Spectrochimica Acta Part A 64 (2006) 383–390
Simultaneous determination of titanium and molybdenum in steel samples
using derivative spectrophotometry in neutral micellar medium
Anitha Varghese, A.M.A. Khadar
∗
, Balakrishna Kalluraya
Department of Chemistry, Mangalore University, Mangalagangothri, Mangalore 574199, India
Received 2 February 2005; accepted 14 July 2005
Abstract
A simple, selective and sensitive spectrophotometric method has been developed for the individual and simultaneous determination of Ti(IV)
and Mo(VI) using resacetophenone p-hydroxybenzoylhydrazone (RAPHBH) in presence of Triton X-100, without any prior separation. Beer’s
law is obeyed between 0.13–1.2 gmL
−1
and 0.18–1.90 gmL
−1
concentration of Ti(IV) and Mo(VI) at 455 nm and 405 nm, respectively.
The molar absorptivity and Sandell’s sensitivity of the coloured complexes at pH 3.0 are 3.1 × 10
4
L mol
−1
cm
−1
, 4.2 × 10
4
L mol
−1
cm
−1
, and
1.6 ng cm
−2
, 2.3 ng cm
−2
for Ti(IV) and Mo(VI), respectively. The stoichiometry of the complexes were found to be 1:2 and 1:1 (metal:ligand)
for Ti(IV) and Mo(VI), respectively. These metal ions interfere with the determination of each other in zero-order spectrophotometry. The
first derivative spectra of these complexes permitted a simultaneous determination of Ti(IV) and Mo(VI) at zero crossing wavelengths of
500.0 nm and 455.0 nm, respectively. The effect of foreign ions in the determination of Ti(IV) and Mo(VI) were investigated. The pro-
posed method has been successfully applied for the determination of titanium and molybdenum in standard alloy steel, mineral and soil
samples.
© 2005 Elsevier B.V. All rights reserved.
Keywords: Titanium; Molybdenum; Resacetophenone p-hydroxybenzoylhydrazone; Derivative spectrophotometry; Simultaneous determination; Micellar
medium
1. Introduction
Determination of trace amounts of titanium and molybde-
num is of great interest because of their increasing industrial
applications. They have very important and extensive uses in
catalysts, paint pigments and corrosion inhibitors. They are
valuable alloying agents and coexist in a number of industri-
ally important alloys and steels. Alloys of these metals are
used principally in missile, aircraft parts and filament mate-
rial in electrical applications where lightweight, strength and
ability to withstand extremes of temperature are important.
Besides its widespread industrial uses, molybdenum is an
essential micronutrient element for plants, where it plays an
important role in regulating nitrogen metabolism [1]. Soil
that has no molybdenum at all cannot support plant life. It is
however harmful to both plants and animals at higher con-
∗
Corresponding author. Tel.: +91 824 2287262; fax: +91 824 2287367.
E-mail address: amakhader@yahoo.com (A.M.A. Khadar).
centrations [2]. Therefore, it is important from the analytical
point of view to develop simple, sensitive and reliable meth-
ods for the trace level determination of titanium and molyb-
denum in various complex matrixes when present alone or in
the presence of each other.
Various analytical techniques used for the determina-
tion of titanium and molybdenum in different types of
matrices include neutron activation analysis [3,4], induc-
tively coupled plasma atomic emission spectrophotome-
try [5,6], X-ray fluorescence [7,8], and spectrophotometry
[9–14]. Spectrophotometric methods occupy special posi-
tion due to their simplicity, less expensive instrumentation
and high sensitivity. A number of chromogenic reagents,
such as O,O
-bis(2-ethylhexyl)dithiophosphoric acid, isoth-
ipendyl hydrochloride, pipazethate hydrochloride, 3,4-
dihydroxybenzoic acid, 2-(2
-furyl)-3-hydroxy chromone,
N-hydroxy-N,N
-diphenylbenzamidine, [15–19] have been
reported for the determination of titanium and molyb-
denum at trace levels. The reagent—7,8-dihydroxy-4-
1386-1425/$ – see front matter © 2005 Elsevier B.V. All rights reserved.
doi:10.1016/j.saa.2005.07.034