Diagnostic assay of trace lead in an ex vivo tissue using a combination electrode

A voltametric diagnosis of trace lead was performed using macro type combination sensors of fluorine-doped graphite pencil electrodes (FPE). Two pencils were used as the reference and auxiliary instead of expensive Ag/AgCl standards and Pt counters. Under optimized conditions, a square wave (SW) stripping working curve was attained at 10-70 mg/L and a micro range of 10-70 μg/L. The developed sensor was not only inexpensive but also had a fast (90-s) accumulation time. An analytical detection limit of 10 μg/L was obtained. The results were applied to an ex vivo tissue and an artificial turf.

Analysis of Lead Ions in a Waste Solution Using Infrared Photo-Diode Electrode

To detect lead ions using electrochemical voltammetric analysis, Infrared Photo-Diode Electrode (IPDE) was applied via cyclic and square wave stripping voltammetry. Lead ions were deposited at 0.5 V (versus Ag/AgCl) accumulation potential. Instrumental measurements systems were made based on a simple and compact detection system. The stripping voltammetric and cyclic voltammetric optimal parameters were searched. The results yielded a cyclic range of 40∼240 mgl-1 Pb(II) and a square wave stripping working range of 0.5∼5.00 mgl-1 Pb(II). The relative standard deviation at 2 and 4 mgl-1 Pb(II) was 0.04% and 0.02% (n = 15), respectively, using the stripping voltammetric conditions. The detection limit was found to be 0.05 mgl-1 with a 40 sec preconcentration time. Analytical interference ions were also evaluated. The proposed method was applied to determine lead ions in various samples.

Sample treatment in chromatography-based speciation of organometallic pollutants

Speciation analysis is nowadays performed routinely in many laboratories to control the quality of the environment, food and health. Chemical speciation analyses generally include the study of different oxidation state of elements or individual organometallic compounds. The determination of the different chemical forms of elements is still an analytical challenge, since they are often unstable and concentrations in different matrices of interest are in the microg l(-1) or even in the ng l(-1) range (e.g., estuarine waters) or ng g(-1) in sediments and biological tissues. For this reason, sensitive and selective analytical atomic techniques are being used as available detectors for speciation, generally coupled with chromatography for the time-resolved introduction of analytes into the atomic spectrometer. The complexity of these instrumental couplings has a straightforward consequence on the duration of the analysis, but sample preparation to separate and transfer the chemical species present in the sample into a solution to be accepted readily by a chromatographic column is the more critical step of total analysis, and demands considerable operator skills and time cost. Traditionally, liquid-liquid extraction has been employed for sample treatment with serious disadvantages, such as consumption, disposal and long-term exposure to organic solvent. In addition, they are usually cumbersome and time-consuming. Therefore, the introduction of new reagents such as sodium tetraethylborate for the simultaneous derivatization of several elements has been proposed. Other possibilities are based in the implementation of techniques for efficient and accelerated isolation of species from the sample matrix. This is the case for microwave-assisted extraction, solid-phase extraction and microextraction, supercritical fluid extraction or pressurized liquid extraction, which offer new possibilities in species treatment, and the advantages of a drastic reduction of the extraction time and the embodiment into on-line flow analysis systems. This new generation of treatment techniques constitutes a good choice as fast extraction methods for feasible species-selective analysis of organometallic compounds under the picogram level, that can be used for national regulatory agencies, governmental and industrial quality control laboratories, and consequently, for manufacturers of analytical instrumentation.

Chemical modification of analytes in speciation analysis by capillary electrophoresis, liquid chromatography and gas chromatography

Chemical modification of target analytes is widely used in modern analytical methods. This review focuses on the application of chemical modification techniques is the simultaneous analysis of metallic species by capillary electrophoresis, liquid chromatography and gas chromatography. Emphasis is placed on the procedures relating to analyses carried out by capillary electrophoresis. The development of this topic in the past five years is evaluated for liquid chromatography and gas chromatography. The advantages, performance and application in real samples are compared for the three techniques.