Inductively Coupled Plasma Optical Emission Spectrometer

What is the Inductively Coupled Plasma Optical Emission Spectrometer?

An ICP-OES atomizes samples in an argon plasma and measures the light emitted by excited atoms and ions. It is chosen for simultaneous multi-element analysis from microgram per litre to percent levels in routine laboratories.

Overview

A radio-frequency generator sustains an argon plasma at 6000 to 10000 K in a quartz torch, where the nebulized sample is desolvated, vaporized, atomized and excited. Excited species emit characteristic lines that are dispersed by an echelle or a charge-coupled device optical system and measured simultaneously across many wavelengths. The wide linear dynamic range allows major and trace elements in one run, and radial, axial or dual-view torch configurations balance sensitivity against matrix tolerance. Because thousands of emission lines are available, interference correction and elemental wavelength selection are routine. Internal standards such as yttrium or indium correct for drift and matrix effects. Sample introduction uses a nebulizer and spray chamber, with optional hydride generation, laser ablation or ultrasonic nebulization when higher sensitivity or solid sampling is needed. Detection limits are typically micrograms per litre.

How does it work?

In atomic spectroscopy a sample is converted into free atoms in a flame, graphite furnace, plasma or hydride generation cell. The atoms absorb or emit light at wavelengths characteristic of each element. Atomic absorption passes a hollow-cathode lamp emission line through the atom cloud and measures the decrease in intensity according to the Beer-Lambert law. Atomic emission excites atoms in a plasma or flame and measures the light they emit as they relax. Atomic fluorescence excites atoms with a source and measures emitted light at a right angle, giving high sensitivity for hydride-forming elements. Inductively coupled plasma sources reach 6000 to 10000 K, atomizing and ionizing most elements; the resulting ions can be counted by mass spectrometry for very low detection limits. Calibration uses series of standards, internal standards, and background and matrix correction.

What are the key features?

• Argon plasma torch with radial, axial or dual view
• Simultaneous multi-element CCD or echelle detection
• Wide linear range from µg/L to percent
• Internal standard correction channels
• Optional hydride generation and ultrasonic nebulizer
• Full-wavelength coverage with interference correction software

What are the technical specifications?

A typical inductively coupled plasma optical emission spectrometer configuration offers wavelength range of 165–900 nm, optical resolution of ≤ 0.007 nm at 200 nm, plasma temperature of 6000–10000 K, detection limit of 0.1–10 µg/L typical, linear dynamic range of up to 6 orders and RF generator power of 1000–1600 W. Values are indicative of the product class; the exact figures for each configuration are confirmed on the quotation and the calibration documents supplied with the instrument.

Which applications is it used for?

The Inductively Coupled Plasma Optical Emission Spectrometer is used in multi-element water and wastewater analysis, pharmaceutical elemental impurity screening, food, feed and agricultural element analysis and metals, alloys and geological sample assays. Across the wider Atomic Spectroscopy class, laboratories also deploy it for elemental impurity testing of pharmaceutical materials, trace metals in drinking water, wastewater and soil and food safety and nutritional element analysis.

Which standards and certifications apply?

Relevant standards and methods include USP <730> Plasma Spectrochemistry, USP <233> Elemental Impurities — Procedures, ICH Q3D Elemental Impurities, ISO 11885 Water quality — ICP-OES determination of elements, ISO 17294-2 Water quality — ICP-MS determination of elements, US EPA Method 200.7, US EPA Method 200.8, ISO/IEC 17025 and IEC 61010-1. Certification candidates for this model are CE, ISO 9001 manufacturing and IEC 61010-1 safety compliance; each is to be confirmed for the specific configuration before shipment, and certificates are supplied only where they have been issued.

Atomic spectroscopy installations need gas supplies, extraction and, for plasma systems, argon of high purity and substantial electrical power. Acetylene and nitrous oxide require proper regulators, flashback arrestors and ventilation. Sample preparation by acid digestion is a major source of error and contamination, so ultrapure acids and clean vessels are essential. Hollow-cathode lamps have limited life and may need warm-up and alignment. Background correction, internal standards and matrix matching control interferences from easily ionized elements, molecular species and viscosity. Verify performance daily with calibration standards and check stability with a continuing calibration verification. Maintain service records and monitor lamp, torch and graphite tube usage.

How do I select the right Inductively Coupled Plasma Optical Emission Spectrometer?

Select ICP-OES when many elements must be measured together across a wide concentration range with good throughput and reasonable operating cost. Compare torch view and optical resolution for your matrices, and confirm argon supply and exhaust capacity. Specify whether hydride generation or solid sampling is required, and check that the software handles the interference corrections your method needs.

How does it compare with other Atomic Spectroscopy variants?

Choose the atomic technique by element, concentration and matrix. Flame atomic absorption is simple, robust and suited to milligram per litre levels in routine water, soil and metal samples. Graphite furnace atomic absorption reaches microgram per litre and below for a limited number of elements with small sample volumes. Inductively coupled plasma optical emission handles multi-element analysis at microgram per litre to percent levels with wide linear range. Inductively coupled plasma mass spectrometry reaches nanogram per litre and below for most elements and can measure isotopes. Atomic fluorescence is efficient for mercury, arsenic, selenium and antimony after hydride generation. Microwave plasma emission is an alternative to flame for some elements using nitrogen instead of acetylene. Confirm required detection limits, sample throughput, number of elements and available gases before selecting.