A Simple HPLC-DAD Method for the Analysis of Melamine in Protein Supplements: Validation Using the Accuracy Profiles

Table 1

Accuracy profile validation results for melamine in dietary supplements.

Linearity
(𝑘=3,𝑚=3,𝑛=3)
Range (𝜇g mL^−1)	0.05–3.0
Slope	0.9659
Intercept	0.0081
𝑟^2	0.9999
Trueness (mg kg^−1)	Relative bias (%)	Recovery (%)
(𝑘=3,𝑚=3,𝑛=3)
0.05	−1.4	98.6
1.5	−0.6	99.4
3.0	−1.7	98.3
Precision (mg kg^−1)	Repeatability (RSD %)	Intermediate precision (RSD %)
(𝑘=3,𝑚=3,𝑛=3)
0.05	2.1	2.2
1.5	2.3	2.7
3.0	2.0	2.3
Accuracy (mg kg^−1)		𝛽-expectation tolerance limits (%)
(𝑘=3,𝑚=3,𝑛=3)
0.05		[−7.5;4.7]
1.5		[−9.2;7.9]
3.0		[−8.9;5.5]
Uncertainty (mg kg^−1)		Relative expanded uncertainty (%)
(𝑘=3,𝑚=3,𝑛=3)
0.05		4.7
1.5		5.8
3.0		4.9
Limits of quantitation (LOQ)
Lower LOQ	Upper LOQ
0.05	3.0

𝑘: number of series; 𝑚: number of amount levels; 𝑛: number of replicates.
RSD: relative standard deviation.