Table 1.

Back calculated concentrations of calibration standards

Back calculation (n = 5)	Nominal concentration (mg/L)
	60	30	10	1	0.5	0.25
Mean (mg/L)	58.0	30.2	10.3	0.99	0.49	0.25
SD	2.09	1.24	0.31	0.07	0.02	0.01
Recovery (%)	96.6	100.7	103.5	99.2	99.6	100.3
CV (%)	3.61	4.11	3.03	6.93	4.61	3.23