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Two novel and low cost liquid-liquid extraction methods for the separation of bismuth(III) at trace level from aqueous medium have been developed. The two methods were based upon the formation of yellow colored ternary complex ion associates of tetraiodobismuth(III) complex anion, BiI4 - with the ion-pairing reagent 2,3,5-tetraphenyltetrazoliumchloride (Tz+.Cl-) and 1, 10 phenanthroline (Phen) in sulfuric acid medium. The effect of various parameters e.g. pH, organic solvent, shaking time, etc. on the preconcentration of bismuth(III) from the aqueous media by the reagent was investigated. The developed colored complex ion associates [Tz+.BiI4 -] and [Phen+.BiI4 -] were extracted quantitatively into acetone-chloroform (1:1v/v) and methylisobutylketone (MIBK), respectively. The compositions of the formed complex ion associates [Tz+.BiI4 -] and [Phen+.BiI4 -] were determined by the Job's method at 500 and 490 nm, respectively. The plots of bismuth(III) concentration (0-17 μg mL-1) versus absorbance of the associates at 500 and 490 nm were linear with good correlation coefficient (R²=0.998). The developed method of the ion associate [Tz+.BiI4 -] two methods was applied successfully for the analysis of bismuth in water. [ABSTRACT FROM AUTHOR]

Detection and identification of single nucleotide polymorphisms (SNPs) have garnered increasing interest in the past decade, finding potential application in detection of antibiotic resistance, advanced forensic science, as well as clinical diagnostics and prognostics, moving toward the realization of personalized medicine. Many different techniques have been developed for genotyping SNPs, and ideally these techniques should be rapid, easy-to-use, cost-effective, flexible, scalable, easily automated, and requiring minimal end-user intervention. While high-resolution melting curve analysis has been widely used for the detection of SNPs, fluorescence detection does not meet many of the desired requirements, and electrochemical detection is an attractive alternative due to its high sensitivity, simplicity, cost-effectiveness, and compatibility with microfabrication. Herein, we describe the multiplexed electrochemical melting curve analysis of duplex surfaces tethered to electrodes of an array. In this approach, thiolated probes designed to hybridize to a DNA sequence containing the SNP to be interrogated are immobilized on gold electrodes. Asymmetric PCR using a ferrocene-labeled forward primer is used to generate this single-stranded redox-labeled PCR amplicon. Following hybridization with the probe immobilized on the electrode surface, the electrode array is exposed to a controlled ramping of temperature, with concomitant constant washing of the electrode array surface while simultaneously carrying out voltammetric measurements. The optimum position of the site complementary to the SNP site in the immobilized probe to achieve maximum differentiation in melting temperature between wild-type and single base mismatch, thus facilitating allelic discrimination, was determined and applied to the detection of a cardiomyopathy associated SNP., Competing Interests: The authors declare no competing financial interest., (© 2021 The Authors. Published by American Chemical Society.)