Frequently Asked Questions
- What is analytical accuracy?
- How can improved accuracy help me?
- I’m still not sure how IDMS and SIDMS can help me. Can you explain?
- What is isotope dilution?
- Why does AIT focus on stable isotopes?
- What are species and why are they important?
- What is speciation?
- Why is speciation important?
- My question wasn’t answered here. Where should I direct it?
According to the International Union for Pure and Applied Chemistry (IUPAC), “accuracy” (in analysis) is described this way:
A quantitative term to describe the (lack of) accuracy of a chemical measurement process; comprises the imprecision and the bias. Inaccuracy must be viewed as a two-component quantity (vector); imprecision and bias should never be combined to give a scalar measure for chemical measurement process inaccuracy. (One or the other component may, however, be negligible under certain circumstances.) Inaccuracy should not be confused with uncertainty. Inaccuracy is characteristic of the measurement process, whereas error and uncertainty are characteristics of a result. (The latter characteristic, of course, derives from the imprecision and bounds for bias of the chemical measurement process.) The resultant bias and imprecision for the overall measurement process generally arise from several individual components, some of which act multiplicatively (e.g. sensitivity), and some of which act additively (e.g. the blank*).
* The “blank” is the analysis of the liquid solution called “matrix” without the sample. The counts (raw measurement) produced by the blank measurement in a mass spectrometer is typically subtracted from the counts produced by the sample. This analytical protocol is one of the many steps that helps achieve higher accuracy.
One of the chief benefits of improved accuracy is that it almost impossible for critics and competitors to argue against your superior quantification and consistent/reliable results. You also avoid the wide error margins that lead to ambiguous data, which can generate risky corporate or research decisions. In mission-critical applications, such decisions could have unfortunate consequences ranging from loss of economic opportunity to environmental degradation.
IDMS (Isotope Dilution Mass Spectrometry) and SIDMS (Speciated Isotope Dilution Mass Spectrometry) are AIT’s patented mass spectrometry techniques that provide higher quality results than those available anywhere else. We urge you to contact us to discuss how this technology can help your unique project.
Isotope dilution analysis is an analytical technique based on the measurement of isotope ratios in a sample where its isotopic composition has been altered by the addition of a known amount of an isotopically enriched element.
Simply put, stable isotopes are nature’s best measuring yardsticks. They have several benefits in measurement, including:
- Stable isotopes never change. They have fixed and defined properties.
- When used as spikes to the nucleus of target compound, stable isotopes don’t alter the sample chemically. Most other spectrometric spiking methods do.
- Researchers often choose stable isotopes in their sample preparation methods because they are highly distinctive and much easier to identify in the mass spectrometry spectrum among all other compounds in the sample mixture.
- Stable isotopes are totally safe. They are even ingested in drug clearance studies.
The IUPAC provides a useful definition: “A species is a form of an element specified as to isotopic composition, electronic or oxidation state, and/or complex or molecular structure.” For example, chromium (III) and chromium (VI) are different species of chromium. Chromium (VI) is highly toxic to humans and chromium (III) is a beneficial mineral in the body, emphasizing the importance of distinguishing between species.
Speciation (sometimes called “speciated analysis”) is the analytical activity of identifying and/or measuring the quantities of one or more individual chemical or biochemical species in a sample.
Reasons include radically improved accuracy and precision, analytical simplicity, and unchallengeable results. These benefits are important across all industries and disciplines.
Metals, for example, seldom exist as free metals or as free ions. They occur as part of a chemical compound – a metal species. An element itself does not have toxic or beneficial effects. Rather, it is the chemical properties of the compounds formed by elements. Therefore, information which is based solely on total element (e.g. metal) concentration can be useless at best or misleading at worst.
We are happy to answer any remaining questions! Contact us for more information on our technology and how it applies to your project or industry.