Table 2.

Linear correlation coefficients (r²).

Amino acid	Quantitation ion (m/z)∗	Retention time (min)			Py					DMF
			a	b	Correlation coefficient (r2)∗∗	LOD (ng)	LOQ (ng)	a	b	Correlation coefficient (r2)∗∗	LOD (ng)	LOQ (ng)
Ala	158 (100)	10.81	0.003	0.484	0.9666	0.126	0.421	0.003	0.508	0.9973	0.028	0.094
Gly	218 (76)	11.59	0.001	0.376	0.9836	0.115	0.382	−0.041	0.355	0.9882	0.056	0.188
Val	186 (100)	12.78	−0.013	0.613	0.9672	0.190	0.632	0.003	0.616	0.9977	0.030	0.102
Leu	200 (100)	13.42	−0.004	0.677	0.9432	0.201	0.670	−0.007	0.665	0.9986	0.031	0.103
Ile	200 (100)	14.10	−0.006	0.616	0.9631	0.198	0.661	0.003	0.617	0.9981	0.034	0.114
Pro	184 (100)	15.49	−0.009	0.647	0.8909	0.174	0.580	−0.03	0.795	0.9963	0.046	0.154
Ser	288 (100)	18.23	−0.001	0.273	0.9251	0.163	0.543	−0.002	0.43	0.9923	0.056	0.187
Met	292 (83)	19.21	0.003	0.225	0.9595	0.234	0.780	−0.011	0.221	0.9957	0.061	0.203
Phe	302 (100)	21.24	−0.004	0.324	0.9528	0.255	0.850	−0.004	0.331	0.9969	0.059	0.195
Asp	302 (100)	21.42	0.002	0.276	0.9656	0.272	0.905	0.002	0.333	0.8017	0.241	0.804
Hyp	314 (100)	21.55	0.001	0.107	0.7197	0.411	1.369	0.007	0.588	0.9555	0.168	0.561
Glu	432 (100)	23.23	−0.015	0.319	0.9873	0.457	1.522	0.004	0.334	0.8224	0.372	1.241

Note. Linear correlation coefficients (r²), LOD and LOQ of amino acids were derivatized using Py or DMF as solvent. ^∗Number in parentheses indicate % relative intensity of ions; ^∗∗correlation coefficients obtained from linear regression analysis of calibration curve.