ICP-OES (Inductively Coupled Plasma Optical Emission Spectrometry), also known as ICP-AES (Inductively Coupled Plasma Atomic Emission Spectrometry), is a multi-element analytical technique that determines the elemental composition of samples by exciting atoms in a high-temperature argon plasma (approximately 6,000–10,000 K) and measuring the characteristic light emitted as excited electrons return to their ground state. Each element emits light at specific wavelengths, and the intensity of emission is proportional to its concentration.
A key strength of ICP-OES is its ability to simultaneously measure 20–40 or more elements within a single 1–2 minute analysis, making it highly efficient for comprehensive elemental screening. In food safety laboratories, ICP-OES is routinely used for quantifying heavy metals including lead (Pb), cadmium (Cd), arsenic (As), mercury (Hg), chromium (Cr), nickel (Ni), and copper (Cu), alongside nutritionally important elements such as calcium, magnesium, iron, zinc, and selenium. Ovalab’s advanced instrumental methods laboratory employs ICP-OES for efficient multi-element screening before confirmatory analysis by ICP-MS when ultra-trace sensitivity is required.
Sample preparation for ICP-OES typically involves acid digestion (using concentrated nitric acid with or without hydrogen peroxide, in a closed microwave system) to fully dissolve the food matrix and release all bound metals into solution. This digestion step is critical for accurate and complete elemental recovery.
Applications in Elemental Analysis
- Simultaneous multi-element screening (20+ elements in one run)
- Heavy metal quantification (Pb, Cd, As, Hg, Cr, Ni, Cu) in food and feed
- Essential mineral content determination (Ca, Mg, Fe, Zn, Se, Mn)
- Drinking water and environmental water elemental analysis
- Fertilizer and soil nutrient profiling
- Industrial raw material and packaging material QC
- Pharmaceutical excipient and API elemental impurity screening (ICH Q3D)
- Compliance testing for EU food contaminant regulations
Standards & Regulatory Framework
ICP-OES elemental analysis in food and environmental laboratories is performed according to validated methods under the following frameworks:
- ISO 11885:2007 — Water quality: determination of selected elements by ICP-OES; widely adapted for food matrix analysis after appropriate sample preparation.
- EN 15763:2010 — Foodstuffs: determination of trace elements — arsenic, cadmium, mercury, and lead by ICP-MS after pressure digestion; ICP-OES is used in parallel for elements where its detection limits are sufficient.
- Commission Regulation (EC) No 1881/2006 (as amended) — Sets maximum levels for contaminants including lead, cadmium, and mercury in foodstuffs; ICP-OES is a primary measurement technique for compliance testing.
- ISO/IEC 17025 — Governs laboratory competence for all ICP-OES measurements, requiring full method validation including LOD, LOQ, accuracy, and precision determination.
- ICH Q3D — EMA/FDA guideline on elemental impurities in pharmaceutical products; ICP-OES is used for screening of elements at concentration levels above 30% of the Permitted Daily Exposure (PDE).
ICP-OES achieves typical detection limits in the range of 0.1–100 µg/L in solution (approximately 0.01–10 mg/kg in food after standard digestion and 10-fold dilution), sufficient for most regulatory requirements except for ultra-trace elements where ICP-MS offers better sensitivity.
Frequently Asked Questions
What is the difference between ICP-OES and ICP-MS?
Both techniques use inductively coupled plasma to atomize samples. ICP-OES measures the light emitted by excited atoms (optical emission), while ICP-MS measures their mass-to-charge ratio. ICP-OES is better suited for major and minor elements at mg/kg levels, while ICP-MS excels at ultra-trace detection at µg/kg levels.
Which elements can ICP-OES measure?
ICP-OES can simultaneously measure over 70 elements including heavy metals (lead, cadmium, mercury, arsenic), essential minerals (calcium, iron, zinc, magnesium), and trace elements (selenium, chromium, copper). It covers virtually the entire periodic table except gases and halogens.
How sensitive is ICP-OES?
Detection limits typically range from 1 to 100 µg/L depending on the element and matrix. For heavy metals in food, this translates to approximately 0.01 to 1 mg/kg, which is sufficient for regulatory compliance with Regulation (EU) 2023/915 maximum levels for most matrices.
What sample types can be analyzed?
ICP-OES analyzes liquid samples, so solids must first be digested (typically with nitric acid in a microwave). Common sample types include food products, drinking water, wastewater, soil, pharmaceuticals, and biological materials. The technique handles complex matrices well after proper sample preparation.
Is ICP-OES accredited for food testing?
Yes. ICP-OES methods are validated under ISO/IEC 17025 and referenced in multiple standards including EN 15763 (foodstuffs), EN ISO 11885 (water analysis), and various European Pharmacopoeia methods. Ovalab operates ICP-OES under full accreditation from the Czech Accreditation Institute.