Polyaniline/graphene oxide nanocomposite as a sorbent for extraction and determination of nicotine using headspace solid-phase microextraction and gas chromatography–flame ionization detector

A solid-phase microextraction fiber was prepared by polyaniline/graphene oxide nanocomposite as sorbent on the surface of a platinized stainless steel wire using electrospinning technique. The nanocomposite structure was characterized by scanning electron microscopy and Fourier transform infrared spectroscopy. The polyaniline/graphene oxide nanocomposite fiber was used for the determination of nicotine from tobacco samples using headspace solid-phase microextraction method and gas chromatography–flame ionization detection. Influential experimental variables on the extraction efficiency of nicotine, such as extraction time and temperature, humidity and desorption conditions, were evaluated and optimized. Under the optimal experimental conditions? the limit of detection, linear dynamic range, intraday and inter-days precisions were found to be 0.01 μg g^?1, 0.05–700 µg g^?1 (R²?=?0.996), 6.9 and 8.1%, respectively. Comparison of the polyaniline/graphene oxide nanocomposite sorbent with polyaniline and commercial fibers shows longer durability, larger capacity and higher extraction efficiency. The polyaniline/graphene oxide nanocomposite fiber was successfully applied for the determination of nicotine in tobacco samples.     

Trace analysis of Pt (IV) metal ions in roadside soil and water samples by Fe3O4/graphene/polypyrrole nanocomposite as a solid-phase extraction sorbent followed by atomic absorption spectrometry

A novel Fe₃O₄/graphene/polypyrrole nanocomposite has been successfully synthesised via a simple chemical method and applied as a new magnetic solid-phase extraction (MSPE) sorbent for the separation and pre-concentration of trace amounts of Pt (IV) in environmental samples followed by flame atomic absorption spectrometric (FAAS) detection. The nanocomposite has been characterised by scanning electron microscopy (SEM), transmission electron microscopy (TEM) and Fourier transform infrared (FTIR) spectroscopy. Seven important parameters, affecting the extraction efficiency of Pt (IV), including pH, adsorption time, desorption solvent type and concentration, desorption time, elution volume and sample volume, were investigated. Under the optimised conditions, the calibration graph was linear in the range of 50–1500 μg L^?1 (R = 0.993). The detection limit and pre-concentration factor (PF) for Pt (IV) were found to be 16 μg L^?1 and 112.5, respectively. Under the optimised solid-phase extraction (SPE) conditions, the adsorption isotherm and the adsorption capacity of the nanocomposite for Pt (IV) were studied. Pt (IV) adsorption equilibrium data were fitted well to the Langmuir isotherm and the maximum adsorption capacity of the magnetic sorbent was calculated from the Langmuir isotherm model as 416.7 mg g^?1. The precision of the method was studied as intraday and interday variations. A relative standard deviation percentage (RSD%) value less than 3.0 indicates that the method is precise. Also, the accuracy of the method was tested by the analysis of the standard reference material (NIST SRM 2556) and by recovery measurements on spiked real samples. It was also shown that the optimised method was suitable for the analysis of trace amounts of Pt (IV) in roadside soil, tap water and wastewater samples.     

A highly thermal-resistant electrospun-based polyetherimide nanofibers coating for solid-phase microextraction

A high-temperature-resistant solid-phase microextraction (SPME) fiber was prepared based on polyetherimide (PEI) by the electrospinning method. The PEI polymeric solution was converted to nanofibers using high voltages and directly coated on a stainless steel SPME needle. The scanning electron microscopy images of PEI coating showed fibers with diameter range of 500–650 nm with a homogeneous and smooth surface morphology. The SPME nanofibers coating was optimized for PEI percentage, electrospinning voltage, and time. The extraction efficiency of the coating was investigated for headspace SPME of some environmentally important polycyclic aromatic hydrocarbons from aqueous samples followed by gas chromatography–mass spectrometry measurement. In addition, the important extraction parameters including extraction temperature, extraction time, ionic strength, as well as desorption temperature and time were investigated and optimized. The detection limits of the method under optimized conditions ranged from 1 to 5 ng L^?1 using time-scheduled selected ion monitoring mode. The relative standard deviations of the method were between 1.1 and 7.1 %, at a concentration level of 500 ng L^?1. The calibration curves of polycyclic aromatic hydrocarbons showed linearity in the range of 5–1000 ng L^?1. The developed method was successfully applied to real water samples and the relative recovery percentages obtained from the spiked water samples were from 84 to 98 % for all the selected analytes except for acenaphthene which was from 75 to 106 %.     

Determination of Chlorophenoxy Acid Herbicides in Water Samples by Suspended Liquid-Phase Microextraction�CLiquid Chromatography

In this study, directly suspended liquid-phase microextraction was investigated for the extraction and determination of five chlorophenoxy acid herbicides in water samples. The optimized parameters for extraction of chlorophenoxy acid herbicides were 1 M HCl concentration in sample solution, solution temperature 20 °C, 45-min extraction time, 1,000 rpm stirring rate, 25 ??L extracting solvent volume and without NaCl addition. Under the optimum conditions, the enrichment factor ranged from 192 to 390. Calibration curves yielded good linearity (R ² > 0.999) and the linear range was 5.0?C500.0 ??g L^?1, limit of detection was 0.3?C0.4 ??g L^?1 and limit of quantification was 1?C2 ??g L^?1 for analytes and the relative standard deviations were in the range of 3?C10% (n = 3). Finally, the proposed method was successfully applied to the quantification of five chlorophenoxy acid herbicides in water samples and recovery was in the range of 74?C110%.     

Ultrasound-Assisted Dispersive Liquid�CLiquid Microextraction Combined with Low Solvent Consumption for Determination of Polycyclic Aromatic Hydrocarbons in Seawater by GC�CMS

Ultrasound-assisted dispersive liquid?Cliquid microextraction (USA-DLLME) with low solvent consumption was demonstrated for gas chromatography-mass spectrometry (GC?CMS) determination of 16 typical polycyclic aromatic hydrocarbons (PAHs) in seawater samples. Factors affecting the extraction process, such as extraction and dispersive solvent, phase ratio, temperature, extraction and centrifugation time, were investigated thoroughly and optimized. The linear range was 20?C2,000 ng L^?1 except for acenaphthylene (Acy) at 10?C2,000 ng L^?1 and phenanthrene (Phe), fluoranthene (Flu) and pyrene (Py) all at 5?C2,000 ng L^?1. Enrichment factors (EFs) ranging from 722 to 8,133 were obtained, achieving limits of detection at 1.0?C10.0 ng L^?1. The method attained good precision (relative standard deviation, RSD) from 3.4 to 14.2% for spiked 50 ng L^?1 individual PAHs standards. Method recoveries were in the range 87?C124% and 70?C127% for spiked samples from simulated seawater and beach seawater, respectively. The proposed USA-DLLME helped to obtain about 1.1?C10 times higher EFs in a minimum amount of solvent and in less time than traditional DLLME.     

Simultaneous determination of eight antibiotics from distinct classes in surface and wastewater samples by solid-phase extraction and high-performance liquid chromatography–electrospray ionisation mass spectrometry

A reliable multiclass method has been developed and validated for the determination of eight antibiotics from distinct classes (sulfonamides, macrolides, fluoroquinolones, tetracyclines, cephalosporins and dihydrofolate reductase inhibitors) in wastewater – influent and effluent – and surface water from Porto Alegre, Brazil. The pre-concentration and clean-up was conducted with a simple and fast protocol using solid-phase extraction allowing a 100-fold concentration factor. The proposed method was validated by using spiked blank wastewater samples in terms of linearity, repeatability, reproducibility, recovery, matrix effects and limits of detection and quantification. Recovery was obtained in the range of 66–149%. Method limit of quantification ranged between 1.6 and 61.7 ng L^?1. Samples (n = 16) were taken from January to August 2011 in one wastewater treatment plant, which uses conventional biological treatment. Sulfamethoxazole and trimethoprim show higher concentration, ranging from >10 to <6500 ng L^?1, whereas erythromycin presented the lower amount. Differences between influent and effluent profiles were discussed. Surface water samples (n = 8) were collected in Arroio Diluvio, in four sampling points, in February 2012. From the eight antibiotics analysed, five were detected: sulfamethoxazole, trimethoprim, azythromicyn, ciprofloxacin and norfloxacin, in a concentration range of 376–572 ng L^?1, 27–94 ng L^?1, 24–40 ng L^?1, 16–66ng L^?1 and 30–54 ng L^?1, respectively.     

Graphene oxide reinforced polyamide nanocomposite coated on paper as a novel layered sorbent for microextraction by packed sorbent

ABSTRACT

In this work, a novel layered sorbent for microextraction by packed sorbent (MEPS) was introduced, which has been prepared by coating graphene oxide/polyamide (GO/PA) nanocomposite (NC) onto cellulose paper through solvent exchange method. Scanning electron microscopy (SEM) was applied to investigate the surface characteristic and morphology of PA and GO/PA NC coated on cellulose paper. The prepared MEPS device was used for extraction of organophosphorous pesticides (OPPs) including chlorpyrifos, fenthion, fenithrothion, ethion, edifenphos and phosalone in environmental aqueous samples followed by detection using gas chromatography-flame ionisation detector (GC-FID). Important parameters affecting the MEPS method including pH of sample solution, extraction draw-discard cycles, sorbent layers, desorption solvent volume and desorption draw-eject number were studied and optimised using central composite design (CCD). Based on the method validation, limits of detection (LODs) were in the range of 0.2–1 µg L^?1. The calibration graphs for chlorpyrifos, fenthion and edifenphos are linear in the concentration range of 1 to 500 µg L^?1; for ethion and phosalone are linear in the range of 1–1000 µg L^?1 and for fenithrothion is linear in the range of 3–1000 µg L^?1. The method precision (RSD %) with six replicates determinations was in the range of 3 to 9.4 % and 3.9 to 11.9% for distilled water and spiked river water sample, respectively, at the concentration level of 300 µg L^?1 . The developed method was applied successfully to determine OPP compounds in river, dam and tap water samples; accordingly, the relative recoveries (RR%) were obtained in the range of 77.8 to 113.3%.     

A new approach to extraction and preconcentration of Ce(III) from aqueous solutions using magnetic reduced graphene oxide decorated with thioglycolic-acid-capped CdTe QDs

In the present study, a nanocomposite consisting of magnetic reduced graphene oxide decorated with thioglycolic-acid-capped CdTe quantum dots (TGA/CdTe QDs/Fe₃O₄/rGO) was synthesised using simple ‘hydrothermal method’ and applied as a nanosorbent for extraction and preconcentration of cerium (Ce)(III) from aqueous solutions prior to inductively coupled plasma-optical emission spectroscopy detection. Under the optimised extraction conditions, the calibration graph for Ce(III) was linear in a concentration range of 0.1–511.0 μg L^?1 with a correlation coefficient of 0.9986. A detection limit of 0.1 μg L^?1 Ce(III) with an enrichment factor of 125 was obtained. Precisions, expressed as relative standard deviation for single-sorbent repeatability and sorbent-to-sorbent reproducibility, were 3.6% and 9.1% (n = 5), respectively. Finally, spiked sea, mineral and tap waters were analysed to evaluate the performance of the proposed method. The high recoveries indicated that the suggested protocol was acceptable for determination of Ce(III) ions in the water samples. The use of QDs and study of their ability for preconcentration of metal ions is an important achievement towards designing novel adsorbents with high efficiency.     

Evaluation of the Counter Ions in Doped Porous Polyaniline Coatings on Stainless Steel Wires for Solid Phase Microextraction of Chlorophenolics in Water Combined with High-Performance Liquid Chromatography

Porous polyaniline coatings doped with different counter ions were electrodeposited on the surface of stainless steel wires using controlled potentiostatic coulometry. Prior to electropolymerization, the stainless steel wires were chemically etched to improve subsequent immobilization of the polyaniline coatings on the substrate and to increase the effective surface area. Porous polyaniline coatings doped with sulfate, nitrate, and perchlorate counter ions were employed for solid-phase microextraction (SPME) of 2-chlorophenol, 2,4-dichlorophenol, triclosan, and 2,4-dichlorophenoxyacetic acid coupled to high-performance liquid chromatography. The results demonstrated that the perchlorate doped polyaniline coating exhibited the highest extraction efficiency for 2-chlorophenol, 2,4-dichlorophenol, and triclosan at pH 5.0, indicating that the extraction capability was modified by introducing different counter ions into the coatings. As a result, the perchlorate doped polyaniline coated fiber was further used for the optimization of extraction condition s . The method provided linear dynamic ranges over 2 to 4 orders of magnitude. The limits of detection were 0.006 µg · L^?1, 0.005 µg · L^?1, and 0.040 µg · L^?1 for 2-chlorophenol, 2,4-dichlorophenol, and triclosan, respectively. The precision expressed as the relative standard deviation ranged from 2.20% to 5.04% for spiked water at 10 µg · L ^?1 (n = 5) and the fiber to fiber reproducibility was between 3.27% and 5.91% (n = 5). The method was successfully applied to the determination of chlorophenolics in real water samples. The recoveries of chlorophenolics in spiked water at 5.0 µg · L^?1 were between 99.60% and 108.7% with relative standard deviations between 3.24% and 5.47%.     

Imprinted Azorubine electrochemical sensor based upon composition of MnO<Subscript>2</Subscript> and 1-naphthylamine on graphite nanopowder

A new sensitive and selective molecularly imprinted electrochemical sensor was developed for Azorubine determination. This sensor was based on molecularly imprinted polymer composed of poly(1-naphthylamine), triphenylamine (as cross-linkers) and dispersed MnO₂ nanorod particles on graphite nanopowders. The structure of the prepared nanocomposite was characterized by X-ray powder diffraction, energy-dispersive X-ray spectroscopy, field emission scanning electron microscopy, transmission electron microscopy and Fourier transform infrared spectroscopy. Calibration curve of the imprinted sensor was linear in the concentration range 1–12 mg L^??1 with a detection limit of 0.57 mg L^??1. The application of the sensor was checked by the determination of Azorubine in a water sample.     

Determination of Zn(II) in rock and vegetable samples after acidic digestion followed by ultrasound-assisted solid-phase extraction with reduced graphene oxide as novel sorbent,in combination with flame atomic absorption spectrometry

Graphene, a novel class of carbon nanostructures, has great promise for use as sorbent materials because of its ultrahigh specific surface area. A new method using reduced graphene oxide (RGO) as sorbent was developed for the preconcentration of trace amounts of zinc (Zn) to its determination by flame atomic absorption spectrometry. Zinc could be adsorbed quantitatively on RGO in the pH range of 1–9, and then eluted completely with 0.5 mL of 0.1 mol L^?1 HCl. Some effective parameters on the extraction were selected and optimized. Under optimum conditions, the calibration graph was linear in the concentration range of 0.2–15 μg L^?1 with a detection limit of 0.14 μg L^?1 with an enrichment factor of 100.12. The relative standard deviation for ten replicate measurements of 10 μg L^?1 of Zn was 0.58 %, respectively. The proposed method was successfully applied in the analysis of rock and vegetable samples. Good spiked recoveries over the range of 99.9–100 % were obtained. This work not only proposes a useful method for sample preconcentration, but also reveals the great potential of graphene as an excellent sorbent material in analytical processes.     

Rotating disk sorptive extraction of triclosan and methyl-triclosan from water samples

A method of sample preparation based on use of rotating disk sorptive extraction (RDSE) has been developed for determination of triclosan (TCS) and methyl-triclosan (MTCS) in water samples. The sorptive and desorptive behavior of the analytes was studied by use of a rotating disk coated with polydimethylsiloxane (PDMS) on one of its surfaces. Chemical and extraction behavior were studied to establish the best conditions for extraction. The optimum conditions for both analytes were: sample volume 25 mL, pH?4.5, NaCl concentration 6 % (w/v), disk rotational velocity 1,250 rpm, and extraction time 80 min. A desorption time of 30 min was used with 5 mL methanol. The detection limits for TCS and MTCS were 46 and 34 ng?L^?1, respectively. Recovery was evaluated at two concentrations, 160 and 800 ng?L^?1, and the values obtained were between 80 and 100 %. The method was applied to analysis of influent water at two treatment plants in Santiago, Chile.     

Electrochemical oxidation behavior of 8-azaguanine at graphene-Nafion composite film-modified glassy carbon electrode

A simple but highly sensitive electrochemical sensor for the determination of 8-azaguanine based on graphene-Nafion nanocomposite film-modified glassy carbon electrode (G-Nafion/GCE) was reported. The electrochemical behaviors of 8-azaguanine at G-Nafion/GCE were investigated by cyclic voltammetry (CV), square wave voltammetry (SWV), chronoamperometry (CA), and chronocoulometry (CC). The results showed that the electrochemical sensor exhibited excellent electrocatalytic activity to 8-azaguanine. 8-Azaguanine can be effectively accumulated at G-Nafion/GCE and produce a sensitive anodic peak, due to the synergetic functions of graphene and Nafion. Under the selected conditions, the modified electrode in pH 1.98 Britton-Robinson buffer solution showed a linear voltammetric response to 8-azaguanine within the concentration range of 5.0 × 10^?8～3.0 × 10^?5 mol L^?1, with the detection limit of 1.0 × 10^?8 mol L^?1. And, the method was also applied to detect 8-azaguanine in spiked human urine with wonderful satisfactory results.     

Simultaneous Determination of Zoalene and Its Metabolite in Chicken Muscle and Liver by SPE and UPLC�CMS-MS

This paper presents an analytical method for the simultaneous determination of zoalene and its metabolite 3-amino-5-nitro-o-toluamide (3-ANOT) in chicken muscle and liver by solid phase extraction and UPLC?CMS-MS operated in the positive and negative ionization switching mode. Samples were extracted with phosphate buffer solution and purified with OASIS^? HLB cartridge after pH adjustment. The determination was carried out using UPLC?CMS-MS on a Waters Acquity BEH C₁₈ column with 0.1% formic acid in water/acetonitrile as mobile phase with gradient elution. The linearity of the analytical response across the studied range of concentrations (2.0?C1,000 ??g L^?1) was excellent, obtaining correlation coefficients higher than 0.999. Matrix effects had been investigated for zoalene and 3-ANOT. Recovery studies were carried out on spiked chicken muscle and liver blank samples, at four concentration levels (50, 1,500, 3,000, and 4,500 ??g kg^?1 for chicken muscle and 50, 3,000, 6,000, and 9,000 ??g kg^?1 for chicken liver) performing six replicates at each level. Mean recoveries of 77.9?C94.2% with CVs of 3.2?C8.7% were obtained. The method demonstrated to be suitable for the simultaneous determination of zoalene and 3-ANOT in chicken tissues.     

Determination of Trace Chloroanilines in Environmental Water Samples Using Hollow Fiber-Based Liquid Phase Microextraction

A liquid phase microextraction method using hollow fiber to support extraction solvent was developed for enrichment of trace level chloroanilines in environmental water samples. Target analytes, 2-chloroaniline, 3-chloroaniline, 2,3-dichloroaniline, 2,4-dichloroaniline, 3,4-dichloroaniline, and 3,5-dichloroaniline were determined using gas chromatography-flame ionization detector after extraction. Experimental conditions that affect extraction efficiency were investigated and optimized. The proposed method showed a wide linear range from lower ??g L^?1 to 1,000 ??g L^?1, low detection limits (??5.1 ??g L^?1), and reasonable relative standard deviations (RSDs < 13%). Feasibility of the method was evaluated by analyzing river water samples collected from the Hudson River and the East River in New York City.     

Determination of trace amounts of nystatin in water and vaccine samples using sodium dodecyl sulfate-coated iron oxide magnetic nanoparticles followed by high-performance liquid chromatography–ultraviolet detection

In this work, magnetic solid-phase extraction based on sodium dodecyl sulfate-coated Fe₃O₄ nanoparticles has been successfully applied for extraction and preconcentration of trace amounts of nystatin from water and vaccine samples prior to high-performance liquid chromatography–ultraviolet detection. Various experimental parameters affecting extraction and recovery of the analyte, such as the amount of sodium dodecyl sulfate, pH of the sample solution, salt concentration, extraction time, sample volume and desorption conditions, were systematically studied and optimized. Under optimized conditions, nystatin was quantitatively extracted. Proper linear range with good coefficient of determination, (R ² > 0.99) and limit of detection and quantification (based on signal-to-noise ratios of 3 and 10) of 2.0 and 5.0 µg L^?1, over the investigated concentration range (5–700 µg L^?1), were obtained, respectively. The intra-day and inter-day relative standard deviations at 50 µg L^?1 level of NYS were 1.4 and 4.5% based on six replicate determinations. The accuracy of the method was evaluated by recovery measurements on spiked samples. Suitable recoveries of 96–102 and 26–44% were achieved (at spiked levels of 50, 300 and 500 µg L^?1) for water and vaccine samples, respectively.     

Fibers coated with a graphene-polyaniline nanocomposite for the headspace solid-phase microextraction of organochlorine pesticides from seawater samples

We have prepared a fiber for solid-phase microextraction of organochlorine pesticides. A graphene-polyaniline composite was electrochemically deposited on a platinum fiber by exploiting the unique properties of polyaniline and graphene. The modified fiber displays thermal stability up to 320 °C and can be used more than 70 times. It possesses high extraction efficiency due to the high specific surface of graphene. The Pt fiber was used for the extraction and subsequent GC determination of the pesticides heptachlor, aldrin, endrin and p,p’-DDT in aqueous samples. The effects of extraction time, extraction temperature, stirring rate, salinity and headspace volume were optimized. Calibration plots are linear (with an R² of 0.990) in the 0.2 to 250 μg L^–1 concentration range, and the limits of detection are below 11 ng L^–1 (at an S/N of 3). The relative standard deviations for three replicate measurements with a single fiber were <11.0 %. The recovery of the pesticides from spiked seawater samples ranged from 81 % to 112 %.

Headspace solid-phase microextraction of menthol using a sol–gel titania-based coating along with multiwalled carbon nanotubes on the surface of stainless steel fiber

Sol–gel coating technology for the preparation of solid-phase microextraction fibers involves a single-step procedure and allows for in situ creation of chemically bonded coatings which are characterized by high thermal and solvent stabilities. A novel titania sol–gel coating was prepared for the first time on a stainless steel fiber and applied for the headspace solid-phase microextraction (HS-SPME) of menthol with gas chromatography and flame ionization detection. Important parameters influencing the efficiency of SPME process, such as extraction time, extraction temperature and ionic strength, were optimized by central composite design. An extraction time of 40 min at 60 °C gave maximum extraction efficiency, when NaCl (10% w/v) was added to the aqueous sample. The analytical characteristics of the proposed method were comparable with other reported fibers. Under optimized conditions, the linearity was between 0.05 and 100 µg mL^??1. The relative standard deviations (RSDs) determined at 0.5 µg mL^??1 concentration level (n?=?5) were as follows: intra-day RSD 7.26%; inter-day RSD 10.87%; fiber-to-fiber RSD 9.05%. The relative recoveries determined after spiking a mint distillate sample at three concentration levels from 0.067 to 50.0 µg mL^??1 varied from 86 to 102%. The proposed method was successfully applied for the analysis of menthol in peppermint samples.     

LC�CMS�CMS Quantitative Determination of Brivudine in Human Plasma and Its Application to Pharmacokinetic Studies

A sensitive and specific liquid chromatography?Celectrospray ionization?Ctandem mass spectrometry method has been developed and validated for the identification and quantification of brivudine in human plasma using diclofenac as an internal standard. The method involves extraction with ethyl acetate. The analyte was separated on a C₁₈ column and analyzed in multiple reaction monitoring mode with a negative electrospray ionization interface using the [M?CH]^? ions, m/z 332.8??m/z 80.9 for brivudine, m/z 293.6??m/z 249.5 for diclofenac. The method was validated over the concentration range of 5.54?C2,836 ??g L^?1 for brivudine. The intra-and inter-day precisions were less than 8.91% in terms of relative standard deviation (RSD), and the accuracy was within ?4.22% in terms of relative error (RE). The lower limit of quantification (LLOQ) was 5.54 ??g L^?1 with acceptable precision and accuracy. There were almost no matrix effects. Recovery of brivudine spiked in drug-free plasma was higher than 77.17%. The method was used to study the pharmacokinetic profile of brivudine in human plasma after oral administration of brivudine tablets.     

Silver Nanoparticles–Polyaniline Nanocomposite for Microextraction in Packed Syringe

A rapid, convenient and reliable method for microextraction in packed syringe (MEPS) of the loop diuretic furosemide (FUR) in urine along with high-performance liquid chromatography (HPLC) was developed. A nanocomposite based on silver nanoparticles/polyaniline (Ag-NPs/PANI) was synthesized and used as the MEPS packing material. This nanocomposite was prepared conveniently using interfacial polymerization without the need for any templates or functional dopants. The feasibility of the synthesized nanocomposites was examined by isolation of FUR from diluted urine samples. After extraction, the analyte was desorbed by 200 μL of methanol. It was then dried and the residue was dissolved in 30 μL of methanol and an aliquot of 25 μL was, finally, injected into the HPLC system. Important parameters influencing the extraction and desorption processes were optimized and 25 cycles of draw–eject gave maximum peak area, when desorption was performed. The linearity was studied by preconcentration of 5 mL of diluted urine sample spiked with a standard solution of FUR in the concentration range of 15–750 μg L^?1. The coefficient of determination was satisfactory (r ² > 0.99) and the relative standard deviation (RSD %) value under the optimized condition was 8.8 %. The limit of detection and limit of quantification were 7 and 15 μg L^?1, respectively.