Near-electrode pH change for voltammetric detection of insoluble lead carbonate

Reagentless Dissolution and Quantification of Particulate Lead in Tap Water via Membrane Electrolysis

The presence of particulate Pb in tap water has been a limiting factor in the design of accurate and portable platforms for quantifying this toxic metal. Convenient and affordable electrochemical techniques are blind toward particulate species and thus require addition of reagents and additional chemical processing such as sample acidification. This study describes the fundamentals and the first use of membrane electrolysis for the reagentless sample preparation of tap water for the detection of particulate Pb contaminants. Membrane electrolysis allows for the in-situ generation of nitric acid, which, in combination with anodic stripping voltammetry, provides a powerful tool for the accurate and reagent-free detection of Pb²⁺. The configuration of the setup allows for its semi-autonomous operation and requires minimal attention, making electrochemical methods more suitable and accessible for continuous measurements of particulate contaminants in tap-water. The voltammetric response is linear in the range of 24.1-398 nM of Pb, which covers the action level of 48 nM suggested by the World Health Organization.

An Electroanalytical Solution for the Determination of Pb2+ in Progressive Hair Dyes Using the Cork-Graphite Sensor

Lead is one of the most toxic metals for living organisms: once absorbed by soft tissues, it is capable of triggering various pathologies, subsequently bioaccumulating in the bones. In consideration of this, its detection and quantification in products for human consumption and use is of great interest, especially if the procedure can be carried out in an easy, reproducible and economical way. This work presents the results of the electroanalytical determination of lead in three different commercial products used as progressive hair dyes. Analyses were performed by cyclic voltammetry (CV) and differential pulse stripping voltammetry (DPSV) using a composite cork–graphite sensor in 0.5M H₂SO₄ solution or 0.1M acetate buffer (pH 4.5), in the presence and absence of hair dye samples. The H₂SO₄ solution gave better results in terms of analyte sensitivity than the acetate buffer electrolyte. In both cases, well-defined signals for lead were obtained by DPSV analyses, enabling the calibration curve and figures of merit to be determined. The limits of detection (LOD) were found to be approximately 1.06 µM and 1.26 µM in H₂SO₄ and acetate buffer, respectively. The DPSV standard addition method was successfully applied to quantify the lead in hair dye samples, yielding values below 0.45% in Pb. All three analyzed samples were shown to comply with the limit set by the Brazilian Health Regulatory Agency, i.e., 0.6% lead in this type of product. The comparison of the electroanalytical results with those obtained by the reference method, based on the use of inductively coupled plasma optical emission spectrometry (ICP–OES), confirmed that the electroanalytical detection approach is potentially applicable as a strategy for quality control.

Impact of physical and chemical parameters on square wave anodic stripping voltammetry for trace Pb2+ detection in water

Exposure to lead, a toxic heavy metal, in drinking water is a worldwide problem.