Ultratrace analysis for trans,trans-muconic acid by electrophoric derivatization and capillary gas chromatography

A highly sensitive method is described for the determination of trans,trans-muconic acid (MA), a biomarker of benzene exposure. The method is based on the derivatization of MA with an electrophoric reagent, 2-(pentafluorophenoxy)ethyl-2-(piperidino)ethanesulfonate, using potassium carbonate and 18-crown-6 ether as reaction activators. The resulting pentafluorophenoxy derivative of MA was analyzed by capillary GC with an electron-capture detector (ECD). The lower quantitation limit of the method is attainable at 0.3 μM of MA with a detection limit of about 60 nM (S/N=3) (60 fmol per 1.0 μl injection). Application of the method to the analysis of MA in urine proved feasible.     

Poly(vinyl chloride)-membrane ion-selective bulk optode based on 1,10-dibenzyl-1,10-diaza-18-crown-6 and 1-(2-pyridylazo)-2-naphthol for Cu and Pb ions

An ion-selective bulk optode (ISBO) for sensing Cu²⁺ and Pb²⁺ ions based on plasticized poly(vinyl chloride) containing 1,10-dibenzyl-1,10-diaza-18-crown-6 (DBzDA18C6) as ionophore and 1-(2-pyridylazo)-2-naphthol (PAN) as chromoionophore was prepared. The effects of DBzDA18C6/PAN and NaTPB/PAN mole ratios on the response behavior of the ISBO were investigated. The ISBO membrane shows enhanced selectivities for Cu²⁺ (at 530 nm) and Pb²⁺ (at 467 nm) over alkali, alkaline earth and other transition metal ions. The optical selectivity coefficients were measured using the separate solution method (SSM) in the two corresponding wavelengths at pH=5. The detection limit for Cu²⁺ and Pb²⁺ are 3.2×10⁻⁷ and 1.0×10⁻⁸ M, respectively.     

Simultaneous determination of l-ascorbic acid, ascorbic acid-2-phosphate magnesium salt, and ascorbic acid-6-palmitate in commercial cosmetics by micellar electrokinetic capillary electrophoresis

l-Ascorbic acid (LAA) can be used as a whitening agent in cosmetics. Because of its instability, some more stable derivatives have been developed to control melanin production, such as ascorbic acid-2-phosphate magnesium salt (AAPM) and ascorbic acid-6-palmitate (AA6P). To assess the quality of cosmetics, a micellar electrokinetic capillary electrophoresis technique (MEKC) was established for simultaneous analysis of AA and its two derivatives. Separation was performed with 10 mM borate (pH 9.5) containing 50 mM sodium dodecyl sulfate (SDS) at 20 kV. The detection wavelength was 265 nm. Several parameters, including borate concentration, buffer pH, and SDS level, were investigated. On method validation, calibration curves were linear over a concentration range of 150.0-1000.0 μM for LAA and 200.0-1000.0 μM for AAPM and AA6P. For intraday and interday analysis, relative standard deviation and relative errors were all less than 3%. Limits of detection were 70 μM for AAPM and AA6P, and 50 μM for LAA. All recoveries were greater than 95%. This method was applied to quality control of commercial cosmetics.     

Determination of 3-nitroaniline in water samples by directly suspended droplet three-phase liquid-phase microextraction using 18-crown-6 ether and high-performance liquid chromatography

Liquid–liquid–liquid microextraction (LLLME) with directly suspended droplet in high-performance liquid chromatography (HPLC) has been applied as a new, rapid and easy method for the determination of 3-nitroaniline in environmental water samples. The target compound was extracted from the aqueous sample solution (donor phase, pH 13) into an organic phase and then was back-extracted into a directly suspended droplet of an acidic aqueous solution (acceptor phase, pH 0.3). In this method, without using a microsyringe as supporting device, an aqueous large droplet is freely suspended at the top-center position of an immiscible organic solvent, which is laid over the aqueous sample solution while being agitated. Then, the droplet was withdrawn into the microsyringe and directly was injected into the HPLC system with UV detection at 227 nm. Up to 148-fold enrichment of the analyte could be obtained under the optimal conditions [i.e. donor phase: 0.1 M sodium hydroxide solution (4.5 mL); organic phase: o-xylene/1-octanol (90:10, v/v; 250 μL); acceptor phase: 0.5 M hydrochloric acid and 500 mM 18-crown-6 ether (6 μL); extraction time: 60 s; back-extraction time: 6 min and stirring rate: 600 rpm]. The limit of detection was 1 μg/L (n = 7) and the relative standard deviation (RSD, n = 5) was 4.9 at S/N = 3. The calibration graph was linear in the range of 5–1500 μg/L with r = 0.9983. All experiments were carried out at room temperature (22 ± 0.5 °C).     

Determination of nateglinide in human plasma by high-performance liquid chromatography with pre-column derivatization using a coumarin-type fluorescent reagent

A sensitive and selective high-performance liquid chromatographic method has been developed and validated for the determination of nateglinide in human plasma. Nateglinide and the internal standard, undecylenic acid, were extracted from plasma by liquid-liquid extraction using a mixture of ethyl acetate-diethyl ether, 50:50 (v/v). Pre-column derivatization reaction was performed using a coumarin-type fluorescent reagent, N-(7-methoxy-4-methyl-2-oxo-2H-6-chromenyl)-2-bromoacetamide. The derivatization proceeded in acetone in the presence of potassium carbonate and catalyzed by 18-crown-6 ether. The fluorescent derivatives were separated under isocratic conditions on a Hypersil BDS-C8 analytical column (250.0 mm × 2.1 mm i.d., particle size 5 μm) with a mobile phase that consisted of 65% acetonitrile in water and pumped at a flow rate of 0.50 mL min⁻¹. The excitation and emission wavelengths were set at 345 and 435 nm, respectively. The assay was linear over a concentration range of 0.05-16.00 μg mL⁻¹ for nateglinide with a limit of quantitation of 0.05 μg mL⁻¹. Quality control samples (0.05, 4.50 and 16.00 μg mL⁻¹) in five replicates from five different runs of analysis demonstrated intra-assay precision (%coefficient of variation <6.8%), inter-assay precision (%coefficient of variation <1.6%) and an overall accuracy (%relative error) less than −3.4%. The method can be used to quantify nateglinide in human plasma covering a variety of pharmacokinetic or bioequivalence studies.     

Highly sensitive fluorescence detection with Hg-lamp and photon counter in microchip capillary electrophoresis

A microchip capillary electrophoresis system with highly sensitive fluorescence detection is reported. The system was successfully constructed using an inverted fluorescence microscope, a highly sensitive photon counter, a photomultiplier tube (PMT) and a capillary electrophoresis microchip. This system can be applied to the fluorescence detection with various wavelengths (300-600 nm). Different fluorescence reagents require different excitation wavelengths. The wavelengths of UV light (300-385 nm), blue light (450-480 nm) and green light (530-550 nm) are employed to excite Titan yellow, fluorescence-5-isothiocyanate (FITC) and Rhodamine 6G, respectively. The detection limit (S/N = 3) of FITC is 7 × 10⁻¹⁰ M, which is 2-3 orders of magnitude lower than that obtained with the lamp-based fluorescence and PMT detection system and approaches the data gained by the laser-induced fluorescence detection. The linear relationship is excellent within the range of concentration 1.3 × 10⁻⁹ to 6.5 × 10⁻⁸ M FITC. It offers a new method to widen the application of the lamp-based fluorescence detection.     

Development and validation of LC methods with visible detection using pre-column derivatization and mass detection for the assay of voglibose

Two sensitive and selective liquid chromatographic methods were developed for the assay of voglibose (VB) and validated as per International Conference on Harmonization (ICH) guidelines. First method is based on the pre-column derivatization of VB followed by visible detection (LC-VD) and second method involves mass spectrometric detection (LC-MS). In LC-VD method, VB was derivatized with sodium metaperiodate and 3-methyl-2-benzothiazolinone hydrazone hydrochloride monohydrate (MBTH). The derivatized color product of VB (DCPVB) was run through Novapak C18 (300 × 3.9 mm, 4 μm) column using the mobile phase containing buffer (0.01 M mixture of sodium di hydrogen orthophosphate and disodium hydrogen orthophosphate, pH 6.0) and acetonitrile in 35:65 v/v ratio. The eluted DCPVB was monitored at 667 nm. The fixation of optimum conditions in LC-VD method is described. DCPVB structure was confirmed by mass spectral analysis. In LC-MS method, VB was passed through Venusil XBPPH (150 × 4.6 mm, 5 μm) column using a 95:5 v/v mixture of 0.01% formic acid and methanol as mobile phase. The assay concentrations of VB in pure form and in tablets for LC-VD and LC-MS methods are 25 and 5 ng ml⁻¹, respectively.     

Quantification of glutathione and glutathione disulfide in human plasma and tobacco leaves by capillary electrophoresis with laser-induced fluorescence detection

A new capillary electrophoresis (CE) method with laser-induced fluorescence (LIF) detection was developed for the rapid separation and sensitive detection of glutathione (GSH) and glutathione disulfide (GSSH) after derivatization by 4-chloro-7-nitrobenzo-2-oxa-1,3-diazol (NBD-Cl). The derivatization and separation conditions were investigated in detail and the optimums were obtained. Under the optimum experiment conditions, linear relationships between the peak height and concentrations of the analytes in normal and second-derivative electrophoregrams were obtained (0.22-45.00 μM). The detection limits for glutathione and glutathione disulfide in normal and second-derivative electrophoregrams were 0.046 and 0.012 μM and 0.046 and 0.014 μM, respectively. The method was applied to the analysis of glutathione and glutathione disulfide in human plasma and tobacco leaves with satisfactory results.     

Development of a rapid and sensitive method for determination of cysteine/cystine ratio in chemically defined media

Two rapid, sensitive and quantitative methods for the determination of the cysteine and cystine ratio in complex defined media feedstock using monolithic reversed-phase liquid chromatography (RPLC) and RPLC–MS are presented. Cysteine is pre-derivatised with purified 2-chloro-1-methylquinolinium tetrafluoroborate (CMQT) and separated from other derivatisation products on a narrow-bore 50 mm × 2 mm I.D. monolithic C₁₈ column with UV detection at 355 nm. For reversed-phase LC (RPLC) the separation is carried out isocratically using a mobile phase of 50 mM trichloroacetic acid (TCA) adjusted to pH 2.5 with lithium hydroxide (LiOH) and acetonitrile (83:14) pumped at 1.5 mL/min with an elevated column temperature. For RPLC–MS an ammonium acetate and acetonitrile gradient method was developed with a reduced flow rate of 0.3 mL/min. The treatment of the samples consisted of dividing them into two aliquots, the first aliquot is analysed for cysteine and the second aliquot is analysed for cystine after its quantitative reduction to cysteine using tris(2-carboxyethyl)phosphine (TCEP). Both methods are linear, with R² > 0.999 for 0.25–500 μM for cysteine and 0.25–250 μM for cystine using the LC–UV method, sensitive, with detection limit of 36 nM for cysteine, and precise, with ≤1.1% RSD for both retention time and peak area (n = 6). Samples (n = 31) of an industry standard and supplied chemically defined media feedstock were analysed, finding cysteine ranging from 1.56 to 2.26 μg/mL and cystine from 1062.02 to 1348.13 μg/mL.     

Optimized chromatographic and bioluminescent methods for inorganic pyrophosphate based on its conversion to ATP by firefly luciferase

Two new methods for inorganic pyrophosphate (PPi) quantification are described. They are based on the enzymatic conversion of PPi into ATP by firefly luciferase (Luc, E.C. 1.13.12.7) in the presence of dehydroluciferyl-adenylate (L-AMP) followed by the determination of ATP by one of two different procedures, either UV-monitored (260 nm) ion-pair-HPLC (IP-HPLC) (method A) or luciferase-dependent bioluminescence in the presence of its substrate, firefly luciferin (d-LH₂) (method B). These methods were subjected to optimization using experimental design methodologies to obtain optimum values for the selected factors: method A—incubation time (t_inc = 15 min), inactivation time of the enzyme (t_inac = 2 min), pH of the reaction mixture (pH 7.50) and the concentrations of L-AMP ([L-AMP] = 40 μM) and luciferase ([Luc] = 0.1 μM); method B—concentrations of L-AMP ([L-AMP] = 2 μM), luciferase ([Luc] = 50 nM) and luciferin ([LH₂] = 30 μM). Method A has a linear response over the range of 0.1-20 μM of PPi, with a limit of detection (LOD) of 0.5 μM and a limit of quantitation (LOQ) of 1.8 μM. Precision, expressed as relative standard deviation (R.S.D.), is 7.4% at 1 μM PPi and 5.9% at 8 μM PPi. Method B has a linear response over the range of 0.75-6.0 μM of PPi, with LOD and LOQ of 0.624 and 2.23 μM, respectively, and a R.S.D. of 5.1% at 2.5 μM PPi and 4.9% at 5 μM PPi. Under optimized conditions sensitive and robust methods can be obtained for the analysis of PPi impurities in commercial nucleotides and tripolyphosphate (P₃).     

On-line solid-phase extraction-HPLC-fluorescence detection for simultaneous determination of puerarin and daidzein in human serum

Response surface methodology (RSM) was applied to the optimization of on-line solid-phase extraction (SPE) parameters, and an automated system of on-line SPE coupled with high-performance liquid chromatography (HPLC) with fluorescence detection was developed for the determination of puerarin and daidzein in human serum. The human serum sample of 50 μL was injected into a conditioned C18 SPE cartridge, and the matrix was washed out with acetonitrile-KH₂PO₄-triethylamine buffer (0.01 M, pH 7.4) (3:97, v/v) for 3 min at a flow rate of 0.25 mL/min. Then the target analytes were eluted and transferred to the analytical column. A chromatographic gradient elution was programmed with the mobile phase consisting of acetonitrile and KH₂PO₄-triethylamine buffer, and the analytes were determined with a fluorescence detector at excitation wavelength of 350 nm and emission wavelength of 472 nm, respectively. The proposed method presented good linear relations (0.85-170 μg/mL for puerarin and 0.2-40 μg/mL for daidzein), satisfactory precision (RSD < 8%), and accredited recovery (92.5-107.8%).     

Determination of ammonium,calcium, magnesium,potassium and sodium in drinking waters by capillary zone electrophoresis on a column-coupling chip

This work deals with simultaneous determination of ammonium, calcium, magnesium, sodium and potassium in drinking waters by capillary zone electrophoresis (CZE) on a column-coupling (CC) chip with suppressed hydrodynamic and electroosmotic transports. CZE separations were carried out in a propionate background electrolyte at a low pH (3.2) containing 18-crown-6-ether (18-crown-6) to reach a complete resolution of the cations. In addition, triethylenetetramine (TETA) coated the inner wall surface of the chip channels. The concentration limits of detection (cLOD) for the studied cations ranged from 4.9 to 11.5 μg/l concentrations using a 900 nl volume of the sample injection channel. 93–106% recoveries of the cations in drinking waters indicate a good predisposition of the present method to provide accurate analytical results.     

Electrochemical detection of dopamine using arrays of liquid-liquid micro-interfaces created within micromachined silicon membranes

The detection of protonated dopamine by differential pulse voltammetry (DPV) and square wave voltammetry (SWV) at arrays of micro-interfaces between two immiscible electrolyte solutions (μITIES) is presented. Microfabricated porous silicon membranes (consisting of eight pores, 26.6 μm in radius and 500 μm pore-pore separation, in a hexagonal layout) were prepared by photolithographic and etching procedures. The membrane pores were fabricated with hydrophobic internal walls so that the organic phase filled the pores and created the liquid interface at the aqueous side of the membrane. These were used for harnessing the benefits of three-dimensional diffusion to the interface and for interface stabilisation. The liquid-liquid interface provides a simple method to overcome the major problem in the voltammetric detection of dopamine at solid electrodes due to the co-existence of ascorbate at higher concentrations. Selectivity for dopamine over ascorbate was achieved by the use of dibenzo-18-crown-6 (DB18C6) for the facilitated ion transfer of dopamine across the μITIES array. Under these conditions, the presence of ascorbate in excess did not interfere in the detection of dopamine and the lowest concentration detectable was ca. 0.5 μM. In addition, the drawback of current signal saturation (non-linear increase of the peak current with the concentration of dopamine) observed at conventional (millimetre-sized) liquid-liquid interfaces was overcome using the microfabricated porous membranes.     

A new high-speed hollow fiber based liquid phase microextraction method using volatile organic solvent for determination of aromatic amines in environmental water samples prior to high-performance liquid chromatography

A new and fast hollow fiber based liquid phase microextraction (HF-LPME) method using volatile organic solvents coupled with high-performance liquid chromatography (HPLC) was developed for determination of aromatic amines in the environmental water samples. Analytes including 3-nitroaniline, 3-chloroaniline and 4-bromoaniline were extracted from 6 mL basic aqueous sample solution (donor phase, NaOH 1 mol L⁻¹) into the thin film of organic solvent that surrounded and impregnated the pores of the polypropylene hollow fiber wall (toluene, 20 μL), then back-extracted into the 6 μL acidified aqueous solution (acceptor phase, HCl 0.5 mol L⁻¹) in the lumen of the two-end sealed hollow fiber. After the extraction, 5 μL of the acceptor phase was withdrawn into the syringe and injected directly into the HPLC system for the analysis. The parameters influencing the extraction efficiency including the kind of organic solvent and its volume, composition of donor and acceptor phases and the volume ratio between them, extraction time, stirring rate, salt addition and the effect of the analyte complexation with 18-crown-6 ether were investigated and optimized. Under the optimal conditions (donor phase: 6 mL of 1 mol L⁻¹ NaOH with 10% NaCl; organic phase: 20 μL of toluene; acceptor phase: 6 μL of 0.5 mol L⁻¹ HCl and 600 m mol L⁻¹ 18-crown-6 ether; pre-extraction and back-extraction times: 75 s and 10 min, respectively; stirring rate: 800 rpm), the obtained EFs were between 259 and 674, dynamic linear ranges were 0.1-1000 μg L⁻¹ (R > 0.9991), and also the limits of detection were in the range of 0.01-0.1 μg L⁻¹. The proposed procedure worked very well for real environmental water samples with microgram per liter level of the analytes, and good relative recoveries (91-102%) were obtained for the spiked sample solutions.     

Development of novel detection reagent for simple and sensitive determination of trace amounts of formaldehyde and its application to flow injection spectrophotometric analysis

In this paper, a novel detection reagent for formaldehyde determination is proposed, and is applied to a simple and highly sensitive flow injection method for the spectrophotometric determination of formaldehyde. The method is based on the reaction of formaldehyde with methyl acetoacetate in the presence of ammonia. The increase in the absorbance of the reaction product was measured at 375 nm. An inexpensive light emitting diode (LED)-based UV detector (375 nm) was, for the first time, used. Under the optimized experimental conditions, formaldehyde in an aqueous solution was determined over the concentration range from 0.25 to 20.0 × 10⁻⁶ M with a liner calibration graph; the limit of detection (LOD) of 5 × 10⁻⁸ M (1.5 μg L⁻¹) was possible. The relative standard deviation of 12 replicate measurements of 5 × 10⁻⁶ M formaldehyde was 1.2%. Maximum sampling throughput was about 21 samples/h. The effect of potential interferences such as metals, organic compounds and other aldehyde was also examined. The analytical performance for formaldehyde determination was compared with those obtained by the conventional acetylacetone method, which uses visible absorption spectrophotometry. Finally, the proposed method was successfully applied to the determination of formaldehyde in natural water samples.     

A simple and sensitive resonance scattering spectral method for determination of hydroxyl radical in Fenton system using rhodamine S and its application to screening the antioxidant

Based on resonance scattering (RS) effect of rhodamine dye association particles, a new resonance scattering method for the determination of hydroxyl free radical from Fenton reaction was developed. In HCl-NaAc buffer solution, the OH of Fenton reaction oxidized the excess I⁻ to I₃⁻. The I₃⁻ combined, respectively, with rhodamine B (RhB), butyl rhodamine B (b-RhB), rhodamine 6G (RhG) and rhodamine S (RhS) to form association particles that exhibit stronger resonance scattering effect at 420 nm and 610 nm. However, the RS peak at about 610 nm was interfered with its synchronous fluorescence peak at 580 nm for RhB, 580 nm for b-RhB, 560 nm for RhG and 560 nm for RhS, respectively. The concentration of H₂O₂ in the range of 0.648-21.6 μmol/L, 0.423-13.0 μmol/L, 0.216-13.0 μmol/L and 0.092-13.0 μmol/L was linear to its resonance scattering intensity at 420 nm. Its detection limit was 0.15 μmol/L, 0.10 μmol/L, 0.092 μmol/L and 0.044 μmol/L, H₂O₂, respectively. This RhS RS method was applied to selection of the antioxidant, with satisfactory results.     

Functionalization of graphene with electrodeposited Prussian blue towards amperometric sensing application

Prussian blue (PB) was grown compactly on graphene matrix by electrochemical deposition. The as-prepared PB-graphene modified glassy carbon electrode (PB-graphene/GCE) showed excellent electrocatalytic activity towards both the reduction of hydrogen peroxide and the oxidation of hydrazine, which could be attributed to the remarkable synergistic effect of graphene and PB. The PB-graphene/GCE showed sensitive response to H₂O₂ with a wide linear range of 10-1440 μM at 0.0 V, and to hydrazine with a wide linear range of 10-3000 μM at 0.35 V. The detection limit was 3 μM and 7 μM, respectively, and both of them had rapid response within 5 s to reach 95% steady state response. The wide linear range, good selectivity and long-time stability of the PB-graphene/GCE make it possible for the practical amperometric detection of hydrogen peroxide and hydrazine.     

Simultaneous determination of nitrite and nitrate in dew, rain, snow and lake water samples by ion-pair high-performance liquid chromatography

A simple, fast, sensitive and accurate reversed-phase ion-pair HPLC method for simultaneous determination of nitrite and nitrate in atmospheric liquids and lake waters has been developed. Separations were accomplished in less than 10 min using a reversed-phase C₁₈ column (150 mm × 2.00 mm i.d., 5 μm particle size) with a mobile phase containing 83% 3.0 mM ion-interaction reagent tetrabutylammonium hydroxide (TBA-OH) and 2.0 mM sodium phosphate buffer at pH 3.9 and 17% acetonitrile (flow rate, 0.4 mL/min). UV light absorption responses at 205 nm were linear over a wide concentration range from 100 μg/mL to the detection limits of 10 μg/L for nitrite and 5 μg/L nitrate. Quantitation was carried out by the peak area method. The relative standard deviation for the analysis of nitrite and nitrate was less than 3.0%. This method was applied for the simultaneous determination of nitrite and nitrate in dew, rain, snow and lake water samples collected in southeast Massachusetts. Nitrate was found being present at 4.79-5.99 μg/mL in dew, 1.20-2.63 μg/mL in rain, 0.32-0.60 μg/mL in snow and 0.12-0.23 μg/mL in lake water. Nitrite was only a minor species in dew (0.62-0.83 μg/mL), rain (<0.005-0.14 μg/mL), snow (0.021-0.032 μg/mL) and lake water (0.12-0.16 μg/mL). High levels of nitrite and nitrate observed in dew water droplets may constitute an important source of hydroxyl radicals in the sunny early morning.     

Liquid chromatographic determination of vanadium in petroleum oils and mineral ore samples using 2-acetylpyridne-4-phenyl-3-thiosemicarbazone as derivatizing reagent

Liquid chromatographic method has been developed, based on precolumn derivatization of vanadium(V) with 2-acetylpyridine-4-phenyl-3-thiosemicarbazone (APPT). The complex is extracted in chloroform together with palladium(II), tin(II) and iron(III) and eluted and separated completely from Kromasil 100 C-18, 10 μm (25 cm × 4.6 mm i.d.) column with methanol:water:acetonitrile (60:30:10, v/v/v) with a flow rate of 1 ml/min. UV detection was at 260 nm. Linear calibration curve was obtained with 1-12.5 μg/ml vanadium(V) with detection limit of 8 ng/injection (20 μl). A number of metal ions tested did not affect the determination of vanadium. The test mixtures were analyzed for vanadium(IV) and vanadium(V) contents and relative% error was obtained ±1-8%. The method was applied for the determination of vanadium in petroleum oils and mineral ore samples with vanadium contents of 0.32-2.3 and 121.7-717.3 μg/g with R.S.D. of 1.5-4.5 and 0.38-4.7%, respectively. The results correlated with reported values and by atomic absorption spectrophotometry.     

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%.