Separation and Preconcentration of Trace Amounts of Manganese and Nickel from Natural Water Samples by a Diimine Derivative Schiff Base-Coated Silica-Gel Minicolumn

Table 1

Effect of eluent type and volume on recovery of Ni (II) and Mn (II) Sample flow rate, 5 mL min⁻¹. pH = 4. Eluent type, 5 mL mixture of nitric acid 5 mol L⁻¹, and methanol (1 : 1). Elution flow rate, 2 mL min⁻¹.

Eluent	Volume (mL)	Recovery (%)
		Mn	Ni
1 mol L^−1 HCl	2	45.2	48.3
	5	46.8	49.2
	10	47.3	53.2
2 mol L^−1 HCl	2	45.6	55.0
	5	48.9	56.0
	10	50.2	56.9
1 mol L^−1 HNO3	2	50.0	53.1
	5	58.7	56.8
	10	59.6	57.9
2 mol L^−1 HNO3	2	60.0	58.0
	5	63.4	59.4
	10	68.2	63.7
1 mol L^−1 HNO3 + Methnol (1 : 1)	2	70.0	69.8
	5	72.0	73.0
	10	75.6	75.8
2 mol L^−1 HNO3 + Methanol (1 : 1)	2	75.4	74.9
	5	78.6	76.9
	10	81.0	80.0
5 mol L^−1 HNO3 + Methanol (1 : 1)	2	89.5	85.3
	5	99.9	99.5
	10	99.8	99.9