Trace Elemental Analysis
Introduction
As analytical technology improved, and it became known that some elements were present at these very low levels, the term "trace" was coined to describe them. There are many areas of science and industry where the presence of elements at extremely low levels has a significant impact on human health, the environment or industry[1]. Therefore, trace elemental analysis (TEA) technology has become an important part of chemical analysis today. The boundaries of trace analysis are described by the definition of "trace element" in the IUPAC Compendium of Chemical Terminology, second edition[2]: "Any element having an average concentration of less than about 100 parts per million atoms or less than 100 μg/g". TEA allows scientists to identify and determine small amounts of chemical elements in a sample by analytical instruments; It is an integral part of understanding the natural world and can be used in fields ranging from environmental monitoring, geology to toxicology, forensic science and food safety. There are many kinds of trace element analysis techniques and suitable techniques can be selected according to the purpose of analysis and the nature of the detected substance.
Measurement Methods
Several methods for trace element analysis are described below:
- Neutron Activation Analysis (NAA): Neutrons are used to irradiate and activate a sample. As a result of a nuclear reaction between the neutron and the isotope of the element of interest radionuclides with characteristic half-lives may be produced, emitting radiation of varying energies that are characteristic of the element from which they were produced and may be measured by a suitable detector which allows for the identification and quantification of elements. It has been used to analyze cancerous tissues, trace elements in human hair and drinking water [1].
- Inductively Coupled Plasma Mass Spectrometry (ICP-MS): ICP-MS is an element and isotope analysis technique which combines the high temperature ionization characteristics of inductively coupled plasma (ICP) and the advantages of fast and sensitive scanning of quaternary bar mass analyzer (MS). ICP-MS can detect elements in the range of ng/kg (ppt) to mg/kg (ppm), and can achieve more accurate and reliable detection results by adding internal standard to adjust the matrix interference in complex samples.
- X-ray Fluorescence (XRF): This is a technique widely used for geological materials, steel and cement, as well as archaeological, forensic or environmental samples. The method is non-destructive and can be used to analyze routinely for almost any element from Na to U, including non-metals.
- Flame Atomic Absorption Spectrometry (FAAS): FAAS works by introducing the sample into a flame where it is dissociated into its constituent atoms. Electromagnetic radiation in the UV/Visible part of the spectrum is directed through the flame and is partially absorbed in a manner characteristic of the atoms present. FAAS can be used for the analysis of liquid samples only and relatively large sample volumes are required. FAAS is best used when only single elements or a few elements are to be determined within a sample.
- Stripping Voltammetry: In trace element detection applications, stripping voltammetry can determine Cu, Pb, Cd, Zn, S, As, Se, Te, Hg and other elements with the lower determination limit of 1 to 10 ng.
Attention
In addition to the requirement of the instrument detection limit, the key of trace elemental analysis is the control of pollutants and the purity of reagents.
- First of all, the pre-treatment process should not introduce or as much as possible control the introduction of pollutants, otherwise the results are not accurate.
- Secondly, the purity of the reagents and water used in the experiment should meet the relevant requirements. Trace elemental analysis requires that the reagent must be guaranteed reagent or has higher purity. For analysis of some elements, the reagent must be spectrum pure reagent or higher purity. Generally, the water used in the experiment is ultra-pure.
- Finally, the utensils during the whole experiment should be clean enough to meet the requirements of trace analysis of elements.
Alfa Chemistry is a global leading supplier of analytical chemistry reagents. We can provide a wide range of analytical chemicals and instruments for trace elemental analysis. Our products cover a range of instrumental analytical reagents such as chromatography reagents & solvents, spectroscopy reagents, electrochemistry reagents, etc., as well as various analytical standards, chromatography standards and trace analysis reagents & solvents. Please check our product list to find your desired products. If you cannot find the suitable products, Alfa Chemistry also offers you with custom synthesis service. If necessary, please don't hesitate to contact us.
References
- Brown R J C, Milton M J T. Analytical techniques for trace element analysis: an overview[J]. TrAC Trends in Analytical Chemistry, 2005, 24(3): 266-274.
- Z.B. Alfassi (Editor), Determination of Trace Elements, VCH, New York, USA, 1994.
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