Chemistry
Test for Metal Ions
The test for metal ions is a chemical procedure used to identify the presence of metal ions in a solution. The test involves the use of reagents that react with specific metal ions to produce a characteristic color or precipitate. The test is commonly used in analytical chemistry to identify and quantify metal ions in various samples.
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6 Key excerpts on "Test for Metal Ions"
- Hans Brandenberger, Robert A. A. Maes, Hans Brandenberger, Robert A. A. Maes(Authors)
- 2011(Publication Date)
- De Gruyter(Publisher)
2.10.20 Review and Preview During the last half century, we could witness a spectacular development of the possibilities for analyzing metal ions in general and for the toxicological detection and quantitative determination of trace metals in biological materials in special. 50 years ago, wet chemical methods combined with colorimetric and electrochemical measurements dominated the field, while radioisotope and flame emission techniques were used only occasionally for special applications. The 25 years after 1960 have been characterized by a triumphant advance of atomic absorption analysis, first with flames as atomizing units, later with flameless techniques such as thermic ato-mization in furnaces, cold-vapor atomization for Hg, and hydride methods for some semi-metals. During the same period, flame emission, as a leading sequential method of metal analysis, was substituted by the more sensitive plasma emission techniques. In the past 10 years, another development has been initiated. Metal analyses based on mass spectrometric techniques are rapidly gaining ground, especially (but not exclusively) in the form of ICP-MS.
eBook - ePubInorganic Chemical Biology
Principles, Techniques and Applications
- Gilles Gasser(Author)
- 2014(Publication Date)
- Wiley(Publisher)
in vitro rapid detection of analytes at suitable concentrations. For luminescent probes, a “turn-on” detection with an analyte-induced fluorescence enhancement, rather than fluorescence quenching (“turn-off”), is favored. Similarly, a significant increase in relaxivity that contributes to a higher contrast is desirable for MRI imaging. While “on” and “off” sensors report on the presence of a species, ratiometric probes are more amenable to quantitative reporting of the concentration of the analyte and less prone to artifacts. A change in absorption or emission upon analyte recognition is monitored at two wavelengths and the ratio of their signal intensity depends on the concentration of the analyte.8.2 Metal Complexes for Detection of Metal Ions
Metal ions play fundamental roles in a wide range of biological processes (see also Chapter 9 on the photo-release of metal ions in living cells). Among the essential transition metals in the human body, iron (4–5 g), zinc (2–3 g), and copper (250 mg) are the three most abundant elements [7]. While adequate levels of these metal ions are essential for growth and development, disruption of metal homeostasis is associated with pathological conditions including cardiovascular diseases, cancer, and neurodegenerative disorders [8–10].Some heavy metal ions, such as mercury and lead, are categorized as hazardous substances due to their potent toxicity. The concentration limits of these metal ions in drinking water are therefore strictly defined by the World Health Organization [11]. Traditional quantitation of these metal ions mainly relies on expensive analytical instruments with tedious sample preparation procedures [12]. Hence, development of small molecule sensors that offer rapid detection, immediate signal feedback and in vivo tracking of metal ions represents an attractive direction for heavy metal sensing and quantification.Monitoring local concentrations as well as global distributions of both essential and toxic metals is highly desirable. Optical techniques based on luminescent or colorimetric sensors represent the main strategy for visualizing metal ions in biological fluids or cells [13]. Most optical sensors for metal ions rely on metal coordination-induced alteration in emission intensity, wavelength or lifetime of chromophores including traditional organic dyes, fluorescent proteins, and emissive metal complexes. Our focus in this section is specifically metal complexes as chromophores. Their advantages over organic dyes include a large Stokes shift, long emission lifetimes, enhanced sensitivity, and high photostability (see also Chapter 4 for the use of metal complexes for cell and organism imaging).
eBook - ePubMetal Sustainability
Global Challenges, Consequences, and Prospects
- Reed M. Izatt(Author)
- 2016(Publication Date)
- Wiley(Publisher)
12 Application of Molecular Recognition Technology to Green Chemistry: Analytical Determinations of Metals in Metallurgical, Environmental, Waste, and Radiochemical SamplesYoshiaki Furusho1 GL Sciences Inc., Shinjuku, Tokyo, 163‐1130, Japan 2 Institute of Environmental Radioactivity, Fukushima University, Fukushima, 960‐1296, Japan 3 Institute of Science and Engineering, Kanazawa University, Kanazawa, 920‐1192, Japan 4 IBC Advanced Technologies, Inc., American Fork, Utah, 84003, U.S.A.1, Ismail M.M. Rahman2, Hiroshi Hasegawa3, and Neil E. Izatt412.1 Introduction
Rapid, simple, and accurate metal analysis capability is important in many industries, since processing and financial decisions are based on these analyses. Metals to be analyzed may occur in complex ores, end‐of‐life (EOL) products, environmental samples, or radioactive waste and may coexist with multiple interfering elements that must be removed prior to final analysis. Secondary materials such as low‐grade waste, contaminated water, or EOL products containing metals can also exhibit complex matrices making it time‐ and labor‐intensive to separate the desired metal for analysis [1]. Because the target metal to be determined is usually present in the sample at low, ~mg L–1 (ppm), concentrations, often in the presence of g L–1 concentrations of other potentially interfering ions, the metal must be selectively concentrated prior to analysis. Precious metal and other laboratories generally use conventional methods such as sedimentation, liquid‐liquid extraction, or ion exchange (IX) extraction to separate metals prior to analysis with inductively coupled plasma mass spectrometry (ICP‐MS) and inductively coupled plasma atomic emission spectrometry (ICP‐AES), also referred to as inductively coupled plasma optical emission spectrometry (ICP‐OES), procedures. These separation techniques are time‐consuming and labor‐intensive, requiring multiple extraction steps to obtain a pure sample, which increases laboratory costs and generates much waste. In addition, conventional methods become less effective in separating metals as metal concentrations decrease, especially if complex matrices are present. At mg L–1
eBook - ePub- Katarzyna Chojnacka, Agnieszka Saeid, Katarzyna Chojnacka, Agnieszka Saeid(Authors)
- 2018(Publication Date)
- Wiley-Blackwell(Publisher)
As mentioned earlier, metallomics is an emerging technique that provides disease‐specific fingerprints of perturbations in trace or ultra‐trace elements, reflecting the change in molecular mechanisms due to disease pathophysiology [18]. From an analytical point of view, analytical techniques applied in metallomics can be divided into a few groups:- classical techniques (e.g., titration)
- spectrometric techniques (especially: SIMS, ICP‐MS)
- spectroscopic techniques (e.g., AAS, XPS, AES)
- electrochemical techniques (especially: DPASV, CSV, ISE).
Titration techniques are still applied in metal analyses and are an important part of routine analyses. For example, EDTA‐based titration methods can be applied for the determination of Ca2+ or Mg2+ . When is the application of titration techniques possible? If the analyte is present at an appreciable concentration, that is, contaminants at the 0.01–5% m/m range in metallic samples. This classical technique can offer very accurate and precise results [67]. On the other hand, titrations can be time consuming and do not usually offer very great sensitivity; this technique is limited to applications for many sample types [67]. Hence, appropriate knowledge about the sample and the analytical method is needed to prevent interferences.Spectrometric techniques applied for the determination of elements and (bio)imaging/mapping elements are techniques based on mass spectrometry (MS). It should be noted that MS is characterized by unique high sensitivity and incomparable limits of detection. MS in the first stage involves the formation of analyte ions with an appropriate kind of ionization, where the ions of large molecules can be fragmented. Then, ions separate according to their mass‐to‐charge ratio and are subject to detection in proportion to their number. Hence, the obtained mass spectrum of the analyte can be presented as a table or a graph [8]. The spectrometric techniques commonly applied to elements' determination and (bio)imaging/mapping elements are secondary ion mass spectrometry (SIMS) and inductively coupled plasma‐mass spectrometry (ICP‐MS). Due to the fact that the ICP‐MS technique is an example of hyphenated technique, it is described in next paragraph dedicated to other analytical techniques (see also Figure 3.1
eBook - ePubImpurities in Engineering Materials
ImPatt, Reliability, & Control
- Clyde Briant(Author)
- 2017(Publication Date)
- CRC Press(Publisher)
With an understanding of the chemistry of the nitrogen species in the alloy, it is possible to selectively dissolve the metal and not insoluble nitrides. A second Kjeldahl determination on the dissolved metal solution will enable the calculation of the amount of insoluble nitride present. Similar chemical approaches can be found for oxygen-containing species. F Other Techniques A variety of other techniques are available for determination of the light elements and nonmetals in materials. These techniques, including X-ray fluorescence spectrometry (XRF), molecular spectrophotometry using ultraviolet and visible light (UV-Vis), ion chromatography, and electrochemistry are also used for determining metal and metalloid elements and are discussed in the following section. IV Determination of Trace Metal and Metalloid Elements in Materials A Atomic Spectroscopy The most important instrumental method of analysis for quantitative determination of trace concentrations of metals, metalloids, and some nonmetals in materials is analytical atomic spectroscopy. There are three major branches of this discipline: atomic absorption spectrophotometry (AAS), atomic emission spectrometry (AES) or optical emission spectrometry (OES), * and atomic fluorescence spectrometry (AFS). All of the methods are based on the interaction of light with gas-phase atoms. Light may be absorbed, promoting an outer shell electron to an excited state. The wavelength of light absorbed is characteristic of the element, and the amount of light absorbed is proportional to the amount of the element present. This forms the basis of atomic absorption spectrophotometry. Alternatively, an electron may be excited to a higher level by light, electric energy, or thermal energy and will eventually return to the ground-state electronic configuration, usually by emitting a photon of light. This photon is characteristic of the element, and the amount of light emitted is proportional to the amount of the element present
eBook - ePub- Andreas Grabrucker(Author)
- 2020(Publication Date)
- Academic Press(Publisher)
Multiple independent factors affect the metal status, including diet and other lifestyle factors such as stress, immune system dysregulation and gastrointestinal health. While some metals are relatively easy to detect, other metals such as zinc (King, 1990) and metals with very low abundance impose significant challenges. AAS became widely available in the 1960s for accurately measuring trace amounts of mineral in biological samples. Afterward, in the 1970s, inductively coupled plasma–atomic emission spectroscopy (ICP-AES) brought further enhancement in measuring metals more accurately and rapidly. Lately, ICP-MS has been developed, which can measure metals with extremely low detection limits (Miller and Rutzke, 2010). AAS is one of the most frequently used tools for the determination of most metals (and metalloids). It is based on the absorption of light by free metallic ions and able to detect metals in either liquid or solid samples through their characteristic wavelengths of electromagnetic radiation. To that end, biosamples are reduced into free atoms, for example, using a flame technique (flame atomic absorption spectroscopy [FAAS]) or electrothermal (graphite tube) atomizers. Every atomic metal has its distinct pattern at which it will absorb energy (photons of light), leading to a change in the wavelengths that initially passed through the sample. During excitation, electrons of the element move up one energy level, and as electrons return to their original energy state, they emit energy in the form of light. This light has a wavelength that is characteristic of the metal. With increasing concentration of the metal in the sample, absorption will increase proportionally. This allows the qualitative and quantitative analysis of a sample
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