Elemental Speciation Measurement 

Experts in Combining Chromatography and ICP-MS

Hyphenated techniques involving ICP-MS are among the fastest growing research and application areas in atomic spectroscopy. This trend is driven by the need to determine not just the total amount of an element, but also its chemical form, since this can have a dramatic impact on the element’s bioavailability, mobility, toxicity and other chemical properties. Hyphenated ICP-MS is achieved through the coupling of the ICP-MS to a separation technique – normally a chromatographic separation. In this way, target analytes are separated into their constituent chemical forms or oxidation states before elemental analysis.

Most common separation techniques are gas chromatography (GC), liquid chromatography (LC) and ion chromatography (IC), but other separation techniques such as capillary electrophoresis (CE) are also used. As a premier supplier of GC, LC and CE as well as ICP-MS, Agilent is leading the way with routine hyphenated solutions and supporting the rapid growth in speciation measurement worldwide.

• Agilent developed the first commercial GC-ICP-MS interface in 2001, featuring a heated transfer line capable of handling high boiling point compounds
• Also available is an LC-ICP-MS Connection Kit
• Plus complete analytical solutions such as the Arsenic Speciation Kit

Agilent’s expertise in separation techniques ensures seamless installation and implementation of these hyphenated systems.

Speciation Application Areas

For convenience, hyphenated ICP-MS can be divided into two application areas, elemental speciation and molecular speciation. The differences are subtle, as the ICP-MS is always measuring elemental signals, but the distinction arises from whether the elements being separated and detected are present in the sample in the elemental state, as in the case of Cr(III)/Cr(VI) species, or as part of a larger molecule, such as a brominated flame retardant.

Elemental speciation is important in many application areas and is becoming particularly important in the environmental, food, and clinical industries. This is because, for many elements, properties such as those listed below depend on the species or chemical form of the element present in the sample.

• Toxicity or nutritional value
• Environmental mobility and persistence
• Bioavailability
• Volatility
• Chemical reactivity

A common example would be the measurement of Cr (VI) – toxic – and Cr (III) – non-toxic – as opposed to total Cr in environmental samples. Similar examples of elemental speciation include As (III)/As (V), Se (IV)/Se (VI) and other elements that can exist at different stable oxidation states.

Molecular speciation is the term applied when the ICP-MS is used to identify and quantify the presence of a particular element or elements in molecular chromatographic peaks. When used in conjunction with organic MS techniques, this technique can permit quick screening for molecules (peaks) containing specific elements in a complex mixture, prior to analysis by organic MS. With modern, integrated systems and software, simultaneous analysis by ICP-MS and organic (e.g. ESI) MS is also possible, using a split flow from a single chromatography device.

Examples of ICP-MS in molecular speciation are many and cover a broad variety of applications:

• Total sulfur and sulfur species in hydrocarbon fuels
• Organotin species in marine sediments and biota, consumer goods and drinking water
• Mercury species in fish, industrial discharges, and petroleum processing
• Arsenic species in marine algae, food products and drinking water
• Brominated and phosphorus based flame retardants in consumer goods
• Phosphorus and sulfur in biological samples
• Protein bound metals
• Pesticides and herbicides
• Chemical warfare agents
• Volatile organohalides in air samples

Application and Technical Notes

Products and Solutions

• 7500 Series ICP-MS
• 1200 Series LC Systems
• 1200 Series Rapid Resolution LC System
• 6890N GC

Reference Information

• EVISA