Showing posts with label Voltametry. Show all posts

Thursday, March 5, 2009

Theory in Voltametry

Voltammetry
An Introduction in Theory
Metrohm Ltd.
CH-9100 Herisau
Switzerland
Voltammetry
Overview
What is Voltammetry?
Electrode Types
Voltammetric Techniques
Measurement Modes
Calibration Techniques
Advantages of Voltammetry
Summary

[PDF]Theroy in Voltammetry

An arsenic(III)-oxidizing bacterial population: selection, characterization, and performance in reactors

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An arsenic(III)-oxidizing bacterial population: selection, characterization, and performance in reactors

F. Battaglia-Brunet ¹ , M.-C. Dictor ¹ , F. Garrido ¹ , C. Crouzet ² , D. Morin ¹ , K. Dekeyser ³ , M. Clarens ⁴ and P. Baranger ¹

¹ BRGM, Environment & Process Division, Biotechnology Unit, Orléans, ² BRGM, Analysis and Mineral Characterization Division, Orléans, ³ Guigues Recherche Appliquée en Microbiologie, Aix-en-Provence, ⁴ BIO-ID, Pépinière d'Entreprise EOLE, Narbonne, France

Correspondence to: Fabienne Battaglia-Brunet, BRGM, Environment &Process Division, Biotechnology Unit, 3 avenue Claude Guillemin, BP 6009, 45060 Orléans cedex 2, France (e-mail: f.battaglia@brgm.fr).

f. battaglia-brunet , m.-c. dictor , f. garrido , c. crouzet , d. morin , k. dekeyser , m. clarens and p. baranger. 2002 .

ABSTRACT

Aims: To select an autotrophic arsenic(III)-oxidizing population, named CASO1, and to evaluate the performance of the selected bacteria in reactors.
Methods and Results: An As(III)-containing medium without organic substrate was used to select CASO1 from a mining environment. As(III) oxidation was studied under batch and continuous conditions. The main organisms present in CASO1 were identified with molecular biology tools. CASO1 exhibited significant As(III)-oxidizing activity between pH 3 and 8. The optimum temperature was 25°C. As(III) oxidation was still observed in the presence of 1000 mg l⁻¹ As(III). In continuous culture mode, the As(III) oxidation rate reached 160 mg l⁻¹ h⁻¹. The CASO1 consortium contains at least two organisms – strain b3, which is phylogenetically close to Ralstonia picketii, and strain b6, which is related to the genus Thiomonas. The divergence in 16S rDNA sequences between b6 and the closest related organism was 5·9%, suggesting that b6 may be a new species.
Conclusions: High As(III)-oxidizing activity can be obtained without organic nutrient supply, using a bacterial population from a mining environment.
Significance and Impact of the Study: The biological oxidation of arsenite by the CASO1 population is of particular interest for decontamination of arsenic-contaminated waste or groundwater.

73/02/02: received 20 February 2002, revised 6 June 2002 and accepted 19 June 2002

DIGITAL OBJECT IDENTIFIER (DOI)

10.1046/j.1365-2672.2002.01726.x About DOI

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Friday, February 20, 2009

Trace analysis and metal speciation with voltammetry

Voltammetry instruments are favorably priced and compact, yet great in their detection capabilities. You can analyze water, environmental samples or ultrapure chemicals!

Convincing applications

Total metal concentration and speciation: Apart from the determination of the total concentration, which is normally obtained with spectroscopic methods, voltammetry allows to distinguish the different oxidation stages of metal ions or differentiate between free and bound metal ions as well as to specify the biological availability of heavy metals. This makes voltammetry into an essential tool for environmental analysis. Comparable insights can only be gained by spectroscopy after complicated separation of the metal species. Its compact size means that the VA instrument can also be used in mobile laboratories. Samples with high ionic concentration are no problem for voltammetry.

Organics and anions: Not only metals but also various organic compounds can be determined by voltammetry. VA techniques are used in organic chemistry and in the pharmaceutical industry. Some special anions can also be determined by voltammetry. The determination of environmentally relevant anions like cyanide, sulfide, nitrite or nitrate is particularly interesting

Voltammetric trace analysis

has extremely low detection limits
has no problems with high salt concentrations
allows speciation
differentiates between free and complexed metal ions
can also analyze non-metals such as anions or organics.

Typical Detection Limits

(1 ppt = 1 part per trillion = 1 ng/kg)

Antimony	Sb(III), Sb(V)	200 ppt	e.g. Application Bulletin 74
Arsenic	As(III), As(V)	100 ppt	e.g. Application Bulletin 226
Bismuth	Bi	500 ppt	e.g. Application Bulletin 74
Cadmium	Cd	50 ppt	e.g. Application Bulletin 231
Chromium	Cr(III), Cr(VI)	25 ppt	e.g. Application Bulletin 116
Cobalt	Co	50 ppt	e.g. Application Bulletin 231
Copper	Cu	50 ppt	e.g. Application Bulletin 231
Iron	Fe(II), Fe(III)	50 ppt	e.g. Application Bulletin 123
Lead	Pb	50 ppt	e.g. Application Bulletin 231
Mercury	Hg	100 ppt	e.g. Application Bulletin 96
Molybdenum	Mo	50 ppt	e.g. Application Bulletin 146
Nickel	Ni	50 ppt	e.g. Application Bulletin 231
Platinum	Pt	0.1 ppt	e.g. Application Bulletin 220
Rhodium	Rh	0.1 ppt	e.g. Application Bulletin 220
Thallium	Tl	50 ppt	e.g. Application Bulletin 231
Tungsten	W	200 ppt	e.g. Application Note V-65
Uranium	U	25 ppt	e.g. Application Bulletin 266
Zinc	Zn	50 ppt	e.g. Application Bulletin 231

The applications can be downloaded from the Info Center (registration required). Download of bulletins: English, French, German.

Products: Instruments, Software, Electrodes

> 10 good reasons why you should consider the Metrohm 797 VA Computrace instead of an AAS or ICP

MVA: Metrohm VA Systems
	Metrohm VA Systems
VA Modules
	797 VA Computrace
	863 Compact Autosampler
Software
	VA Database 2.2
Instruments for Sample Preparation
	705 UV Digester
Electrodes for Voltammetry > Which electrode for which application?