Table 1.

Comparison of MS, NMR and SERS in metabolite detection. The descriptions of MS and NMR are according to reference [58].

	MS	NMR	SERS
Sensitivity	High and the limit of detection (LOD) reaches nM	Low but can be improved with high field intensity or low temperature	High and LOD reaches the range of nM - pM
Selectivity	Selective and non-selective analysis	Generally for non-selective analysis	Selective and non-selective analysis
Destruction	Destructive but a small number of samples required	Non-destructive and samples can be recycled after measurements	Non-destructive and a small number of samples required
Reproducibility	Moderate	High	Moderate, depending on substrate uniformity
Sample pretreatment	Demanding	Not necessary	Not necessary but recommended
Sample analysis time	Longer than NMR, and chromatography techniques required	Fast and the whole sample can be analyzed simultaneously	Fast and multiple analytes can be analyzed in one measurement
Targeted analysis	Relatively better	Not optimal	Not optimal