Inductively Coupled Plasma Mass Spectrometry (ICP-MS) is a sensitive and comprehensive technique for the multi-element analysis of trace elements in solution.Our laboratory uses a Finnigan MAT Element High Resolution ICP-MS,which  combines the strengths of two established technologies: the ion source (or ICP), a well proven analytical source which operates at temperatures in excess of 8000 K and a double focusing magnetic sector mass spectrometer used as a detector to separate the elements and their isotopes for subsequent detection and measurement.
Resolutions of 380,4800,and 10,500 amu are attainable,compared to only about 300 amu with Low Resolution Instruments.

Sample Handling and Introduction

Samples are introduced through a peristaltic pump to a nebulizer, which produces a very fine aerosol ("fog") within a spray chamber.

The aerosol is first carried by a stream of argon gas into the central injector of a quartz plasma torch and then to the high temperature plasma where the elements transported are desolvated and vaporized.

Dissociation is virtually complete during transit through the plasma core and elements with a first ionization energy less than 10 eV are fully ionized. Ions are extracted from the central channel of the plasma at the sampling interface consisting of a one millimetre aperture in a water cooled cone. The ions are transmitted through the reduced pressure stage behind the sampling interface, through a second cone, referred to as a skimmer and into an ion lens region, which operates at further reduced pressure. The ion lens causes the focused and energy corrected ion beam to pass into the double focusing mass filter where the ions are separated according to their mass to charge ratio, m/e. All the separated ion species are detected sequentially by a continuous dynode channeltron detector placed at the exit to the mass filter; this is accomplished by scanning the mass range from lithium at m/e 6 through uranium at m/e 238. The scan process is controlled by varying the radio frequency voltage applied to rods within the double focusing mass filter. The double focusing ICP/MS can operate at a nominal resolution setting equivalent to a quadrupole system, but also at higher resolutions of 3000 and 10,000 which significantly reduces spectral and polyatomic interferences.

The pulses of ions are amplified and accumulated in a high capacity multi-channel analyzer/scaler then subsequently processed by a microcomputer.

ICP-MS is a cost effective technique to determine the concentration of selected elements with a very high level of accuracy and precision.