ICP-OES Analysis

What Is ICP-OES Analysis?

ICP-OES is based on exciting the sample in an argon plasma and resolving the light emitted by the excited atoms as they return to ground state, by wavelength. Each element emits light at characteristic wavelengths; the light intensity is proportional to concentration.

Purpose of ICP-OES Analysis

The purpose is to measure many elements in a sample simultaneously and over a wide concentration range. It is more robust than ICP-MS in samples with high salt or high matrix load.

Which Products Is ICP-OES Analysis Applied To?

Metal and alloy samples
Wear metals in used engine and transmission oils
Fertiliser and soil samples
Wastewater and treatment sludge
Ceramics, glass and construction materials

In Which Sectors Is ICP-OES Analysis Used?

MetalPlasticsElectronicsAutomotiveConstructionEnvironmentAgricultureOil & Gas

Standards Related to ICP-OES Analysis

ISO 11885 (water quality — determination of elements by ICP-OES)
ASTM D5185 (determination of elements in oils)
EN 16943 / EN 15621 (determination of elements in food and feed)
ISO 17025 (competence of testing laboratories)

ICP-OES Analysis Conditions

Plasma: Argon plasma; RF power and gas flows by method
viewing angle: Axial or radial; is selected according to the concentration range
Dalga boyu: An interference-free analytical line is selected for each element.
sample environment: Acidic solution; solubilization method depends on the matrix

Equipment for ICP-OES Analysis

ICP-OES spectrometer
Argon plasma source and nebuliser
Microwave digestion system
Automatic sample changer
Acid and ultrapure water preparation infrastructure

Sample Requirements for ICP-OES Analysis

Solid samples are digested with acid
Solvent dilution or ashing is applied for oil samples
A few grams or millilitres of sample is generally sufficient
Sample matrix and expected concentration range must be stated

Duration of ICP-OES Analysis

Measurement takes minutes per sample; digestion determines the total duration. Routine reporting is a few working days.

ICP-OES Analysis Procedure

1The sample is weighed and digested using a suitable method.
2The solution is made up to a defined volume.
3Calibration solutions and a blank are prepared.
4The sample is nebulised into the plasma and emission intensity is measured.
5Corrections are applied for spectral interferences.
6Concentration is calculated from the calibration curve.
7Accuracy is checked with a certified reference material.

ICP-OES Analysis Acceptance Criteria

A method produces a result; it does not set a limit. Whether the result is acceptable is determined by the regulation or specification the product is subject to.

Evaluation of Results

Spectral overlap is the main source of interference in ICP-OES; analytical line selection and background correction determine the accuracy of the result. Matrix-matched calibration or the standard addition method is used for high-matrix samples.

ICP-OES Analysis Report

Sample description, receipt date and laboratory number
Method applied and reference standard, if any
Instrument and measurement conditions
Sample preparation steps
Measurement results and units
Measurement uncertainty (if requested)
A statement that the results relate only to the sample submitted for testing

Accreditation

EUROLAB holds internationally recognised accreditation obtained from accreditation bodies party to the IAF and ILAC multilateral recognition arrangements, under ISO/IEC 17025 for laboratory testing, ISO/IEC 17020 for inspection and surveillance, and ISO/IEC 17021-1 and ISO/IEC 17065 for system and product certification. This chain ensures the reports and certificates issued are accepted worldwide.

Whether this test can be offered within accredited scope depends on your product and the standard applied; since accreditation is method-based, the scope is confirmed in writing at the quotation stage.

Scope and authorisations

Related Regulations

Water Pollution Control Regulation and discharge limits
EU 2023/915 (contaminants in food)
Composition requirements in alloy product standards

Pages Where This Method Is Used

Analytical Methods — What Does This Group of Methods Do?

The section below describes the field that the ICP-OES Analysis test belongs to; the conditions and acceptance criteria of this particular test are given in the sections above. The scope specific to your product is confirmed in writing at the quotation stage.

Analytical method pages are pages about a MEASUREMENT TECHNIQUE rather than about a test. The difference matters: "salt spray testing" is a test and answers one question; "ICP-MS" is a technique and is used in dozens of different tests. Sometimes the user is looking not for the test but for the technique — because the method name is what appears in their specification.

This distinction becomes decisive in choosing a laboratory. When a customer asks for "heavy metal analysis", the real question is by which technique it will be done: XRF is fast and non-destructive but does not distinguish compounds; AAS is economical for a single element; ICP-OES screens multiple elements; ICP-MS sees trace levels. The same sample gives results with different detection limits and different uncertainties across the four techniques.

Method selection is made against three criteria. DETECTION LIMIT: is the concentration sought within the range the method can see? MATRIX COMPATIBILITY: is the sample matrix (plastic, food, soil, metal) one the method can handle, and is pre-treatment required? SPECIFICATION LINK: does the product standard or legislation mandate a particular method? The third often overrides the first two — the specification binds the method.

Method pages build a CHAIN. A technique is linked to the test pages where it is used, to the standards those tests rest on, to the legislation those standards are tied to and ultimately to market access regimes. The example chain in the source document works like this: XRF → metal analysis → RoHS compliance → heavy metal restriction → coating pages. Whichever link the user enters from, they reach the others.

Sample preparation is the invisible half of the result in this family and is a greater source of error than the technique itself. The digestion method, degree of grinding, extraction solvent and dilution ratio change the result markedly. The same sample on the same instrument gives a different result with different preparation; the definition of the method therefore covers preparation too.

Calibration and verification are the third determining component. An instrument is calibrated with certified reference material, the calibration curve is verified periodically and a control sample is run in each batch. Without these steps, a number produced is not traceable even if the instrument is working correctly.

Method groups in this field

Elemental analysis
ICP-OES, ICP-MS, AAS and XRF. They differ in detection limit, matrix tolerance and multi-element capacity.
Chromatography
GC, GC-MS, HPLC, LC-MS/MS and ion chromatography. It separates a mixture into its components and measures each separately.
Spectroscopy
FTIR, Raman, UV-Vis and optical emission. For material identity, functional group identification and alloy composition.
Thermal analysis
DSC, TGA, DMA and dilatometry. Transition temperatures, composition, decomposition and dimensional behaviour.
Microscopy and imaging
Optical microscopy, SEM-EDS, radiography and tomography. Structure, defects and elemental distribution.
Classical (wet) chemistry
Titration, gravimetry and colorimetry. Used as a reference method and in confirming instrumental results.

Commonly confused in this field

XRF is a screening tool; it sees elements and does not distinguish compounds. A decision on a restricted compound requires confirmation by wet chemistry.
The phrase "not detected" is not proof of absence; it is read together with the detection limit of the method.
The specification binds the method. A technically better method is not accepted if the specification calls for another.
Sample preparation is part of the result; a report that does not state the preparation is not reproducible.
Results obtained by different techniques cannot be compared directly; their detection limits and uncertainties differ.
A method page is not a test page; which method applies to which test comes from the product standard.

Which decisions these results support

Matching the method written in the specification to the laboratory's scope
Method selection according to detection limit and matrix compatibility
Confirming an instrumental result with a reference method
Eliminating deviations arising from sample preparation

Related Tests

Frequently Asked Questions About ICP-OES Analysis

ICP-OES or spark OES for alloy composition?

If a fast result is wanted on a solid metal sample, spark OES works directly on the solid. ICP-OES requires digestion but offers a wider element range and an advantage for irregular samples such as chips or powder.

Can both high and trace elements be measured in the same sample?

Yes; using different analytical lines and dilutions, a wide concentration range can be covered in a single run.