Table 3.

Intra- and inter-assay coefficients of variability (CV)

Samples		Volume/well (μl)	Mean ACE2 activity (ng/ml)	Intra-assay CV (%)a	Inter-assay CV (%)b
Human urine	1	7.5	57.65	5.87	11.70
	2	7.5	167.28	3.64	14.29
	3	7.5	151.49	3.67	13.51
	Mean ± SE			4.39 ± 0.74	13.17 ± 0.77
Mouse urine	1	7.5	402.82	1.86	5.52
	2	7.5	159.50	3.36	6.49
	3	7.5	175.34	3.90	9.01
	Mean ± SE			3.04 ± 0.61	7.01 ± 1.04
Culture medium	1	15	74.76	1.76	9.38
	2	15	69.35	1.06	9.88
	3	15	100.72	1.49	9.14
	Mean ± SE			1.43 ± 0.20	9.47 ± 0.22
Mouse plasma	1	2	420.47	4.99	8.88
	2	2	400.10	3.69	9.20
	3	2	162.49	2.83	14.67
	Mean ± SE			3.84 ± 0.63	10.92 ± 1.88

CV coefficient of variability, SE standard error of the mean

^aThe intra-assay CV is an average value of the individual CVs for the duplicates in six measurements

^bThe inter-assay CV is calculated for each sample by dividing the standard deviation of six measurements by the mean ACE2 activity of six measurements