**8. References**


For each groundwater sample, average total As concentrations determined by both methods were compared by means of a paired t-test. Calculated *t* value was compared with the tabulated *t* value for 9 degrees of freedom and a significance level of p=0.05 (*t*=2.26). The calculated *t* value (1.00) is lower than the tabulated one, thus the null hypothesis that the methods do not give significantly different values for the mean total As concentration is

A sequential injection system with anodic stripping voltammetric detection for speciation of inorganic arsenic has been exploited. The reagents consumption is minimal. Limits of detection of 1 and 2 μg l-1 for As(III) and total As can be achieved. The tubular configuration of the working electrode, in combination with binary sampling strategy, was successfully applied to determine As(III) and total As in groundwater samples without any pre-

The LODs obtained for As(III) and total As were similar to those reported using continuous flow as sample introduction method. The SI-ASV system uses 0.4 ml of water sample for each determination, which is noticeably smaller than the sample amount reported using

The proposed SI voltammetric system is an alternative for cost-effective higher degree of automation. The linearity and response achieved with the system makes it very suitable for arsenic measurements in natural waters with usual concentrations. Samples with higher or lower concentration can also be easily measured by varying the amount of sample aspirated

The authors wish to thank the economical support provided by Consejería de Educación, Junta de Castilla y León (projects VA023A10-2 y GR170) and CONACyT (project 61310).

B'Hymer, C., Caruso, J.A. (2004). Arsenic and its speciation analysis using high-performance

Bednar, A.J., Garbarino, J.R., Burkhardt, M.R., Ranville, J.F., Wildeman, T.R. (2004). Field

Billing, C., Groot, D.R., van Staden, J.F. (2002). Determination of arsenic in gold samples

Bryce, D.W., Izquierdo, A., Luque de Castro, M.D. (1995). Flow injection anodic stripping

Burguera, M. & Burguera, J.L. (1997). Analytical methodology for speciation of arsenic in environmental and biological samples. *Talanta*. Vol 44. pp. 1581-1604

liquid chromatography and inductively coupled plasma mass spectrometry. *Journal* 

and laboratory arsenic speciation methods and their application to natural water

using matrix exchange differential pulse stripping voltammetry. *Analytica Chimica* 

voltammetry at a golg electrode for selenium (IV) determination. *Analytica Chimica* 

other flow methodologies without loss of sensitivity.

*of Chromatography A.* Vol. 1045, pp. 1-13

*Acta.* Vol. 453, pp. 201-208

*Acta.* Vol. 308, pp. 96-101

analysis. *Water Research*. Vol. 38, pp. 355-364

accepted.

treatment.

**6. Conclusions** 

and/or the deposition time.

**7. Acknowledgments** 

**8. References** 


**10** 

*México* 

**Electrode Materials a Key Factor** 

Erika Méndez1, Erika Bustos1, Rossy Feria2, Guadalupe García2 and Margarita Teutli3\*

*Electroquímica, Sanfandila, Pedro Escobedo, Querétaro,* 

*Universitaria, Puebla, Pue;* 

**to Improve Soil Electroremediation** 

*1Laboratorio de Tratamiento de Suelo, Centro de Investigación y Desarrollo Tecnológico en* 

*2Departamento de Química, Universidad de Guanajuato, Centro Guanajuato, Guanajuato,* 

Pollution of top and subsurface soil, as well as underneath groundwater has been one of the consequences of industrial activities; actually environmental professionals are facing a time consuming issue when they look for potential solutions for heavy metals and organic compounds removal. Although many soil remediation technologies are available, electrokinetic processing has been an emerging technology offering advantages for a wide variety of pollutants being either organic or inorganic; as well as its versatility of being applied in soil wetting conditions ranging from unsaturated to saturated; one of the main advantages of this technology is the fact that this process can be applied to low permeability

Initially electrokinetics was applied for soil consolidation, in this process water flux is forced by an electrical field action, an approach to explain how it works is based on setting up a soil structural change analysis based on modification of soil matrix, plasticity index and crystalline state (Gray, 1970). For clayey soils it has been accepted that they behave like an osmotic membrane, therefore it is important to understand how physicochemical factors affect its response in regulating osmotic pressure into the soil matrix (Fritz, 1986). Another report (Darmawan, 2002) reinforce the necessity of knowing how the solid matrix response to the electric field, since obtained electrical current is function of electrolyte concentration, buffering capacity, and chemical form of involved metals, these can be in either soluble, electrostatically adsorbed, or surface complexed forms; also, metal migration is favored when soil is dominated by clay minerals, otherwise migration is lowered when soil has a high buffering capacity and/or high humic content, the last one acts like an additional

Electrokinetics as a remediation experimental procedure requires having a wetted soil in which electrodes are inserted and terminals are connected to a power source. As soon as an electric field is generated, electrode reactions take place producing protons (H+) at the anode

resistance to the current transference throughout the soil.

**1. Introduction** 

soils, like clays.

*3Facultad de Ingeniería, Benemérita Universidad Autónoma de Puebla, Ciudad* 

