Inductively coupled plasma (ICP) spectroscopy is a useful analytical technique for the detection and measurement of elements in chemical samples. ICP is suitable for use in a wide range of applications – particularly in the pharmaceutical and biomedical fields.
ICP spectroscopy works by using plasma to ionize a sample. This plasma is typically generated via the ionization of argon gas using radiofrequency energy.
Inductively coupled plasma mass spectrometry (ICP-MS) and inductively coupled plasma optical emission spectrometry (ICP-OES) instruments offer several key advantages over comparable trace element detection technologies.
These techniques enable the simultaneous measurement of multiple elements. They offer a large analytical range, effectively outstripping the limited analytical range and single element capabilities of flame atomic emission and flame atomic absorption.
The central role of ICP spectroscopy in many industries means that there is a vital need for reliability and accuracy. Instrument calibration with calibration standards is key to ensuring measurement accuracy.
Image Credit: New Africa/Shutterstock.com
The Importance of ICP Calibration Standards
Signals measured via ICP-MS and ICP-OES detectors are linked to the number of ions contacting the detector per second. Calibration standards are needed to help convert this data into a concentration value.
These calibration standards contain known concentrations of elements. A calibration curve is constructed, and this can be used in conjunction with compound-independent calibration - a technique involving the calibration of one chemical species of one element using another element as the calibrant.
Both of these methods are examples of ‘external calibration’ techniques.
Internal standardization is frequently employed to correct for changes in instrument operating conditions and to account for any sample-specific matrix effects that may suppress or enhance the analyte signal.
Results can be calculated using the ratio of analyte and internal standard signal by adding the same quantity of internal standard to each sample.
An internal standard should, ideally, feature physical and chemical properties closely matched to the analyte, meaning that this will behave similarly under operating conditions.
If samples and calibration standards are not matrix-matched, analytical bias may still occur, even if these calibrations are followed. ‘Matrix-match solution’ may be added to calibration standards to mimic the matrix within a sample.
When working with ICP-MS, it is possible to correct matrix effects using ‘isotopic dilution.’ This involves an isotopically-enriched isotope (calibration standard) of the analyte being added to the sample. Using this approach, the sample’s initial composition can be determined by measuring the change in the isotope ratio.
Inorganic Ventures’ Calibration Standards
It is essential to use suitable and reliable calibration standards to ensure the accuracy of ICP results.
Leveraging the company’s extensive expertise in wet chemistry and analysis has enabled Inorganic Ventures to develop a comprehensive range of certified reference materials (CRMs), including a robust suite of ICP and ICP-MS standards.
Its expansive catalog includes an array of single- and multi-element solutions that have been designed exclusively for the calibration of spectroscopic instruments based on ICP.
ICP standards include:
- Single-element standards
- Multi-element standards
- Cyanide standards
- Isotopic standards
- High purity ionization buffers
- EPA standards
- Speciation standards
- Platinum cobalt color standard
- Custom standards
The use of high-purity starting materials and adherence to stringent quality assurance guidelines allows Inorganic Ventures to provide a range of NIST-traceable ICP standards that are produced to exacting specifications.
Custom-engineered ICP-OES and ICP-MS standards are also available, each offering excellent precision and absolute customer assurance.
This information has been sourced, reviewed and adapted from materials provided by Inorganic Ventures, Inc.
For more information on this source, please visit Inorganic Ventures, Inc.