Table 2.

Precision of the spectrophotometry method at two intra- and inter-day levels for each analyte (1- 20 μg/mL) at the presence of the other two analytes (4 μg/mL).

Conc. (µg/mL)	Intra-day (RSD%)			Inter-day (RSD%)
	TRG	DI	NA	TRG	DI	NA
1	10.7	3.6	5.8	7.5	7.9	5.5
2	7.7	6.1	7.9	6.9	6.8	8.0
4	2.6	2.5	6.7	1.2	2.4	4.6
8	2.9	1.1	8.2	3.1	2.8	8.2
10	2.6	1.2	6.8	3.8	1.8	6.7
20	2.3	2.4	6.6	2.3	2.5	5.3