Simple, Fast, and Sensitive Method for Quantification of Tellurite in Culture Media

Abstract

A fast, simple, and reliable chemical method for tellurite quantification is described. The procedure is based on the NaBH 4 -mediated reduction of TeO 3 2؊ followed by the spectrophotometric determination of elemental tellurium in solution. The method is highly reproducible, is stable at different pH values, and exhibits linearity over a broad range of tellurite concentrations.The tellurium oxyanion tellurite is toxic for most organisms, making important its accurate assessment. Several methods for quantifying tellurite have been described to date. However, most of them are rather complicated and require sophisticated equipment and in some cases the detection is not quite sensitive enough to allow the assessment of TeO 3 2Ϫ concentrations below 50 g/ml (200 M). For example, the analytical determination of tellurium (Te) oxyanions by atomic absorption spectrometry (AAS) is hampered by poor sensitivity. Where flame or electrothermal AAS routinely yields detection limits of less than 10 ppb for iron (16), normal flame AAS tellurium detection limits are 100 to 1,000 times higher and require pretreatment to achieve the ϩIV oxidation state before analysis (11).On the other hand, hydride generation AAS (HGAAS) is used to achieve ppb-level detection limits for Se and Te as well as arsenic and antimony among others. For Te the volatile hydride gas H 2 Te is generated by first converting the metalloid to the ϩIV oxidation state and then by chemical reduction to the gaseous hydride using-almost universally-sodium borohydride (NaBH 4 ). In automated HGAAS systems, an inert purge gas sweeps the volatile hydride formed in a glass reaction vessel into a quartz cell heated by the AAS flame where gaseous hydride decomposition and atomization occur. Though tellurite reduction, precipitation, and detection methods have been reported (3, 17), they are temporally relatively unstable and pH dependent.Since tellurium is toxic and environmentally important (7,8), determining low concentrations in bacterial cultures is very desirable and a simple analysis without pretreatment steps that could quickly establish total metalloid oxyanion content in a liquid sample would be a plus. Here we report a new method for the determination of tellurite in bacterial culture media. This procedure is based on the NaBH 4 reduction of tellurite to the elemental form, which is analyzed spectrophotometrically at 500 nm or 320 nm (see below), by which the light scattered by the particles of elemental metalloid in solution is measured.

DNA, Cell Wall and General Oxidative Damage Underlie the Tellurite/Cefotaxime Synergistic Effect in Escherichia coli

“…As in the case of other cephalosporin antibiotics, CTX-mediated damage to the cell wall is well known and in this scene, increased uptake/adsorption of tellurite may be expected. Indirect evaluation of tellurite uptake in tellurite/CTX-exposed cells -using a previously reported strategy [37] - proved this to be the case although this effect did not depend on CTX concentration ( Fig. 1 ).…”

Glutathione Reductase-Mediated Synthesis of Tellurium-Containing Nanostructures Exhibiting Antibacterial Properties

“…Nonetheless, no particular absorbance peaks were observed, a common characteristic of tellurium (Fig. 3D) (22). The chemical composition of TeNSs, as determined by EDS, is shown in Fig.…”

Biosynthesis and recovery of rod-shaped tellurium nanoparticles and their bactericidal activities

“…A fast, simple, and reliable chemical method recently described for the direct spectrophotometric determination of residual Te 4+ ion concentration in bacterial culture media was used in this study [28]. With this method, the Te 4+ ions were reduced to elemental Te using NaBH 4 (4.5 mM).…”