Simple Instrumental and Visual Tests for Nonlaboratory Environmental Control

Table 1

The comparison of test results using various portable equipment.

Equipment	Model impurity	Concentration range, mg L^−1	LOQ,; mg L^−1	RSD (for median range)
Reflectometer	Со(II)	0.1–1.5	0.012	0.01
	Fe(III)	0.1–1.5	0.08	0.01
		0.3–2.4	0.016	0.05
Photometer; “Phototest”	Со(II)	0.1–1.3	0.08	0.06
	Fe(III)	0.05–0.4	0.14	0.17
		0.3–3.9	0.38	0.15
Scanner	Со(II)	0.1–1.3	0.05	0.06
	Fe(III)	0.05–1.5	0.025	0.13
		0.1–3.2	0.02	0.12

RSD is relative standard deviation expressed as a decimal fraction; LOQ is limit of quantification (sample volume = 5).
LOQ under 6 of the blank.
LOQ under RSD = 0.3.