Synthesis of flower-like ZnO nanoparticles for label-free point of care detection of carcinoembryonic antigen.

In this work, flower-like ZnO nanoparticles (ZnONPs) were synthesized using zinc nitrate (Zn(NO3)2 6H2O) as a precursor with KOH. The morphology of the ZnONPs was controlled by varying the synthesis temperature at 50, 75 and 95 °C. The morphology and structure of ZnONPs were characterized using Scanning Electron Microscopy, and X-Ray Diffraction and Brunauer-Emmett Teller analysis. ZnONPs were successfully synthesized by a simple chemical precipitation method. A synthesis temperature of 75 °C produced the most suitable flower-like ZnONPs, which were combined with graphene nanoplatelets to develop a label-free electrochemical immunosensor for the detection of the colon cancer biomarker carcinoembryonic antigen in human serum. Under optimum conditions, the developed immunosensor showed a linear range of 0.5-10.0 ng mL-1 with a limit of detection of 0.44 ng mL-1. The label-free electrochemical immunosensor exhibited good selectivity, reproducibility, and repeatability, and recoveries were excellent. The immunosensor is used with a Near-Field Communication potentiostat connected to a smartphone to facilitate point-of-care cancer detection in low-resource locations.

Single laser synthesis of gold nanoparticles-polypyrrole-chitosan on laser-induced graphene for ascorbic acid detection.

The simultaneous synthesis of gold nanoparticles (AuNPs) and graphene by laser ablation was demonstrated. The in-situ synthesis was performed by laser ablation of a polymer substrate covered with a gold precursor dispersion. The gold precursor was prepared in a copolymer solution of pyrrole (Py) and chitosan (Chi) to improve the nucleation of gold embedded on the laser-induced graphene electrode (LIGE). The morphology of AuNPs-pPy-Chi/LIGE was studied by scanning electron microscopy and characterized electrochemically by cyclic voltammetry. A comprehensive investigation of the electrochemical and physical features of the AuNPs-pPy-Chi/LIGE was carried out. The parameters of differential pulse voltammetry were adjusted to enhance the response to ascorbic acid (AA). The AuNPs-pPy-Chi/LIGE produced two linear ranges: from 0.25 to 5.00 and 5.00-25.00 mmol L-1. The limit of detection was 0.22 mmol L-1. Hundreds of electrodes were tested to demonstrate the excellent reproducibility of the AuNPs-pPy-Chi/LIGE fabrication. Overall, the proposed electrode allows the successful detection of AA in orange juice products with acceptable accuracy (recoveries = 97 ± 2 to 109.1 ± 0.7). The preparation strategy of the proposed AuNPs-pPy-Chi/LIGE could be adapted to detect other compounds or biomarkers.

Nano-palladium-decorated bismuth sulfide microspheres on a disposable electrode integrated with smartphone-based electrochemical detection of nitrite in food samples.

Nitrite (NO2-) is widely used as an additive to extend the shelf life of food products. Excessive nitrite intake not only causes blood-related diseases but also has the potential risk of causing cancers. A disposable screen-printed electrode was modified with nano­palladium decorated bismuth sulfide microspheres (nanoPd@Bi2S3MS/SPE), and integrated with a smartphone-interfaced potentiostat to develop a portable, electrochemical nitrite sensor. NanoPd@Bi2S3MS was prepared by the hydrothermal reduction of a Bi2S3MS and Pd2+ dispersion and drop cast on the SPE. The nanoPd@Bi2S3MS/SPE was coupled with a smartphone-controlled portable potentiostat and applied to determine nitrite in food samples. The linear range of the sensor was 0.01-500 µM and the limit of detection was 0.0033 µM. The proposed system showed good repeatability, reproducibility, catalytic stability, and immunity to interferences. The proposed electrode material and a smartphone-based small potentiostat created a simple, portable, fast electrochemical sensing system that accurately measured nitrite in food samples.

A dual-electrode label-free immunosensor based on in situ prepared Au-MoO3-Chi/porous graphene nanoparticles for point-of-care detection of cholangiocarcinoma.

A novel label-free electrochemical immunosensor was prepared for the detection of carbohydrate antigen 19-9 (CA19-9) and carcinoembryonic antigen (CEA) as biomarkers of cholangiocarcinoma (CCA). A nanocomposite of gold nanoparticles, molybdenum trioxide, and chitosan (Au-MoO3-Chi) was layer-by-layer assembled on the porous graphene (PG) modified a dual screen-printed electrode using a self-assembling technique, which increased surface area and conductivity and enhanced the adsorption of immobilized antibodies. The stepwise self-assembling procedure of the modified electrode was further characterized morphologically and functionally. The electroanalytical detection of biomarkers was based on the interaction between the antibody and antigen of each marker via linear sweep voltammetry using ferrocyanide/ferricyanide as an electrochemical redox indicator. Under optimized conditions, the fabricated immunosensor showed linear relationships between current change (ΔI) and antigen concentrations in two ranges: 0.0025-0.1 U mL-1 and 0.1-1.0 U mL-1 for CA19-9, and 0.001-0.01 ng mL-1 and 0.01-1.0 ng mL-1 for CEA. The limits of detection (LOD) were 1.0 mU mL-1 for CA19-9 and 0.5 pg mL-1 for CEA. Limits of quantitation (LOQ) were 3.3 mU mL-1 for CA19-9 and 1.6 pg mL-1 for CEA. The selectivity of the developed immunosensor was tested on mixtures of antigens and was then successfully applied to determine CA19-9 and CEA in human serum samples, producing satisfactory results consistent with the clinical method.

A portable electrochemical immunosensor for ovarian cancer uses hierarchical microporous carbon material from waste coffee grounds.

A simple label-free electrochemical immunosensor for ovarian cancer (OC) detection was developed using a hierarchical microporous carbon material fabricated from waste coffee grounds (WCG). The analysis method exploited near-field communication (NFC) and a smartphone-based potentiostat. Waste coffee grounds were pyrolyzed with potassium hydroxide and used to modify a screen-printed electrode. The modified screen-printed electrode was decorated with gold nanoparticles (AuNPs) to capture a specific antibody. The modification and immobilization processes were characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The sensor had an effective dynamic range of 0.5 to 50.0 U mL-1 of cancer antigen 125 (CA125) tumor marker with a correlation coefficient of 0.9995. The limit of detection (LOD) was 0.4 U mL-1. A comparison of the results obtained from human serum analysis with the proposed immunosensor and the results obtained from the clinical method confirmed the accuracy and precision of the proposed immunosensor.

One-step electrodeposition of poly(o-phenylenediamine)-Zn composite on plaswood propeller as an extraction device for polycyclic aromatic hydrocarbons in coffee.

Coffee beans can be contaminated during roasting by polycyclic aromatic hydrocarbons (PAHs), some of which have been classified as carcinogens. An extraction device for PAHs in coffee drinks was designed with six compact DC motors rotating six sorbents. The sorbents were plaswood propellers modified by one-step electrodeposition of a poly(ortho-phenylenediamine) and Zn composite (PoPD-Zn). Benzo(a)anthracene (BaA), chrysene (Chry), benzo(b)fluoranthene (BbF), and benzo(a)pyrene (BaP) were chosen as representative PAHs. Scanning electron micrographs of the PoPD-Zn showed a porous structure. The extracted PAHs were quantified by gas chromatography coupled with a flame ionization detector. Detected concentrations of PAHs in coffee drink samples were as follows: BaA 1.4 ± 0.4 to 16.5 ± 0.8 µg L-1; Chry 0.5 ± 0.2 to 2.1 ± 0.5 µg L-1; BbF 2.2 ± 0.6 µg L-1; and BaP 6.2 ± 1.0 µg L-1. Good recoveries ranging from 82.7 ± 1.9% to 99.0 ± 0.5% were obtained.

A polypyrrole-cotton pad sorbent as micro-solid phase extractor enclosed in tea bag envelope for determination of synthetic antioxidants in non-alcoholic beverage products.

A polypyrrole (PPy)-cotton pad sorbent enclosed in tea bag envelope was developed and used in micro-solid phase extraction (µ-SPE) for the determination of butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT). After extraction, the extract was qualified and quantified by a gas chromatograph equipped with a flame ionization detector (GC-FID). Parameters influencing this developed method and the efficiency of µ-SPE were studied and optimized. Under the optimal conditions, the developed method provided good linearity in a concentration range of 0.100-100 µg L-1 for BHA and 0.050-50 µg L-1 for BHT, respectively. The limits of detection were 39.27 ± 0.52 ng L-1 for BHA and 16.96 ± 0.17 ng L-1 for BHT. Satisfactory relative recoveries of BHA and BHT were achieved in the range from 86.8 ± 1.9 to 117.1 ± 2.3% with acceptable relative standard deviation (RSD) below 8.1%. Good reproducibility was obtained with RSDs < 3.1%, for n = 6. The developed adsorbent is easy to operate, low cost, eco-friendly, reusable, with high extraction efficiency, and was successfully applied in the simultaneous synthetic antioxidant determination of non-alcoholic beverage samples.

Disposable label-free electrochemical immunosensor based on prussian blue nanocubes for four breast cancer tumor markers.

A compact and low-cost multi-electrode array (MEA) is presented, comprising four working electrodes with shared reference and auxiliary electrodes. Prussian blue was electrodeposited on the MEA using chronoamperometry with a positive potential of 0.3 V. Prussian blue nanocubes (PBNCs) were formed, which were observed using scanning electron microscopy. The precision of the four working electrodes was demonstrated using ferric/ferro cyanide (RSD <5.8%). The surface roughness of the working electrodes of the fabricated MEA was investigated by atomic force microscopy and compared with that of a commercial MEA. The PBNCs were the platform for a label-free immunosensor that detected four breast cancer tumor markers (CEA, CA125, CA153, and CA199) using specific antibodies. The processes of antibody immobilization were investigated using cyclic voltammetry and electrochemical impedance spectroscopy. The immunosensor was evaluated using real human serum samples, yielding acceptable recoveries (95.1-104.1%, RSD < 3.9) for the four tumor markers. These findings confirmed that our label-free immunosensor based on PBNCs could be a promising device for point-of-care testing and could pave the way for the establishment of new platforms for the screening of various breast cancer tumor markers.

A wireless smartphone-based "tap-and-detect" formaldehyde sensor with disposable nano-palladium grafted laser-induced graphene (nanoPd@LIG) electrodes.

We developed a fully integrated smart sensing device for on-site testing of food to detect trace formaldehyde (FA). A nano-palladium grafted laser-induced graphene (nanoPd@LIG) composite was synthesized by one-step laser irradiation of a Pd2+-chitosan-polyimide precursor. The composite was synthesized in the form of a three-electrode sensor on a polymer substrate. The electrochemical properties and morphology of the fabricated composite were characterized and the electrochemical kinetics of FA oxidation at the nanoPd@LIG electrode were investigated. The nanoPd@LIG electrode was combined with a smart electrochemical sensing (SES) device to determine FA electrochemically. The proposed SES device uses near field communication (NFC) to receive power and transfer data between a smartphone interface and a battery-free sensor. The proposed FA sensor exhibited a linear detection range from 0.01 to 4.0 mM, a limit of detection of 6.4 µM, good reproducibility (RSDs between 2.0 and 10.1%) and good anti-interference properties for FA detection. The proposed system was used to detect FA in real food samples and the results correlated well with the results from a commercial potentiostat and a spectrophotometric analysis.

Electrochemical sensor based on molecularly imprinted polymer cryogel and multiwalled carbon nanotubes for direct insulin detection.

Insulin is the polypeptide hormone that regulates blood glucose levels. It is used as an indicator of both types of diabetes. An electrochemical insulin sensor was developed using a gold electrode modified with carboxylated multiwalled carbon nanotubes (f-MWCNTs) and molecularly imprinted polymer (MIP) cryogel. The MIP provided specific recognition sites for insulin, while the macropores of the cryogel promoted the mass transfer of insulin to the recognition sites. The f-MWCNTs increased the effective surface area and conductivity of the sensor and also reduced the potential required to oxidize insulin. Insulin oxidation was directly measured in a flow system using square wave voltammetry. This MIP cryogel/f-MWCNTs sensor provided a linear range of 0.050-1.40 pM with a very low limit of detection (LOD) of 33 fM. The sensor exhibited high selectivity and long-term stability over 10 weeks of dry storage at room temperature. The results of insulin determination in human serum using the sensor compared well with the results of the Elecsys insulin assay. The developed MIP sensor offers a promising alternative for the diagnosis and treatment of diabetes.

A stir bar sorptive extraction device coupled with a gas chromatography flame ionization detector for the determination of abused prescription drugs in lean cocktail samples.

A lean cocktail is a mixed drink for the non-medical use of prescription medications that has emerged in recent years as a drug of abuse and is related to drug-facilitated crimes. The determination of active ingredients in a lean cocktail is necessary for forensic investigations. This work presents an in-house developed stir bar sorptive extraction (SBSE) device with an XAD-2 adsorbent followed by analysis using GC-FID for the extraction and determination of the five main abused prescription drugs (diphenhydramine, tramadol, chlorpheniramine, dextromethorphan and promethazine) in lean cocktail samples. Under optimized conditions, the developed method provided linearity for 1.0-250 µg mL-1 of each of the five abused prescription drugs. The limits of detection and limits of quantitation were in the respective ranges of 0.25-0.5 µg mL-1 and 1.0-1.5 µg mL-1. The percentage of extraction was 85.0-94.9%. The intra-day and inter-day precisions were 1.2-14.4% RSD and 1.4-15.8% RSD, respectively. Good relative recoveries in the range of 86.7-110.3% and 88.5-107.9% were obtained when the proposed method was applied for extraction and analysis of abused prescription drugs in five lean cocktail samples. The developed method can be a useful tool for measuring the levels of abused prescription drugs in a lean cocktail and the data could also be used as evidence in a forensic investigation.

A Fabrication of Multichannel Graphite Electrode Using Low-Cost Stencil-Printing Technique.

Multichannel graphite electrodes (MGrEs) have been designed and fabricated in this study. A template was cut from an adhesive plastic sheet using a desktop cutting device. The template was placed on a polypropylene substrate, and carbon graphite ink was applied with a squeegee to the template. The size of the auxiliary electrode (AE) as well as the location of the reference electrode (RE) of MGrEs design were investigated. Scanning electron microscopy was used to determine the thickness of the ink on the four working electrodes (WEs), which was 21.9 ± 1.8 µm. Cyclic voltammetry with a redox probe solution was used to assess the precision of the four WEs. The intra-electrode repeatability and inter-electrode reproducibility of the MGrEs production were satisfied by low RSD (<6%). Therefore, the MGrEs is reliable and capable of detecting four replicates of the target analyte in a single analysis. The electrochemical performance of four WEs was investigated and compared to one WE. The sensitivity of the MGrEs was comparable to the sensitivity of a single WE. The MGrEs' potential applications were investigated by analyzing the nitrite in milk and tap water samples (recoveries values of 97.6 ± 0.4 to 110 ± 2%).

Fluorescent cysteine probe based on a signal amplification unit, a catalyzed hairpin assembly reaction and Förster resonance energy transfer.

This work developed a sensitive DNA-based fluorescent probe comprising a cysteine binding unit and a signal amplification unit based on a catalyzed hairpin assembly (CHA) reaction. The cysteine binding unit comprises a homodimer of single-stranded DNA (ssDNA) rich in cytosine and held together by silver ions. In the presence of cysteine, the homodimer is disintegrated because of cysteine-silver binding that liberates the ssDNA, which drives the CHA reaction in the signal amplification unit. Förster resonance energy transfer (FRET) was used to report the generation of the amplified double-stranded DNA (dsDNA) product. Under the optimal conditions, the probe provided a good linearity (100-1200 nM), a good detection limit (47.8 ± 2.7 nM) and quantification limit (159.3 ± 5.3 nM), and a good sensitivity (1.900 ± 0.045µM-1). The probe was then used to detect cysteine in nine real food supplement samples. All results provided good recoveries that are acceptable by the AOAC, indicating that it has potential for practical applications.

Cavitas electrochemical sensors for the direct determination of salivary thiocyanate levels.

Noninvasive diagnosis using salivary samples to detect thiocyanate provides vital information on individual health. This article demonstrates the first example of a wearable sensing device to noninvasively assess thiocyanate levels. The customized screen-printed electrode system is integrated into a form of a mouthguard squarewave-voltammetric sensor toward the convenient and fast detection of the salivary biomarker within 15 s. The sensor with a protective film to mitigate the effect of biofouling offers high sensitivity and selectivity toward the detection of thiocyanate ions. Partial least square regression is applied to analyze the high-order squarewave-voltammetric data over the applied potential range of 0-1.75 V vs Ag/AgCl and quantify the thiocyanate concentration in a complex matrix. The mouthguard sensor operating under physiological conditions can monitor a wide range of thiocyanate (up to 11 mM) with a low detection limit of 30 µM. The demonstration introduces a unique approach, that obviates the requirement for blood sampling, to study thiocyanate levels of healthy people, cigarette smokers, or people with other health conditions. It is envisioned that the new cavitas device possesses a substantial promise for diverse biomedical diagnosis applications.

An ultrasensitive label-free electrochemical immunosensor based on 3D porous chitosan-graphene-ionic liquid-ferrocene nanocomposite cryogel decorated with gold nanoparticles for prostate-specific antigen.

A highly sensitive and selective label-free electrochemical immunosensor was successfully fabricated for measuring prostate-specific antigen (PSA). A composite of chitosan, graphene, ionic liquid and ferrocene (CS-GR-IL-Fc) was drop casted onto a screen-printed carbon electrode (SPCE) and frozen to create a layer of 3D porous cryogel (CS-GR-IL-Fc cry) which was decorated with gold nanoparticles (AuNPs). The biocompatibility and porosity of the cryogel increased the surface area available for AuNPs loading via amino groups and the population of anti-PSA, immobilized on the AuNPs via chemisorption, could be increased. The CS-GR-IL-Fc cry displayed excellent conductivity, enhancing electron transfer and amplifying the current signal. Differential pulse voltammetry was employed to determine PSA by measuring the reduction in the Fc oxidation peak current in response to the formation of PSA/anti-PSA immunocomplex. Under the optimized incubation time and electrolyte pH, the developed immunosensor displayed excellent analytical performances, including a wide linear range at concentrations from 1.0 × 10-7 to 1.0 × 10-1 ng mL-1, with a very low limit of detection of 4.8 × 10-8 ng mL-1 and good reproducibility (relative standard deviation of <4.6%, n = 6), stability (90% sensitivity within 20 days), repeatability (12 cycles of binding-rebinding, the sensitivity > 90%) and selectivity. The results obtained from the device for the determination of PSA in human serum were consistent with results from the enzyme-linked immunosorbent assay (P > 0.05), and indicated the promising potential of the proposed immunosensor in clinical diagnosis.

Magnetic microsphere sorbent on CaCO3 templates: Simple synthesis and efficient extraction of trace carbamate pesticides in fresh produce.

Polypyrrole magnetic microspheres were synthesized and used to extract carbaryl, carbofuran, and methomyl before analysis by a high-performance liquid chromatography with diode array detection. Under optimal conditions, four times the preconcentration was achieved with the use of only 1.2 mL of sample. Good linearity with ranges of 3.0-7.5 × 103, 6.0-4.5 × 103, and 15-3.0 × 103 ng kg-1 and limits of detection of 1.37 ± 0.10, 4.7 ± 1.2, and 10.1 ± 5.7 ng kg-1 were obtained, respectively. Good reproducibility (RSDs < 5%) was achieved over 24 cycles of extraction and regeneration. Good accuracy (recoveries 81.6 ± 1.5%-108.3 ± 2.2%) and good precision (RSDs 0.11%-4.5%) were obtained. Carbaryl was detected in apple (2.75 ± 0.23 ng kg-1), carbofuran in tomato (11.34 ± 0.61 ng kg-1), and methomyl in watermelon (34.7 ± 1.7 ng kg-1). The relative expanded uncertainty of the measurement method was less than 14% for all three pesticides.

Multiplexed label-free electrochemical immunosensor for breast cancer precision medicine.

A novel multiplexed label-free electrochemical immunosensor was fabricated using graphene/methylene blue-chitosan/antibody and bovine serum albumin on indium tin oxide glass electrode for the simultaneous determination of three types of tumor markers including carcinoembryonic antigen (CEA), cancer antigens 153 (CA153), and cancer antigen 125 (CA125). Cyclic voltammetry, electrochemical impedance spectroscopy, and scanning electron microscopy were employed to monitor each fabrication step. Under the optimized experiment conditions, the immunosensor exhibited good reproducibility and selectivity with linear ranges of 0.10-1.00 pg mL-1 and 1.00-100.00 pg mL-1 for CEA, 0.10-2.50 mU mL-1 and 2.50-100.00 mU mL-1 for CA153, 0.10-2.50 mU mL-1 and 2.50-100.00 mU mL-1 for CA125, a detection limit of 0.04 pg mL-1 for CEA, 0.04 mU mL-1 for CA153, and 0.04 mU mL-1 for CA125. This electrochemical immunosensor was successfully applied to detect three tumor markers in blood serum samples with good recoveries. The reliability of the electrochemical immunosensor to detect three tumor markers in blood serum samples was in good agreement (P > 0.05) with that of the enzyme-linked fluorescent assay method.

A miniature stainless steel net dumbbell-shaped stir-bar for the extraction of phthalate esters in instant noodle and rice soup samples.

This work reports the development of a very-simple-to-construct stir-bar extraction device so called "a dumbbell-shaped stainless steel stir-bar." The extraction device was assembled from a rolled up stainless steel net filled with an XAD-2 sorbent and a metal rod to allow the use of a magnetic stirrer during extraction. The dumbbell-shaped stainless steel stir-bar was used to extract diethyl phthalate (DEP), dibutyl phthalate (DBP), and di(2-ethylhexyl) phthalate (DEHP) before analysis by a gas chromatograph equipped with an electron capture detector (GD-ECD). Under the optimal conditions, the developed method provided a good linearity from 10.0 to 1,000.0 ng mL-1 for all three compounds. Limits of detection and limits of quantification were 9.37 ± 0.29 ng mL-1 and 31.22 ± 0.95 ng mL-1 for DEP, 5.73 ± 0.31 ng mL-1 and 19.1 ± 1.0 ng mL-1 for DBP and 3.30 ± 0.06 ng mL-1 and 11.0 ± 0.19 ng mL-1 for DEHP, respectively. Good recoveries in the range of 81.89 ± 0.17 to 109.5 ± 2.0% were achieved when the method was used to extract phthalate esters in five instant noodle and two rice soup samples.

A polypyrrole doped with fluorescent CdTe quantum dots and incorporated into molecularly imprinted silica for fluorometric determination of ampicillin.

A fluorometric method is described for the detection of ampicillin. A polypyrrole containing fluorescent CdTe quantum dots was incorporated into a silica-based molecularly imprinted polymer. The composite MIP displays good fluorescence (with excitation/emission maxima at 355/548 nm), and high selectivity and affinity for ampicillin due to the use of polypyrrole. Ampicillin is found to quench the fluorescence of composite much more strongly than the emission of a non-imprinted polymer. The imprinting factor of 7.5 implies that the nanocomposite probe contains specific binding sites. The MIP probe has two linear response ranges, one from 0.10 to 25 µg L-1 of ampicillin, and one from 25 to 100 µg L-1. The limit of detection is 0.05 µg L-1. The method was applied to the determination of ampicillin in (spiked) milk and meat samples and gave recoveries between 81.7 and 98.7%. The results agreed well with HPLC techniques. Graphical abstract Schematic presentation of nanocomposite fluorescence probe of polypyrrole and quantum dots incorporated in a molecularly imprinted polymer. Integrating of QDs, high specificity of MIPs and high affinity of polypyrrole, the method exhibited highly sensitive and selective for ampicillin detection.

Environmentally friendly etching of stainless steel wire for plunger-in-needle liquid-phase microextraction of polycyclic aromatic hydrocarbons.

An environmentally friendly method of etching a stainless steel plunger wire, to replace the conventional hydrofluoric acid approach, was developed for plunger-in-needle liquid phase-microextraction (PIN-LPME). The one-step etching procedure was performed by immersing the plunger wire in a ferric chloride-hydrochloric acid (FeCl3-HCl) solution. The etched wire was then used for LPME as the organic solvent holder. After solvent coating, the wire was directly exposed to a water sample for extraction of polycyclic aromatic hydrocarbons (PAHs), which were then subjected to thermal desorption in the injector of a gas chromatograph for gas chromatography-mass spectrometric (GC-MS) analysis. The parameters affecting PIN-LPME efficiencies (i.e., extraction solvent, solvent coating mode and time, stirring rate, extraction time and salting effect) were also investigated. Under the most favourable conditions, PIN-LPME-GC-MS exhibited high enrichment factors of between 70 and 349 for the 9 PAHs, low detection limits (between 0.006 and 0.058 ng mL-1), and good precision (with relative standard deviations ranging from 4.4% to 9.7%). The developed method was successfully applied for the extraction and determination of PAHs in tap, river and drain water samples. Good relative recoveries of the PAHs over the range of 84.3-101.9% were obtained with spiked genuine water samples.