMI-VOLATILE COMPOUNDS FROM DRIED LEAVES OFMikania glomerataSprengel

This paper reports on the identification of volatile and semi-volatile compounds and a comparison of the chromatographic profiles obtained by Headspace Solid-Phase Microextraction/Gas Chromatography with Mass Spectrometry detection (HS-SPME-GC-MS) of dried leaves of Mikania glomerata Sprengel (Asteraceae), also known as 'guaco.' Three different types of commercial SPME fibers were tested: polydimethylsiloxane (PDMS), polydimethylsiloxane/divinylbenzene (PDMS/DVB) and polyacrylate (PA). Fifty-nine compounds were fully identified by HS-SPME-HRGC-MS, including coumarin, a marker for the quality control of guaco-based phytomedicines; most of the other identified compounds were mono- and sesquiterpenes. PA fibers performed better in the analysis of coumarin, while PDMS-DVB proved to be the best choice for a general and non-selective analysis of volatile and semi-volatile guaco-based compounds. The SPME method is faster and requires a smaller sample than conventional hydrodistillation of essential oils, providing a general overview of the volatile and semi-volatile compounds of M. glomerata.

HS-SPME-GC-MS analysis of volatile and semi-volatile compounds from Mikania glomerata dried leaves

This study reports on the identification of volatile and semi-volatile compounds and a comparison of the chromatographic profiles obtained by HS-SPME-GC-MS (Headspace Solid Phase Microextraction – Gas Chromatography with Mass Spectrometry detection), from dried leaves of Mikania glomerata Sprengel (Asteraceae), one of the species known in Brazil as “guaco” and employed as raw material in phytopharmaceutical industry. Three different types of commercial SPME fibers were tested: poly(dimethylsiloxane) (PDMS), poly(dimethylsiloxane)-divinylbenzene (PDMS-DVB) and polyacrylate (PA). 59 compounds were fully identified by HS-SPME-HRGC-MS, most of them identified as being mono- and sesquiterpenes. Considering the sum of the areas of the detected peaks in TIC as a criterion to measure extraction efficiency, PDMS-DVB showed the highest efficiency. PA fiber showed better performance in the analysis of coumarin, a marker for the quality control of guaco-based phytomedicines [1]. Coumarin was better extracted by PA fiber than by conventional hydrodistillation of essential oils (EO), and the HS-SPME method also offers the advantages of requiring smaller samples and shorter time of analysis than the HPLC-UV and the HRGC-FID methods previously reported for M. glomerata analysis [1, 2]. The results enable us to suggest the use of HS-SPME-HRGC-MS method as a valuable tool for quality control of guaco-based phytomedicines and also for the screening and characterizing the chemical composition of volatile and semi-volatile compounds of M. glomerata in further studies requiring a large number of plant samples and/or when a limited amount of plant material is available for several samplings, such as metabolomic or agronomical studies.

Electroenhanced solid-phase microextraction of methamphetamine with commercial fibers

Electroenhanced solid-phase microextraction (EE-SPME) method with gas chromatographic mass spectrometric analysis was investigated for the determination of methamphetamine in urine sample with commercial fibers. In this approach, commercial SPME fibers were used in direct immersion mode with an applied potential to extract methamphetamine. EE-SPME was more effective in the extraction compared to conventional SPME (i.e. application of potential). The method was simple to use, and avoided the need for alkalization and derivatization of methamphetamine. Experimental conditions were optimized to achieve better extraction performance. Various conditions including applied potential, sample pH, extraction and desorption time were investigated. Based on the optimized conditions, EE-SPME achieved a higher enrichment factor of 159-fold than conventional SPME. The calibration plot under the best selected parameters was linear in the range of 0.5–15ng/mL (r=0.9948). The feasibility of EE-SPME was demonstrated by applying it to the analysis of human urine samples. The limit of detection of methamphetamine was 0.25ng/mL with a satisfactory relative standard deviation of 6.12% (n=3) in human urine.

Determination of haloanisoles in paper samples for food packaging by solid-phase microextraction and gas chromatography

A method was developed for the determination of trichloroanisole, tribromoanisole and pentachloroanisol by solid-phase microextraction and gas chromatography in paper samples (Kraft liner, Test liner and Miolo). Four commercial SPME fibers were evaluated: Polydimethylsiloxane (PDMS), Polyacrylate (PA), Carbowax/Divinylbenzene (CW/DVB) and Divinylbenzene/Carboxen/Polydimethylsiloxane (DVB/CAR/PDMS). DVB/CAR/PDMS gave the best results and was therefore selected. Other variables involved in the extraction procedure were studied and optimized, such as: sample volume, salting-out effect, temperature and extraction time, effect of organic solvent and previous sample preparation. Optimum conditions were obtained using 20 mL of sample with 5 mol L−1 NaCl in a 40 mL vial, extraction temperature of 70 °C and sonication and extraction time of 30 and 40 min, respectively. Detection limits ranged from 0.43 to 1.32 ng g−1 for all analytes. Recoveries between 70 and 100% were obtained and relative standard deviation was below 10% for all compounds.

Solid-phase Microextraction of Phosphate and Methylphosphonate Using Novel Fibers Coated with a Sol-Gel-Derived Silicone-Divinylbenzene Co-Polymer

Co-poly (hydroxy-terminated silicone divinylbenzene) coating was first prepared by sol-gel and cross-linking methods and applied to the solid-phase microextraction of phosphate and methylphosphonate from air and water. The possible mechanism is discussed. The characteristics of the new films were also investigated. Compared with commercial SPME fibers, the novel films showed better selectivity and sensitivity towards phosphate and methyphosphonate. Moreover, the coating proved to be very stable at high temperatures and in different solvents. Some important parameters, such as extraction time, extraction temperature, effect of salt and desorption time were optimized. The limits of detection for dimethyl methylphosphonate (DMMP), trimethyl phosphate (TMP) and tributyl phosphate (TBP) were 1.11, 1.46, and 1.64 μg L−1 in air and 0.34, 2.20, and 0.01 μg mL−1 in water. A relative standard deviation (n=6) below 7% can be achieved depending on the compounds both in air and in water. Linear ranges were about 1–2 orders of magnitude. The recovery of spiked water samples was from 89.46 to 90.88%.

Determination of pharmaceutical process impurities by solid phase microextraction gas chromatography

AbstractA methodology for automated headspace solid‐phase microextraction for the trace analysis of pharmaceutical process‐related toxic impurities such as benzyl chloride, triethyl amine, chloroethyl methyl ether, N‐methylmorpholine, and N‐methylpyrrolidinone by gas chromatography and flame ionization detection is reported. Carboxen/polysiloxane/divinylbenzene fiber showed excellent sensitivity towards these analytes compared to direct injection and the highest sensitivity among the commercial SPME fibers evaluated in this study. However, a profound effect of competition for the available adsorption sites was observed on the Carboxen/PDMS/DVB fiber. The effects of extraction parameters such as extraction time, temperature, agitation rate, and headspace volume were studied. The influence of the addition of inorganic salt on the analyte extraction efficiency was also investigated. The sensitivity of method extended to the sub‐ppm level with acceptable precision and accuracy. The linearity of the method covered one order of magnitude. The narrower linear dynamic range is attributed largely to the limited number of adsorption sites on the Carboxen/PDMS/DVB fiber.