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Analytical and Bioanalytical Chemistry (v.372, #7-8)


Development of a chemiluminescent enzyme immunoassay for urinary 1-hydroxypyrene by Aldo Roda; P. Simoni; M. Mirasoli; M. Baraldini; S. F. Violante (pp. 751-758).
A chemiluminescent enzyme-immunoassay for urinary 1-hydroxypyrene has been developed and optimized. The enzymatic activity of horseradish peroxidase-labeled tracer was measured with an enhanced chemiluminescent system and the results were compared with those from conventional colorimetric detection. The method fulfilled all the requirements of accuracy and precision and the detection limit was 0.001 pmol/well, which enabled analysis in less than 1 µL urine. Subjects working in the center of Bologna who were exposed daily to vehicular exhaust gas were studied. Their urinary 1-hydroxypyrene concentrations were compared with the levels of benzo(a)pyrene in air particulate matter. Urinary 1-hydroxypyrene, which ranged from 0.5 to 10 nmol L–1, correlated poorly with the concentration of benzo(a)pyrene in air particulate matter, which ranged from 5 to 140 ng m–3. No significant effect of vehicle exhaust gas exposure was observed among the different groups of subjects working in different areas of the town. Thus, at a relatively low level of exposure 1-hydroxypyrene does not seem to be a sensitive biomarker of exposure to polycyclic aromatic hydrocarbons.

Keywords: 1-Hydroxypyrene Polycyclic aromatic hydrocarbons Environmental exposure biomarker Immunoassay Chemiluminescence


Trace determination of gadolinium in biomedical samples by diode laser-based multi-step resonance ionization mass spectrometry by K. Blaum; C. Geppert; W. Schreiber; J. Hengstler; P. Müller; W. Nörtershäuser; K. Wendt; B. Bushaw (pp. 759-765).
The application of high-resolution multi-step resonance ionization mass spectrometry (RIMS) to the trace determination of the rare earth element gadolinium is described. Utilizing three-step resonant excitation into an autoionizing level, both isobaric and isotopic selectivity of >107 were attained. An overall detection efficiency of ~10–7 and an isotope specific detection limit of 1.5×109 atoms have been demonstrated. When targeting the major isotope 158Gd, this corresponds to a total Gd detection limit of 1.6 pg. Additionally, linear response has been demonstrated over a dynamic range of six orders of magnitude. The method has been used to determine the Gd content in various normal and tumor tissue samples, taken from a laboratory mouse shortly after injection of gadolinium diethylenetriaminepentaacetic acid dimeglumine (Gd-DTPA), which is used as a contrast agent for magnetic resonance imaging (MRI). The RIMS results show Gd concentrations that vary by more than two orders of magnitude (0.07–11.5 µg mL–1) depending on the tissue type. This variability is similar to that observed in MRI scans that depict Gd-DTPA content in the mouse prior to dissection, and illustrates the potential for quantitative trace analysis in microsamples of biomedical materials.

Keywords: Biomedical samples Contrast agent Gadolinium Gadolinium-DTPA Magnetic resonance imaging Resonance ionization mass spectrometry Trace determination


Determination of endocrine-disrupting pesticides and polychlorinated biphenyls in human serum by GC–ECD and GC–MS–MS and evaluation of contributions to the uncertainty of the results by Martínez J. Vidal; Moreno M. Frías; Garrido A. Frenich; F. Olea-Serrano; N. Olea (pp. 766-775).
The chemicals endosulfan-α, endosulfan-β, endosulfan sulfate, endosulfan ether, endosulfan lactone, PCB-21, PCB-48, PCB-61, and PCB-136 have been determined in 100 serum samples from women living in agricultural areas of Almería (Spain). The study includes a surgically treated breast cancer patient and a matching group of women with no sign of estrogenic-dependent disease. The determination was performed by gas chromatography with electron capture detection (GC–ECD) and tandem mass spectrometry (GC–MS–MS). Recovery, precision, linear range, detection limit (LOD), and quantification limit (LOQ) were calculated for each pesticide as was the expanded uncertainty (U). The method was evaluated for our laboratory and could be applied to subsequent results with relevant quality-control data. Comparison of the results was performed. The advantage of MS–MS over ECD for determination of endocrine-disrupting compounds in complex matrices is presented. The most commonly encountered pesticide was endosulfan-α. Endosulfan-β and the PCB-48 congener were detected at concentrations lower than their LOQ. Endosulfan sulfate, endosulfan ether, endosulfan lactone, PCB-21, PCB-61 and PCB-136 were not found in any of the serum samples analysed.

Keywords: Endocrine-disrupting pesticides Polychlorinated biphenyls GC-ECD GC-MS-MS Organochloride compounds Human serum Uncertainty


Analysis of biogenic carbonates by inductively coupled plasma–mass spectrometry (ICP–MS). Flow injection on-line solid-phase preconcentration for trace element determination in fish otoliths by Z. Arslan; A. Paulson (pp. 776-785).
The aragonite deposits within the ear bones (otoliths) of teleost fish retain a chemical signal reflecting the life history of fish (similar to rings of trees) and the nature of fish habitats. Otoliths dissolved in acid solutions contain high concentrations of calcium and a variety of proteins. Elimination of matrix salts and organic interferences during preconcentration is essential for accurate determination of trace elements in otolith solutions by inductively coupled plasma–quadrupole mass spectrometry. An iminodiacetate-based chelating resin (Toyopearl AF-Chelate 650 M) has been used for on-line preconcentration and matrix separation for the determination of 31 transition and rare elements. Successful preconcentration of the elements was achieved at pH 5 by on-line buffering, except Mn which required pH 8.8. Sample solutions were loaded on to the column for 1 min at 3.2 mL min–1, and then eluted directly into the mass spectrometer with 4% v/v nitric acid. This procedure enabled up to 25-fold preconcentration with successful removal of the calcium matrix. The effect of heat-assisted oxidation with concentrated nitric acid was investigated to eliminate the organic matrix. It was found that heating to dryness after dissolution and further mineralization with the acid significantly improved the retention of the transition elements. The method was validated by analysis of a certified reference material produced from saggittal otoliths of emperor snapper (Lutjanus sebae), and then applied to the determination of trace metal concentrations in juvenile bluefin tuna (Thunnus thynnus) from the Western Pacific Ocean.

Keywords: Fish otoliths Trace elements Preconcentration Inductively coupled plasma–mass spectrometry


Potentiometric behavior of electrodes based on overoxidized polypyrrole films by Arzu Ersöz; Vasilis G. Gavalas; Leonidas G. Bachas (pp. 786-790).
Electrodes based on oxidized polypyrrole films have potentiometric selectivity toward anions. When the films are overoxidized, however, electron-rich groups are introduced on to the polymer chains, reversing the selectivity of the electrodes from anionic to cationic. In this study, electrochemically overoxidized polypyrrole film electrodes were prepared, and the conditions for film formation that lead to near-Nernstian potentiometric response were investigated. It was found that the doping ion, overoxidation solution, and pH affect the response of these electrodes. Redox interference is significantly lower for the overoxidized polypyrrole films than for polypyrrole electrodes.

Keywords: Overoxidized polypyrrole Potentiometric behavior Templating effect


Amperometric determination of glutathione and cysteine on a Pd-IrO2 modified electrode with high performance liquid chromatography in rat brain microdialysate by Fang Xu; Lin Wang; Mengnan Gao; Litong Jin; Jiye Jin (pp. 791-794).
A Pd/IrO2 co-electrodeposited glassy carbon electrode was prepared and the electrochemical behavior of glutathione (GSH) at this chemically modified electrode (CME) has been studied by cyclic voltammetry (CV). The results indicated that the modified electrode efficiently exhibited electrocatalytic oxidation for GSH with relatively high sensitivity, stability, and long-life. Coupled with high-performance liquid chromatography (HPLC), the Pd/IrO2 modified electrode was utilized for the electrochemical detection (ECD) of the thiocompounds, glutathione and cysteine (Cys). The peak currents were linear with the substance concentrations in the range of 1.0×10–5 mol L–1 to 8.0×10–4 mol L–1 for GSH and 4.0×10–6 mol L–1 to 2.0×10–4 mol L–1 for Cys. The detection limits were 2.0×10–6 mol L–1 for GSH and 5.0×10–7 mol L–1 for Cys with S/N of 3. The method has been successfully applied to assess the contents of GSH and Cys in rat brain microdialysates.

Keywords: Pd/IrO2 codeposition Modified electrode Thiocompounds Microdialysis Rat brain


Simple and rapid determination of iodide in table salt by stripping potentiometry at a carbon-paste electrode by Ivan Švancara; Božidar Ogorevc; Milko Nović; Karel Vytřas (pp. 795-800).
A simple and rapid procedure, utilising constant-current stripping analysis (CCSA) at a carbon-paste electrode containing tricresyl phosphate as a pasting liquid (TCP-CPE), has been developed for the determination of iodide in table salt. Because of a synergistic accumulation mechanism based on ion-pairing and extraction of iodide in combination with electrolytic pretreatment of the TCP-CPE, the method is selective for iodide and enables direct determination of iodide in samples of table salt containing anticaking agents such as K4[Fe(CN)6] (food additive "E 536") or MgO. The iodide content (calculated as KI) can be determined in a concentration range of 2 to 100 mg kg–1 salt, with a detection limit (S/N=3) of 1 mg kg–1, and a recovery from 90 to 115%. The proposed method has been used to determine iodide in several types of artificially iodised table salt and in one sample of natural sea salt. The results obtained agreed well with those obtained by use of three independent reference methods (titration, spectrophotometry, and ICP–MS) used to validate the CCSA method, indicating that the developed method is applicable as a routine procedure for rapid testing in salt production process control and in the analysis of marketed table salts.

Keywords: Constant-current stripping analysis Carbon-paste electrode Iodide Table salts


Resolution of uncertainty of a four-stage sequential extraction procedure using analysis of variance by S. Eichfeld; J. Einax; G. Knapp (pp. 801-807).
Sequential extraction procedures are mostly applied to soils and sediments. Investigations were made for testing the applicability of a selected extraction scheme on spoil pile material. Therefore, different spoil pile samples from uranium mining were extracted into four steps (exchangeable, reducible, oxidizable, and aqua regia soluble phase) and the contents of the elements Cr, Cu, Fe, K, Ni, and Zn were analyzed. To substitute the sequential extraction by a sequence of single extractions and thus keep uncertainties of extraction on a low level, both procedures were compared regarding conformity of their results. The effects of sample handling as well as those of analysis on the measured metal contents were determined by means of analysis of variance and sources of uncertainties were discussed.

Keywords: Sequential extraction Spoil piles Uncertainty Analysis of variance


Comparison of methods for extraction, storage, and silylation of pentafluorobenzyl derivatives of carbonyl compounds and multi-functional carbonyl compounds by R. Spaulding; M. Charles (pp. 808-816).
The employment of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatization along with bis-(trimethylsilyl)trifluoroacetamide (BSTFA) or N,N-(tert-butyldimethylsilyl)trifluoroacetamide (MTBSTFA) derivatization is a popular method for measurement of oxygenated organics in environmental and biological samples. Most notably, the derivatization method enables the measurement of atmospheric photooxidation products not detected by using other methods. PFBHA derivatization is often conducted in an aqueous solution. Accordingly, experiments were performed to compare the efficiency of hexane, methyl-tert-butyl ether (MTBE), and dichloromethane (CH2Cl2) for extraction of O-(2,3,4,5,6-pentafluorobenzyl)hydroxylamine (PFBHA) derivatives of carbonyl compounds from water. Further, the stability of these compounds when stored at 4 °C in CH2Cl2 was determined, and commonly used methods for silylation of –OH and –COOH groups on the PFBHA derivatives were compared. Overall, CH2Cl2 was the most efficient solvent for extraction of PFBHA derivatives of hydroxycarbonyl compounds, dicarbonyl compounds, and keto-acids from water. Derivatives of carbonyl compounds that do not have secondary functional groups were extracted with approximately equal efficiency by each of the three solvents examined. The PFBHA derivatives of aromatic and saturated aliphatic carbonyl compounds and hydroxycarbonyl compounds were stable in CH2Cl2 at 4 °C for ≥66 days whereas the derivatives of keto-acids and unsaturated aliphatic aldehydes begin to degrade after approximately 38 days. Comparison of four procedures for bis-(trimethylsilyl)trifluoroacetamide (BSTFA) derivatization of –OH and –COOH groups on PFBHA derivatives revealed that primary –OH groups react efficiently in 20–100% BSTFA in CH2Cl2, and do not require a catalyst. Secondary –OH groups also react efficiently in 20–100% BSTFA, but the reaction yield improves slightly when trimethylchlorosilane (TMCS) is added as a catalyst. Reaction of tertiary –OH groups with BSTFA was very inefficient, but improved with addition of 10% TMCS to the BSTFA solution. Finally, –COOH groups seemed to react most efficiently and consistently in 100% BSTFA, without catalyst.

Keywords: PFBHA Carbonyls Oxygenated organics Silylation BSTFA


A new split-flow injector for preparative liquid chromatography columns. Annular injection system by F. Dardoize; G. Clodic; J. Chevalet (pp. 817-821).
The packing of large-diameter columns for liquid chromatography is still difficult and numerous publications have reported results from tests which prove the packing is heterogeneous. The slurry is more compact in the wall region and this reduces the flow of the mobile phase, leading to distortion of the sample zone in the column and generation of peak tailing. A new type of injection system for the head of the column has been developed which divides the flow of the solvent from the pump into two parts. One, without sample, is directed to a crown injector, close to the wall. By adjusting the ratio of this flow to that of the bulk flow it is possible to increase the speed of the mobile phase in this part of the stationary phase and reduce distortion of the sample zone. The other part of the solvent carries the sample to the stationary phase through a distributor. The results demonstrate the benefits of this annular injection system, which include increased efficiency and improved column stability.

Keywords: Preparative liquid chromatography Autocompression Phthalic acid esters


Determination of polyphenols in wines by reaction with 4-aminoantipyrine and photometric flow-injection analysis by Jan W. Schoonen; Goreti M. Sales (pp. 822-828).
A new flow-injection analytical procedure is proposed for the determination of the total amount of polyphenols in wines; the method is based on the formation of a colored complex between 4-aminoantipyrine and phenols, in the presence of an oxidizing reagent. The oxidizing agents hexacyanoferrate(III), peroxodisulfate, and tetroxoiodate(VII) were tested.Batch trials were first performed to select appropriate oxidizing agents, pH, and concentration ratios of reagents, on the basis of their effect on the stability of the colored complex. Conditions selected as a result of these trials were implemented in a flow-injection analytical system in which the influence of injection volume, flow rate, and reaction-coil length, was evaluated. Under the optimum conditions the total amount of polyphenols, expressed as gallic acid, could be determined within a concentration range of 36 to 544 mg L–1, and with a sensitivity of 344 L mol–1 cm–1 and an RSD <1.1%. The reproducibility of analytical readings was indicative of standard deviations <2%. Interference from sugars, tartaric acid, ascorbic acid, methanol, ammonium sulfate, and potassium chloride was negligible.The proposed system was applied to the determination of total polyphenols in red wines, and enabled analysis of approximately 55 samples h–1. Results were usually precise and accurate; the RSD was <3.9% and relative errors, by the Folin–Ciocalteu method, <5.1%.

Keywords: Total polyphenols Photometry Wines Flow injection and FIA


The use of silylation for minimizing the interference effects caused by contamination in ultra-low level mercury analytics by Teemu Näykki (pp. 829-831).
The use of silylation of glassware in mercury analytics was investigated. By treating the glassware with 5% (v/v) dichlorodimethylsilane in toluene, the surfaces of the vessels were inactivated. Method development proved that silylation can extend the range of stabile, contamination-free area as low as 1 ng/L mercury without any significant investments in laboratory clean-room facilities. The resilylation had to be done once a month.

Keywords: Contamination Mercury Silylation


Capillary electrophoretic separation between Fe(II) and Ni(II) precomplexed with 1,10-phenanthroline in a high concentration buffer of n-butyric acid/n-butyrate and its application by Takashi Yokoyama; Hirokazu Tsuji; Takenobu Kamada; Michio Zenki (pp. 832-836).
The capillary electrophoretic separation was accomplished for Fe(II) and Ni(II) precomplexed with 1,10-phenanthroline (phen) in 2 M n-butyric acid/n-butyrate buffer at pH 4.5 with direct UV detection at 260 nm. The applied voltage was 5 kV. The high concentration buffer of the n-butyrate resulted in a similar separation mechanism to that of ion-pair reversed-phase high-performance liquid chromatography. The separation would be due to the hydrophobic interaction between the ionic associates, [Fe(phen)3](n-butyrate)+ and [Ni(phen)3](n-butyrate)+, with the n-butyrate ion and n-butyric acid as background electrolyte. Linear calibration ranges were obtained for Fe(II) and Ni(II) from 100 to 500 ng ml–1. The relative standard deviations (n=10) for 3 g mL–1 Fe(II) and Ni(II) were 0.090 and 0.086, respectively. Detection limits (S/N=3) for Fe(II) and Ni(II) were 20 ng mL–1. The method was applied to the determination of nickel in aluminium and duralumin alloys.

Keywords: 1,10-phenanthroline Nickel N-butyrate Duralumin alloy Capillary electrophoresis


Selective preconcentration and determination of tributyltin in fresh water by electrothermal atomic absorption spectrometry by P. Bermejo-Barrera; R. Anllo-Sendín; M. Cantelar-Barbazán; A. Bermejo-Barrera (pp. 837-839).
A rapid and simple method for separation and determination of tributyltin (TBT) in mineral and tap water is described. The procedure is based on the selective retention of TBT by a chelating resin, Amberlite XAD-2 impregnated with tropolone. The addition of 0.8% sulfuric acid to the water sample leads to the retention of TBT by the resin while monobutyltin (MBT), dibutyltin (DBT) and inorganic tin remain in solution. TBT is eluted with methyl isobutyl ketone (MIBK) obtaining a preconcentration factor of 80. Tin concentration is determined by ETAAS using zirconium coated tubes. Multi-injection and hot injection techniques are used in order to enhance the sensitivity of the method. A detection limit of 14.4 ng L–1 is achieved with recoveries near to 100%. The procedure has been successfully applied to TBT determination in various fresh water samples.

Keywords: TBT Amberlite XAD-2 Tropolone ETAAS Water


Speciation of Cr(III) and Cr(VI) in potable waters by using activated neutral alumina as collector and ET–AAS for determination by A. Sahayam (pp. 840-842).
The speciation of Cr(III) and Cr(VI) has been performed by using activated neutral alumina as adsorbent. Both species were quantitatively adsorbed on a small column filled with neutral alumina. The adsorbed Cr(III) was eluted with 4 mol L–1 HNO3 and Cr(VI) with 1.0 mol L–1 ammonia solution. Recoveries of Cr(III) and Cr(VI) were 99% and 100%, respectively. Using ET–AAS for Cr determination the limit of detection in the sample was 0.01 µg L–1. The combined procedure is fast and sensitive. It can be applied for routine analysis of water samples at sub-µg L–1 levels with a relative standard deviation (RSD) of 2–10% (three determinations).

Keywords: Speciation CR (III) CR (VI) Activated neutral alumina ET-AAS


Differential pulse polarographic determination of poly(8-hydroxyquinoline) in the presence and absence of an insulating poly(vinyl alcohol) matrix by Mostafa M. Kamal; Seddique M. Ahmed; Mohamed M. Shahata; Yassien M. Temerk (pp. 843-848).
The electrochemical activity of poly(8-hydroxyquinoline) (PHQ) in acid and alkaline media has been investigated by use of differential pulse polarography (DPP). The reduction peak height (Ip) of PHQ in universal buffer solutions is not useful as an analytical signal, because it is highly affected by hydrogen evolution in acid media and appears as a small peak located at more negative potential values in alkaline media. A new and highly sensitive reduction peak (Ep=–0.45, pH 9.25) appears, however, after addition of trace amounts of PHQ to Cu(II), or vice versa. This reduction peak is a result of the reduction of Cu(II) chelates in the PHQ–Cu(II) complex and is highly promising for the trace determination of PHQ at nanomolar and submicromolar levels. The response current (Ip/µA) for the reduction peak of Cu(II) chelates in a PHQ–Cu(II) matrix results in sensitivity to the concentration of PHQ at least three orders of magnitude higher than that for the reduction peak of PHQ alone under the same conditions. The limit of detection is as low as 5.264 ppb (µg L–1). The effect of a variety of anions and cations and of an insulating poly(vinyl alcohol) (PVA) matrix has been investigated. Electroactive PHQ–Cu(II) at a level of 0.685% could induce a current of approximately 240 nA in an insulating PVA matrix, suggesting possible application for the preparation of a PHQ–Cu(II)–PVA electroactive composite.

Keywords: Differential pulse polarography Poly(8-hydroxyquinoline) Copper(II) determination Poly(vinyl alcohol)
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