Table 4. Comparison of Protein Quantification Methods Applied to NIST SRM BSA.

method	target compound	matrix	relative uncertainty U, k = 2 (%)	reference
online ID CE/ICP–MS	albumin	serum	6.7	this work
ID ICP–MS	albumin	aqueous standard solution	3.6	Lemke et al.30
AAA ID LC–MS	albumin	aqueous standard solution	2.0	NIST SRM 927e BSA
AAA ID LC–MS	albumin	aqueous standard solution	0.8	NIST SRM 927f BSA