Novel catalytic fluorescence method for speciative determination of chromium in environmental samples
Adurty and Sabbu Journal of Analytical Science and Technology
Novel catalytic fluorescence method for speciative determination of chromium in environmental samples
Sunil Adurty 0
Jagadeeswara Rao Sabbu 0
0 Department of Chemistry, Sri Sathya Sai Institute of Higher Learning (Deemed to be university) , Prasanthi Nilayam-515134, Puttaparthi, Anantapur District, Andhra Pradesh , India
Background: Thiourea derivatives act as promising chemosensors for sensing transition metal ions. 1-(2-hydroxyphenyl) thiourea (HPTU) is one such chromophore that has potential for metal ion sensing. The current investigation reports the sensing of chromium species using transition metal-oxo-based reaction of 1,2-hydroxyphenylthiourea. Methods: The catalytic effect of chromium (III) and chromium (VI) on the oxidation of HPTU was studied. The reaction was followed spectrofluorimetrically by measuring the fluorescence intensities of the reaction product at ex = 416 and em = 520 nm, respectively. Results: Under the optimum analytical conditions, HPTU acts as a chromogenic sensor for the detection of chromium species in nano-gram levels with a determination range of 0.3 to 250 ng/mL. Conclusions: The methods are fairly sensitive, and the role of activators and sensitizers in enhancing the catalysis was studied. Interference due to various cations and anions in the experiment was investigated. The proposed method was applied to environmental samples for the analysis of chromium content.
1-(2-hydroxyphenyl) thiourea; Chromium; Speciative determination; Catalytic fluorescence
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Background
The toxicological and biological characteristics of many
transition metals like chromium are related to their
chemical forms. A great interest in chromium speciation
originates from applications of this metal in various
industrial activities such as tanning of leather, electroplating,
pigment production and wood preservation. Owing to
these industrial processes, large amounts of chromium
compounds discharge into the environment, which can
affect biology and ecology of the environment. Therefore,
speciation analysis of chromium is of great importance to
assess pollution levels. Chromium mainly exist in two
oxidation states, i.e. Cr(III) and Cr(VI). Cr(III) appears to be
one of the essential elements for the proper functioning of
living organisms, effective in the maintenance of normal
glucose, cholesterol and fatty acid metabolism, while water
soluble Cr(VI) is toxic to human and living organisms and
was found to be carcinogenic. Due to the different
toxicities of Cr(III) and Cr(VI), and due to their association in
many sample matrices, it is necessary to develop methods
where both species can be determined simultaneously
(Kotas and Stasicka 2000).
In the past years, various analytical techniques such as
atomic absorption spectrometry (AAS) (Karosi et al. 2006;
Ren et al. 2007) spectrophotometry (Wu et al. 2007),
stripping voltammetry (SV) (Grabarczyk et al. 2006), inductively
coupled plasma-mass spectrometry (ICP-MS) (Sun et al.
2006), inductively coupled plasma-optical emission
spectrometry (ICPOES) (Schramel et al. 1992), and high
performance liquid chromatography (HPLC) (Padarauskas
and Naujalis 1998) have been successfully used to
determine chromium in various samples. An extensive
coverage of the available methods for chromium determination
was put forth by Gomez and Callao, including the various
types of sample matrices selected for the determination
(Gomez and Callao 2006). Reagents such as
bis-[2-hydroxy-1-naphthaldehyde] thiourea (Kiran et al. 2008),
quercetin (Hosseini and Belador, 2009), chromotropic
acid (CA) (Themelis et al. 2006), bis (salicylaldehyde)
orthophenylenediamine (BSOPD) (Arancibia et al. 2012
and Soomro et al. 2011), etc. have been used. Methods
such as solidified floating organic drop microextraction
(SFODME) in combination with graphite furnace atomic
absorption spectrometry (GFAAS) (Moghadam et al. 2011),
cloud point extraction (CPE) using diethyldithiocarbamate
(DDTC) as the chelating agent (Yildiz et al. 2011), solid
phase extraction procedure using ICP-MS (Guerrero et al.
2012), fluorescence method using tetraphenylphosphonium
bromide (TPP+Br) (El-Shahawi et al. 2011), EPA methods
3060A and 3052 (Martone et al. 2013), a disposable dual
screen-printed electrode method using batch and flow
analysis (SnchezMoreno et al. 2010), p-aminoacetophenone
and phloroglucinol (Parmar et al. 2010),
ultrasoundassisted cloud point extraction (UACPE) (Hashemi and
Daryanavard 2012), electrospray ionization mass
spectrometry using CYDTA (Hotta et al. 2012), HPLC and
preconcentration by CPE with
1-(2-thiazolylazo)-2-naphthol (TAN) as the chelating agent (Wang et al. 2010),
ytterbium (III) hydroxide (Duran et al. 2009), mixed-micelle
cloud point extraction using electrothermal atomic
absorption spectrometry (ET-AAS) (Ezoddin et al. 2010),
room temperature ionic liquids (RTILs) for hollow fiber
liquid phase microextraction (HF-LPME) com (...truncated)