Speciation of inorganic tellurium from seawater by ICP‐MS following magnetic SPE separation and preconcentration

Abstract

A new method was developed for the speciation of inorganic tellurium species in seawater by inductively coupled plasma-MS (ICP-MS) following selective magnetic SPE (MSPE) separation. Within the pH range of 2 -9, tellurite (Te(IV)) could be quantitatively adsorbed on c-mercaptopropyltrimethoxysilane (c-MPTMS) modified silicacoated magnetic nanoparticles (MNPs), while the tellurate (Te(VI)) was not retained and remained in solution. Without filtration or centrifugation, these telluriteloaded MNPs could be separated easily from the aqueous solution by simply applying external magnetic field. The Te(IV) adsorbed on the MNPs could be recovered quantitatively using a solution containing 2 mol/L HCl and 0.03 mol/L K 2 Cr 2 O 7 . Te(VI) was reduced to Te(IV) by L-cysteine prior to the determination of total tellurium, and its assay was based on subtracting Te(IV) from total tellurium. The parameters affecting the separation were investigated systematically and the optimal separation conditions were established. Under the optimal conditions, the LOD obtained for Te(IV) was 0.079 ng/L, while the precision was 7.0% (C = 10 ng/L, n = 7). The proposed method was successfully applied to the speciation of inorganic tellurium in seawater.

Food for Thought: A Critical Overview of Current Practical and Conceptual Challenges in Trace Element Analysis in Natural Waters

“…How can one decide which value is the right one? Accuracy is usually checked by using certified reference materials (CRM) but, in this case, their use is only mentioned in two cases [11,12] and the Te concentrations in the CRM used are much higher than expected seawater concentrations (100 µg mL −1 [11] and 1 ng mL −1 [12]). Analytical methods used were (number of studies in brackets): colorimetry (1), catalytic polarography (1), HG-AAS (4), NAA (1), ICP-MS (2), ETV-ICP-MS (1), and ETTAS (1), and no apparent relationship seems to exist between the method chosen and the range of Te concentration measured.…”

Speciation and determination of ultra trace amounts of inorganic tellurium in environmental water samples by dispersive liquid–liquid microextraction and electrothermal atomic absorption spectrometry

“…The detection limit was 12 g L −1 . Other reported methods for the separation and preconcentration of tellurium include on-line SPE [3], magnetic solid-phase extraction [7], ion exchange [10], using mercapto modified silica microcolumn [14], using cotton impregnated with thioglycollic acid (thiol cotton) [27] and coprecipitation [12,28,29]. These suggested methods are complicated and involve sequential steps and have disadvantages such as time-consumption, unsatisfactory enrichment factor, large organic solvents and secondary waste, which limit their application, thus they are not practical for routine analysis.…”

“…Several instrumental techniques have been applied for the determination of inorganic tellurium speciation. These include inductively coupled plasma-mass spectrometry (ICP-MS) [6,7], inductively coupled plasma atomic emission spectrometry (ICP-AES) [8], electrothermal atomic absorption spectrometry (ETAAS) [3,[9][10][11][12], hydride generation atomic absorption spectrometry (HG-AAS) [13,14], hydride generation atomic fluorescence spectrometry (HG-AFS) [15][16][17][18], gas chromatography-mass spectrometry (GC-MS) [19], cathodic stripping voltammetry [20], capillary electrophoresis with UV detection (CE-UV) [21], capillary electrophoresis coupled with ICP-MS detection (CE-ICP-MS) [22] and anion exchange HPLC-ICP-MS [23,24]. Low concentration and matrix interference are two problems in detecting tellurium compounds.…”

Application of Modified Magnetite Nanoparticles as a New Sorbent for Separation/Preconcentration of Mercury(II) Trace Amounts and its Determination by Cold Vapor Atomic Absorption Spectrometry

“…[32][33][34][35] Magnetite nanoparticles have been successfully applied to separate some proteins and organic compounds 36,37 and some heavy metal ions. [38][39][40][41][42][43] These methods were based on the solid-phase extraction of trace amounts of silver and lead ions using dithizone/sodium dodecyl sulfateimmobilized on alumina-coated magnetite nanoparticles. 44,45 Surfactant molecules are known to form selfaggregates called "hemimicelles" or "admicelles" on solid alumina surfaces in acidic medium.…”