On-line solid phase extraction of bismuth by FI–HG–AAS using l-proline immobilised on carbon nanotubes combined with factorial design

Preconcentration of bismuth using nickel hydroxide nanoflower from water samples and determination by FAAS

In this study, a preconcentration strategy based on Ni(OH)2 nanoflowers (NFs) was developed for the extraction/separation of bismuth ions from environmental water samples before the determination by flame atomic absorption spectrometry (FAAS). The homogeneous coprecipitation method was employed for the synthesis of the flower-shaped Ni(OH)2 and used as an adsorbent for the preconcentration of bismuth. The extraction variables were determined by a univariate optimization strategy to obtain maximum extraction performance. The optimal parameters of the method were as follows: 15 min mechanical shaking at 120 rpm, pH 6.0 buffer solution (1.0 mL), 20 mg of sorbent, and 250 µL of 6.0 M nitric acid for the elution. Under the optimized instrumental and extraction conditions, LOD (limit of detection), LOQ (limit of quantitation), and linear dynamic range were determined as 2.8 µg/L, 9.4 µg/L, and 0.010-0.30 mg/L, respectively. The enhancement factor of the sorbent-based method was calculated as 139.1-folds by comparing the slopes of calibration plots obtained from FAAS and the preconcentration method. To assess the feasibility and reliability of the developed method, tap water and spring water samples were analyzed under optimized conditions. The satisfactory %recoveries were obtained close to 100% using the direct comparison method. The obtained results show that the presented method is a promising candidate for efficient extraction and trace determination of bismuth in several sample mediums.

A retrospective and prospective of the use of bio- and nanomaterials for preconcentration, speciation, and determination of trace elements: a review spanning 25 years of research

This review covers the investigations carried out with my colleagues and students during the last 25 years aimed at the development of analytical procedures for the preconcentration and/or speciation analysis of trace and ultra-trace elements using bio- and nanosorbents employing different methodologies, analytical techniques, and instrumental approaches. In the last years, an important part of this research was based on the use of nanomaterials for preconcentration and/or speciation studies. For their properties, they constitute a break point in the evolution of analytical chemistry. Special attention was paid to carbon nanotubes (CNTs) that resulted effective sorbents in flow systems using different immobilization strategies to improve their sorption capabilities. They resulted unique tools for on-line solid-phase (micro)extraction methods providing the appropriate selectivity (clean-up) and sensitivity (preconcentration) to reach the expected levels of many elements in matrices of biological or environmental interest. The performance of the different substrates, their strengths and weaknesses for the determination of trace elements, and their species in different matrices by a variety of analytical techniques are discussed in detail, along with perspectives and possible challenges in future development. This survey contains 96 references and covers primarily the literature published over the last 25 years by our research group. Relevant publications on the topics discussed were also included.