Check out our New Publishers' Select for Free Articles

Analytical and Bioanalytical Chemistry (v.363, #1)

Identification of alkyl dinitrates in ambient air of Central Europe by Jürgen Kastler; K. Ballschmiter (pp. 1-4).

Bifunctional organic nitrates – organic esters of nitric acid – are part of the pool of components of odd nitrogen (NO_Y) in the atmosphere. In this paper, we report the identification of dinitrates in ambient air of Central Europe (Ulm, Germany). The organic nitrates were sampled by adsorptive high volume sampling of 100 m³ of air with 100 g precleaned silica. Sample preparation and group separation was performed by NP-HPLC. Separation and detection was done by HRGC/EI-MSD. We have extended the identification of dinitrates in ambient air to a number of 30, of which only five have been reported by other authors before. To our knowledge, this is the first time that 13 non-vicinal dinitrates and two branched dinitrates have been identified in ambient air. Four organic nitrates have never been reported before: the non-vicinal 1,3-dinitrooxy-pentane (1,3C5), the two branched 2-methyl-1,2-dinitrooxy-propane (2M1,2C3) and 2-methyl-2,3-dinitrooxy-butane (2M2,3C4), and one diastereomer of 3,4-dinitrooxy-hexane (RR/SS-3,4C6). We are also assigning the configuration of the two diastereomers of 2,4-dinitrooxy-pentane (2,4C5) found in air before using reference standards obtained by enantioselective synthesis.

Improvement scheme for the determination of arsenic species in mussel and fish tissues by F. Lagarde; M. B. Amran; M. J. F. Leroy; C. Demesmay; M. Ollé; A. Lamotte; H. Muntau; P. Michel; P. Thomas; S. Caroli; E. Larsen; P. Bonner; G. Rauret; M. Foulkes; A. Howard; B. Griepink; E. A. Maier (pp. 5-11).

Six interlaboratory studies were organised by the Standard, Measurement and Testing Programme of the European Commission on the determination of arsenic species (arsenobetaine, arsenocholine, monomethylarsonic acid, dimethylarsinic acid, As(III) and As(V)) in marine matrices and soil. A step-by-step approach was used and a meeting was held at the end of each study to help the participants to discover errors and to improve their analytical methods. The successive steps investigated the calibration procedures on various solutions, the separation and derivatisation techniques on solutions and extracts and the extraction on mussel and fish tissues. All materials used for the study were monitored for their stability. Verified calibration solutions and compounds were distributed to the participants in each exercise in order to trace calibration problems. The agreement between the results improved regularly and at the end of the six campaigns allowed the certification of a reference material of tuna-fish tissue (BCR-CRM 627) for its total arsenic, arsenobetaine and dimethylarsinic acid contents.

Preparation of pure calibrants (arsenobetaine and arsenocholine) for arsenic speciation studies and certification of an arsenobetaine solution – CRM 626 by F. Lagarde; Z. Asfari; M. J. F. Leroy; C. Demesmay; M. Ollé; A. Lamotte; P. Leperchec; E. A. Maier (pp. 12-17).

Interlaboratory studies have been organised by the Standards, Measurement and Testing Programme in order to certify the content of some chemical forms of arsenic in fish and mussel tissue, soil and sediment. Among the six compounds of interest (arsenite, arsenate, dimethylarsinic and monomethylarsonic acids, arsenobetaine and arsenocholine) only four are commercially available. Arsenobetaine and arsenocholine of well defined purity had therefore to be prepared by the pilot laboratories in charge of the management of the project. The present work deals with the synthesis and characterisation of these two compounds and the certification of the content of arsenobetaine in a standard solution (BCR-CRM 626).

Certification of total arsenic, dimethylarsinic acid and arsenobetaine contents in a tuna fish powder (BCR-CRM 627) by F. Lagarde; M. B. Amran; M. J. F. Leroy; C. Demesmay; M. Ollé; A. Lamotte; H. Muntau; P. Michel; P. Thomas; S. Caroli; E. Larsen; P. Bonner; G. Rauret; M. Foulkes; A. Howard; B. Griepink; E. A. Maier (pp. 18-22).

Tuna fishes were collected in the Straits of Messina (Italy), were dissected and dorsal muscles minced, freeze-dried, ground and sieved. The obtained powder was stabilised by γ-irradiation and filled into brown glass bottles. The homogeneity and stability at +20 °C and +40 °C were verified with regards to the total arsenic, dimethylarsinic acid and arsenobetaine contents. Ten laboratories participated in the certification study. All participants had demonstrated beforehand their ability to produce accurate results for the As speciation in fish tissue. The certified values are: total arsenic (4.8 ± 0.3) mg/kg, arsenobetaine (52 ± 3) μmol/kg, dimethylarsinic acid (2.0 ± 0.3) μmol/kg. The material is available from the BCR since early 1998.

Certification of reference materials for the quality control of major element determinations in groundwater Part 2: Certification by P. Quevauviller; M. J. Benoliel; R. Neves Carneiro; L. Cortez (pp. 23-27).

The quality control of groundwater monitoring requires the availability of representative CRMs. This paper describes the preparation of two artificial groundwater reference materials, CRM 616 (high carbonate content) and CRM 617 (low carbonate content), the homogeneity and stability studies and the analytical work performed for the certification of a range of major elements (Ca, Cl, Fe, K, Mg, Mn, Na, NO₃, PO₄ and SO₄).

Certification of Cr(VI) and total leachable Cr contents in welding dust loaded on a filter (CRM 545) by J. M. Christensen; K. Byrialsen; K. Vercoutere; R. Cornelis; P. Quevauviller (pp. 28-32).

In order to improve and control the quality of measurement of Cr(VI) and leachable Cr in welding dust loaded on a filter, the Standards, Measurements and Testing Programme (formerly BCR) of the European Commission has carried out a project, of which the final aim was to certify a reference material. This paper describes the preparation of a batch of 1100 filters loaded with welding dust, containing approximately 100 μg Cr(VI) per mg dust, which is as normally encountered on the personal filter monitors of stainless steel welders. The homogeneity and stability studies and the analytical work performed for the certification of the contents of Cr(VI) and the total leachable Cr content are also described, as well as the methods used to certify the mass fraction of Cr(VI) (40.16 ± 0.60 g · kg^–1 on a dry matter basis) and total leachable Cr (39.47 ± 1.30 g · kg^–1 on a dry matter basis). A brief description of the preliminary feasibility study is also given.

Certification of contents of aromatic hydrocarbons in charcoal tubes – CRM 562 by U. Risse; Elke Flammenkamp; A. Kettrup; Stefaan Vandendriessche (pp. 33-37).

A Certified Reference Material (CRM) for determination of aromatic hydrocarbons in air was developed. The CRM 562 consists of aromatic hydrocarbons sorbed on charcoal in glass tubes. Initial feasibility studies established that a homogeneous and stable batch could be prepared. Three intercomparisons prior to the certification allowed the identification of various sources of error. Then, a batch of about 3000 tubes was charged and certified on the basis of analyses carried out in 15 European laboratories. The preparation of the reference material and the results of the certification exercise is described. An overview on the analytical techniques used and the quality control guidelines are also presented. The certified values are 15.0 ± 0.4 μg benzene, 147.3 ± 3.8 μg toluene, 96.4 ± 2.5 μg m-xylene and 93.0 ± 2.9 μg o-xylene per tube. This reference material is recommended for quality control of measurements in the field of occupational hygiene.

In-situ spectroelectrochemical analysis of the passivating surface film formed on a carbon film electrode as a function of the water content in 1 M LiPF6-EC/DEC solution by S.-I. Pyun (pp. 38-45).

The in-situ spectroelectrochemical technique has been applied to investigate the role of water in the formation of a passivating surface film on a plasma enhanced chemical vapor deposited (PECVD) carbon film electrode in 1 M LiPF₆-ethylene carbonate (Li-EC) and diethyl carbonate (DEC) solution, combined with cyclic voltammetry. In-situ Fourier transform infra-red (FTIR) spectra of the surface film showed that all the peak intensities of the Li₂CO₃, ROCO₂Li, and LiPF₆ constituents significantly increase with increasing water content under application of the negative potentials with respect to open circuit potential (OCP). It is suggested that the reduction of Li-EC to ROCO₂Li runs via a one-electron transfer pathway with the help of the unrestricted supply of the electron transfer path as a result of diffusion of water through the surface film; then Li₂CO₃ formation proceeds concurrently by the chemical reaction of ROCO₂Li with water. Moreover, the compact sedimentation of ROCO₂Li in the presence of water in the electrolyte is subjected to severe interference of the salt reduction product, Li_xPF_y, than in the absence of water in the electrolyte. These FTIR results coincide well with those of cyclic voltammetry. From the combined results of in-situ FTIR spectroscopy and cyclic voltammetry, it is indicated that, unlike other salt and solvent reaction products, ROCO₂Li, Li₂CO₃ and Li_xPF_y simultaneously increase to constitute the outer layer of the surface film with equal amounts.

Coulter particle analysis used for studying the effect of sample treatment in slurry sampling electrothermal atomic absorption spectrometry by G. Wibetoe; David T. Takuwa; Walter Lund; Gerald Sawula (pp. 46-54).

This work focuses on the potential of using a Coulter particle analyzer for method development in slurry sampling ETAAS. Plant materials were used as an example; the particle size distributions obtained after grinding in a mixer mill were measured for ground material and slurries prepared from flowers, leaves, stem and roots of the same plant material. Normally the particle size distribution is reported either as number of particles versus size or volume of particles versus size. The advantage of using the latter mode of reporting is demonstrated. It is shown that detailed information about the larger particles is lost when the distribution is reported in terms of the number-percentage. In the present case, 60 min of grinding gave similar size distribution for all the plant materials. All particles had diameters less than 50 μm and the calculated number of particles per mg was 6–8 × 10⁷. It is shown that the ultrasonic agitation used to homogenize the slurries, prior to injection of the sample, also had an effect on the particle size distribution.

Voltammetry of biologically active species and surfactants on new miniaturized and contractible (compressible) mercury electrodes by Ladislav Novotný (pp. 55-58).

The adsorption of the polyether-antibiotic monensin from an aqueous solution on mercury was used to investigate the effect of the decreasing size of a stationary mercury drop electrode on the shape of the voltammetric desorption peak of the surfactant. The change of the i-E curve indicated an acceleration of the transport of the surfactant to the electrode as well as of time-dependent changes in the adsorption layer. A decrease of the radius of the hanging mercury drop electrode from 220 μm to 80 μm at a constant accumulation time of t_ac = 70 s resulted in an about 4-fold increase of the evaluated signal (i-E pre-wave) of monensin. A 7-fold increase of the voltammetric desorption peak of monensin at conc. 5 · 10^–7 mol/L was observed as result of a compressive accumulation of the surfactant due to a contraction of the mercury drop electrode. A scheme of an apparatus for voltammetric/polarographic measurements by means of the contractible (compressible) mercury drop electrode is described. The controlled contraction of the electrode surface is presented together with preliminary results covering a new way of accumulation of surfactants, new accumulation effects, effective in adsorptive voltammetry, and other electroanalytical techniques.

An integrated reaction-retention and spectrophotometric detection flow system for the determination of nickel by M. J. Ayora Cañada; M. I. Pascual Reguera; A. Molina Díaz (pp. 59-63).

An integrated flow-through photometric sensor for the determination of nickel in real samples of various origins has been developed. The sensor is based on the reaction of Ni(II) with 1-(2-pyridylazo)-2-naphthol (PAN) immobilized on a cationic resin which was placed in a flow-cell using a spectrophotometer tuned at 566 nm as detector. The Ni(II) ion from the sample injected into the carrrier stream (pH = 5.0) of a monochannel continuous flow system reacts with the immobilized chromogenic reagent to form a red chelate which remains on the active solid support and generates the analytical signal. When this reached its maximum value the Ni(II)-PAN chelate was destroyed using 1 M H₂SO₄ as eluents, leaving the sorbed PAN untouched. The response of the sensor was linear in the three concentration ranges assayed: 0.3–4.0, 0.1–1.6 and 0.05–0.8 μg mL^–1 for sample volumes of 100, 400 and 800 μL, respectively, and the R.S.D.(%) (n = 10) were 1.80(100 μL), 3.04(400 μL) and 2.29(800 μL). The sensor showed an excellent selectivity which could also be increased with a simple on-line modification to avoid interference from copper. It was applied to a variety of real samples with very good results in all cases.

Analysis of aluminium-based ceramic powders by electrothermal vaporization inductively coupled plasma atomic emission spectrometry using a tungsten coil and slurry sampling by M. Lucic; V. Krivan (pp. 64-72).

Slurry sampling followed by electrothermal vaporization was used as sample introduction technique for digestion-free analysis of aluminium nitride and aluminium oxide by inductively coupled plasma atomic emission spectrometry. The vaporizer consisted of a tungsten coil in a quartz chamber. Spectral interferences and background emission caused by tungsten ablation from the coil were reduced by coating it with tungsten carbide. Different approaches for background correction techniques were considered. The analytes Ca, Cd, Co, Cr, Cu, Fe, Mg, Ni and Zn were determined simultaneously, whereas Mn and Na were determined in the sequential mode. Calibration was performed using the standard additions method. The accuracy was checked by comparison of the results with those of independent methods. Detection limits between 0.01 (Mg) and 8.5 μg/g (Co) were achieved.

Laboratory and field measurements of a badge type passive sampler for the determination of ambient sulfur dioxide concentrations by Anne Kasper-Giebl; S. Krenn; H. Puxbaum (pp. 73-76).

The performance of a badge type passive sampler for the determination of sulfur dioxide is described. The trapping agent is triethanolamine. Analysis is performed by ion chromatography. Thus, the method allows the simultaneous detection of sulfur dioxide and nitrogen dioxide. The sampler was tested in the laboratory and in the field. The intercomparison with independent methods in the field showed very good agreement against two active sampling methods. Regression analyses (the results of the passive sampler always represent the y-axes) gave r² = 0.81 and k = 1.07 ± 0.01 for the intercomparison with an annular denuder technique and r² = 0.92 and k = 0.96 ± 0.01 for the intercomparison with a commercial fluorescence sulfur dioxide analyzer. The average reproducibility in the field was 7% (RSD). The detection limit was 0.18 μg SO₂/m³ for an exposure time of two weeks.

An internal surface reversed phase column for the effective removal of humic acid interferences in the trace analysis of mecoprop in soils with coupled-column RPLC-UV by P. Parrilla; P. Kaim; E. A. Hogendoorn; R. A. Baumann (pp. 77-82).

In the development of a screening method for the determination of residues of mecoprop in soils involving coupled-column RPLC-UV (228 nm) the cleanup performance of a 5 μm GFF-II internal surface reversed phase (ISRP, Pinkerton) analytical column (50 × 4.6 mm I.D.) as a first column was investigated. In comparison to an analytical C18 column the ISRP column substantially improved the separation between acidic analyte and co-extracted humic substances. Under the selected coupled-column conditions soil extracts obtained after hydrolysis with an aqueous alkaline solution, acidifying and centrifugation could be analyzed directly allowing the determination of mecoprop in soils to a level of about 0.02 mg/kg. A rapid concentration step on a 100 mg C18 solid phase extraction (SPE) cartridge was adopted into the procedure providing a limit of detection (S/N = 3) of 0.01 mg/kg of mecoprop in soil. The method was validated by analyzing freshly spiked soil samples and samples with aged residues. In case of freshly spiked samples the overall recovery was 87% (n = 18, spiked level 0.02–8.0 mg/kg) with a repeatability of 6.8% and a reproducibility of 8.3%. No significant decrease of the recovery was observed for samples with aged residues (n = 15, spiked level 0.1 and 8.0 mg/kg) during a storage of 29 days in the refrigerator at about 4 °C; a storage of 67 days provided a mean recovery of 76% (n = 14, spiked level 8.0 mg/kg).

Amperometric method for the determination of myoglobin based on the electrochemical reduction on the glassy carbon electrode by Fang Yan; Chuanmin Ruan; Xiaohong Chen; J. Deng; Jilie Kong (pp. 83-87).

An irreversible reduction peak of oxymyoglobin (MbO₂) was observed on the bare glassy carbon electrode (GCE) in acetate buffer solution under atmospheric conditions. It is the reduction of bonded oxygen in Mb, but not the heme Fe(III)/Fe(II) redox couple that underwent electrochemical reaction on the electrode. The peak current achieved a maximum value in acetate buffer solution of pH 4.0. The peak potential was pH dependent, suggesting that the proton was involved in the electrochemical reaction. Furthermore, the peak current was linearly related to the concentration of myoglobin in the range of 2.5 × 10^–8∼ 1.0 × 10^–6 mol · L^–1 with a detection limit of 5 × 10^–9 mol · L^–1.

Biomonitoring of benzene and toluene in human blood by headspace-solid-phase microextraction by E. Schimming; K. Levsen; C. Köhme; W. Schürmann (pp. 88-91).

A simple and rapid method for the determination of benzene and toluene in whole blood by headspace-solid-phase microextraction (HS-SPME) is described. Using SPME fibres coated with 65 μm carboxene/polydimethylsiloxane, limits of quantification (LOQ) of 5 ng/L for benzene and 25 ng/L for toluene are achieved. As a result of its large linear range (i.e. 5–5000 ng/L for benzene) the method is suitable for biomonitoring of both occupationally and environmentally exposed people. The reproducibility of the determination of benzene is ≤ 8%. An interlaboratory comparison demonstrated that the method proposed here compares favorably with existing methods (dynamic headspace, purge and trap).

Determination of ascorbic acid by use of a flow-through solid phase UV spectrophotometric system by A. Molina-Díaz; A. Ruiz-Medina; M. L. Fernández-de Córdova (pp. 92-97).

A continuous flow-through solid phase spectrophotometric system was developed for the determination of ascorbic acid based on the measurement of its intrinsic absorbance in the UV region when retained on a 1 mm Sephadex QAE A-25 anion exchanger gel layer which is placed into an appropriate quartz flow-through cell, the absorbance exhibited by this solid phase being monitored at 267 nm. A monochannel manifold was used, the sample (300, 600 or 1000 μL) being injected into the carrier solution (acetate buffer). This solution also elutes the analyte after developing the analytical signal, and regenerates the resin layer which, therefore, remains ready for the next sample. The linear dynamic range and other analytical parameters vary according to the sample volume injected. Three calibration lines were established for 300, 600 and 1000 μL sample volume, which ranged from 1.0 to 20.0, 0.5 to 10.0 and 0.2 to 6.0 μg mL^–1, respectively. The detection limits were 0.04 (300 μL), 0.03 (600 μL) and 0.02 μg mL^–1 (1000 μL), the sampling rates 28, 24 and 21 h^–1, and the RSDs (n = 10) 0.87%, 1.08% and 0.90%, respectively. The amount of ascorbic acid in various samples (pharmaceuticals, sweets and urine) were successfully determined with this method.

Novel methods of TXRF analysis for silicon wafer surface inspection by L. Fabry; Siegfried Pahlke; Ludwig Kotz; Peter Wobrauschek; Christina Streli (pp. 98-102).

TXRF became a standard, on-line inspection tool for controlling the cleanliness of polished Si wafers for semiconductor use. Wafer makers strive for an all-over metallic cleanliness of < 10¹⁰ atoms · cm^–2. The all-over cleanliness can be analyzed using VPD/TXRF. For VPD preparation and scanning we have developed an automatic system coupled with TXRF. With synchrotron radiation TXRF we were able to detect 13 fg of Ni in a residual microdroplet, i.e.10⁵ atoms · cm^–2.

Characteristics of glucose electrode with enzyme immobilised on nylon net by E. Miller; Malgorzata Przybyt (pp. 103-107).

Glucose oxidase was immobilised on nylon net by the method of O-alkylation using dimethyl sulfate and lysine as a spacer. The influence of alkylation conditions on the characteristics of the resulting glucose electrode was evaluated. The best electrode was then tested under batch and flow conditions, respectively. The influence of pH and temperature on electrode response were examined. The glucose oxidase immobilised on nylon net seemed to be inhibited by glucose in alkaline pH and at higher temperatures. Moreover, the shape of the electrode signal after addition of glucose was unusual. Glucose oxidase immobilised on nylon net was unstable and lost its activity rather quickly, especially when stored dry in the refrigerator. Also the operational stability of the electrode in the flow system was rather poor.

Studies on the cationic selectivity of the potentiometric membrane containing thiamine metatungstate as ionophore by E. Doniga (pp. 108-110).

An unconventional structure was obtained by extraction of K⁺ ions with nitrobenzene solution of thiamine metatungstate. This shows that K⁺ penetration into the organic phase is not an exchange process. The solution of thiamine metatungstate in nitrobenzene acts as a spacial structure that entraps K⁺ ions in a molar ratio of 1 : 2. The absence of a chemical reaction between K⁺ and the metatungstic anion (proved experimentally) and the specificity of the interaction with K⁺, suggests that the formation of the structure potassium – thiamine metatungstate (KTM) could be controlled by dimensional criteria. The nitrobenzene solution of KTM shows a remarkable potentiometric selectivity for K⁺ compared with any other alkaline and alkaline earth cations. The potentiometric K⁺-selective electrode, based on KTM as ionophore, responds linearly in the range 3.8 × 10^–5–1.0 × 10^–1 mol/L, with a slope of 56 mV/ decade and a detection limit of 1.2 × 10^–5 mol/L. The electrode maintained these response characteristics over a period of more than two months.

Preconcentration of some metals using metalfix chelamine resin prior to ICP-AES analysis by B. Prusisz; W. Żyrnicki (pp. 110-112).

Preconcentration and separation of Ni, Pb and Cd have been investigated using the metalfix chelamine resin prior to inductively coupled plasma – atomic emission spectrometry (ICP-AES) under various experimental conditions. The recoveries of the analytes obtained with 95% confidence level were 92 ± 1% for Ni, 100 ± 4% for Pb and 93 ± 3% for Cd.

Elimination of sulfide interference by sodium hypochlorite solution in the cold vapor atomic absorption spectrometric determination of mercury using tin(II) reduction in alkaline medium by S. Kagaya; T. Nishimura; K. Hasegawa (pp. 112-113).

An addition of sodium hypochlorite solution effectively eliminated the interference by sulfide in the cold vapor atomic absorption spectrometric determination of mercury using tin(II) reduction in alkaline medium. Mercury ranging from 0.01 to 0.5 μg could be determined within ±10% error in 100 mL of sample solution containing 10 mg of sulfide by the addition of 1 mL of 10.4%(w/v) sodium hypochlorite solution. The proposed method is rapid (5 min per determination) and has good reproducibility (3.0%).

Preconcentration and voltammetric determination of palladium (II) at sodium humate modified carbon paste electrodes by Qiaoyu Sun; C. Wang; Liangxi Li; Hulin Li (pp. 114-117).

A chemically modified carbon paste electrode was prepared by incorporating appropriate amounts of sodium humate(NaA). Palladium(II) was selectively accumulated in a solution of Britton-Robinson(B-R) buffer (pH 2.8) onto the electrode surface in open circuit mode. The subsequent electrochemical measurement was carried out by cyclic voltammetry (CV) and linear sweep anodic stripping voltammetry (LSASV) in a supporting electrolyte of 1.0 M HCl. The obtained oxidation currents (I_pa1 and L_pa2) were proportional to the Pd(II) concentration in the range of 4.7 × 10^–6 - 9.4 × 10^–8 M. The developed method was applied to the quantitative determination of palladium in real samples.

FI spectrophotometric determination of Pd with DBOK-chlorophosphonazo by Jian Huang; Xingguo Chen; Zhide Hu; Zhengfeng Zhao; Martin Hooper (pp. 117-118).

A flow injection method was developed for the determination of palladium, based on the reaction of palladium with DBOK-chlorophosphonazo with a detection limit of 0.07 μg/mL and a linear calibration range from 0.1 to 3.2 μg/mL of palladium. The reaction product has a maximum absorption at 630 nm. The method was applied to determine Pd²⁺ in catalysts and in anode mud samples. The relative error is less than 3% and the recovery of palladium is in the range 95% to 105%

Organic solvent-soluble membrane filters for the preconcentration and spectrophotometric determination of iron(II) traces in water with Ferrozine by Ying Chen; Chang-Ming Ding; Tian-Ze Zhou; Da-Yong Qi (pp. 119-120).

An organic solvent-soluble membrane filter (MF) is proposed for the simple and rapid reconcentration with subsequent spectrophotometric determination of trace levels of iron (II) in water. Iron (II) is collected on a nitrocellulose membrane filter as ion associate of an anionic complex, which is formed by iron (II) and Ferrozine and a cation-surfactant. The ion-pair compound and the MF can be dissolved in small volumes of 2-ethoxyethanol and the absorbance of the resulting solution is measured at 560 nm against a reagent blank with molar absorptivity of 4.01 × 10⁴ L mol^–1 cm^–1. Beer’s law is obeyed over the concentration range 0–10 μg L^–1 of iron (II) in water and the detection limit is 0.03 μg L^–1 with a 50-fold enrichment factor. The proposed method can satisfactorily be applied to the determination of iron (II) in natural water and sea water.

Determination of cyanides in electroplating solutions as Ni(CN)42– and analysis by capillary electrophoresis by Manuel Aguilar; A. Farran; Vicenç Martí (pp. 121-123).

A CE method was developed for the determination of total (free and weakly bound) cyanide in electroplating solutions based on the use of a cationic surfactant (TTAB) and complexation with Ni(II)-NH₃ solutions to Ni(CN)₄ ^2–. Both direct complexation and cyanide distillation combined with complexation were tested. Under optimized conditions, this method is time-saving compared to standard methods. Total cyanide determined by CE had detection limits (with respect to the initial sample concentration) of 0.5 μg/mL for direct complexation and 50 ng/mL for distillation combined with complexation. Total cyanide and cyanide not amenable by chlorination (CNAC) were determined in real samples from spent electroplating baths.

Determination of EDTA in used fixing solutions by capillary electrophoresis by S. Pozdniakova; R. Ragauskas; A. Dikčius; A. Padarauskas (pp. 124-125).

A capillary electrophoretic method for the determination of EDTA has been developed. EDTA was converted to Ni(II)-EDTA prior to separation, separated from Fe(III)-EDTA, thiosulphate, bromide and polythionates using a fused silica capillary (57 cm × 75 μm I.D.) filled with a borate buffer (50 mmol L^–1; pH 8.5; applied voltage, 30 kV) and detected at 214 nm. The separation time is about 6 min. The detection limit achieved is 2 × 10^–6 mol L^–1 for EDTA. This method was applied for the determination of free EDTA in used fixing solutions.

Flow injection chemiluminescence determination of isoniazid with electrogenerated hypochlorite by Jiachu Huang; Chengxiao Zhang; Zhujun Zhang (pp. 126-128).

A flow-injection chemiluminescence method for the determination of isoniazid based on the sensitizing effect of isoniazid on the chemiluminescence generating luminol-hypochlorite reaction is described. The hypochlorite was electrogenerated on-line by constant current electrolysis, thus, eliminating instability of hypochlorite solution prepared from commercially available sodium hypochlorite. The calibration graph is linear in the range 1 × 10^–8 to 1 × 10^–6 g mL^–1, and the detection limit is 6 × 10^–9 g mL^–1. The relative standard deviation for determination of 5 × 10^–8 g mL^–1 is 2.8%. The proposed method has been successfully applied to the determination of isoniazid in pharmaceutical preparations.

Interference with ammonium determination by the indophenol-type reaction of salicylate and dichloroisocyanurate by F. Jüttner (pp. 128-129).

Two widely accepted indophenol-type reactions with ammonium, which use phenol/hypochlorite and salicylate/dichloroisocyanurate as reagents, were compared for possible interferences with other naturally occurring nitrogen-containing compounds. Unlike the first method, the second showed strong interference from all amino acids and peptides tested. As much as 57 mole % of threonine and 49 mole % of serine were degraded to ammonium. Pyrimidines, purines, nucleosides and urea were negative in both reactions. The wide distribution and importance of free and combined amino acids in naturally occurring waters favours the application of the classical phenol/ hypochlorite reaction with ammonium rather than the modified salicylate/dichloroisocyanurate reaction.

A rapid method for the determination of the Fusarium mycotoxinbeauvericin in maize by R. D. Josephs; R. Krska; R. Schuhmacher; M. Grasserbauer (pp. 130-131).

The development of a rapid method for the determination of the Fusarium mycotoxin beauvericin (BEA) in corn and cereals is described. This method allows to prepare at least 5 times more samples simultaneously with similar analytical performance characteristics as previously published analytical methods.

Ultra-trace analysis of nitrite in food samples by flow injection with spectrophotometric detection by A. A. Ensafi; G. Bagherian Dehaghei (pp. 131-133).

A flow injection system with spectrophotometric detection is proposed for the determination of low levels of nitrite based on its catalytic effect on the oxidation of gallocyanine by bromate in acidic media. Various analytical parameters such as acidity, reagent concentration, flow rate, sample size, time, temperature, and interfering species were studied. The calibration graph was linear for 0.020–0.500 μg/mL of nitrite. The method is successfully applied to food samples. Up to 30 ± 5 samples can be analyzed per hour.

Effect of sample preparation on the operational speciation of cadmium and lead in a freshwater sediment by C. M. Davidson; Lorna E. Wilson; Allan M. Ure (pp. 134-136).

The three-stage sequential extraction procedure recommended by BCR has been applied in the operational speciation of cadmium and lead in a relatively unpolluted freshwater sediment, following various types of sample pre-treatment. Changes in speciation occurred when the sediment was air-dried, oven-dried or frozen. Cadmium speciation was particularly perturbed by freezing, whilst lead was more affected by oven-drying. Metals were determined by electrothermal atomic absorption spectrometry, using direct calibration with reagent-matched standard solutions.

Sections

Personal tools

Analytical and Bioanalytical Chemistry (v.363, #1)

Sections

Personal tools

Local resources

Analytical and Bioanalytical Chemistry (v.363, #1)