Development of a Paper-Based Analytical Method for the Selective Colorimetric Determination of Bismuth in Water Samples

A novel, direct and simple colorimetric method employing μicroanalytical paper-based devices (μ-PADs) for the selective determination of bismuth is described. The suggested exploits variation after its rapid reaction with methyl thymol blue (MTB) in an acidic medium (pH ranging between 0.7 3.0), modified nitric acid, on surface a paper device at room temperature. are low cost, composed chromatographic wax barriers analytical protocol easily applicable minimal technical expertise without need experimental apparatus. user must add test sample read color intensity colored Bi(III)–MTB complex formed sensing area using imaging such as flatbed scanner. Various chemical variables, HNO3 MTB concentration, time, ionic strength, detection zone size photo-capture detector optimized. study interfering ions K+, Na+, Ca2+, Mg2+, Cl−, SO42− HCO3− was also conducted. stability studied different maintenance conditions particularly satisfactory results, rendering suitable field analysis. limits 3.0 mg L−1 very precision, from 4.0% (intra-day) to 5.5% (inter-day). Natural water samples successfully analyzed, percentage recoveries were calculated range 82.8 115.4%.