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Analytical and Bioanalytical Chemistry (v.375, #3)

Specialist or generalist? by J. Fetzer (pp. 331-332).

Multiplex PCR design strategy used for the simultaneous amplification of 10 Y chromosome short tandem repeat (STR) loci by Richard Schoske; Pete M. Vallone; Christian M. Ruitberg; John M. Butler (pp. 333-343).

The simultaneous amplification of multiple regions of a DNA template is routinely performed using the polymerase chain reaction (PCR) in a process termed multiplex PCR. A useful strategy involving the design, testing, and optimization of multiplex PCR primer mixtures will be presented. Other multiplex design protocols have focused on the testing and optimization of primers, or the use of chimeric primers. The design of primers, through the close examination of predicted DNA oligomer melting temperatures (T _m) and primer–dimer interactions, can reduce the amount of testing and optimization required to obtain a well-balanced set of amplicons. The testing and optimization of the multiplex PCR primer mixture constructed here revolves around varying the primer concentrations rather than testing multiple primer combinations. By solely adjusting primer concentrations, a well-balanced set of amplicons should result if the primers were designed properly. As a model system to illustrate this multiplex design protocol, a 10-loci multiplex (10plex) Y chromosome short tandem repeat (STR) assay is used.

Keywords: Multiplex PCR design Y chromosome Short tandem repeats Primer design

HPLC assay for methylmalonyl–CoA epimerase by Thomas A. Bobik; Madeline E. Rasche (pp. 344-349).

Methylmalonyl–CoA epimerase (MCE) is broadly distributed in nature and has diverse cellular roles. Many MCE homologues are represented in public databases, but the biochemical function and physiological roles of the majority of these putative proteins have not been investigated. Here, a simplified assay for MCE is described. In this assay, MCE converted (2S)-methylmalonyl–CoA to (2R)-methylmalonyl–CoA which in turn was converted to succinyl–CoA by methylmalonyl–CoA mutase, an enzyme specific for the 2R isomer. MCE activity was quantified by measuring the disappearance of methylmalonyl–CoA by HPLC. To obtain the methylmalonyl–CoA mutase which was required as a reagent for the assay, an Escherichia coli strain was constructed that expressed high levels of this enzyme as a fusion protein with an 8× histidine tag. This allowed purification of the mutase in a single affinity chromatography step. Previously reported MCE assays required radioactive substrates and/or multiple reagent enzymes that were difficult to obtain. The assay reported here overcomes these difficulties and hence will facilitate studies of MCEs. Such enzymes play important roles in the metabolism of both prokaryotes and higher eukaryotes including humans.

Keywords: Methylmalonyl–CoA epimerase Methylmalonyl–CoA mutase Methylmalonyl aciduria Methylmalonyl–CoA racemase

Gramicidin A interaction at a dioleoyl phosphatidylcholine monolayer on a mercury drop electrode by Britta Lindholm-Sethson; Josefina Nyström; Paul Geladi; Andrew Nelson (pp. 350-355).

A biosensor where the sensing surface is a fluid dioleyl phosphatidylcholine monolayer (DOPC) deposited on a mercury drop was used. The lipid monolayer was held in 0.1 M NaCl and a concentration of gramicidin A in the range 0–12 nM was used. Electrochemical impedance spectroscopy in the frequency range 0.1–65 kHz was employed to investigate how the defect-free monolayer responds to interactions of gramicidin A in solution.The data was analyzed both with multivariate data analysis and classical electrochemical methods. The principal component analysis of the resulting impedance spectra gave a linear dependence on the concentration of gramicidin A. An increasing permittivity was observed in the low-frequency regime with increasing concentration of gramicidin A in solution.

Keywords: Phospholipid monolayer Gramicidin A DOPC Impedance spectroscopy Multivariate analysis

Determination of siloxanes, silicon, and platinum in tissues of women with silicone gel-filled implants by Daniela Flassbeck; Bettina Pfleiderer; Patrick Klemens; Klaus G. Heumann; Elke Eltze; Alfred V. Hirner (pp. 356-362).

Silicone [poly(dimethylsiloxane)] gel used in breast implants has been known to migrate through intact silicone elastomer shells, resulting in the clinically observable "gel bleed" on the implant surface. Although silicon concentrations in capsular tissues of women with silicone prostheses have been measured with element-specific silicon analyses, no silicone-specific investigation of these tissues has been performed as yet.A combination of element-specific inductively coupled plasma high-resolution isotope dilution mass spectrometry (ICP–HR–IDMS) and species-specific gas chromatography coupled mass spectrometry (GC–MS) was used to analyze silicon, platinum, and siloxanes in prosthesis capsule, muscle, and fat tissues of women (n=3) who had silicone gel-filled breast implants and in breast tissue of non-augmented women (n=3) as controls.In all tissues of augmented women, siloxanes, in particular octamethylcyclotetrasiloxane (D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6) were identified. Depending on the siloxane species and type of tissue analyzed, siloxane levels in the range of about 10–1,400 ng g⁻¹ were detected; total silicon was found in all tissue samples in the range of about 8,900–85,000 ng g⁻¹. Higher platinum levels ranging from 25–90 ng g⁻¹were detected in fibrin layer and fat tissue of two patients with prostheses. No siloxanes were detected in control breast tissue samples.This investigation of human tissues by a combination of element-specific and species-specific analytical techniques clearly demonstrates for the first time that platinum and siloxanes leak from prostheses and accumulate in their surrounding tissues.

Keywords: Siloxane Silicone Silicon Platinum Silicone breast implants Capsule tissue

Study of chromium-containing proteins in subcellular fractions of rat liver by enriched stable isotopic tracer technique and gel filtration chromatography by Weiyue Feng; Bai Li; Jing Liu; Zhifang Chai; Peiqun Zhang; Yuxi Gao; Jiujiang Zhao (pp. 363-368).

Ten male Wistar rats were intravenously injected with a single approximately physiological dose of enriched stable isotopic Cr-50 tracer solution (200 ng ⁵⁰Cr³⁺/100 g body wt). The fundamental distribution patterns of the chromium-containing proteins in the nucleic, mitochondrial, lysosomal, microsomal, and cytosolic subcellular fractions of the rat liver were investigated by means of Sephadex G-100 gel chromatography combined with neutron activation analysis via ⁵⁰Cr (n, γ) ⁵¹Cr reaction. In total, nine kinds of Cr-containing proteins were found in the five subcellular fractions, whose relative molecular masses were 96.6±6.2, 68.2±1.4, 57.9±4.7, 36.6±1.2, 24.2±1.8, 14.0±1.5, 8.8±0.6, 6.9±0.4, and 4.2±0.4 kDa. Approximately 64.5% of Cr proteins accumulated in the cytosolic fraction. The second enriched part was the nucleic fraction; about 12.2% Cr proteins were stored in this section. The 4.2-kDa molecular mass might contain the so-called low molecular weight chromium-containing substance; however, in this research, it was only observed in the mitochondria, lysosome, and microsome. In the mitochondrial fraction, most of the Cr proteins were present as relatively low molecular weight substances: about 56% of chromium-containing proteins had molecular masses ≤6.9 kDa. Nevertheless, more than 69% of Cr-containing proteins were observed with molecular masses ≥57.9 kDa in the liver cytosolic fraction.

Keywords: Cr-containing protein Speciation Enriched stable isotopic tracer technique Subcellular Rat

Cathodic adsorptive stripping square-wave voltammetric determination of nifedipine drug in bulk, pharmaceutical formulation and human serum by M. M. Ghoneim; A. Tawfik; P. Y. Khashaba (pp. 369-375).

Nifedipine is a calcium-channel antagonist drug used in the management of angina pectoris and hypertension through inhibition of calcium influx. A fully validated sensitive cathodic adsorptive stripping square-wave voltammetry procedure was optimized for the determination of the drug at trace levels. The procedure was based on the reduction of the nitrophenyl group after the interfacial accumulation of the drug onto a hanging mercury drop electrode in Britton–Robinson buffer of pH 11.0. The optimal conditions of the procedure were found to be: accumulation potential=–0.9 V vs. Ag/AgCl/KCl_s), accumulation time=30 s, scan increment=10 mV, pulse amplitude=50 mV and frequency=120 Hz. Under these conditions, a well-defined peak was obtained; its peak current showed a linear dependence on drug concentration in the range of 2×10^–9–2×10^–7 mol L^–1 bulk nifedipine. The mean recoveries based on eight replicate measurements for 1×10^–8 and 5×10^–8 mol L^–1 bulk nifedipine solutions were 98.46±0.86% and 98.23±0.92%, respectively. A detection limit of 3.42×10^–10 mol L^–1 bulk nifedipine was achieved. The procedure was successfully applied for assay of the drug in tablets and spiked human serum with mean recoveries of 101.95±1.42% and 98.70±0.63%, respectively. The limit of detection of the drug in spiked human serum was found to be 3.90×10^–10 mol L^–1.

Keywords: Nifedipine determination in tablets and spiked human serum Cathodic adsorptive stripping square-wave voltammetry

Determination of antioxidant activity of phenolic antioxidants in a Fenton-type reaction system by chemiluminescence assay by Zhiyong Cheng; Guangtao Yan; Yuanzong Li; Wenbao Chang (pp. 376-380).

The hydroxyl radical (^·OH) has been implicated in various diseases, and it is therefore important to establish efficient methods to screen hydroxyl radical scavengers for antioxidant therapy. In this paper, a simple chemiluminescence assay was established to evaluate the ^·OH-scavenging capacity of phenolic compounds. This assay took advantage of the transient property of the Fenton reaction and the reaction between luminol and the hydroxyl radical, and effectively avoided the pro-oxidant action of some phenolic compounds. Fifteen phenolic compounds were assessed for their antioxidant activity in the Fenton reaction system, and even in the case of "pro-oxidants" that were excluded from the widely used deoxyribose (DR) assay. Since it overcomes the challenges that the traditional DR assay encounters, our method has promising applicative values: it is low-cost, time-saving, and reliable. It would also be more favorable than electron spin resonance (ESR) and radiolysis technology, which are known to be expensive and not commonly available to those specialized in free radical biology and medicine.

Keywords: Phenolic antioxidants Hydroxyl radical Fenton reaction system Chemiluminescence assay Antioxidant activity

Determination of nitrated polycyclic aromatic hydrocarbons in diesel particulate-related standard reference materials by using gas chromatography/mass spectrometry with negative ion chemical ionization by Dawit Z. Bezabeh; Holly A. Bamford; Michele M. Schantz; Stephen A. Wise (pp. 381-388).

Gas chromatography/mass spectrometry (GC/MS) with negative ion chemical ionization (NICI) detection was utilized for quantitative determination of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) in diesel particulate-related standard reference materials (SRMs). Prior to GC/MS analysis, isolation of the nitro-PAHs from the complex diesel particulate extract was accomplished using solid phase extraction (SPE) and normal-phase liquid chromatographic (LC) fractionation using an amino/cyano stationary phase. Concentrations of eight to ten mononitro-PAHs and three dinitropyrenes were determined in three diesel particulate-related SRMs: SRM 1650a Diesel Particulate Matter, SRM 1975 Diesel Particulate Extract, and SRM 2975 Diesel Particulate Matter (Industrial Forklift). The results from GC/MS NICI using two different columns (5% phenyl methylpolysiloxane and 50% phenyl methylpolysiloxane) were compared to each other and to results from two other laboratories for selected nitro-PAHs. 1-Nitropyrene was the most abundant nitro-PAHs in each of the diesel particulate SRMs (19.8±1.1 µg g⁻¹ particle in SRM 1650a and 33.1±0.6 µg g⁻¹ particle in SRM 2975). Three dinitropyrene isomers were measured in SRM 1975 at 0.5–1.4 µg g⁻¹ extract and in SRM 2975 at 1–3 µg g⁻¹ particle.

Keywords: Diesel particulate matter Gas chromatography/mass spectrometry Nitrated polycyclic aromatic hydrocarbons Normal-phase liquid chromatography Standard reference materials (SRMs)

Analysis of PAH compounds in soil with on-line coupled pressurised hot water extraction–microporous membrane liquid–liquid extraction–gas chromatography by K. Kuosmanen; T. Hyötyläinen; K. Hartonen; J. Å. Jönsson; M.-L. Riekkola (pp. 389-399).

Pressurised hot water extraction (PHWE) was coupled on-line with microporous membrane liquid–liquid extraction (MMLLE) and gas chromatography (GC) in the analysis of polycyclic aromatic hydrocarbon (PAH) compounds in soil. The MMLLE serves as a trapping device after the PHWE. Water from PHWE is directed to the donor side of the membrane unit and the analytes are extracted to the acceptor solution on the other side of the membrane. The role of MMLLE is to clean and concentrate the extract, which is then transferred on-line to the GC via a sample loop and an on-column interface using partially concurrent solvent evaporation. Separate optimisation of MMLLE and simulations of the PHWE-MMLLE connection were carried out before the actual on-line coupling. After optimisation of the whole on-line system, the efficiencies of the PHWE–MMLLE–GC and PHWE–solid-phase trap extractions were compared. The PHWE–MMLLE–GC method allowed on-line analysis of soil samples. The method was linear, with limits of detection in the range 0.05–0.13 ng and limits of quantification 0.65–1.66 μg g⁻¹. Comparison of the results with those obtained by other techniques confirmed the good performance.

Keywords: Pressurised hot water extraction Microporous membrane liquid–liquid extraction Solid-phase trapping Large volume GC On-line coupling

Labile rhizosphere soil solution fraction for prediction of bioavailability of heavy metals and rare earth elements to plants by Xiao-quan Shan; Zhongwen Wang; Weisheng Wang; Shuzhen Zhang; Bei Wen (pp. 400-407).

A labile rhizosphere soil solution fraction has been recommended to predict the bioavailability of heavy metals and rare earth elements to plants. This method used moist rhizosphere soil in combination with a mixture of 0.01 mol L^–1 of low-molecular-weight organic acids (LMWOAs) as extractant. The extracted soil solutions were fractionated into two colloidal fractions of <0.45 μm (F₃) and <0.2 μm (F₂), and one truly dissolved fraction including free metal ions and inorganic and organic complexes (fractionlrss. For the soil solutions extracted with a mixture of LMWOAs the concentrations of heavy metals and rare earth elements in F₂ and F₃ were quite similar. However, the mean concentrations of Cr, Ni, Zn, Cu, Pb, Cd, La, Ce, Pr, and Nd in F_lrss accounted for 79.9%, 91.3%, 90.8%, 60.1%, 77.5%, 75.3%, 81.2%, 77.2%, 80.3%, and 79.5%, respectively, of their concentrations in F₂. In contrast, there were no differences in the extractable metal concentrations between the three fractions while the first step of the method recommended by the European Community of Reference (BCR), where 0.1 mol L^–1 acetic acid was used as an extractant. The single correlation analysis was made between metal concentrations in the different fractions of soil solutions and their concentrations in wheat. If the first step of BCR method was used there was no good correlation between heavy metals in soil pools and that in wheat shoots and roots. When LMWAOs were used a good correlation was obtained between the concentrations of heavy metals in soil pools and that in wheat roots, which followed a general order of r_{1 kD, LMWOAs} >r_{0.2 μm, LMWOAs} ≈r_{0.45 μm, LMWOAs}. In the case of rare earth elements the good correlation was obtained for both the wheat roots and shoots. Generally, the correlation coefficients obtained by LMWAOs were better than that obtained by the first step of BCR method. Therefore, LMWAOs and F_lrss were strongly recommended to predict the bioavailability of metals in soil pools to plants.

Keywords: Labile rhizosphere soil solution fraction Bioavailability Heavy metals Rare earth elements

Highly sensitive and selective spectrophotometric method for determination of trace gold in geological samples with 5-(2-hydroxy-5-nitrophenylazo)rhodanine by Li Zaijun; Pan Jiaomai; Tang Jian (pp. 408-413).

A excellent sensitive and selective method for spectrophotometric determination of trace gold has been developed, the method is based on the color reaction of gold(III) with new reagent 5-(2-hydroxy-5-nitrophenylazo)rhodanine (HNAR). Under optimal conditions, HNAR reacts with gold(III) to form a 1:5 orange complex, which has an maximum absorption peak at 480 nm. Maximum enhancement of the absorbance of the complex was obtained in the presence of the mixed surfactant of Triton X-100 and CTMAB; the reaction completed rapidly and the absorbance is stable for 5 h at least at 20 °C; 0–48 μg L^–1 Au(III) obeyed Beer's law. The apparent molar absorptivity of the complex, Sandell's sensitivity, the limit of quantification, the limit of detection and relative standard deviation were found to be 2.0×10⁶ L mol^–1 cm^–1, 0.000,098,483 µg cm^–2, 1.02 ng mL^–1, 0.35 ng mL^–1 and 1.09%, respectively. The effect of co-existing ions was studied seriously; most metal ions can be tolerated in considerable amounts. Its sensitivity and selectivity are remarkably superior to other reagents in the literature. The proposed method was used successfully to determine trace gold in geological samples. Moreover, the synthesis, characteristics and analytical reaction of HNAR with gold are also described in detail.

Keywords: Spectrophotometry Determination of gold Geological samples 5-(2-hydroxy-5-nitrophenylazo)rhodanine

Applying non-parametric statistical methods to the classical measurements of inclusion complex binding constants by E. Almansa López; J. M. Bosque-Sendra; L. Cuadros Rodríguez; A. M. García Campaña; J. J. Aaron (pp. 414-423).

A study on using non-parametric statistical methods was carried out to calculate the binding constant of an inclusion complex and to estimate its associated uncertainty. First, a correct evaluation of the stoichiometry was carried out in order to ensure an accurate determination of the binding constant. For this purpose, the modified Benesi-Hildelbrand method had been previously applied. Then, four statistical methods (three non-parametric methods: two bootstrap approaches, the jackknife method and a parametric one: Fieller's theorem) were employed in order to compute the binding constant. The results obtained from applying these methods and the combination of the methods: jackknife after bootstrap and bootstrap after jackknife were compared. The best results in terms of accuracy were obtained from the application of a bootstrap method: the resampling residuals approach. These procedures were applied to the inclusion complex 2-hydroxil-propyl-β-cyclodextrin-2,4-dichloro-phenoxyacetic, which shows photochemically-induced fluorescence.

Keywords: Inclusion complex Benesi-Hildebrand method Bootstrap Jackknife Fieller's theorem

Flow-injection chemiluminescence determination of chlorinated isocyanuric acids by Afsaneh Safavi; Mohammad Ali Karimi (pp. 424-427).

A rapid and sensitive flow-injection chemiluminescence method is described for the determination of dichloro- and trichloroisocyanuric acids based on the chemiluminescence produced during their reaction with luminol in alkaline medium. The effects of analytical and flow-injection variables on these chemiluminescence systems and determination of both oxidants are discussed. The optimized method yielded 3σ detection limits of 8×10^–8 and 5×10^–8 mol L^–1 for the sodium dichloroisocyanurate and trichloroisocyanuric acid, respectively. The optimum conditions were found to be as follows: NaOH, 1×10^–1 mol L^–1; luminol, 5×10^–3 mol L^–1; KI, 2×10^–3 mol L^–1 and flow rate, 3.5 mL min^–1.

Keywords: Chemiluminescence (CL) Chlorinated isocyanuric acids Luminol Flow injection analysis (FIA)

Speciation of mercury in soil and sediment by selective solvent and acid extraction by Y. Han; H. M. Kingston; H. M. Boylan; G. M. M. Rahman; S. Shah; R. C. Richter; D. D. Link; S. Bhandari (pp. 428-436).

In order to characterize the mercury hazard in soil, a sequential extraction scheme has been developed to classify mercury species based on their environmental mobility and/or toxicity for either routine lab analysis or on-site screening purposes. The alkyl mercury species and soluble inorganic species that contribute to the major portion of potential mercury toxicity in the soil are extracted by an acidic ethanol solution (2% HCl+10% ethanol solution) from soil matrices as "mobile and toxic" species. A High-Performance Liquid Chromatography (HPLC) system coupled with Inductively Coupled Plasma Mass Spectrometry (ICP–MS) detection has been developed to further resolve the species information into soluble inorganic species (Hg²⁺), methylmercury(II) (MeHg⁺) and ethylmercury(II) (EtHg⁺) species. Alternatively, these species can be separated into "soluble inorganic mercury" and "alkyl mercury" sub-categories by Solid-Phase Extraction (SPE). A custom Sulfydryl Cotton Fiber (SCF) material is used as the solid phase medium. Optimization of the SCF SPE technique is discussed. Combined with a direct mercury analyzer (DMA-80), the SCF SPE technique is a promising candidate for on-site screening purposes. Following the ethanol extraction, the inorganic mercury species remaining in soil are further divided into "semi-mobile" and "non-mobile" sub-categories by sequential acid extractions. The "semi-mobile" mercury species include mainly elemental mercury (Hg) and mercury-metal amalgams. The non-mobile mercury species mainly include mercuric sulfide (HgS) and mercurous chloride (Hg₂Cl₂).

Keywords: Mercury Speciation Extraction Soil

Superheated water extraction of cholesterol from solid food by V. Fernández–Pérez; M. D. Luque de Castro (pp. 437-442).

A method based on superheated water extraction has been developed for the removal of cholesterol from solid food thus providing a clean approach by avoiding the use of organic solvents. A preconcentration step was also studied with the aim of solving the problem derived from low-cholesterol-content samples and dilution effect. The research also involved the optimisation of the parameters affecting the extraction process by a central composite experimental design as well as a univariate study of the optimisation of the preconcentration step. The time required for total removal of the target compound was 60 min. The method was validated using a certified reference material (NIST–CRM 1845) and was used to analyse food samples within a wide range of cholesterol concentrations. The efficiency for the CRM was 105%. The precision of the method yielded values less than 6.5% (expressed as relative standard deviation) in all instances.

Keywords: Superheated water extraction Cholesterol Hydrolysis Preconcentration

Use of factorial design and Doehlert matrix for multivariate optimisation of an on-line preconcentration system for lead determination by flame atomic absorption spectrometry by S. L. C. Ferreira; W. N. L. dos Santos; M. A. Bezerra; V. A. Lemos; J. M. Bosque-Sendra (pp. 443-449).

A system for on-line preconcentration and determination of lead by flame atomic absorption spectrometry (FAAS) was proposed. It was based on the sorption of lead(II) ions on a minicolumn of polyurethane foam loaded with 2-(2-thiazolylazo)-5-dimethylaminophenol (TAM). The optimisation step was carried out using two-level full factorial and Doehlert designs for the determination of the optimum conditions for lead preconcentration. The proposed procedure allowed the determination of lead with a detection limit of 2.2 μg L⁻¹, and a precision, calculated as relative standard deviation (RSD), of 2.4 and 6.8 for a lead concentration of 50.0 and 10.0 μg L⁻¹, respectively. A preconcentration factor of 45 and a sampling frequency of 27 samples per hour were obtained. The recovery achieved for lead determination in the presence of several cations demonstrated that this procedure has enough selectivity for analysis of environmental samples. The validation was carried out by analysis of certified reference material. This procedure was applied to lead determination in natural food.

Keywords: Lead determination Doehlert matrix On-line preconcentration Polyurethane foam FAAS

Sorption of trace metals on human hair and application for cadmium and lead pre-concentration with flame atomic absorption determination by Jamal A. Sweileh (pp. 450-455).

Human hair shavings were characterized as a sorbent for trace metals. At pH 7.0 metal sorption follows the order Pb(II)>Cd(II)>Cr(VI)>Fe(III)>Cu(II)>Ni(II)>Mn(VI). Metal recovery is quantitative for Pb and Cd after 30 min of equilibration. Recovery of other metals is less quantitative and varies with pH. For example, while Cu is best recovered at pH 5, Ni and Mn are sorbed optimally in the basic pH region. Sorbed metals can be washed off the sorbent with 0.5 mol L^–1 strong mineral acids or more completely with 0.1 mol L^–1 ethylenediaminetetraacetic acid (EDTA). Typical sorption isotherms were obtained for Cd and Pb with sorption capacities of 39 and 26 μmol g^–1, respectively.Hair sorbent was used for 40-fold pre-concentration of Cd and Pb from treated wastewater samples followed by flame atomic absorption spectroscopic (FAAS) determination. Comparison of the data obtained for lead and cadmium by the proposed pre-concentration method with that by graphite furnace atomic absorption spectroscopy (GFAAS) showed 79 to 86% recovery and comparable analytical precision. Common cations and anions at the levels normally present in natural water do not interfere in the proposed pre-concentration-FAAS method.

Keywords: Atomic absorption Cadmium Hair Lead Preconcentration Sorption

Condenser-type diffusion denuders for the collection of sulfur dioxide in a cleanroom by In-Hyoung Chang; Dong Soo Lee; Soon-Ho Ock (pp. 456-459).

High-efficiency condenser-type diffusion denuders of cylindrical and planar geometries are described. The film condensation of water vapor onto a cooled denuder surface can be used as a method for collecting water-soluble gases. By using SO₂ as the test gas, the planar design offers quantitative collection efficiency at air sampling rates up to 5 L min⁻¹. Coupled to ion chromatography, the limit of detection (LOD) for SO₂ is 0.014 ppbv with a 30-min successive analysis sequence. The method has been successfully applied to the analysis of temperature- and humidity-controlled cleanroom air.

Keywords: Condenser-type diffusion denuder Trace airborne contaminants Cleanroom air

Solid-phase micro extraction (SPME) and headspace derivatization of clenbuterol followed by GC–FID and GC–SIMMS quantification by M. D. Engelmann; D. Hinz; B. W. Wenclawiak (pp. 460-464).

Solid-phase micro extraction (SPME) and on-fiber derivatization followed by Gas Chromatography coupled with Flame Ionization Detection (GC–FID) or Selected Ion Monitoring Mass Spectrometry (GC–SIMMS) allows for simple yet sensitive quantification for the hexamethyldisilazane derivative of the β-agonist clenbuterol. Using an 85-µm polyacrylate fiber, the analysis method is optimized with respect to extraction time, derivatization time and temperature, and solution pH. In addition, the use of a rapid temperature ramping injection port allows for optimization of fiber desorption conditions. Under optimal conditions, the limits of detection for the hexamethyldisilazane derivative of clenbuterol are 1.1 ppb by FID and 0.20 ppb by SIMMS.

Keywords: Drugs SPME GC Derivatization Doping test

Investigation of antioxidant and catalytic properties of some biologically active substances by voltammetry by E. I. Korotkova; Y. A. Karbainov; O. A. Avramchik (pp. 465-468).

Antioxidants play a major role in protecting biological systems against many incurable diseases. The biological activity of 12 plant aqueous–alcohol extracts, some standard antioxidants (vitamin C, glucose, resorcinol, and catechol), Na₂SO₃, humic acids, phthalocyanines, and chlorophyll have been investigated in this work together with evaluation of their influence on the kinetics of the oxygen electroreduction. Finally the use of these substances for prophylactic purposes has been recommended.

Keywords: Antioxidant Biologically active substances Oxygen Voltammetry

BERM 9 9th International Symposium on Biological and Environmental Reference Materials (pp. 469-470).

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Analytical and Bioanalytical Chemistry (v.375, #3)