US EPA

1786380 

Journal Article 

Proposition of a simple method for chromium (VI) determination in soils from remote places applying digital images: A case study from Brazilian Antarctic Station 

Oliveira, LF; Canevari, NT; Guerra, MBB; Pereira, FMV; Schaefer, C; Pereira-Filho, ER 

2013 

1 

Microchemical Journal
ISSN: 0026-265X
EISSN: 1095-9149 

109 

165-169 

10.1016/j.microc.2012.03.007 

WOS:000318665300028 

http://linkinghub.elsevier.com/retrieve/pii/S0026265X12000537
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In this study, we proposed a straightforward approach that
could be used for Cr redox speciation in soil samples from remote places. For this aim, soil
samples under strong anthropogenic impact, from the vicinity of the Brazilian Antarctic Station
were studied. Control samples with no direct impact, were also collected further (4 km) from the
station. A preliminary laboratory evaluation for Cr (VI) presence was performed using X-ray
absorption spectroscopy. The proposed method was based on a hot alkaline extraction to promote
the quantitative extraction of Cr (VI) from soil samples. The colorimetric reagent 1,5-
diphenylcarbazide (DPC) was added to the extracts to form a violet complex with Cr (VI). A simple
and inexpensive commercial scanner was used to acquire the digital images of the formed complex.
Partial Least Squares models were constructed with the following average color descriptors: red
(R), green (G), blue (B), hue (H), saturation (S), value (V), relative color descriptors Cr, g
and b) and luminosity (L). The results obtained with this scanner approach were consistent with
the official method that uses a spectrophotometer at 540 nm. Besides that, this is the first
study that reports Cr redox speciation in soils from Antarctica, which is regarded as the less
polluted place on the Earth. (C) 2012 Elsevier B.V. All rights reserved. 

Hexavalent chromium; Digital images; Antarctica; Soil; Partial Least Squares