A flow system for the spectrophotometric determination of lead in different types of waters using ion-exchange for pre-concentration and elimination of interferences

Abstract

A flow system for the spectrophotometric determination of lead in natural and waste waters is proposed. The determination is based on the colorimetric reaction between malachite green and iodide, followed by the formation of a ternary complex between those reagents and lead cations. The developed flow system includes a lead pre-concentration step in a column packed with a cationic resin (Chelex 100) operating in a sequential injection mode. To improve the mixture of sample and reagents, a flow injection approach was adopted for the colorimetric determination. This way a hybrid flow system, involving both sequential and flow injection concepts was designed. Another feature of the proposed system is the efficient elimination of major interferent species, such as cadmium and copper. The elimination of cadmium interference is obtained by complexing Cd(2+) with chloride and retaining the formed negatively charged complexes in an anionic resin, AG1 X-8. As for copper, with the presence of both ionic resins as well as the conditions for cadmium elimination, it no longer acts as an interferent. Different ranges of lead concentration (50-300 and 300-1000mugl(-1)) can be determined with minor changes in the controlling software, useful for application to both natural and waste waters. Therefore, a detection limit of 25mugl(-1) was achieved. Repeatability was evaluated from 10 consecutive determinations being the results better than 4%. The recoveries of lead spikes added to the samples ranged from 93 to 102%. The sampling frequency was 17 and 24 determinations per hour, for 50-300 and 300-1000mugl(-1) ranges, respectively.

Iron speciation in natural waters by sequential injection analysis with a hexadentate 3-hydroxy-4-pyridinone chelator as chromogenic agent

“…2 cm length, entrapped with ordinary dish washing sponge. The size of the column was adopted from previous work [9] as the best option for sequential injection application.…”

“…Since first described [7], sequential injection analysis has proven to be an efficient tool in water analysis [8]. The versatility of this technique enables to cope with the variability of water samples in dynamic aquatic systems, namely the need for implementing pre-concentration and/or cleaning up procedures [9,10]. Consequently, the variability of sample matrices, analyte concentration and speciation are problems effectively handled inline with the sequential injection approach.…”

Adsorptive stripping voltammetric determination of trace amounts of lead in environmental water samples with complicated matrix

“…Lead is introduced into the environment from a variety of human activities such as the manufacture of batteries, metal products, paints, and ceramic glazes. Even small amounts of lead that enter the environment can result in its elevated concentrations and, consequently, in its accumulation [Mesquita et al, 2004]. Therefore, there is a need to develop simple and cheap procedures for monitoring of lead in the environment.…”

Preparation of nano-sized Pb2+ imprinted polymer and its application as the chemical interface of an electrochemical sensor for toxic lead determination in different real samples

“…Lead is an important environmental pollutant, found in soil, water and air with no biological function, but many toxicological effects to human life [1][2][3]. The determination of lead is difficult due to its low concentrations in environmental samples [2].…”