Fast screening immunoassay of sulfonamides in commercial fish samples

An indirect competitive enzyme-linked immunosorbent assay (ELISA) was developed in plate to detect three sulfonamide residues (sulfamerazine (SMR), sulfadimetoxine (SDM), and sulfadiazine (SDZ)) in gilthead sea bream (Sparus aurata) samples. Different extraction methodologies—using methanol/water 1:1 (v/v) + ethylene diamine tetraacetic acid (EDTA) 0.5% (m/v), acetonitrile, phosphate-buffered saline (PBS) 10 mmol L⁻¹ pH 7 and acetate buffer 100 mmol L⁻¹ pH 5—and cleanup steps, based on solid-phase extraction (C₁₈, SCX, Si) or liquid extraction with hexane, were assayed. As optimum, a fast and simple method using acetonitrile was selected to extract the sulfonamide residues from the edible muscle of fish. Due to matrix effects, a standard addition calibration curve in fish extract is necessary for quantification purposes. Sulfonamide-free samples were spiked at different concentration levels (between 30 and 90 ng g⁻¹, 5–15 ng mL⁻¹ in plate) and average recoveries (n = 8), ranging from 71% to 95%, 65% to 79%, and 72% to 95%, were obtained for SMR, SDM, and SDZ, respectively. The assay detection limits for these antibiotics were lower than 100 μg kg⁻¹ (maximum residue level established by the European Union). The accuracy was evaluated by spiking blank fish extracts at different concentrations (10–40 ng mL⁻¹, 5–20 ng mL⁻¹ in plate), and the relative errors ranged between ±20%. Finally, in order to confirm the utility of the developed ELISA as a screening methodology, fish samples from different supermarkets were analyzed, and results were compared with those obtained by a validated high-performance liquid chromatography (HPLC) method. The correlation between the results obtained by both ELISA and HPLC methods is satisfactory.      

Development of a colloidal gold-based lateral-flow immunoassay for the rapid simultaneous detection of clenbuterol and ractopamine in swine urine

A multianalyte lateral-flow immunochromatographic technique using colloidal gold-labeled polyclonal antibodies was developed for the rapid simultaneous detection of clenbuterol and ractopamine. The assay procedure could be accomplished within 5 min, and the results of this qualitative one-step assay were evaluated visually according to whether test lines appeared or not. When applied to the swine urines, the detection limit and the half maximal inhibitory concentration (IC₅₀) of the test strip under an optical density scanner were calculated to be 0.1 ± 0.01 ng mL⁻¹ and 0.1 ± 0.01 ng mL⁻¹, 0.56 ± 0.08 ng mL⁻¹, and 0.71 ± 0.06 ng mL⁻¹, respectively, the cut-off levels with the naked eye of 1 ng mL⁻¹ and 1 ng mL⁻¹ for clenbuterol and ractopamine were observed. Parallel analysis of swine urine samples with clenbuterol and ractopamine showed comparable results obtained from the multianalyte lateral-flow test strip and GC-MS. Therefore, the described multianalyte lateral-flow test strip can be used as a reliable, rapid, and cost-effective on-site screening technique for the simultaneous determination of clenbuterol and ractopamine residues in swine urine.      

Evaluation of solid-phase microextraction conditions for the determination of polycyclic aromatic hydrocarbons in aquatic species using gas chromatography

This paper describes a headspace solid-phase microextraction (HS-SPME) procedure coupled to gas chromatography with mass spectrometric detection (GC–MS) for the determination of eight PAHs in aquatic species. The influence of various parameters on the PAH extraction efficiency was carefully examined. At 75 °C and for an extraction time of 60 min, a polydimethylsiloxane–divinylbenzene (PDMS/DVB) fiber coating was found to be most suitable. Under the optimized conditions, detection limits ranged from 8 to 450 pg g⁻¹, depending on the compound and the sample matrix. The repeatability varied between 7 and 15% (RSD). Accuracy was tested using the NIST SRM 1974b reference material. The method was successfully applied to different samples, and the studied PAHs were detected in several of the samples. Figure Headspace SPME sampling followed by GC–MS facilitates routine monitoring of PAHs in aquatic species     

GC–MS analysis of low-molecular-weight dicarboxylic acids in atmospheric aerosol: comparison between silylation and esterification derivatization procedures

This paper describes methods for the determination of low-molecular-weight (LMW) dicarboxylic acids in atmospheric aerosols as important chemical tracers for source apportionment of aerosol organics and for studying atmospheric processes leading to secondary organic aerosol formation. The two derivatization procedures most widely used in GC analysis of dicarboxylic acids were compared: esterification using BF₃/alcohol reagent and silylation using N,O-bis(trimethylsilyl)-trifluoroacetamide (BSTFA). The advantages and drawbacks of the two methods are investigated and compared in terms of (1) precision and accuracy of the results and (2) sensitivity and detection limit of the procedure. The comparative investigation was performed on standard solutions containing target C₃–C₉ dicarboxylic acids and on experimental particulate matter (PM) samples. Attention was focused on low-volume sampling devices that collect small amounts of sample for organic speciation. The results show that, overall, both the techniques appear suitable for the analysis of LMW dicarboxylic acids in atmospheric aerosols since they provide low detection limits (≤4 ng m⁻³) and satisfactory reproducibility (RSD% ≤ 15%). Between them, BSTFA should be the reagent of choice under the most limiting conditions of PM filters collected by low-volume air samplers: It provides determination of all the target C₃–C₉ dicarboxylic acids with lower detection limits (≤2 ng m⁻³) and higher reproducibility (RSD% ≤ 10%)      

Analysis of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction combined with gas chromatography

A novel method was developed for the determination of captan, folpet, and captafol in apples by dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD). Some experimental parameters that influence the extraction efficiency, such as the type and volume of the disperser solvents and extraction solvents, extraction time, and addition of salt, were studied and optimized to obtain the best extraction results. Under the optimum conditions, high enrichment factors for the compounds were achieved ranging from 824 to 912. The recoveries of fungicides in apples at spiking levels of 20.0 μg kg⁻¹ and 70.0 μg kg⁻¹ were 93.0–109.5% and 95.4–107.7%, respectively. The relative standard deviations (RSDs) for the apple samples at 30.0 μg kg⁻¹ of each fungicide were in the range from 3.8 to 4.9%. The limits of detection were between 3.0 and 8.0 μg kg⁻¹. The linearity of the method ranged from 10 to 100 μg kg⁻¹ for the three fungicides, with correlation coefficients (r ²) varying from 0.9982 to 0.9997. The obtained results show that the DLLME combined with GC–ECD can satisfy the requirements for the determination of fungicides in apple samples. Figure Dispersive liquid–liquid microextraction (DLLME) coupled with gas chromatography–electron capture detection (GC–ECD) allows satisfactory determination of fungicides in apple samples     

Kinetic spectrophotometric determination of amodiaquine and chloroquine

Abstract  Two simple, sensitive, and selective spectrophotometric methods were developed for determining amodiaquine (AQ) and chloroquine (CQ) based on their oxidation with potassium iodate and potassium bromate, respectively. The initial rates of oxidation of AQ and CQ were monitored at 342 and 343 nm, the wavelengths of maximum absorptions of the two drugs. The various experimental parameters affecting oxidation reactions were thoroughly studied and optimized. Beer’s law was obeyed for 0.2–4.0 and 0.5–5.0 μg cm⁻³, with correlation coefficients of 0.9999 and 0.9998 (n = 6) and a detection limit (based on the 3S _b -criterion) of 0.04 and 0.06 μg cm⁻³ for AQ and CQ. The proposed methods were conveniently applied to determining AQ and CQ in pure and dosage forms. Graphical abstract        

Effects of 17β-trenbolone in male eelpout Zoarces viviparus exposed to ethinylestradiol

To evaluate the interaction between 17β-trenbolone (TB) and 17α-ethinylestradiol (EE2), male eelpout, Zoarces viviparus, was exposed for 21 days (April to May 2008) to 5 ng l⁻¹ EE2 and 5 or 20 ng l⁻¹ TB, separately or in combination in a flow-through SW system. The effects on hepatosomatic (HSI) and gonadosomatic index (GSI), plasma vitellogenin (Vtg) concentration, gonadal histology, hepatic and testicular Vtg mRNA and estrogen receptor (ERα) mRNA expression were investigated. No effects on HSI were observed. A significant decrease was observed in the GSI of all males exposed to EE2 (<0.7%) when compared to controls (1.4%). Histological alterations and immature stages were observed in the testis of all exposed males; however, males exposed to EE2 were the most affected. Increased tubule number and proportionally decreased tubule diameter were observed in the testis of all EE2 groups. No effects in Vtg mRNA expression were observed in the testis; however, a significant decrease in testis ERα mRNA was observed in males exposed to 20 ng l⁻¹ TB. The groups exposed to EE2 showed a significant increase in plasma Vtg (>300-fold), hepatic Vtg mRNA (>450-fold), and ERα mRNA (>100-fold) when compared to controls. This study shows that lower concentrations of 17β-trenbolone are unable to counteract the EE2 estrogenic effects when the exposure is simultaneous.      

Development of a highly precise ID-ICP-SFMS method for analysis of low concentrations of lead in rice flour reference materials

Microwave digestion and isotope dilution inductively coupled plasma mass spectrometry (ID-ICP-SFMS) has been applied to the determination of Pb in rice flour. In order to achieve highly precise determination of low concentrations of Pb, the digestion blank for Pb was reduced to 0.21 ng g⁻¹ after optimization of the digestion conditions, in which 20 mL analysis solution was obtained after digestion of 0.5 g rice flour. The observed value of Pb in a non-fat milk powder certified reference material (CRM), NIST SRM 1549, was 16.8 ± 0.8 ng g⁻¹ (mean ± expanded uncertainty, k = 2; n = 5), which agreed with the certified value of 19 ± 3 ng g⁻¹ and indicated the effectiveness of the method. Analytical results for Pb in three brown rice flour CRMs, NIST SRM 1568a, NIES CRM 10-a, and NIES CRM 10-b, were 7.32 ± 0.24 ng g⁻¹ (n = 5), 1010 ± 10 ng g⁻¹ (n = 5), and 1250 ± 20 ng g⁻¹ (n = 5), respectively. The concentration of Pb in a candidate white rice flour reference material (RM) sample prepared by the National Metrology Institute of Japan (NMIJ) was observed to be 4.36 ± 0.28 ng g⁻¹ (n = 10 bottles). Figure Digestion blank of Pb was carefully reduced to approximately 0.2 ng g^-1 which permitted the highly precise determination of Pb at low ng g^-1 level in foodstuff samples by ID-SFMS     

Determination of diquat by flow injection–chemiluminescence

A simple, economic, sensitive and rapid method for the determination of the pesticide diquat was described. This new method was based on the coupling of flow injection analysis methodology and direct chemiluminescent detection; to the authors’ knowledge, this approach had not been used up to now with this pesticide. It was based on its oxidation with ferricyanide in alkaline medium; significant improvements in the analytical signal were achieved by using high temperatures and quinine as sensitiser. Its high throughput (144 h⁻¹), together with its low limit of detection (2 ng mL⁻¹), achieved without need of preconcentration steps, permitted the reliable quantification of diquat over the linear range of (0.01–0.6) μg mL⁻¹ in samples from different origins (river, tap, mineral and ground waters), even in the presence of a 40-fold concentration of paraquat, a pesticide commonly present in the commercial formulations of diquat. Figure Quartz luminometer cell     

Use of specific peptide biomarkers for quantitative confirmation of hidden allergenic peanut proteins Ara h 2 and Ara h 3/4 for food control by liquid chromatography–tandem mass spectrometry

A liquid chromatography–electrospray-tandem mass spectrometry (LC–ESI-MS–MS) method based on the detection of biomarker peptides from allergenic proteins was devised for confirming and quantifying peanut allergens in foods. Peptides obtained from tryptic digestion of Ara h 2 and Ara h 3/4 proteins were identified and characterized by LC–MS and LC–MS–MS with a quadrupole-time of flight mass analyzer. Four peptides were chosen and investigated as biomarkers taking into account their selectivity, the absence of missed cleavages, the uniform distribution in the Ara h 2 and Ara h 3/4 protein isoforms together with their spectral features under ESI-MS–MS conditions, and good repeatability of LC retention time. Because of the different expression levels, the selection of two different allergenic proteins was proved to be useful in the identification and univocal confirmation of the presence of peanuts in foodstuffs. Using rice crispy and chocolate-based snacks as model food matrix, an LC–MS–MS method with triple quadrupole mass analyzer allowed good detection limits to be obtained for Ara h2 (5 μg protein g⁻¹ matrix) and Ara h3/4 (1 μg protein g⁻¹ matrix). Linearity of the method was established in the 10–200 μg g⁻¹ range of peanut proteins in the food matrix investigated. Method selectivity was demonstrated by analyzing tree nuts (almonds, pecan nuts, hazelnuts, walnuts) and food ingredients such as milk, soy beans, chocolate, cornflakes, and rice crispy. Figure ESI-QTOF-MS mass spectrum of Ara h3/4 triptig digest     

Analytical procedure for determination of the time profile of eprinomectin excretion in sheep faeces

An analytical procedure has been introduced to enable study of the time profile of eprinomectin excretion in sheep faeces. Eprinomectin was extracted from sheep faeces with acetonitrile, the extract was cleaned by solid-phase extraction (SPE), and, after derivatization by reaction with N-methylimidazole, trifluoroacetic anhydride, and acetic acid, eprinomectin was analysed by high-performance liquid chromatography (HPLC) with fluorescence detection. The method has a low detection limit (1.0 ng g⁻¹ of moist sheep faeces), a low quantification limit (2.5 ng g⁻¹ of moist sheep faeces), good recovery (in the range 78.8 to 87.1%), and good reproducibility (RSD<10%). The method was used to study the time-profile of excretion of eprinomectin in sheep faeces after a single topical administration of 0.5 mg kg⁻¹ b.w. of the drug. Because of its good recovery, precision, and sensitivity, the method has also proved applicable to further ecotoxicological studies of eprinomectin. Figure Autochthonous Slovenian dairy breed sheep – Istrian Pramenka     

Determination of water-soluble and insoluble (dilute-HCl-extractable) fractions of Cd,Pb and Cu in Antarctic aerosol by square wave anodic stripping voltammetry: distribution and summer seasonal evolution at Terra Nova Bay (Victoria Land)

Eight PM10 aerosol samples were collected in the vicinity of the “Mario Zucchelli” Italian Antarctic Station (formerly Terra Nova Bay Station) during the 2000–2001 austral summer using a high-volume sampler and precleaned cellulose filters. The aerosol mass was determined by differential weighing of filters carried out in a clean chemistry laboratory under controlled temperature and humidity. A two-step sequential extraction procedure was used to separate the water-soluble and the insoluble (dilute-HCl-extractable) fractions. Cd, Pb and Cu were determined in the two fractions using an ultrasensitive square wave anodic stripping voltammetric (SWASV) procedure set up for and applied to aerosol samples for the first time. Total extractable metals showed maxima at midsummer for Cd and Pb and a less clear trend for Cu. In particular, particulate metal concentrations ranged as follows: Cd 0.84–9.2 μg g⁻¹ (average 4.7 μg g⁻¹), Pb 13.2–81 μg g⁻¹ (average 33 μg g⁻¹), Cu 126–628 μg g⁻¹ (average 378 μg g⁻¹). In terms of atmospheric concentration, the values were: Cd 0.55–6.3 pg m⁻³ (average 3.4 pg m⁻³), Pb 8.7–48 pg m⁻³ (average 24 pg m⁻³), Cu 75–365 pg m⁻³ (average 266 pg m⁻³). At the beginning of the season the three metals appear widely distributed in the insoluble (HCl-extractable) fraction (higher proportions for Cd and Pb, 90–100%, and lower for Cu, 70–90%) with maxima in the second half of December. The soluble fraction then increases, and at the end of the season Cd and Pb are approximately equidistributed between the two fractions, while for Cu the soluble fraction reaches its maximum level of 36%. Practically negligible contributions are estimated for crustal and sea-spray sources. Low but significant volcanic contributions are estimated for Cd and Pb (∼10% and ∼5%, respectively), while there is an evident although not quantified marine biogenic source, at least for Cd. The estimated natural contributions (possibly including the marine biogenic source) cannot account for the high fractions of the metal contents, particularly for Pb and Cu, and this suggests that pollution from long-range transport is the dominant source. Figure Aerosol sampling in Antarctica     

Highly sensitive spectrofluorimetric determination of trace amounts of lecithin

A new spectrofluorimetric method was developed for the determination of trace amounts of lecithin using the ciprofloxacin (CIP)–terbium (Tb³⁺) ion complex as a fluorescent probe. In a buffer solution at pH=5.60, lecithin can remarkably reduce the fluorescence intensity of the CIP–Tb³⁺ complex at λ=545 nm. The reduced fluorescence intensity of the Tb³⁺ ion is proportional to the concentration of lecithin. Optimum conditions for the determination of lecithin were also investigated. The linear range and detection limit for the determination of lecithin were 1.0×10⁻⁶–3.0×10⁻⁵ mol L⁻¹ and 3.44×10⁻⁷ mol L⁻¹, respectively. This method is simple, practical, and relatively free of interference from coexisting substances. Furthermore, it has been successfully applied to assess lecithin in serum samples.      

A microfluidic device with integrated fluorimetric detection for flow injection analysis

This work describes the development of flow analysis microsystems with integrated fluorimetric detection cells. Channels (width of 300–540 μm and depth of 200–590 μm) were manufactured by deep-UV lithography in urethane–acrylate (UA) resin. Plastic optical fibers (diameter of 250 μm) were coupled to a 2.0-mm-long detection channel in order to guide the excitation radiation from an LED (470 nm) and collect the emitted radiation at a right angle towards a photomultiplier. A single-line miniaturized system, with a total internal volume of 10.4 μL, was evaluated by means of standard fluorescein solutions (0.53–2.66 μmol L⁻¹, pH 8.5). The analytical signals presented a linear relationship in the concentration range studied, with a relative standard deviation of 1.9% (n = 5), providing a detection limit of 0.37 μmol L⁻¹ and an analytical frequency of 60 samples/h, using a flow rate of 60 μL min⁻¹. Optical microscopy images and videos acquired in real time for the hydrodynamic injection of 130 and 320 nL of sample solutions indicated the good performance of the proposed sampling strategy. Another microsystem with a total internal volume of 38 μL was developed, incorporating a confluence point for two solutions. This device was applied to the determination of the total concentration of Ca²⁺ and Mg²⁺ in commercial mineral waters using the calcein method. Microscopy images and videos demonstrated the mixing efficiency of the solutions in the microchannels. A linear relationship was observed for the analytical signal in the Ca²⁺ concentration range from 25 to 125 μmol L⁻¹, with relative standard deviations of 3.5%. The analysis of mineral waters with the proposed system provided results that did not differ significantly from those obtained by the EDTA titration method at a confidence level of 95%. These results demonstrate the viability of developing micro flow injection systems with an integrated fluorimetric detection cell.      

Development of a novel immunobiosensor method for the rapid detection of okadaic acid contamination in shellfish extracts

The mouse bioassay is the methodology that is most widely used to detect okadaic acid (OA) in shellfish samples. This is one of the best-known toxins, and it belongs to the family of marine biotoxins referred to as the diarrhetic shellfish poisons (DSP). Due to animal welfare concerns, alternative methods of toxin detection are being sought. A rapid and specific biosensor immunoassay method was developed and validated for the detection of OA. An optical sensor instrument based on the surface plasmon resonance (SPR) phenomenon was utilised. A polyclonal antibody to OA was raised against OA–bovine thyroglobulin conjugate and OA–N-hydroxy succinimide ester was immobilised onto an amine sensor chip surface. The assay parameters selected for the analysis of the samples were: antibody dilution, 1/750; ratio of antibody to standard, 1:1; volume of sample injected, 25 μl min⁻¹; flow rate, 25 μl min⁻¹. An assay action limit of 126 ng g⁻¹ was established by analysing of 20 shellfish samples spiked with OA at the critical concentration of 160 ng g⁻¹, which is the action limit established by the European Union (EU). At this concentration of OA, the assay delivered coefficient of variations (CVs) of <10%. The chip surface developed was shown to be highly stable, allowing more than 50 analyses per channel. When the concentrations of OA determined with the biosensor method were compared with the values obtained by LC–MS in contaminated shellfish samples, the correlation between the two analytical methods was found to be highly satisfactory (r ² = 0.991). Figure Biacore     

Electrochemical deposition of silicate–cetyltrimethylammonium bromide nanocomposite film on glassy carbon electrode for sensing of methyl parathion

A novel electrochemical sensor for methyl parathion based on silicate– cetyltrimethylammonium bromide nanocomposite film has been fabricated by electro-assisted deposition onto glassy carbon electrode in one-step via an electrochemical modulation of pH at the electrode/solution interface to promote controlled gelification of tetraethylorthosilicate sol, and was characterized with scanning electron microscopy, X-ray diffraction, and electrochemical impedance spectroscopy. The electrochemical sensing of methyl parathion on the film-modified electrode was investigated applying cyclic voltammetry and square wave voltammetry. Compared to the unmodified electrode, the shapes of the redox peaks were improved and the peak currents significantly increased. Experimental parameters such as deposition time, pH value, and accumulation conditions have been optimized. A linear relationship between the peak current and methyl parathion concentration was obtained in the range from 1.0 × 10⁻⁷ to 1.0 × 10⁻⁴ mol L⁻¹ with a detection limit of 1.04 × 10 ⁻⁸ mol L⁻¹ (S/N = 3) after accumulation at 0 V for 120 s. The film electrode shows great promise for determination of methyl parathion in real samples.      

Small-volume fiber-optic evanescent-wave absorption sensor for nitrite determination

A novel small-volume fiber-optic evanescent-wave absorption sensor based on the Griess–Ilosvay reaction has been developed and evaluated for nitrite determination. The sensor was constructed by inserting a decladded optical fiber into a transparent capillary to form an annular column microchannel. The Evanescent wave (EW) field produced on the optical fiber core surface penetrated into the surrounding medium and interacted with the azo dye, which was generated by the reaction of nitrite and nitrite-sensitive reagents. The detector was designed to be parallel to the axis of the optical fiber. The defined absorbance was linear with the concentration of nitrite in the range from 0.05 to 10 mg L⁻¹, and the detection limit was 0.02 mg L⁻¹ (3σ) with the relative standard deviation (RSD) of 2.6% (n = 8). The present sensor was successfully used to determine nitrite in real samples of mineral water, tap water, rain water, and seawater. The results were consistent with the data obtained by standard spectrophotometric method, showing potential of the proposed sensor for practical application.      

Biophysical,spectroscopic vis-à-vis biochemical investigation on DNA–metalloprotein interaction: a model study involving cobalt(II)-glutathione complex

Abstract  The interaction of cobalt(II)-glutathione (CoGSH) with deoxyribonucleic acid (DNA) has been studied by UV–vis, fluorescence, circular dichroism (CD), thin-film infrared (IR), and viscometric techniques. From the UV-spectroscopic method, binding constant (K _b) was determined and was found to be 2.3 × 10⁶ M⁻¹. In fluorimetric analysis, the quenching of fluorescence intensity of DNA bound to ethidium bromide (EB) was investigated. The Stern–Volmer quenching constant (K _sv) was also estimated from this study and was found to be 2.8 × 10⁶ M⁻¹at 37 °C. The solution CD spectra of DNA and DNA–CoGSH indicate that in each case, DNA exists in the ‘B’ conformation and suggested an intercalative binding mode. Thin-film IR data also reveal that DNA attains the ‘B’ family of conformations after interaction with CoGSH complex. The increase in DNA viscosity in the presence of CoGSH complexes is attributed to the lengthening of DNA helix due to intercalation. Graphical Abstract  The spectrophotometric, CD, thin film IR, viscometric and fluorimetric studies on the interaction of CoGSH with DNA indicated an intercalative binding mode with the retention of ‘B’ conformation of DNA.      

Determination of trace platinum by supramolecular catalytic kinetic spectrofluorimetry of β–cyclodextrin–platinum–KBrO3–salicylaldehyde furfuralhydrazone

A supramolecular catalytic kinetic spectrofluorimetric method was developed for the determination of platinum(IV) and the possible mechanism of catalytic reaction was discussed. The method was based on the fluorescence-enhancing reaction of salicylaldehyde furfuralhydrazone (SAFH) with potassium bromate, which was catalysed by platinum(IV) in a water–ethanol medium. β–Cyclodextrin (β-CD) obviously sensitized the determination at pH 5.20 and 25°C. Under optimum conditions, the β-CD–platinum–KBrO₃–SAFH supramolecular kinetic catalytic reaction system had excitation and emission maxima at 372 and 461 nm, respectively. The linear range of this method was 0.60–180 ng ml⁻¹ with a relative standard deviation of 1.2%, and the detection limit was 0.18 ng ml⁻¹. Investigation of the mechanism and the effects of interferences is presented. The proposed method was applied successfully to determine trace platinum(IV) in the chemotherapeutic drug cisplatin and serum from patients with satisfactory results.      

Design of a voltammetric immunosensor for determination of 1-nitropyrene

Abstract  In this study a design of an immunosensor for 1-nitropyrene is illustrated. First the response of 1-nitropyrene reduced at a glassy carbon electrode between 0 and −0.8 V was investigated with respect to pH and solvent. Then polyclonal anti-1-nitropyrene antibodies isolated from a rabbit antiserum were covalently bound to the surface of the glassy carbon electrode. This modified electrode was immersed in standard solutions or sample extracts for 5–15 min. 1-Nitropyrene was bound by the antibodies, accumulated and then analyzed at pH 6.5 in another supporting electrolyte by differential pulse voltammetry. Afterwards the immunosensor could be regenerated for the next measurement by rinsing with acetonitrile–water (40:60, v/v). A linear response was found between 20 and 100 ng/cm³. The limit of detection was 10 ng/cm³ and the intraday reproducibility of three immunosensors assembled during two months was between 4.5 and 10%. This sensor was applied to the analysis of 1-nitropyrene in air particulate matter and smoked tea. Graphical abstract