TITLE:
Spectrophotometric Determination of Water-Soluble Hexavalent Chromium and Determination of Total Hexavalent Chromium Content of Portland Cement in the Presence of Iron (III) and Titanium (IV) Using Derivative Ratio Spectrophotometry
AUTHORS:
K. A. Idriss, H. Sedaira, S. Dardeery
KEYWORDS:
Chromium (VI) Determination; Quinalizarin; Portland Cement Analysis; Derivative Spectrophotometry
JOURNAL NAME:
American Journal of Analytical Chemistry,
Vol.4 No.11,
November
27,
2013
ABSTRACT: A rapid, reliable and accurate method for the determination
of hexavalent chromium in Portland cement is developed. The proposed method
includes direct spectrophotometric determination of Cr (VI) in Portland cement
with 1, 2, 5, 8 Tetrahydroxyanthraquinone, (Quinalizarin, QINZ) at pH 1.5. The
European Directive (2003/53/EC) limits the use of cements so that it contains
no more than 2 mg.Kg-1 of water-soluble Cr (VI). The absorbance at
565 nm due to Cr (VI)-QINZ complex is recommended for the determination of
water-soluble Cr (VI) in Portland cement. The quantification of Cr (VI)
released from cement when mixed with water is performed according to TRGS 613
(Technical Rules of Hazardous Substances). The validity of the
method is thoroughly examined and the proposed method gives satisfactory
results. A derivative spectrophotometric method has been developed for the
determination of total Cr (VI) in Portland cement in the presence of Fe (III)
and Ti (IV). The hexavalent chromium complex formed at pH 1.5 allows precise
and accurate determination of chromium (VI) over the concentration range 0.05
to 3.0 mg.L-1of chromium (VI). The validity of the method was
examined by analyzing several Standard Reference Material (SRM) Portland cement
samples. The MDL (at 95% confidence level) was found to be 25 ng/mL for chromium
(VI) in National Institute of Standards and Technology (NIST) cement samples
using the proposed method.