Flame atomic absorption spectroscopy (AAS) determines the total magnesium content of a biological sample. This method is destructive; biological samples must be broken down in concentrated acids to avoid clogging the fine nebulising apparatus. Beyond this, the only limitation is that samples must be in a volume of approximately 2 mL and at a concentration range of 0.1 – 0.4 μmol/L for optimum accuracy. As this technique cannot distinguish between Mg already present in the cell and that taken up during the experiment, only content not uptaken can be quantified.
Inductively coupled plasma (ICP) using either the mass spectrometry (MS) or atomic emission spectroscopy (AES) modifications also allows the determination of the total ion content of biological samples. These techniques are more sensitive than flame AAS and are capable of measuring the quantities of multiple ions simultaneously. However, they are also significantly more expensive.