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Analytical and Bioanalytical Chemistry (v.365, #8)
Quantitative investigation of boron incorporation in polycrystalline CVD diamond films by SIMS by T. Kolber; K. Piplits; R. Haubner; H. Hutter (pp. 636-641).
Polycrystalline diamond films have been produced on pre-treated silicon substrate by CVD hot filament method, with B(C2H5)3 added to the gas phase. However, under identical surface conditions, boron incorporation is not homogeneous. In {111} growth sectors, the boron concentration is found to be about 5 times higher than in {100} growth sectors. Moreover, a marked increase in contaminating elements such as aluminium and sodium in regions with higher boron concentrations is detected. Under SIMS fine focus conditions it can be shown that the interface between these two different facet regions is smaller than 0.5 μm. With 3D-depth profile images it can also be shown that the carbon distribution in the diamond layer is not totally homogeneous.
Copper determination after FI on-line sorbent preconcentration using 1-nitroso-2-naphthol as a complexing reagent by A. Ali; Y. Ye; G. Xu; X. Yin (pp. 642-646).
The suitability of 1-nitroso-2-naphthol as a complexing agent for on-line preconcentration of copper using RP-C18 material in a microcolumn with flow injection coupled with flame atomic absorption spectrometry (FI-FAAS) has been tested. Various parameters affecting complex formation, such as pH, sample flow rate, etc. and its elution into the nebulizer of FAAS were optimized. ¶A 5 × 10–3 mol/L reagent was on-line mixed with aqueous sample solution acidified with 0.1% (v/v) nitric acid ¶(pH 3–4) and flowed through the microcolumn for 30 s. The adsorbed complexes in the microcolumn were eluted with ethanol in 10 s into the nebulizer of FAAS. A good precision (1.7% for 50 μg/L copper, n = 12), high enrichment factor (19) with detection limit (3σ) 2.0 μg/L, and sample throughput (90 h–1) were obtained. The method was applied to certified reference materials seawater, mussel (biological), NBS-362 and NBS-364 (special low alloy steel), for the determination of copper, and the results were in good agreement with the certified values.
Determination of sulfur-containing inorganic anions by dual ion chromatography and capillary electrophoresis – application to the characterization of bacterial sulfur degradation by F. Hißner; J. Mattusch; K. Heinig (pp. 647-653).
An analytical characterization of microbiological oxidation and reduction of sulfur anions has been performed with dual ion chromatography. The apparatus consisted of two chromatographic lines combined by a sample injection valve that allows the simultaneous introduction of a sample solution to both systems. With system 1 non-suppressed conductivity detection of sulfite and sulfate after separation in phthalate eluent was performed. For sulfide, thiosulfate and thiocyanate amperometric detection using a carbonate eluent was carried out on system 2. Parallel runs were possible for these species which could not be separated with one system. Optimizing separation and detection, limits of quantification of 0.02–0.3 mg/L could be obtained. The on-line coupling of a reaction vial to the injection valve was used to investigate the bacterial conversions, because the samples could be taken without contamination and air introduction. Thiosulfate was detected as a metabolite in both sulfur reduction and oxidation. Capillary electrophoresis with conductivity detection was applied as a complimentary technique for monitoring the bacterial sulfur oxidation. The results showed good correlation to the concentration values obtained by ion chromatography.
Kinetic spectrophotometric determination of sulfide, using in-cuvette mixing and titration techniques with computerized data acquisition by B. Haghighi; A. Safavi (pp. 654-657).
In-cuvette mixing and titration techniques have been used for the kinetic determination of sulfide based on its inhibition effect on the oxidation of indigo carmine with hexacyanoferrate(III) in the presence of silver. The reaction was monitored spectrophotometrically by measuring the decrease in absorbance of indigo carmine at 612 nm. Both initial rate and fixed-time methods were applied to the in-cuvette technique. Using in-cuvette mixing, sulfide up to 1800 ng was determined and detection limit and relative standard deviation for the determination of 120 ng of sulfide were calculated as 23.0 ng and 1.59%, respectively. On the basis of the titration technique, the upper limit of determination was 25 μg of sulfide and detection limit and average relative standard deviation for the determination of 1 μg of sulfide were 0.025 μg and 4.95%, respectively. The effect of foreign ions on the sulfide determination was studied. The proposed methods were applied to the determination of sulfide in water.
Oriented antibody immobilization for atrazine determination by a flow-through fluoroimmunosensor by E. Turiel; P. Fernández; C. Pérez-Conde; A. M. Gutiérrez; C. Cámara (pp. 658-662).
An atrazine flow-through fluoroimmunosensor was developed, based on an oriented antibody covalently bound to Protein-A (Prot-A) immobilized on Controlled Pore Glass (CPG). Atrazine was detected “in-situ” by placing the immobilized antibody in the optical path of the flow cell. Immobilization of 30 μg of polyclonal anti-atrazine antibody on 0.5 g of Prot-A-CPG provided the highest sensitivity. The effect of several solvents on the covalently immobilized antibodies regeneration was evaluated, the optimum conditions being achieved by pumping 5% acetonitrile (pH = 3) at 0.15 mL/min for 100 s. The detection limit of the immunosensor was 0.7 μg/L and the reproducibility was 2% and 4% for 5 μg/L and 40 μg/L, respectively, in the optimum working concentration range (0.7–50 μg/L). This device allowed 12 samples per hour to be analyzed and had a life-time of 200 assays. Simazine and desisopropylatrazine (DIA) were not cross-reactive, desethylatrazine (DEA) has a cross-reactivity of 8% and propazine and prometryn of 44% and 27%, respectively. The immunosensor was applied to the determination of atrazine in tap and ground water samples spiked at the ¶10 and 30 μg/L concentration level.
Evaluation of a mechanically immobilized nickel hexacyanoferrate electrode as an amperometric sensor for thiosulfate determination by D. R. Shankaran; S. S. Narayanan (pp. 663-665).
A nickel hexacyanoferrate modified electrode was constructed by mechanical immobilization. A reversible peak with midpoint potential of 0.38 V was observed in cyclic voltammetry with 0.1 M NaNO3. Electrocatalytic oxidation of thiosulfate was effective on the modified electrode at a significantly reduced overpotential of 0.5 V and at broad pH range. The modified electrode can be used for the determination of thiosulfate in the concentration range of 7.0 × 10–4 to 5.6 × 10–3 M. It has been used for the amperometric determination of thiosulfate in photographic effluents. The results obtained were in good agreement with those obtained by other methods.
The analytical characterization of municipal solid waste incinerator fly ash: methods and preliminary results by P. Fermo; F. Cariati; A. Pozzi; F. Demartin; M. Tettamanti; E. Collina; M. Lasagni; D. Pitea; O. Puglisi; U. Russo (pp. 666-673).
ICP/OES, AES, ETAAS, TXRF, IC, XRPD, XPS, SEM/EDX, FT-IR, Raman, Mössbauer and ESR have been used to characterize inorganic components in a fly ash sample. It has been possible to determine silicates and aluminium silicates (gehlenite, gismondine and cabasite) in addition to many inorganic compounds (halite, sylvite, anhydrite, bassanite, gypsum, syngenite, ettringite, haematite, calcite and rutile).
Determination of linear alkylbenzenesulfonates in communal wastewater by means of solid phase microextraction coupled with API-MS and HPLC-FLD by U. Ceglarek; J. Efer; A. Schreiber; E. Zwanziger; W. Engewald (pp. 674-681).
The use of Solid Phase Microextraction (SPME) for the qualitative and quantitative determination of Linear Alkylbenzenesulfonates (LAS) in waste water samples was investigated. A Carbowax/Templated Resin (CW/¶TPR) coated fiber was directly immersed into influent and effluent samples of a sewage treatment plant (STP). Extraction conditions such as time, pH, ion strength were investigated. The extracted LAS were desorbed with a solvent in a specially designed SPME-LC interface for analysis with HPLC-FLD and Electrospray Ionization Mass Spectrometry (ESI-MS). The combination of SPME with ESI-MS proved to be an alternative technique for the LAS determination in waste water. Linear ranges of the external calibration were found from 0.5–100 ng/mL, with detection limits of 0.5 ng/mL for each individual LAS homologue. The reproducibility of the method is 15% (relative standard deviation).
Determination of catecholamines as their N-hydroxy-succinimidyl-3-indolylacetate derivatives by pre-column derivatization HPLC separation and fluorescent detection by Hong Wang; Hong Jin; Hua-shan Zhang (pp. 682-684).
N-Hydroxysuccinimidyl-3-indolylacetate (SIIA) is a new fluorescent derivatizing reagent with an indole ring and ¶an N-hydroxysuccinimide ester functionality. It can react with catecholamines under mild conditions to form corresponding amides, which have strong fluorescence at λex/λem = 301 nm/¶365 nm. This paper covers the RP-HPLC separation and fluorescent determination of derivatized catecholamines with SIIA. In a mobile phase of methanol-water (36/64, v/v) containing H3cit-Na2HPO4 buffer (pH = 4.00, 10 mmol/L), the derivatives of norepinephrine (NE), epinephrine (E) and dopamine (DA) were eluted within 15 min on a C18 column. The detection limits were 0.043, 0.13 and 0.18 pmol, respectively, when the ratio of signal to noise (S/N) was 3. The excessive reagent is rapidly hydrolyzed to 3-indolylacetic acid (IA) that can be easily separated from derivatives.