Spectrophotometric Determination of Iron(II) and Cobalt(II) by Direct, Derivative, and Simultaneous Methods Using 2-Hydroxy-1-Naphthaldehyde-p-Hydroxybenzoichydrazone

Table 12

Determination of cobalt in environmental water samples.

Sample	cobalt (μg mL^−1)
	Added	Found	Recovery (%)	RSD (%)
Tap water (municipality water supply, Anantapur)	0.0	0.32	—	2.5
	1.5	1.80	98.90	1.8
	3.0	3.35	100.90	3.0
	4.5	4.83	100.20	2.2
River water (Penna, Tadipatri.)	0.0	1.52	—	3.0
	1.5	3.00	99.34	1.6
	3.0	4.55	100.66	2.8
	4.5	5.95	98.84	4.0
Drain water (vanaspati industry, Tadipatri.	0.0	3.60	—	1.7
	1.5	5.31	104.12	3.2
	3.0	6.48	98.18	2.5
	4.5	8.07	99.63	3.6