What Are ICP Standards?

Inductively coupled plasma (ICP) techniques rely on ICP standards in order to produce accurate results. This blog post explains the importance of using traceable ICP standards for the calibration of ICP-AES and ICP-MS systems.

 

Inductively coupled plasma (ICP) spectroscopy techniques use radiofrequency magnetic fields to generate plasma which can be used to carry out elemental analysis via atomic emission spectroscopy (ICP-AES) or mass spectrometry (ICP-MS).1

ICP-AES and ICP-MS bring an incredible level of precision to elemental analysis. By measuring the frequencies of light emitted by atoms and ions in the sample, ICP-AES can be used to measure both trace and major concentrations of chemicals down to parts-per-billion levels. ICP-MS, on the other hand, measures the masses of ions produced by ionizing the sample, delivering detection and measurement of concentrations down to parts-per-trillion levels.

As well as being an important tool in scientific research, ICP techniques play a crucial role in many industries, where they are used to ensure compliance with regulatory guidelines and requirements. For example, both ICP-AES and ICP-MS play vital roles in ensuring the safety of drinking water in accordance with the Environmental Protection Agency’s guideline methods.2,3 ICP techniques are widely used in forensics, material processing, and food testing. They’re also used in medicine to detect trace toxic substances such as mercury in blood or urine.

While the two techniques have different operating mechanisms, ICP-AES and ICP-MS both provide measurements of concentration, showing the level at which certain chemical species exist in the sample.

Conversion of sensor signals into accurate measurements of concentration is only possible using ICP standards: carefully prepared calibration standards that contain extremely well-known concentrations of certain elements.

 

The Importance of Calibration via ICP standards

Any sensor is only as accurate as its last calibration. And, because ICP techniques are so precise, their calibration demands are particularly high.

Both ICP-MS and ICP-AES require the use of ICP standards of various compounds, which are used to construct a “calibration curve” that enables the ICP system to deliver accurate measurements.4 Use of ICP standards in this way is known as “external calibration”.

In addition to external calibration, ICP standards can also be used for “internal standardization”, to correct for changes in instrument operating conditions that may affect the strength of the detector signal.

Internal standardization is carried out by mixing each sample with the same amount of a certain ICP standard (or multiple ICP standards). This way, the analyte signal can be normalized relative to the strength of the signal from the internal ICP standards to improve accuracy.5,6

While attempting to prepare your own standards in-house can be tempting, repeatability and validity can only be ensured by using a traceable and certified ICP standard reference. NIST produces standard reference materials used to establish traceability of certification results to the International System of Units (SI).7

 

ICP Standards from Delta Scientific

With over 1,000 ICP standards in our catalog, Delta Scientific can provide the ideal ICP standards to provide accurate results in your ICP application, including single-element standards, multi-element standards, cyanide standards, isotopic standards, speciation standards, buffers and wastewater standards.

Our ICP standards are available at a range of concentrations from 1 g/L to 10,000 g/L, and all are certified traceable to NIST standards.

Delta Scientific is a world-leading supplier of lab products, specializing in ICP standards and components. To find out more about our range of ICP standards and other ICP consumables and products, get in touch with us today.


 

References and Further Reading

  1. Houk, R. S. et al. Inductively coupled argon plasma as an ion source for mass spectrometric determination of trace elements. Anal. Chem. 52, 2283–2289 (1980).
  2. Environmental Monitoring Systems Laboratory. EPA Method 200.8 | DETERMINATION OF TRACE ELEMENTS IN WATERS AND WASTES BY INDUCTIVELY COUPLED PLASMA - MASS SPECTROMETRY. 88–145 https://www.epa.gov/sites/default/files/2015-06/documents/epa-200.8.pdf (1996) doi:10.1016/B978-0-8155-1398-8.50011-2.
  3. Martin, T. D. EPA Method 200.5 | Determination of Trace Elements in Drinking Water by Axially Viewed Inductively Coupled Plasma - Atomic Emission Spectrometry. https://www.epa.gov/sites/default/files/2015-08/documents/method_200-5_rev_4-2_2003.pdf.
  4. Calibration Standards for ICP Spectroscopy. https://www.inorganicventures.com/blog/news/calibration-standards-icp-spectroscopy.
  5. De Ridder, F. et al. An improved multiple internal standard normalisation for drift in LA-ICP-MS measurements. J. Anal. At. Spectrom. 17, (2002).
  6. Korvela, M., Andersson, M. & Pettersson, J. Internal standards in inductively coupled plasma mass spectrometry using kinetic energy discrimination and dynamic reaction cells. Journal of Analytical Atomic Spectrometry 33, 1770–1776 (2018).
  7. janiel.reed@nist.gov. Standard Solution SRMs Provide Traceability for Millions of Measurements. NIST https://www.nist.gov/programs-projects/standard-solution-srms-provide-traceability-millions-measurements (2009).