Microwave Plasma Atomic Emission Spectrometer

What is the Microwave Plasma Atomic Emission Spectrometer?

A microwave plasma atomic emission spectrometer uses a nitrogen-fed plasma to excite elements for atomic emission. It is chosen as a lower-cost, safer alternative to flame AAS and argon plasmas for routine multi-element analysis.

Overview

This instrument sustains a microwave-induced plasma with nitrogen generated from compressed air, so it avoids acetylene and nitrous oxide and greatly reduces argon consumption. The plasma operates around 5000 K, hot enough to atomize and excite many elements but not as hot as an inductively coupled plasma, which limits refractory elements such as aluminum, titanium and vanadium. Emission is dispersed by an echelle spectrograph and captured with a CCD to record multiple lines simultaneously, giving multi-element capability and dynamic range similar to flame atomic absorption but with less gas handling risk. Running costs are low because nitrogen is supplied by an air compressor or generator, and the instrument can be installed where acetylene is prohibited. Detection limits are typically in the microgram per litre to milligram per litre range.

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?

• Nitrogen plasma generated from compressed air
• No acetylene or nitrous oxide required
• Echelle spectrograph with simultaneous CCD detection
• Multi-element analysis with wide dynamic range
• Lower argon consumption than ICP systems
• Compact benchtop footprint with simple gas supply

What are the technical specifications?

A typical microwave plasma atomic emission spectrometer configuration offers wavelength range of 178–780 nm, plasma gas of nitrogen from compressed air, plasma temperature of approximately 5000 K, detection limit of 1–100 µg/L typical, detector of CCD with echelle optics and simultaneous elements of up to 25. 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 Microwave Plasma Atomic Emission Spectrometer is used in routine water and wastewater metals, agricultural and soil nutrient analysis, food and beverage mineral content and industrial process and plating bath checks. 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 Microwave Plasma Atomic Emission Spectrometer?

Select a microwave plasma instrument when you want multi-element capability without acetylene or high argon cost, and the target elements are not refractory. Specify the element list, detection limits and throughput, and confirm that compressed air of suitable quality is available. If very low detection limits or refractory elements are needed, compare with graphite furnace AAS or ICP-OES.

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.