Markus Stoeppler

Chapter 1 Sampling and sample storage

Publisher Summary This chapter discusses the basic principles and methods, starting with sampling, sample storage and sample treatment. These steps are important for each analytical procedure. Human specimens are analyzed for trace elements in order to find out whether there is a deficiency of an element or if there is excessive exposure to an element. When trace elements are analyzed in living subjects, the specimens that are available are limited; usually only blood, urine, feces or hair is available. The physiological factors that affect the relationship between the concentrations of a trace element in the target tissues and in the body fluids are very important. Various aspects on sources of error in sample collection and storage for trace element analysis are reviewed. Especially toxic concentrations of trace elements are not constant, but change with time, and often show an exposure-related fluctuation. The variations associated with specimen collection and storage is discussed by reviewing the potential of a number of modern trace analytical methods such as atomic absorption and emission spectrometry.

Chapter 14 Arsenic

Publisher Summary This chapter discusses the role of Arsenic in the environment. Arsenic is present in igneous and sedimentary rocks and ores mainly in the form of sulphides, arsenides, and sulpharsenides. Weathering, volcanism, dissolution in water, biological and anthropogenic activities leads to arsenic emissions into the atmosphere, the terrestrial and aquatic environment. Arsenic occurs naturally in water, mainly as arsenite and arsenate, however methylated forms may be present because of the biological activity. Anthropogenic sources of arsenic are mining and preparation of fossil and mineral resources, combustion of fossil fuels, non-ferrous smelteries, production of glass, production of semiconductors, and use of feed additives for poultry and pigs. In some countries, arsenic is also used as a medicine—namely, sodium methylarsinate, and substituted phenylarsonic acids. Most of the arsenic compounds that enter the environment undergo chemical transformation. Arsenic speciation in the environment, with particular emphasis on marine and aquatic systems, is also reviewed. Human exposure to arsenic is assessed in the past by the determination of the total arsenic concentration in blood, hair, nails, and urine. In cases of suspected arsenic poisoning gastric juice are also analyzed.

Chapter 11 Reference materials for trace element analysis

Publisher Summary This chapter discusses the principles of reference materials for trace element analysis. Improved methods of analytical quality assurance and their consistent application by analysts everywhere, appear to be urgent requirements in trace element research. All aspects of quality assurance, both internal and external, need careful attention. The reference materials perform an essential function. The quality assurance encompasses the two concepts quality control and quality assessment. Quality control is the mechanism established to control errors, while quality assessment is the mechanism used to verify that the measurement system is operating within acceptable limits. The suppliers of reference materials which are available internationally are concerned with external quality assurance than with internal quality assurance. These are essential for monitoring the precision of the analytical methods and for establishing statistical control. One of the critical steps in preparing a reference material is homogenization. The stability of a reference material is of great importance since the same material may be used over a period of many years. Certification is the desirable end goal of the procedure used to establish the composition of a reference material; producers are also concerned with lesser degrees of certainty such as are represented by consensus values, best estimates or even “information values”.

Rapid and Reliable Voltammetric Determination of Cadmium in Environmental and Biological Materials

Reliable analytical approaches for the determination of cadmium at trace and ultratrace levels in numerous materials either as routine or reference methods are the voltammetric modes differential pulse anodic stripping voltammetry (DPASV) and square wave voltammetry (SWV). The potential of these methods, partly in direct comparison, in some cases also checked by graphite furnace atomic absorption spectrometry (GFAAS) is presented and demonstrated for a selection of applications to aqueous, biological, food and environmental samples.

Chapter 3 Instrumentation

Publisher Summary There is an urgent demand for reliable and rapid analysis of trace elements in biological materials. The most important are metals and metalloids that are considered as essential, toxic or possibly toxic to man, animals, and plants. In conjunction with similar analytical demands from other research branches, this situation has stimulated in recent decades progressively intensified development and progress mainly in the field of instrumentation. Trace analytical methods have become increasingly accessible and indispensable for numerous scientific, medical, and legal applications. Manufacturers of analytical instruments have therefore increasingly designed and offered highly advanced systems for trace analytical purposes. A great challenge for analytical chemists is therefore to achieve meaningful that is from the present state of the art accurate, data on a more extended scale than before. To achieve this target, some change in analytical philosophy by producers and users of trace analytical data is essential. The chapter discusses the present state of the art with respect to sample preparation and analysis from the practical experience to provide some advice on the performance of trace analysis on a cost-benefit basis.

Chapter 6 Cadmium

Publisher Summary The determinations of cadmium in biological materials were mainly performed by colorimetry. With the exception of radiochemical neutron activation analysis (NAA), cadmium is sensitive but not used as a rapid routine screening technique. These methods typically had absolute detection limits of the order of 1 μg of cadmium. Thus, if lower levels had to be analyzed, pre-concentration was always necessary. These methods, however, were sufficiently sensitive for the determination of cadmium in organs and hair with average concentrations at the micrograms per gram. Normal cadmium levels in body fluids, however, are in the low nanograms per gram range. Even in occupational exposure, average levels of cadmium in urine and whole blood not exceeding a maximum of about 100 ng/ml were reported. Some of these data were obtained by flame atomic-absorption spectrometry (FAAS) after pre-concentration, but the commercial introduction of more powerful trace analytical methods in the decade greatly extended routine analytical potentialities, particularly for cadmium.