A photoelectrochemical wire microelectrode was constructed based on the use of a TiO2 nanotube array with electrochemically deposited CdSe semiconductor. A strongly amplified photocurrent is generated on the sensor surface. The microsensor has a response in the 0.05–20 μM dopamine (DA) concentration range and a 16.7 μM detection limit at a signal-to-noise ratio of 3. Sensitivity, recovery and reproducibility of the sensor were validated by detecting DA in spiked human urine, and satisfactory results were obtained.
Graphical abstract Schematic of a sensitive photoelectrochemical microsensor based on CdSe modified TiO2 nanotube array. The photoelectrochemical microsensor was successfully applied to the determination of dopamine in urine samples.
The authors describe an amperometric sensor for dopamine (DA) by employing olive-like Fe2O3 microspheres (OFMs) as the electrocatalyst for DA oxidization. The OFMs were prepared by using a protein templated method. The structure and properties of the OFMs were characterized by scanning electron microscopy, X-ray powder diffraction, energy dispersive x-ray spectroscopy, cyclic voltammetry and electrochemical impedance spectroscopy. The OFMs possess excellent catalytic activity towards DA oxidization due to their unique morphology. The sensor responds to DA within less than 5 s. The sensor, best operated at a voltage of +0.2 V (vs. SCE) responds linearly in the 0.2 to 115 μM DA concentration range and has a 30 nM detection limit. The selectivity, reproducibility and long-term stability of the sensor are acceptable. It performs well when applied to spiked human urine samples.
Graphical abstract Olive-like Fe2O3 microspheres (OFMs), synthesized using egg white as template, display excellent catalytic activity towards dopamine (DA) oxidization due to their unique morphology. They were applied for DA detection using the amperometric technique. The electrochemical sensor exhibited a high sensitivity and a 30 nM detection limit. DAQ: dopaquinone.
A series of PANI-CNTs/TiO2 nanotubes/Ti electrodes were fabricated via pulse current co-electrodeposition of polyaniline and functionalized carbon nanotubes onto TiO2 nanotubes/Ti electrodes. FT-IR spectrometry, X-ray photoelectron spectroscopy, and scanning electron microscopy were applied in order to characterize the modified TiO2 nanotubes/Ti electrodes. The morphology studies showed that the PANI-CNTs/TiO2 nanotubes/Ti nanocomposite electrode has many interlaced PANI-CNTs nanorods on the surface of TiO2 nanotubes. The electrochemical measurements of the modified electrodes confirmed that the CNTs in the composite can significantly improve the capacitive behavior as well which have been compared with that of PANI/TiO2 nanotubes/Ti electrodes. The modified electrode exhibited much higher specific capacitance (190 mF cm?2 with 90% retention after 1000 cycles) compared to the PANI/TiO2 nanotubes/Ti (70 mF cm?2 with 77% retention after 1000 cycles) at a current density of 0.85 mA cm?2, indicating its great potential for supercapacitor applications.
Thin films of La2O3 were deposited onto glass substrates by ultrasonic spray pyrolysis. Their structural and morphological properties were characterized by X-ray diffraction, Fourier transform Raman spectroscopy, scanning electron microscopy, transmission electron microscopy, X-ray photo-electron spectroscopy, Brunauer-Emmett-Teller and optical absorption techniques. The sensor displays superior CO2 gas sensing performance at a low operating temperature of 498 K. The signal change on exposure to 300 ppm of CO2 is about 75%, and the signal only drops to 91% after 30 days of operation.
Graphical abstract Schematic diagram of the CO2 gas sensing mechanism of an interconnected web-like La2O3 nanostructure in presence of 300 ppm of CO2 gas and at an operating temperature of 498 K.
The paper describes a sensitive method for simultaneous sensing of morphine (MOR) and diclofenac (DCF). The surface of a MgFe2O4/graphite paste electrode was modified with multi-walled carbon nanotubes, and the resulting sensor was characterized by cyclic voltammetry, differential pulse voltammetry, chronoamperometry, and electrochemical impedance spectroscopy. The electrode showed an efficient synergistic effect in term of oxidation of DCF and MOR, with sharp oxidation peaks occurring at +0.370 and 0.540 V (vs Ag/AgCl) at pH 7.0. The calibration plot for MOR is linear in the 50 nM to 920 μM concentration range, and the detection limit is 10 nM (at a signal-to-noise ratio of 3). The respective data for DCF are 100 nM to 580 μM, with a 60 nM LOD. The sensor was applied to the determination of MOR and DCF in spiked serum and urine samples, with recoveries ranging between 91.4 and 100.7 %.
Graphical abstract A sensitive method for simultaneous sensing of morphine (MOR) and diclofenac (DCF) is described. The surface of MgFe2O4/graphite paste electrode was modified with multi-walled carbon nanotubes, and the resulting sensor showed an efficient synergistic effect in terms of oxidation of DCF and MOR. The calibration plot for MOR is linear in the 50 nM to 920 μM concentration range, and the detection limit is 10 nM. The respective data for DCF are 100 nM to 580 μM, with a 60 nM LOD.
A temperature-responsive biosensing film consisting of the temperature-responsive block co-polymer poly (N-isopropylacrylamide)-b-poly(2-acrylamidoethyl benzoate) (referred to as PNIPAM-b-PAAE), graphene oxide (GO), and hemoglobin (Hb) was fabricated and used to modify a glassy carbon electrode (GCE). The film provides a favorable micro-environment for Hb to facilitate the electron transfer to the GCE. Hb at PNIPAM-b-PAAE/GO/Hb (PGH) film exhibits a couple of well-defined redox peaks with a formal potential of ?0.371 V (vs. SCE) and displays intrinsic electro-catalytic activity toward H2O2. The sensing film also shows temperature-tunable catalytic activity toward H2O2 that can be stimulated by temperature. Large peak currents can be seen in amperometry at 0.4 V (vs. SCE) in pH 7.0 phosphate buffer only if the temperature is above the lower critical solution temperature (LCST) of 32 °C. The response of the modified GCE is linear in the 0.1 to 3.7 μmol L?1 concentration range if operated at above 32 °C, but in the 0.2 to 3.7 μmol L?1 concentration range at below 30 °C. This behavior is attributed to the temperature-dependent phase transition of PNIPAM-b-PAAE and cooperative effect of GO. The strategy presented here in our perception meets the requirements of switchable sensors for use in bioscience and biotechnology.
Graphical abstract A temperature-responsive biosensing film consisting of temperature-responsive polymer, graphene oxide and hemoglobin has been fabricated. This film displays favorable electrochemical property and good electro-catalytic activity toward H2O2. It also exhibits catalytic activity change upon temperature stimuli.
The article describes a method for determination of tannic acid in extracts of medicinal plants. Tannic acid (TA) is an antioxidant and has anticancer and antimicrobial properties. Titanium dioxide nanoparticles (TiO2) were co-sensitized with 5-methylphenazinium methosulfate (PMS) and carboxy-functionalized cadmium telluride quantum dots (CdTe QDs), and immobilized on a fluorine-doped tin oxide electrode. The surface morphology and electrochemical properties of the modified electrode were investigated by scanning electron microscopy and amperometry, respectively. A composite consisting of TiO2, PMS and CdTe QDs in a nafion film has a response to TA under LED light higher than that observed for each separate component. Under optimized experimental conditions and at an applied voltage of +0.4 V vs Ag/AgCl, the photoelectrochemical sensor has a linear response in the 0.2 to 200 μmol L?1 TA concentration range and a detection limit of 60 nmol L?1. The sensor was successfully applied to the determination of TA in spiked extracts from three medicinal plants, with recovery values between 98.3 and 103.9 %.
Graphical abstract Schematic diagram for photoelectrochemical detection of tannic acid based on a fluorine doped tin oxide electrode modified with titanium oxide, 5-methylphenazinium methosulfate and carboxy-functionalized cadmium telluride quantum dots
The authors report on the fabrication of Co(OH)2-enfolded Cu2O nanocubes on reduced graphene oxide (rGO), and the use of this material in an electrochemical caffeine sensor. The rGO/Cu2O/Co(OH)2 composite was characterized by X-ray powder diffraction pattern analysis, field emission scanning electron microscopy, energy dispersive X-ray spectroscopy and Raman spectroscopy. A rotating disc glassy carbon electrode covered with the nanocomposite displays enhanced electrocatalytic activity towards the electro-oxidation of caffeine. The peak oxidation potential is at 1.4 V (vs. Ag/AgCl) and hence is strongly shifted to the negative side when compared to other modified electrodes. The calibration plot is linear in the 0.83 to 1200 μM concentration range, with a 0.4 μM detection limit (at a signal-to-noise ratio of 3). The modified electrode is sensitive, selective and stable. It was successfully applied to the determination of caffeine in (spiked) caffeine-containing beverages and coffee powder and gave recoveries that ranged from 95.7 to 98.3 %.
An electrochemical microsensor for chloramphenicol (CAP) was fabricated by introducing magnetic Fe3O4 nanoparticles (NPs) onto the surface of activated carbon fibers. This microsensor exhibited increased electrochemical response toward CAP because of the synergetic effect of the Fe3O4 NPs and the carbon fibers. Cyclic voltammograms were acquired and displayed three stable and irreversible redox peaks in pH 7.0 solution. Under optimized conditions, the cathodic current peaks at ?0.67 V (vs. Ag/AgCl). The calibration plot is linear in the 40 pM to 1 μM CAP concentration range, with a 17 pM detection limit (at a signal-to-noise ratio of 3). The sensor was applied to the determination of CAP in spiked sediment samples. In our perception, this electrocatalytic platform provided a useful tool for fast, portable, and sensitive analysis of chloramphenicol.
Graphical abstract A sensitive carbon fiber microsensor modified with Fe3O4 nanoparticles is found to display two cathodic peaks when detecting chloramphenicol at 100 mV·s?1 and at pH 7.0. The sensor was applied to the determination of chloramphenicol in sediment samples.
This study describes an amperometric sensor for hydrogen peroxide (H2O2) that uses an ITO glass electrode which was modified with a nanocomposite consisting of electrochemically reduced graphene oxide and gold nanoclusters (AuNCs). The sensor was used to quantify extracellular H2O2 released from human neuroblastoma cells of type SH-SY5Y. The calibration plot, established best at a working voltage of ?0.4 V (vs. Ag/AgCl) is linear in the 40 nmol?L?1 to 2 μmol?L?1 concentration range, and the detection limit is 20 nmol?L?1 (at a signal-to-noise ratio of 3). The method was further applied to study bupivacaine-induced cell damage and the protective effects of α-lipoic acid. The study indicated that pretreatment of the cells with lipoic acid retards cell damage induced by bupivacaine. The sensor can be easily fabricated, is disposable and highly sensitive. The sensor is perceived to represent an alternative for studying the interactions of drugs with cells, and as an effective tool to quantify cell-secreted H2O2.
Graphical abstract One-step electrochemical synthesis of graphene oxide and gold nanoclusters on an ITO electrode for studying the release of H2O2 from SH-SY5Y cells and for evaluation of drug-induced cell damage
A photoelectrochemical (PEC) aptasensor for the highly sensitive and specific detection of thrombin is described. This aptasensor is based on an indium tin oxide (ITO) support that is covered with carbon quantum dot (CQD)-sensitized TiO2 and acts as a photoactive matrix. The ITO/TiO2/CQD electrode was prepared by impregnation assembly. It displays an enhanced and steady photocurrent response under irradiation by visible light. A carboxyl-functionalized thrombin-binding aptamer was covalently immobilized on the modified ITO to obtain a PEC aptasensor whose photocurrent decreases with increasing concentration of thrombin. Under 420 nm irradiation at a bias voltage of 0 V, the aptasensor has a linear response in the 1.0 to 250 pM thrombin concentration range, with a 0.83 pM detection limit. Conceivably, this approach can be extended to numerous other PEC aptasensors for the detection of targets for which appropriate aptamers are available.
Graphical abstract Schematic of a PEC aptasensor for thrombin. It is based on the use of CQD as the sensitizer, TiO2/CQDs as the photoactive matrix, and the thrombin aptamer as the recognition element.
A composite material obtained by ultrasonication of graphene oxide (GO) and multi-walled carbon nanotubes (MWCNTs) was loaded with manganese dioxide (MnO2), poly(diallyldimethylammonium chloride) and gold nanoparticles (AuNPs), and the resulting multilayer hybrid films were deposited on a glassy carbon electrode (GCE). The microstructure, composition and electrochemical behavior of the composite and the modified GCE were characterized by transmission electron microscopy, Raman spectra, energy-dispersive X-ray spectroscopy, electrochemical impedance spectroscopy and cyclic voltammetry. The electrode induces efficient electrocatalytic oxidation of dopamine at a rather low working voltage of 0.22 V (vs. SCE) at neutral pH values. The response is linear in the 0.5 μM to 2.5 mM concentration range, the sensitivity is 233.4 μA·mM￣1·cm￣2, and the detection limit is 0.17 μM at an SNR of 3. The sensor is well reproducible and stable. It displays high selectivity over ascorbic acid, uric acid and glucose even if these are present in comparable concentrations.
Graphical abstract Gold nanoparticles were self-assembled onto the surface of the MnO2 decorated graphene oxide-carbon nanotubes composites with poly(diallyldimethylammonium chloride) (PDDA) as a coupling agent. Further, a sensitive electrochemical sensor of dopamine was developed via immobilizing this nanocomposite on a glassy carbon electrode (GCE).
The authors report on the preparation of a hollow-structured cobalt ferrite (CoFe2O4) nanocomposite for use in a non-enzymatic sensor for hydrogen peroxide (H2O2). Silica (SiO2) nanoparticles were exploited as template for the deposition of Fe3O4/CoFe2O4 nanosheets, which was followed by the removal of SiO2 template under mild conditions. This leads to the formation of hollow-structured Fe3O4/CoFe2O4 interconnected nanosheets with cubic spinel structure of high crystallinity. The material was placed on a glassy carbon electrode where it acts as a viable sensor for non-enzymatic determination of H2O2. Operated at a potential of ?0.45 V vs. Ag/AgCl in 0.1 M NaOH solution, the modified GCE has a sensitivity of 17 nA μM?1 cm?2, a linear response in the range of 10 to 1200 μM H2O2 concentration range, and a 2.5 μM detection limit. The sensor is reproducible and stable and was applied to the analysis of spiked urine samples, where it provided excellent recoveries.
Graphical abstract Schematic of a cobalt ferrite (CoFe2O4) hollow structure for use in electrochemical determination of H2O2. The sensor shows a low detection limit, a wide linear range, and excellent selectivity for H2O2.
The authors describe a sensitive surface-enhanced Raman scattering (SERS)-based aptasensor for the detection of the food pathogen Vibrio parahaemolyticus. Nanostructures consisting of Fe3O4@Au particles wrapped with graphene oxide (GO) were used both as SERS substrates and separation tools. A first aptamer (apt 1) was immobilized on the Fe3O4@Au/GO nanostructures to act as a capture probe via the affinity binding of aptamer and V. parahaemolyticus. A second aptamer (apt-2) was modified with the Raman reporter molecule TAMRA to act as a SERS sensing probes that binds to the target the same way as the Fe3O4@Au/GO-apt 1. The sandwich formed between Fe3O4@Au/GO-apt 1/V. parahaemolyticus and apt 2-TAMRA can be separated with the aid of a magnet. The concentration of V. parahaemolyticus can be quantified by measurement of the SERS intensity of TAMRA. Under optimal conditions, the signal is linearly related to the V. parahaemolyticus concentration in the range between 1.4 × 102 to 1.4 × 106 cfu·mL?1, with a detection limit of 14 cfu·mL?1. Recoveries ranging from 98.5% to 105% are found when analyzing spiked salmon samples. In our perception, the assay described here is a useful tool for quantitation of V. parahaemolyticus in real samples.
Graphical abstract GO wrapped Fe3O4@Au nanostructures were synthesized as the substrate and modified with with a first aptamer (apt 1) to capture V. parahaemolyticus. TAMRA labelled aptamer 2 was then used as signal probe. The V. parahaemolyticus concentrations are closely related to the Raman intensity of TAMRA.
The authors report on an efficient method for the voltammetric sensing of dopamine (DA) by using an electrode modified with alternating monolayers of graphene oxide (GO) and Titanium dioxide (TiO2) nanoparticles anchored GO nanosheets (NSs)). The as-prepared nanostructures were characterized by photoluminescence spectroscopy, powder X-ray diffraction, Raman spectroscopy, FT-IR spectroscopy, transmission electron microscopy, scanning electron microscopy, atomic force microscopy and Energy Dispersive X-ray Analysis (EDAX) techniques. The GO/TiO2 nanocomposite (NC) was deposited on a glassy carbon electrode (GCE), where it displayed an excellent electrocatalytic activity toward the oxidation of DA, owing to its excellent conductivity, high specific surface area, enhanced interfacial contact and more negative zeta potential. Figures of merit include (a) a fast response (5 s), (b) a wide linear range (between 0.2 and 10 μM of DA) (c) a particularly low detection limit (27 nM), (d) a working potential as low as 0.25 V (vs. Ag/AgCl) and (e) a sensitivity of 1.549 μA·μM?1·cm?2. The GO/TiO2/GCE exhibited excellent selectivity over the other interferences as revealed by the differential pulse voltammetric and amperometric studies. The analysis of spiked urine samples resulted in recoveries in the range of 96 to 106%, with RSDs between 3.8 and 5.2%.
Graphical abstract A GO/TiO2 (graphene oxide/titanium dioxide) nanocomposite (NC) was prepared and exploited as electrochemical probes in DA detection. It displays a low detection limit, wide linear range and excellent selectivity.
A nanocomposite composed of graphene oxide and magnetite (Fe3O4) was coated with the ionic liquid (IL) 1,3-didecyl-2-methylimidazolium chloride and used to capture and separate hemin from serum samples. The critical parameters affecting the extraction of analyte, such as pH, surfactant and adsorbent amounts, and desorption conditions were studied and optimized. Following magnetic separation and desorption with a 5:1 mixture of acetic acid and acetone, hemin (an iron porphyrin complex) was quantified by FAAS of iron. Under optimum conditions, the enrichment factor was 96. The calibration curve was linear in the 4.8 to 730 μg L?1 concentration range, the limit of detection was 3.0 μg L?1, and the relative standard deviations (RSDs) for single-sorbent repeatability and sorbent-to-sorbent reproducibility were less than 3.9 % and 10.2 % (n = 5), respectively. The adsorbent displayed adsorption capacity as high as 200 mg g?1, indicating IL-coated Fe3O4/GO to be a good sorbent for the adsorption of hemin. The method was validated by determining serum hemin in the presence of a large excess (480-fold) of Fe3+ without considerable interference. The results compare well to those obtained with a commercial hemin assay kit. The results show that this method can be successfully applied to the enrichment and determination of hemin in acid digested serum samples of breast cancer patients.
Graphical abstract Fe3O4/GO nanocomposites were coated with the ionic liquid 1,3-didecyl-2-methylimidazolium chloride and used as the sorbent for the separation and preconcentration of hemin from blood serum samples prior to determination using by flame AAS.
The authors describe an electrochemical sensor for hydrogen peroxide (H2O2). It was constructed by consecutive, selective modification of a glassy carbon electrode (GCE) with Prussian Blue (PB), layered molybdenum disulfide (MoS2), and reduced graphene oxide (rGO). The properties of the modified GCE were characterized via high-resolution transmission electron microscopy, UV-vis spectroscopy and X-ray diffraction. The electrochemical properties of the electrode were studied using cyclic voltammetry and electrochemical impedance spectroscopy. The sensor exhibits excellent electrocatalytic activity for the reduction of hydrogen peroxide in comparison to GCEs modified with MoS2-rGO or PB only. Response is linear in the 0.3 μM to 1.15 mM H2O2 concentration range at a working analytical voltage of 0.1 V, with a 0.14 μM detection limit. The electrochemical sensitivity is 2883.5 μA·μM?1·cm?2, and response is fast (<10 s). The sensor is selective, stable and reproducible. This is attributed to the efficient electron transport properties of the MoS2-rGO composite and the high loading with PB.
Graphic abstract Prussian Blue nanoparticles were deposited on MoS2-rGO modified glassy carbon electrode by electrochemical method. This sensor was used for the detection of H2O2 in tap water and river water.
We describe an amperometric sensor for nitrite that is based on a glassy carbon electrode modified with a 3-dimensional network consisting of Ni7S6 and multi-walled carbon nanotubes. The nickel sulfide was prepared by a hydrothermal method starting from nickel chloride and thiourea. The morphology and catalytic properties of the sensor material were characterized by X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, transmission electron microscopy, cyclic and linear sweep voltammetry, electrochemical impedance spectroscopy, and chronoamperometry. The results showed the Ni7S6/MWCNTs to possess improved catalytic activity towards the oxidation of nitrite when compared to plain Ni7S6. The sensor is best operated at 0.425 V (vs. Ag/AgCl) in 0.1 M NaOH solution where it shows a linear response in the 1.0 μM to 4.2 mM nitrite concentration range, with a sensitivity as high as 185.0 μA·mM?1·cm?2 and a 0.3 μM detection limit (at a signal-to-noise ratio of 3). These features are mainly attributed to the large specific surface area of Ni7S6, the good electrical conductivity of the MWCNTs, and the synergy between Ni7S6 and the MWCNTs. The method was applied to the determination of nitrite in (spiked) water samples where it gave recoveries that ranged between 98.6 and 100.1 %.
Graphical abstract Ni7S6 was synthesized by a hydrothermal method. The sensor based on Ni7S6/MWCNTs is best operated at 0.425 V (vs. Ag/AgCl), where it shows a linear response in the 1.0 μM - 4.2 mM nitrite concentration range, with a sensitivity as high as 185.0 μA·mM￣1·cm￣2 and a 0.3 μM detection limit. SC(NH2)2: thiourea; EA: ethanolamine; MWCNTs: multi-walled carbon nanotubes
We report on a widely applicable approach for protein detection by using triple-helix DNA mediated CuInS2 quantum dot (QD) and graphene oxide (GO) nanocomposite. The CuInS2 QDs were coated with mercaptopropionic acid and then covalently linked to a hairpin aptamer against lysozyme (HLA). Single-stranded DNA (triple helix-forming oligonucleotide; THFO) readily absorbs on the surface of GO via π-stacking interaction, and this results in the formation of THFO-GO. If HLA-CuInS2 QDs are added to the THFO-GO system, the fluorescence of HLA-CuInS2 QDs (at excitation/emission wavelengths of 590/665 nm) is quenched. Lysozyme has a higher affinity for HLA than THFO. Therefore, in the presence of lysozyme, it will bind to the HLA-CuInS2 QD and displace the THFO-GO. This results in the restoration of fluorescence that is related to the concentration of lysozyme. The fluorescence of the QDs is turned on. The calibration plot is linear in the 0.01 to 1.8 ng·mL￣1 concentration range, with a 3 pg·mL￣1 detection limit (at a signal-to-noise ratio of 3). The method was also applied to study the inhibition of lysozyme by IvyEc. In our perception, this method has a wide scope in that it may become applicable to any protein for which an appropriate aptamer is available.
Graphical abstract A novel convenient and universal fluorescence nanoprobe for sensitive and selective detection of lysozyme and inhibitor screening was established using triple-helix DNA mediated CuInS2 QDs and GO nanocomposites
The authors describe a cataluminescence (CTL) based sensing method via signals generated at the surface of In3LaTi2O10 nanoparticles for simultaneous determination of trimethylamine, formaldehyde and benzene in air. The analytical wavelengths are 340 nm, 440 nm and 600 nm, and the best surface temperature of the catalytic material is 275 °C. The limits of detection of this method are 0.3 mg?m?3 for trimethylamine, 0.07 mg?m?3 for formaldehyde, and 0.2 mg?m?3 for benzene. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m?3 for trimethylamine, from 0.2 to 72.5 mg?m?3 for formaldehyde, and from 0.5 to 77.5 mg?m?3 for benzene. The recoveries after testing 10 standard samples ranged from 98.1% to 102.6% for trimethylamine, from 98.1% to 102.6% for formaldehyde, and from 97.7% to 103.8% for benzene. Gaseous ammonia, acetaldehyde, toluene, ethylbenzene, ethanol, sulfur dioxide and carbon dioxide do not interfere. The relative deviation of the CTL signals after 200 h of continuous detection of trimethylamine, formaldehyde and benzene is <3%.
Graphical abstract Schematic of a cataluminescence (CTL) based method for simultaneous determination of trimethylamine (TMA), formaldehyde (HCHO) and benzene (C6H6) in air. The linear ranges of CTL intensity versus gas/vapor concentration are from 1.0 to 65.1 mg?m?3 for TMA, from 0.2 to 72.5 mg?m?3 for HCHO, and from 0.5 to 77.5 mg?m?3 for C6H6.
