Non-immersive method and apparatus for quantitative analysis of liquid metals and alloys

A non-contact, non-immersive method of measuring quantitatively one or more elements in a liquid metal or alloy sample, comprising:

• obtaining a sample of the liquid metal or alloy to be analysed,
• maintaining or placing the sample in a sample container which is substantially upwardly open,
• heating or maintaining the sample at or above a desired temperature,
• placing an instrument head such that the instrument head is fully above the sample surface and not immersed in the sample, wherein the instrument head comprises laser excitation optics that are connected to a laser, receiving optics for receiving emission from the sample, and an open-bottom chamber providing plasma confinement and stable environmental conditions through which the laser excitation optics guide laser light and wherein the instrument head is provided with a distance sensor,
• positioning the receiving optics at a pre-determined distance in the range from about 5 mm to about 100 mm from the sample surface such that emission from a particular part of the plasma plume is collected, wherein said receiving optics are arranged at an angle relative to the sample surface, in the range of about 30° to about 75°, and measuring with the distance sensor a distance to the sample surface and automatically moving the receiving optics to position the receiving optics at a pre-determined distance from the sample surface,
• directing a stream of inert gas through a gas channel into the open-bottom chamber,
• emitting one or more laser pulse on the sample through the excitation optics,
• receiving emitted light through the receiving optics from the sample and transmitting to a detector for recording spectral information of the detected light,
• comparing one or more selected emission peaks to calibration values in order to obtain quantitative determination of one or more elements.