Material For Solid-phase Microextraction Research Articles

Ionic liquids in solid-phase microextraction: A review

Solid-phase microextraction (SPME) has undergone a surge in popularity within the field of analytical chemistry in the past two decades since its introduction. Owing to its nature of extraction, SPME has become widely known as a quick and cost-effective sample preparation technique. Although SPME has demonstrated extraordinary versatility in sampling capabilities, the technique continues to experience a tremendous growth in innovation. Presently, increasing efforts have been directed towards the engineering of novel sorbent material in order to expand the applicability of SPME for a wider range of analytes and matrices. This review highlights the application of ionic liquids (ILs) and polymeric ionic liquids (PILs) as innovative sorbent materials for SPME. Characterized by their unique physico-chemical properties, these compounds can be structurally-designed to selectively extract target analytes based on unique molecular interactions. To examine the advantages of IL and PIL-based sorbent coatings in SPME, the field is reviewed by gathering available experimental data and exploring the sensitivity, linear calibration range, as well as detection limits for a variety of target analytes in the methods that have been developed.

Role of counteranions in polymeric ionic liquid-based solid-phase microextraction coatings for the selective extraction of polar compounds

A polymeric ionic liquid (PIL) poly(1-vinyl-3-hexylimidazolium chloride) (poly(ViHIm +Cl −)) was designed as a coating material for solid phase microextraction (SPME) to extract polar compounds including volatile fatty acids (VFAs) and alcohols. The extracted analytes were analyzed by using gas chromatography (GC) coupled with flame ionization detection (FID). Extraction parameters of the HS–SPME–GC–FID method, such as ionic strength, extraction temperature, pH and extraction time were optimized. Calibration studies were carried out under the optimized conditions to further evaluate the performance of the PIL-based SPME coating. For comparison purposes, the PIL poly(1-vinyl-3-hexylimidazolium bis[(trifluoromethyl)sulfonyl]imide) (poly(ViHIm +NTf 2 −)) was also used as the SPME coating to extract the same analytes. The results showed that the poly(ViHIm +Cl −) PIL coating had higher selectivity towards more polar analytes due to the presence of the Cl − anion which provides higher hydrogen bond basicity than the NTf 2 − anion. The limits of detection (LODs) determined by the designed poly(ViHIm +Cl −) PIL coating ranged from 0.02 μg L −1 for octanoic acid and decanoic acid and 7.5 μg L −1 for 2-nitrophenol, with precision values (as relative standard deviation) lower than 14%. The observed performance of the poly(ViHIm +Cl −) PIL coating was comparable to previously reported work in which commercial or novel materials were used as SPME coatings. The selectivity of the developed PIL coatings was also evaluated using heptane as the matrix solvent. This work demonstrates that the selectivity of PIL-based SPME coatings can be simply tuned by incorporating different counteranions to the sorbent coating.

Solid phase microextraction using new sol–gel hybrid polydimethylsiloxane-2-hydroxymethyl-18-crown-6-coated fiber for determination of organophosphorous pesticides

A new sol–gel hybrid coating, polydimethylsiloxane–2-hydroxymethyl-18-crown-6 (PDMS–2OHMe18C6) was prepared in-house for use in solid phase microextraction (SPME). The three compositions produced were assessed for its extraction efficiency towards three selected organophosphorus pesticides (OPPs) based on peak area extracted obtained from gas chromatography with electron capture detection. All three compositions showed superior extraction efficiencies compared to commercial 100 μm PDMS fiber. The composition showing best extraction performance was used to obtain optimized SPME conditions: 75 °C extraction temperature, 10 min extraction time, 120 rpm stirring rate, desorption time 5 min, desorption temperature 250 °C and 1.5% (w/v) of NaCl salt addition. The method detection limits (S/N = 3) of the OPPs with the new sol–gel hybrid material ranged from 4.5 to 4.8 ng g −1, which is well below the maximum residue limit set by Codex Alimentarius Commission and European Commission. Percentage recovery of OPPs from strawberry, green apple and grape samples with the new hybrid sol–gel SPME material ranged from 65 to 125% with good precision of the method (%RSD) ranging from 0.3 to 7.4%.

Carbon nanocones/disks as new coating for solid-phase microextraction

In this article, the potential of carbon nanocones/disks as coating for solid-phase microextraction has been evaluated for the first time. The nanostructures were immobilized on a stainless steel needle by means of an organic binder. The fiber coating obtained was ca. 50 microm of thickness and 35 mm in length. The evaluation of the sorbent capacity was carried out through the determination of toluene, ethylbenzene, xylene isomers and styrene in water samples following the headspace sampling modality (15 min, 30 degrees C). The fiber was then transferred to a 10 mL vial which was sealed and heated at 110 degrees C for 15 min in the headspace module of the instrument to achieve the thermal desorption of the analytes. Then 2.5 mL of the headspace generated were injected in the gas chromatograph-mass spectrometer for analytes separation and quantitation. The detection and quantitation limits obtained for 10 mL of sample were 0.15 and 0.5 ng mL(-1) (0.6 and 2 ng mL(-1) for toluene). The optimized procedure was applied to the determination of the selected volatile compounds in waters collected from different locations. The recovery values obtained (average recovery ca. 92%) demonstrated the usefulness of the carbon nanocones/disks as sorbent material in solid-phase microextraction.

SOLID-PHASE MICROEXTRACTION DETERMINATION OF ALCOHOL USING PENCIL LEAD1*

In order to conquer the shortcomings of commercial SPME coatings: they can’t stand high temperature, are easy to drop off, the longevity of usage is short and they are too expensive, we used pencil lead as a new sorbent to analyze the alcohol in water. The linear range is 5×10−6−2.5×10−8g/mL. The detection limit is 5×10−9g/mL. We also used this method to determine the concentration of alcohol in environment water. The recoveries are 107.5% and 97%. The RSD is 5.9%. Hence the pencil lead is a very good material for solid-phase microextraction (SPME). * Nature science fund project in Hu Bei province.