How to overcome inter-electrode variability and instability to quantify dissolved oxygen, Fe(II), mn(II), and S(−II) in undisturbed soils and sediments using voltammetry

Table 2 Comparison of calibration slope ratios for Mn(II) and Fe(II) for different electrodes

Date	Electrode	s_Mn	s_Fe	K = s_Mn/s_Fe	s_S(-II)	K = s_Mn/s_S(-II)	i(nA)	s_Oxygen	K = s_Mn/s_Oxygen
8/19/10	1	0.05607	0.0271	2.07	0.300	0.187	29.3	0.211	0.266
	2	0.06931	0.0311	2.23	0.231	0.300	31.6	0.227	0.305
	3	0.1246	0.0537	2.32	0.553	0.225	45	0.324	0.385
8/20/10	1	0.077	0.0326	2.36	0.262	0.294	27.8	0.200	0.385
	2	0.0633	0.0211	3.00	0.168	0.377	20.2	0.145	0.436
	3	0.06991	0.0266	2.63	0.219	0.319	23.7	0.171	0.410
average (all K values)				2.43		0.284			0.364
standard deviation				0.33		0.068			0.065
95% confidence interval				0.27		0.054			0.052
C.I./average				11%		19%			14%

ISSN: 1467-4866