Simple Instrumental and Visual Tests for Nonlaboratory Environmental Control

Table 2

The metrological characteristics of the developed tests for Co(II), Rh(III), and Pd(II).

Impurity	Analytical reaction/test tool/	Indication way	Concentration range, mg L^−1	LOD; or LOQ, mg L^−1	RSD in decimal fraction (for median range)
Co(II)	Indigocarmine oxidation by H2O2; in the presence of Co(II)/sandwich/	Visual	0.5–10	0.5	—
	Pyrocathechin oxidation in the; presence of Co(II)/sandwich/	Visual	0.01–1.0	0.01	—
		Instrumental (RGB)	0.005–0.1	0.005; 6σ	0.06
		Instrumental; (square of the spot)	0.01–1.0	0.01; the first point	0.12
	Formation of color complex with PAN/paper/	Visual	0.25–10	0.25; 0.25; the first point	—
			0.002–0.1; (preconcentration)	0.002; (preconcentration)
		Instrumental	0.1–10; 0.001–0.1; (preconcentration)	0.05; 6σ; 0.001; (preconcentration) the first point	0.05
	Formation of color complex with thiocyanate/PUF/	Visual	0.1–1.5	0.02	—
		Instrumental	0.01–1.5	0.01; RSD = 0.3	0.01
Rh(III)	Oxidation of Cu(II) by periodate; in the presence of Co(II)/blisters/	Visual	0.01–0.8	0.005	—
		Instrumental	0.01–0.8	0.005; 6σ; 0.01; RSD = 0.3, the first point	0.1
Pd(II)	Formation of color complex with rhodamine 6G/PUF/	Visual	0.04–0.8	0.04	—
		Instrumental	0.04–0.8	0.06; 6σ; 0.08; RSD = 0.3,; 0.04; the first point	0.1
		Visual, instrumental	0.004–0.08; (preconcentration)	0.004; (preconcentration); the first point; 0.008; (preconcentration); RSD = 0.3	0.1

Sample volume ; LOD; LOQ.