Table 2.

Comparison of the microanalytical techniques [23-31,33-35]

Analytical technique	Detection limit	Spatial resolution	Analytical depth (mm)	Quantification	Ref
MS	0.01 mg/g	15-50 mm	200	Semiquantitative	[23,24]
Fluorescence	pM to nM	2-3 mm (in vivo), 0.2-0.5 mm (in vitro)	< 1 cm	Quantitative/semiquantitative	[25,26]
PET	High pM	1-2 mm	No limit	Semiquantitative	[27-29]
SPECT	Low nM	15-20 mm	No limit	Semiquantitative	[28,29]
MRI	mM to low µM	25-100 mm	No limit	Semiquantitative	[30,31]
XRF	0.1-1 mg/g	0.03-0.2 mm	> 100	Quantitative	[33-35]