Patent ID: 7539282

Claim:
A method of analyzing a fluid sample by x-ray fluorescence comprising the steps of: providing a fluid sample; depositing a first portion of the fluid sample onto a substrate; exposing the first portion and the substrate to an x-ray emission; detecting x-rays produced by the x-ray emission hitting the first portion and the substrate; generating a first analytical signal responsive to the detected x-rays; providing an operable first reference material having a first extended position above the substrate and in communication with the x-ray emission, and a second retracted position; periodically extending the first reference material to its first extended position; generating a first calibration signal; providing an operable second reference material having a first extended position below the substrate and in communication with the x-ray emission and a second retracted position; and periodically extending the second reference material to its first extended position and generating at least one second calibration signal.