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Analytical and Bioanalytical Chemistry (v.381, #8)

Mercury analysis by Milena Horvat (pp. 1489-1490).

Detoxification of mercury in the environment by S. Cathum; D. Velicogna; A. Obenauf; A. Dumouchel; M. Punt; C. E. Brown; J. Ridal (pp. 1491-1498).

In this study, a “green chemistry” approach was developed as an option for remediation of toxic mercury in the environment. Twenty mercury compounds were treated with an environmentally friendly agent cyclodextrin to produce stable non-toxic mercury in soil and water. The binding efficiency was determined using high performance liquid chromatography with diode-array detection. The stability of the cyclodextrin mercury complexes toward environmental microorganisms in water was estimated under OECD guidelines using gas chromatography–mass spectrometry. The toxicity of the cyclodextrin mercury compounds to terrestrial organisms was investigated by use of internationally recognized toxicity methods using mercuric acetate as a model contaminant. Key process conditions, for example pH, temperature, and amount of detoxifying agent were investigated and found to have significant effects on the toxicity of mercury. It was found that organic and inorganic mercury pollutants could be mineralized in the environment with cyclodextrins. The bound mercury compounds resisted biodegradation and were found to be non-toxic to environmental microorganisms under laboratory conditions.

Keywords: Mercury; Cyclodextrin; Inclusion; Detoxification; Environment

Study of the suitability of HNO₃ and HCl as extracting agents of mercury species in soils from cinnabar mines by Rodolfo Fernández-Martínez; María Isabel Rucandio (pp. 1499-1506).

The aim of this study was to compare the influence and feasibility of two common extracting agents (50% v/v HCl and 50% v/v HNO₃) on the leaching of Hg from soils. The solubility of a number of Hg species in each acid solution was evaluated under selected conditions. Most species were quantitatively dissolved in both acids with the exception of HgS. The application of both acid solutions to a soil sample from the Almaden mining area provided different recoveries of Hg: about 5% in 50% v/v HNO₃ and 50% in 50% v/v HCl. The following experiments were designed and developed in order to evaluate the matrix influence on HgS solubility and leaching: (1) study of the solubility of HgS in the presence of different potential interfering compounds such as FeCl₃, KCl, KI, Fe₂O₃, CuSO₄, FeSO₄, MnO₂ and NaNO₃; (2) study of the recovery of HgS spiked in soil samples; (3) study of the extraction process in soil samples spiked with the critical interfering compounds. Results showed the existence of a greater matrix influence with the HCl solution, since much higher Hg recoveries were obtained with this reagent. In addition, the presence of nitrates and Mn oxides drastically promotes the solubility of HgS in an HCl solution. On the other hand, halide compounds drastically enhanced the extractability of Hg in the HNO₃ and they must be considered as potential interfering compounds when this acid solution is used as extracting agent. In summary, neither acid is totally free of matrix effects from common soil constituents; conclusions about mercury mobility resulting from the general application of these extraction procedures must therefore be made with caution.

Keywords: Mercury; Extraction; HgS; Almaden; Soil

Mercury and trace element fractionation in Almaden soils by application of different sequential extraction procedures by D. M. Sánchez; A. J. Quejido; M. Fernández; C. Hernández; T. Schmid; R. Millán; M. González; M. Aldea; R. Martín; R. Morante (pp. 1507-1513).

A comparative evaluation of the mercury distribution in a soil sample from Almaden (Spain) has been performed by applying three different sequential extraction procedures, namely, modified BCR (three steps in sequence), Di Giulio–Ryan (four steps in sequence), and a specific SEP developed at CIEMAT (six steps in sequence). There were important differences in the mercury extraction results obtained by the three procedures according to the reagents applied and the sequence of their application. These findings highlight the difficulty of setting a universal SEP to obtain information on metal fractions of different mobility for any soil sample, as well as the requirement for knowledge about the mineralogical and chemical characteristics of the samples. The specific six-step CIEMAT sequential extraction procedure was applied to a soil profile (Ap, Ah, Bt1, and Bt2 horizons). The distribution of mercury and major, minor, and trace elements in the different fractions were determined. The results indicate that mercury is mainly released with 6 M HCl. The strong association of mercury with crystalline iron oxyhydroxides, present in all the horizons of the profile, and/or the solubility of some mercury compounds in such acid can explain this fact. Minor mercury is found in the fraction assigned to oxidizable matter and in the final insoluble residue (cinnabar).

Keywords: Mercury fractionation; Sequential extraction; Leaching; Soils

Metal components analysis of metallothionein-III in the brain sections of metallothionein-I and metallothionein-II null mice exposed to mercury vapor with HPLC/ICP-MS by Satomi Kameo; Kunihiko Nakai; Naoyuki Kurokawa; Tomokazu Kanehisa; Akira Naganuma; Hiroshi Satoh (pp. 1514-1519).

Mercury vapor is effectively absorbed via inhalation and easily passes through the blood–brain barrier; therefore, mercury poisoning with primarily central nervous system symptoms occurs. Metallothionein (MT) is a cysteine-rich metal-binding protein and plays a protective role in heavy-metal poisoning and it is associated with the metabolism of trace elements. Two MT isoforms, MT-I and MT-II, are expressed coordinately in all mammalian tissues, whereas MT-III is a brain-specific member of the MT family. MT-III binds zinc and copper physiologically and is seemed to have important neurophysiological and neuromodulatory functions. The MT functions and metal components of MTs in the brain after mercury vapor exposure are of much interest; however, until now they have not been fully examined. In this study, the influences of the lack of MT-I and MT-II on mercury accumulation in the brain and the changes of zinc and copper concentrations and metal components of MTs were examined after mercury vapor exposure by using MT-I, II null mice and 129/Sv (wild-type) mice as experimental animals. MT-I, II null mice and wild-type mice were exposed to mercury vapor or an air stream for 2 h and were killed 24 h later. The brain was dissected into the cerebral cortex, the cerebellum, and the hippocampus. The concentrations of mercury in each brain section were determined by cold vapor atomic absorption spectrometry. The concentrations of mercury, copper, and zinc in each brain section were determined by inductively coupled plasma mass spectrometry (ICP-MS). The mercury accumulated in brains after mercury vapor exposure for MT-I, II null mice and wild-type mice. The mercury levels of MT-I, II null mice in each brain section were significantly higher than those of wild-type mice after mercury vapor exposure. A significant change of zinc concentrations with the following mercury vapor exposure for MT-I, II null mice was observed only in the cerebellum analyzed by two-way analysis of variance. As for zinc, the copper concentrations only changed significantly in the cerebellum. Metal components of metal-binding proteins of soluble fractions in the brain sections were analyzed by size-exclusion high-performance liquid chromatography (HPLC) connected with ICP-MS. From the results of HPLC/ICP-MS analyses, it was concluded that the mercury components of MT-III and high molecular weight metal-binding proteins in the cerebellum of MT-I, II null mice were much higher than those of wild-type mice. It was suggested that MT-III is associated with the storage of mercury in conditions lacking MT-I, and MT-II. It was also suggested that the physiological role of MT-III and some kind of high molecular weight proteins might be impaired by exposure to mercury vapor and lack of MT-I and MT-II.

Keywords: Mercury vapor; Metallothionein; Brain; ICP-MS; Zinc; Copper

Electrochemical characterisation of dental alloys: its possibilities and limitations by Wolf-Dieter Mueller; C. Schoepf; M. L. Nascimento; A. C. Carvalho; M. Moisel; A. Schenk; F. Scholz; K. P. Lange (pp. 1520-1525).

Dental alloys are metallic biomaterials which have a broad variation of composition compared to technical alloys. It is therefore in the interest of patients and technicians to conduct a good assessment of the electrochemical behaviour of dental alloys in order to collect information about their corrosion resistance. The purpose of this work was to demonstrate possibilities and limitations of two electrochemical techniques: the voltammetry of immobilised microparticles (ViMP) onto lead, and cyclic voltammetry measurements with the help of the mini-cell system (MCS). Based on fingerprints obtained from ViMP it was possible to analyse and differentiate the dental alloys. The results obtained by MCS were comparable with ViMP, but give a better understanding of the corrosion behaviour of the materials.

Keywords: Biomaterials; Dental alloys; Corrosion; Surface characterisation

Investigation of gettering effects in CZ-type silicon with SIMS by D. Krecar; M. Fuchs; R. Koegler; H. Hutter (pp. 1526-1531).

Ion implantation is a well-known standard procedure in electronic device technology for precise and controlled introduction of dopants into silicon. However, damage caused by implantation acts as effective gettering zones, collecting unwanted metal impurities. This effect can be applied for “proximity gettering” reducing the concentration of impurities in the active device region. In this study the consequences of high-energy ion implantation into silicon and of subsequent annealing were analysed by means of secondary ion mass spectrometry (SIMS). Depth profiles were recorded of such impurities as copper, oxygen and carbon to obtain information about their gettering behaviour. The differences in impurities gettering behaviour were studied as a function of the implanted ions, P and Si, of the implantation dose and annealing time at T=900°C. Besides impurities gettering at the mean projected range (Rp) of implanted ions, Rp-effect, defects at around half of the projected ion range, Rp/2-effect, and even in some cases beyond Rp, trans-Rp-effect, have also been found to be effective in gettering of material impurities.

Keywords: Ion implantation; Gettering effect and defects; Rp-effect; Rp/2-effect; Trans-Rp-effect; Secondary ion mass spectrometry (SIMS)

Liquid chromatography–multistage tandem mass spectrometry for the quantification of dihydroxynonene mercapturic acid (DHN-MA), a urinary end-metabolite of 4-hydroxynonenal by E. Rathahao; G. Peiro; N. Martins; J. Alary; F. Guéraud; L. Debrauwer (pp. 1532-1539).

The mercapturic acid conjugate of 1,4-dihydroxynonene (DHN-MA) is a urinary metabolite of 4-hydroxynonenal (4-HNE), one of the main lipid peroxidation products occurring in vivo. To determine its level in urine, a combination of liquid chromatography with positive electrospray–multistage tandem mass spectrometry has been developed. A deuterated analog of the target compound (DHN-MA) with six deuterium atoms was synthesized and used as the internal standard. Three-stage tandem mass spectrometry was used, providing good selectivity for the detection of DHN-MA. The response of the system to DHN-MA was linear in the 5–100 ng range. Urine samples spiked with different levels of standard DHN-MA were used to evaluate the influence of matrix effects on the linearity. The repeatability of the method was also determined by using repeated 5 ng injections of DHN-MA, providing a RSD of 10%. The method was then applied to the determination of DHN-MA in rat urine samples; increased levels of urinary DHN-MA in urine from rats treated with BrCCl₃ indicates that lipid peroxidation processes take place in such rats.

Keywords: Liquid chromatography–mass spectrometry; Quantification; Oxidative stress; Biomarker; 4-Hydroxynonenal

Improved high-performance liquid chromatographic method for the determination of domoic acid and analogues in shellfish: effect of pH by A. López-Rivera; B. A. Suárez-Isla; P. P. Eilers; C. G. Beaudry; S. Hall; M. Fernández Amandi; A. Furey; K. J. James (pp. 1540-1545).

Domoic acid (DA) is a naturally-occurring amino acid that causes a form of human intoxication called amnesic shellfish poisoning (ASP) following the consumption of shellfish. A rapid and sensitive HPLC-UV method has been developed for analysis of DA and analogues in shellfish without the need for SPE clean-up. Isocratic chromatographic separation of DA and its isomers from shellfish matrix interferences and from the prevalent amino acid, tryptophan, was achieved by careful control of the mobile phase pH. The optimised pH was found to be 2.5 when using a Luna(2) C₁₈ column. Sample extraction was verified with control extracts from shellfish spiked at 5.0 and 10.0 μg/g of DA and with certified reference material. The average extraction efficiency was 98.5%. The calibration, based on mussel tissue spiked with DA standard, was linear in the range 0.05–5.0 μg/ml (r=0.9999) and the detection limit (signal:noise 3:1) was better than 25 ng/ml. The DA assay achieved good precision; %RSD=1.63 (intra-day, n=6) and %RSD=3.7 (inter-day, n=8). This method was successfully applied to a variety of shellfish species, allowing the rapid screening of a large number of samples per day (20–30), without the need for SPE clean-up. Quantitative data were obtained for shellfish samples containing domoic acid in the concentration range 0.25–330 μg/g. Using the same chromatographic conditions, LC-MS³ was used to determine DA and its isomers, isodomoic acid D and epi-domoic acid, in scallop tissues.

Keywords: Amnesic shellfish poisoning; Domoic acid; Ion-trap mass spectrometry

Electrochemical determination of the total antioxidant capacity of human plasma by G. K. Ziyatdinova; H. C. Budnikov; V. I. Pogorel’tzev (pp. 1546-1551).

Electrochemical reduction of oxygen at a glassy carbon electrode in a 0.05 mol L⁻¹ solution of (C₂H₅)₄NI in dimethylformamide leads to generation of the superoxide anion-radical. This product of reversible one-electron oxygen reduction reacts with antioxidants, a process which is based on protonation of the anion-radical by the antioxidant. Rate constants of this interaction have been calculated. Human plasma antioxidants also react with electrochemically generated superoxide anion-radical. A voltammetric method is proposed for estimation of the total antioxidant capacity (TAC) of plasma on the basis of on this reaction. The TAC of plasma was also determined using constant-current coulometry with electrogenerated bromine as the active species. A correlation was observed between TAC data obtained by voltammetry ( $${ m O}_{2}^{ullet-}$$ , in α-tocopherol units) and coulometry (Br₂ as titrant). TAC of plasma from patients with purulent infections was determined. Statistically significant differences were found between TAC of patients and control group. Treatment of purulent infections increases the TAC of plasma. So, use of electrochemical methods (voltammetry and coulometry) for determination of TAC can be used for estimation of the effectiveness of treatment.

Keywords: Total antioxidant capacity; Voltammetry; Superoxide anion-radical; Plasma

A kinetic model and its parameter estimation for the process of binding copper to human serum albumin by a voltammetric method by Kejun Zhong; Jianjun Xia; Wanzhi Wei; Yanbo Hu; Han Tao; Wei Liu (pp. 1552-1557).

Linear sweep anodic stripping voltammetry was applied to determine the concentration of free copper ions in the process of binding copper to human serum albumin (HSA) on the mercaptoethane sulfonate modified gold electrode surface. A kinetic model of two consecutive steps for the process of binding copper to HSA was first proposed on the basis of the electrochemical results and compared with a parallel kinetic response model by using residual analysis. The experimental data of the stripping peak currents with time was fitted according to the model and the kinetic parameters, binding rate constants, k₁ and k₂, were estimated to be 0.411 and 0.055 min⁻¹, respectively.

Keywords: Kinetic model; Binding process; Copper; Human serum albumin; Linear sweep anodic stripping voltammetry (LSASV); Mercaptoethane sulfonate (MES)

Monolayers of photosystem II on gold electrodes with enhanced sensor response—effect of porosity and protein layer arrangement by J. Maly; J. Krejci; M. Ilie; L. Jakubka; J. Masojídek; R. Pilloton; K. Sameh; P. Steffan; Z. Stryhal; M. Sugiura (pp. 1558-1567).

Mass transport of the bulk of the analyte to the electrode and through the bioactive layer can be significantly improved by use of the nanoelectrode array and defined arrangement of protein film. This phenomenon has been studied by (i) atomic-force microscopy, (ii) electrochemical measurements of PSII activity, and (iii) digital simulations for an oriented monolayer of histidine-tagged photosystem II (PSII) immobilized on nitrilotriacetic acid (NTA)-modified gold electrodes. The output signal of the electrochemical biosensor is controlled by (i) mass transport from the bioactive layer to electrode and (ii) mass transport between the bulk of the analyte and the electrode. Mass transport through the bioactive layer was electrochemically studied for PSII self-assembled on gold screen-printed electrodes. A densely packed monolayer of PSII has a significant shielding effect toward the diffusion of redox mediator duroquinone (DQ). Mass transport to the planar electrode surface was improved by co-immobilization of bovine-serum albumin (BSA) as spacer biomolecule in the monolayer of PSII. Correlation between the electrochemical properties and surface arrangement of the resulting protein films was clearly observable and confirmed the improved mass-transport properties of structured enzyme monolayers. On the basis of this observation, the application of a bottom-up approach for improvement of electrode performance was proposed and digitally simulated for an infinite array of electrodes ranging in diameter from 50 nm to 5 μm. The nanoelectrode array, with the optimum time window selected for measurements, enables enhancement of mass transport between the bulk of the analyte and the macroelectrode by a factor of up to 50 in comparison with “classical” planar electrodes. Use of a time window enables minimization of crosstalk between individual electrodes in the array. The measurements require methods which suppress the double-layer capacity.

Keywords: Protein monolayer; Photosystem II; Nanostructured electrodes; Biosensors; Mass transport

Validation of a screening method for the simultaneous identification of fat-soluble and water-soluble vitamins (A, E, B₁, B₂ and B₆) in an aqueous micellar medium of hexadecyltrimethylammonium chloride by V. León-Ruiz; S. Vera; M. P. San Andrés (pp. 1568-1575).

Simultaneous determination of the fat-soluble vitamins A and E and the water-soluble vitamins B₁, B₂ and B₆ has been carried using a screening method from fluorescence contour graphs. These graphs show different colour zones in relation to the fluorescence intensity measured for the pair of excitation/emission wavelengths. The identification of the corresponding excitation/emission wavelength zones allows the detection of different vitamins in an aqueous medium regardless of the fat or water solubility of each vitamin, owing to the presence of a surfactant which forms micelles in water at the used concentration (over the critical micelle concentration). The micelles dissolve very water insoluble compounds, such as fat-soluble vitamins, inside the aggregates. This approach avoids the use of organic solvents in determining these vitamins and offers the possibility of analysing fat- and water-soluble vitamins simultaneously. The method has been validated in terms of detection limit, cut-off limit, sensitivity, number of false positives, number of false negatives and uncertainty range. The detection limit is about μg L⁻¹. The screening method was applied to different samples such as pharmaceuticals, juices and isotonic drinks.

Keywords: Vitamins; Surfactants; Screening; Fluorescence; Method validation; Pharmaceuticals; Isotonic drinks

Determination of sterols in biological samples by SPME with on-fiber derivatization and GC/FID by Celia Domeño; Bárbara Ruiz; Cristina Nerín (pp. 1576-1583).

A new procedure for the determination of sterols in serum samples is proposed. The system consists of coating a Solid Phase Microextraction (SPME) microfiber in headspace mode with the derivatizing agent N,O-bis(trimethylsilyl)trifluoracetamide (BSTFA) and then applying this coated fiber to the simultaneous extraction and derivatization of three precursors in the cholesterol biosynthesis pathway (desmosterol, lathosterol and lanosterol) and two phytosterols (sitosterol and sitostanol) in serum samples. Optimization of the analytical procedure via the application of an experimental design, a study of matrix effects, and an analysis of serum pool samples are all described and discussed.

Keywords: Sterols; Analysis; Serum; SPME; On-fiber derivatization

Detector for particulate polycyclic aromatic hydrocarbons in water by Jane Levinson; Chanan Sluszny; Yakov Yasman; Valery Bulatov; Israel Schechter (pp. 1584-1591).

It is estimated that most polycyclic aromatic hydrocarbons (PAHs) in environmental water are not dissolved but rather in particulate form. Nevertheless, the currently available optical detectors are not suited for proper sampling of solid PAHs. A new setup for direct sampling and quantification of suspended particulate PAHs in water is suggested. It is based on a polymeric film that has the capability of dissolving PAH particulates, coupled to a traditional laser-induced fluorescence probe. Kinetics and performance of two sampling modes have been studied: bulk sampling, by immersing the probe into the water, and surface sampling, by laying the film on the water surface. The latter method has proved to be more sensitive; however, it is diffusion-limited. Linear calibration plots have provided quantification over a wide concentration range with detection limits in the ppb range (these could be improved by using a modified probe). The effects due to other particulates in water have been studied and only little interferences have been observed. The possibility of analysis of PAH mixtures has been addressed and it has been concluded that multivariate analysis is needed.

Keywords: PAH; Water; Detector; Hydrosol; Analysis

Determination of ochratoxin A in wine by liquid chromatography tandem mass spectrometry after combined anion-exchange/reversed-phase clean-up by M. Reinsch; A. Töpfer; A. Lehmann; I. Nehls (pp. 1592-1595).

Ochratoxin A (OTA) is a mycotoxin produced by Aspergillus ochraceus and Penicillium verrucosum. It has been found and analysed in several foods and feeds. Owing to its toxicity and occurrence in food and feed, the European Community has issued directives and some countries have their own regulations for OTA contents in food, feed and beverages. This work describes a method for the determination of OTA in mulled and red wine. It is based on combined anion exchange/reversed-phase clean-up and was analysed by liquid chromatography coupled with tandem mass spectrometry (multiple reaction monitoring). The method was validated with natural contaminated and spiked wine samples with OTA contents from 1.34 to 3.48 μg kg⁻¹. Owing to its accuracy, good reproducibility and repeatability, this easy method is a good alternative to liquid chromatography–fluorescence detection methods.

Keywords: Ochratoxin A; Wine; Tandem mass spectrometry; Solid-phase extraction; Anion exchange; Liquid chromatography

Flow-injection technique for determination of uranium and thorium isotopes in urine by inductively coupled plasma mass spectrometry by Karima Benkhedda; Vladimir N. Epov; R. Douglas Evans (pp. 1596-1603).

A sensitive and efficient flow-injection (FI) preconcentration and matrix-separation technique coupled to sector field ICP–mass spectrometry (SF-ICP–MS) has been developed and validated for simultaneous determination of ultra-low levels of uranium (U) and thorium (Th) in human urine. The method is based on selective retention of U and Th from a urine matrix, after microwave digestion, on an extraction chromatographic TRU resin, as an alternative to U/TEVA resin, and their subsequent elution with ammonium oxalate. Using a 10 mL sample, the limits of detection achieved for ²³⁸U and ²³²Th were 0.02 and 0.03 ng L⁻¹, respectively. The accuracy of the method was checked by spike-recovery measurements. Levels of U and Th in human urine were found to be in the ranges 1.86–5.50 and 0.176–2.35 ng L⁻¹, respectively, well in agreement with levels considered normal for non-occupationally exposed persons. The precision obtained for five replicate measurements of a urine sample was 2 and 3% for U and Th, respectively. The method also enables on-line measurements of the ²³⁵U/²³⁸U isotope ratios in urine. Precision of 0.82–1.04% (RSD) was obtained for ²³⁵U/²³⁸U at low ng L⁻¹ levels, using the FI transient signal approach.

Keywords: Uranium; Thorium; Flow injection; Urine; SF-ICP–MS; Isotope ratios

Evaluation of a microwave-assisted extraction technique for determination of water-soluble inorganic species in urban airborne particulate matter by K. Sathrugnan; R. Balasubramanian (pp. 1604-1608).

A simple and rapid microwave-assisted extraction (MAE) technique has been developed for the determination of water-soluble inorganic species (cations: Na⁺, NH₄⁺, K⁺, Ca²⁺ and Mg²⁺ and anions: F⁻, Cl⁻, NO₃⁻, PO₄³⁻ and SO₄²⁻) in airborne particulate matter. The analytes were extracted under different treatment conditions such as microwave power and extraction time. They were quantified using ion chromatography. The observed concentrations and recovery yields obtained under different conditions were compared. The results of a comparison between this MAE and sonication using NIST SRM 1648 are also given in this paper. The optimized MAE technique gave results in good agreement with the values obtained by the sonication. For some ions, for example Mg²⁺ and K⁺, recovery was low with both techniques. The results demonstrated that the optimized MAE is fast and efficient compared with conventional ultrasonic extraction. Urban airborne particles were collected and subjected to the MAE followed by the IC analysis to determine the relative proportions of different water-soluble inorganic species. These results are briefly discussed.

Keywords: MAE; Airborne particulates; Aerosols; Inorganic ions; Ion chromatography; PM_2.5

Evaluation of soot particles of biomass fuels with endocrine-modulating activity in yeast-based bioassay by Jingxian Wang; Ping Xie; Antonius Kettrup; Karl-Werner Schramm (pp. 1609-1618).

Exposure to indoor air pollution (IAP) from the combustion of biomass fuels is an important cause of morbidity and mortality in developing countries. In the work discussed in this paper we evaluated the endocrine activity of soot particles from biomass fuels by using yeast bioassay. These pollutants could have β-galactosidase activity with a relative potency (RP) about 10⁻⁷–10⁻⁹ that of estradiol. Soot particles from wood and straw combustion only partially induced β-galactosidase activity whereas others produced fully inductive activity in the yeast assay system. These pollutants did not have estrogen antagonist and progesterone agonist activity within the defined concentration range. However, these pollutants require 2–4 orders of magnitude higher IC50 to inhibit the activity of progesterone in a similar dose-response manner to mifepristone. We therefore propose that the endocrine activity of some environmental pollutants may be because of inhibition of the progesterone receptor (hPR). GC–MS results showed that substituted polycyclic aromatic hydrocarbon (PAH) compounds, substituted phenolic compounds and derivatives, aromatic carbonyl compounds, and phytosteroids in these soot particles may be mimicking endogenous hormones.

Keywords: Biomass fuel; Soot; Endocrine modulating disrupter; Yeast bioassay; Reproductive health

Rapid and sensitive method for the determination of acetaldehyde in fuel ethanol by high-performance liquid chromatography with UV–Vis detection by Adelir Aparecida Saczk; Leonardo Luiz Okumura; Marcelo Firmino de Oliveira; Maria Valnice Boldrin Zanoni; Nelson Ramos Stradiotto (pp. 1619-1624).

A high-performance liquid chromatography (HPLC) method for the determination of acetaldehyde in fuel ethanol was developed. Acetaldehyde was derivatized with 0.900 mL 2,4-dinitrophenylhydrazine (DNPHi) reagent and 50 μL phosphoric acid 1 mol L⁻¹ at a controlled room temperature of 15°C for 20 min. The separation of acetaldehyde-DNPH (ADNPH) was carried out on a Shimadzu Shim-pack C₁₈ column, using methanol/LiCl_(aq) 1.0 mM (80/20, v/v) as a mobile phase under isocratic elution and UV–Vis detection at 365 nm. The standard curve of ADNPH was linear in the range 3–300 mg L⁻¹ per injection (20 μL) and the limit of detection (LOD) for acetaldehyde was 2.03 μg L⁻¹, with a correlation coefficient greater than 0.999 and a precision (relative standard deviation, RSD) of 5.6% (n=5). Recovery studies were performed by fortifying fuel samples with acetaldehyde at various concentrations and the results were in the range 98.7–102%, with a coefficient of variation (CV) from 0.2% to 7.2%. Several fuel samples collected from various gas stations were analyzed and the method was successfully applied to the analysis of acetaldehyde in fuel ethanol samples.

Keywords: High-performance liquid chromatography; UV–Vis detection; Isocratic elution; Acetaldehyde; 2,4-dinitrophenylhydrazine; Fuel ethanol

Determination of HCN sampled from gasification product gases by headspace gas chromatography with atomic emission detector by Mari-Leena Koskinen-Soivi; Eero Leppämäki; Pekka Ståhlberg (pp. 1625-1630).

Nitrogen-containing fuels produce hydrogen cyanide when the fuel is gasified. The gas is poisonous and produces nitrogen oxides when it is burned. HCN is usually sampled into alkaline solutions and analysed using an ion selective electrode. The method is tedious and the electrode response is temperature-dependent. Samples are not stable and must be analysed immediately, and they contain ions which are poisonous to the electrode. Therefore a new gas chromatographic method was developed. In this new method HCN is released from the alkaline solutions with sulphuric acid in a headspace sampler and analysed by a gas chromatograph connected to an atomic emission detector. Measurements on carbon emission line 193.1 nm gave the limit of detection 0.05 mg CN⁻/l in the solution. The calibration curve was linear to 1000 mg CN⁻/l and the correlation was 0.997. The relative standard deviation of the calibration was 1.7% at the concentration of 5 mg CN⁻/l and 1.0% at 25 mg CN⁻/l. The developed headspace method allows automated analysis and it needs less sample preparations than the ion selective electrode method. This paper also reports the effect of sample preparation and storage time on the stability of the samples.

Keywords: Headspace gas chromatography; AED; HCN; Gasification product gas

Determination of methylmercury fluxes across the air–water and air–soil interfaces by gas chromatography with electron capture detection by Xiang-Rong Xu; Hua-Bin Li; Wen-Hua Wang; An Peng; Ji-Dong Gu (pp. 1631-1634).

A method for the determination of methylmercury (MeHg) fluxes across the air–water and air–soil interfaces was developed using an in situ chamber. The MeHg in the air coming out of the chamber was captured by a column containing sulfhydryl cotton fiber adsorbent. MeHg was then desorbed from the column by using 2 mol L⁻¹ HCl. The MeHg in the effluent was extracted with benzene, and determined by gas chromatography with electron capture detection. Finally, the MeHg flux was calculated using the chamber. The method was applied to simulated experiments, and the results showed that the MeHg fluxes in the air–water system were higher than those in the air–soil–water system. The method was also successfully applied to the field measurements of an environment polluted by a chemical factory, and the results showed that the MeHg fluxes across the air–soil and air–water interfaces were 0.21–3.09 and 0.14–0.79 ng m⁻² h⁻¹, respectively. The method will be a useful tool in the environmental study of MeHg.

Keywords: Methylmercury; Flux; Gas chromatography; Air; Water; Soil

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Analytical and Bioanalytical Chemistry (v.381, #8)