Table 2. Peptide mass calibration standards

Name	Source	Monoisotopic mass [M+H]⁺ (Da)	Average mass [M+H]⁺ (Da)	Sigma product number	SWISS-PROT reference
Leu enkephalin	Human	556.277	556.6	L9133	PENK_HUMAN
Met enkephalin	Human	574.234	574.7	M6638	PENK_HUMAN
[D-Ala-2]-deltorphin II		782.396	782.9		DAD2_PHYBI
Angiotensin II	Human	1046.542	1047.2	A9535	ANGT_HUMAN
Bradykinin	Human	1060.5692	1061.23	B3259	KNH_HUMAN
Lutienizing hormone-releasing hormone	Human	1182.581	1183.3	L7134	GONL_HUMAN
Ala-Pro-Gly-[Ile-3,Val-5] angiotensin II	Human	1271.654	1272.5	A0289	ANGT_HUMAN
Angiotensin I	Human	1296.6853	1297.50	A9650	ANGT_HUMAN
Substance P		1347.7360	1348.7	S6883	TKNB_HUMAN
α-Endorphin	Human	1745.842	1747.0	E6136	COLI_HUMAN
Peptide sequencing standard		1657.841	1658.8	P2046
Neurotensin		1690.928	1692.0	N6383	NEUT_HUMAN
Renin substrate	Porcine	1758.933	1760.1	R8129	ANGT_PIG
Renin substrate	Human	1759.940	1761.0	R5880	ANGT_HUMAN
Dynorphin		2147.1988	2148.52
Adrenocorticotropic hormone fragment 18-39	Human	2465.199	2466.7	A0673	COLI_HUMAN
Insulin A-chain, oxidized	Bovine	2530.921	2532.7	I1633	INS_BOVIN
Melittin	Bee venom	2845.762	2847.5	M1407	MEL1_APIME
β-Endorphin		3463.8296	3466.04
Glucagon	Bovine	3481.624	3483.8	G7774	GLUC_BOVIN
Insulin B-chain, oxidized	Bovine	3494.651	3496.9	I6383	INS_BOVIN
Adrenocorticotropic hormone fragment 7-38		3657.929	3660.2	A1527	COLI_HUMAN
Insulin	Sheep	5700.598	5704.5	I9254	INS_SHEEP
Insulin	Bovine	5730.609	5734.6	I5500	INS_BOVIN
Insulin	Equine	5744.624	5748.6		INS_HORSE
Insulin	Porcine	5774.635	5778.6		INS_PIG
Insulin	Human (recombinant in Escherichia coli)	5804.646	5808.6	I0259	INS_HUMAN
Ubiquitin	Bovine	8560.625	8565.8	U6253	UBIQ_BOVIN