Spectrophotometric determination of tin(II) by redox reaction using 3,3′,5,5′-tetramethylbenzidine dihydrochloride and N-bromosuccinimide

Abstract

5661 Tin(II) compounds are important in 99m Tc radiop harmaceutical kits as stabilizing agents [1], in dental gels and food as preservatives [2][3][4], and in electroless plating as electrochemical catalysts [5][6][7][8]. Common methods to determine tin(II) are limited by some combination of the range and/or limit of detection, ease of application, reproducibility, and inability to distinguish tin(II) from tin(IV). A need to rapidly quantitate tin(II) concentration in an electroless plat ing sensitization solution at concentrations less than 0.3 µg/mL to evaluate its effectiveness motivated the development of the present colorimetric approach. A spectrophotometric approach was selected which complements the existing spectrophotometric meth ods for quantification of boron [9], vanadium(IV) [10], and mercury(II) [11]. Common methods for determining tin(II) concen tration are summarized in Table 1. These methods are: electrochemistry [1-4, 12-19], membrane sensor [18], inductively coupled plasma-optical emission spectrometry (ICP-OES) [19], flame atomic absorp tion spectrometry (FAAS) [20], fluorescence [21], and spectrophotometry [22-29]. The electrochemi cal method, which includes anodic stripping voltam metry (ASV) [1-4, 12] and differential pulse polarog 1 The article is published in the original.raphy (DPP) [13][14][15][16][17], has been widely used because of selective determination of tin(II) in the presence of tin(IV). The ASV method has a low LOD. For exam ple, a LOD equal to 0.00026 µg/mL was achieved by Hutton et al. by using the ASV method with a bismuth film electrode [3]. However, the limitation of the ASV method is that it requires either formation of a tin(II) complex such as a tin(II)-oxine [1] or a tin(II)-tropolone [2], or use of a modified electrode such as an epoxy carbon electrode or the BiFE [3, 4, 12]. The DPP method does not require a tin(II) complex or a modified electrode but it is limited by the detection range and the LOD. Decristoforo et al. [14] reported a DPP method with a LOD of 0.005 µg/mL but the con centration range was from 10 to 15 µg/mL. Similarly, using the DPP method, Sebastian et al. [15] quantified tin(II) within the concentration range 0 to 10 µg/mL but the LOD was 0.5 µg/mL.Recently published methods based on membrane sensor, ICP, FAAS, and fluorescence quenching im proved the detection concentration range and the LOD, but the constraints in the methods limit their usage. The tin(II) selective potentiometric membrane sensor method was reported to have a concentration range of 0.013 to 1190 µg/mL and a low LOD of 0.0025 µg/mL, but preparation of the membrane elec trode was work intensive [18]. ICP-OES was used to Abstract-A rapid, straightforward spectrophotometric method based on the redox reaction of tin(II) with a mixture of N bromosuccinimide (NBS) and 3,3',5,5' tetramethylbenzidine dihydrochloride (TMB) was developed for determining low concentrations of tin(II). The redox method improved sensitivity by 2.3 fold relative to the existing spectrophotometric methods by t...

Reductive spectrophotometry of divalent tin sensitization on soda lime glass

“…Two distinct one-electron products of TMB can be envisaged: TMB radical cation, and the charge-transfer complex of the diamine (electron donor) and the diimine (electron acceptor). Subsequent addition of surface-associated, reductant tin (II) (+0.15 V, NHE) to this volume at Stage 3 reversed the oxidation to a degree, resulting in equilibrium between the diimine and its blue, charge-transfer complex of diamine and diimine ( max = 370, 652 nm), as illustrated in Stage 4 [29,30,32]. The amount of tin (II) added determined the degree of this reversal, as indicated by spectroscopic peaks at 370, 452, and 652 nm shown in Fig.…”

“…TFA concentrations of 30, 68, and 90 mM were tested at sensitization concentration and time of 26 mM and 30 s, respectively. TFA was used instead of HCl during sensitization, due to reports indicating tin (II)-TFA sensitization was effective for subsequent EL plating of uniform gold films with features closely resembling sputtered gold films [7,13,29,30,34,39]. However, tin sensitization in the presence of TFA may reduce tin (II) on substrates, and produce larger grain size and higher pK a (0.23) than HCl (−7.0) [13].…”

“…Jang and Roper first used aqueous acid solutions in which formaldehyde, HCHO, and NBS were balanced with TMB-HCL to quantitate dissolved Au (I) [30]. Subsequently, Wei et al combined equal volumes of equimolar solutions of TMB-HCL and NBS to measure dissolved tin (II) from 0.05 g/mL (lower limit of quantitation, LOQ) to 0.34 g/mL (upper limit of quantitation, UOQ) [29]. To reproducibly quantitate tin (II) deposited on soda lime glass, the present work modified this method, including extending the quantifiable range to UOQ of 1.7 g/mL by tripling volumes of both redox reagents.…”

“…The effects of tin sensitization, and activation steps on EL plating along with substrate properties have been evaluated by Rutherford backscattering [21][22][23], radiochemical tracer analysis [24,25], Mossbauer spectroscopy [26], X-ray fluorescence spectrometry [27] and X-ray photoelectron spectroscopy (XPS) [28]. Challenges of these methods [13,29] underscore a need for rapid, in situ evaluation of tin (II) deposited during sensitization with respect to operational variables, e.g., sensitization time, analyte concentration, aqueous immersion, and acid content.…”

Electron optics of nanoplasmonic metamaterials in bio/opto theranostics

“…37 Control of chemical and photo oxidation during tin 38 and silver 39 steps improves metal layer density and uniformity. Balancing oxidation in solution supports spectrophotometric analysis of Au(I) 40 and Sn(II) 41 at lower limit of detection than alternative methods. Random, two-dimensional (2D) assemblies of AuNP on silica have been thermally transformed from Au island film stably deposited by electroless plating.…”