We use whole blood specimens drawn into lithium-heparin containing tubes with non-contamination precautions, and analysed with HRICPMS (high resolution inductively coupled plasma mass spectrometry) for the most accurate assessment of metal ion levels. The problem with using serum, plasma or erythrocytes is that metal ions are differentially distributed in the intracellular and extracellular compartments and introduces variability. Furthermore the specimen must be centrifuged and separated locally soon after the blood sample is drawn. Delay in achieving this will hemolyze the specimen and can lead to significant errors in assessment. Other instrumentations are also used for analysis. Atomic absorption spectrometry and Quadrupole ICPMS are used but they are not as sensitive or reliable as HRICPMS and can also lead to erroneous values and misinterpretations.