Physical Science International Journal

Comparison of ICP-OES and XRF Performance for Pb and As Analysis in Environmental Soil Samples from Chihuahua City, Mexico

Delgado R. Marcos *

Universidad Autónoma de Cd. Juárez, Instituo de Ciencias Biomédicas. Estocolmo y Anillo Envolvente del Pronaf 32310, Cd. Juárez, México;

Parsons Jason

The University of Texas at El Paso, Chemistry Department and Environmental Sciences and Engineering Ph.D. Program. El Paso, Tx. U.S.A.;

Garcia Humberto

Instituto Tecnológico de Estudios Superiores de Monterrey Campus Cd. Juárez. Ave. Tomás Fernández Campos No. 8945, Parque Industrial A.J. Bermúdez, C.P. 32470, Cd. Juárez, Chih. México;

Corral A. Alba Y

Universidad Autónoma de Cd. Juárez, Instituo de Ciencias Biomédicas. Estocolmo y Anillo Envolvente del Pronaf 32310, Cd. Juárez, México;

Cruz J. Gustavo

Universidad de Guanajuato, Noria Alta s/n, Guanajuato, Gto., México;

Campos T. Alfredo

Centro de Investigación en Materiales Avanzados. Miguel de Cervantes 120, Complejo Industrial Chihuahua 31109, Chihuahua, Chih., México.

Duarte M. Alberto

Centro de Investigación en Materiales Avanzados. Miguel de Cervantes 120, Complejo Industrial Chihuahua 31109, Chihuahua, Chih., México.

Gardea-Torresdey Jorge

The University of Texas at El Paso, Chemistry Department and Environmental Sciences and Engineering Ph.D. Program. El Paso, Tx. U.S.A.

*Author to whom correspondence should be addressed.

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Abstract

Lead (Pb) and arsenic (As) levels on PM₁₀ were measured for indoor and outdoor atmospheres and soil samples in Chihuahua City (Chihuahua, Mexico). The concentration of both Pb and As in the soil samples was determined and compared using two instrumental techniques, Inductively coupled-plasma optical emission spectroscopy (ICP-OES) and X-ray fluorescence (XRF). Statistical analyses were performed to determine if significant differences existed between the instrumental techniques, which included F-test for variances evaluation and t-test for mean comparison. The statistical analysis demonstrated that no statistically significant differences were observed for the As concentrations; however, for the Pb concentrations, significant differences did exist between the instrumental techniques. In addition, two microwave assisted digestion techniques were also tested to determine if the difference in the Pb concentrations were due to the extraction technique rather than instrumental method. The first digestion technique used nitric acid (HNO₃), which commonly is used for the extraction of soluble materials within a sample. The second digestion technique used a 1:4 mixture (1 part of concentrated HNO₃: 4 parts of concentrated HCl) which generally extracts more refractory elements but destroys more of the sample matrix than HNO₃. Similar statistical tests (F-test and t-test) were applied to the data from both digestion types, which showed no significant difference between the extraction techniques.

Keywords: ICP-OES, Pb, XRF, soil

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