Concentration of Zinc, Copper, Selenium, Manganese, and Cu/Zn Ratio in Hair of Children and Adolescents with Myopia

Table 2

Validation parameters of the methods used for the determination of microelements.

Microelement/method	Dilution factor	Recovery of the CRM (%)	Detection limit	Accuracy (%)	Precision (coefficient of variation) (%)
Cu/FAAS	25	95	0.158 ppm	2.2	5.1
Zn/FAAS	250	101	0.013 ppm	1.3	2.1
Mn/ET AAS	125	98	0.084 ppb	1.2	2.1
Se/ETAAS	25	99	1.74 ppb	0.4	1.9

FAAS: flame atomic absorption spectrometry; ETAAS: electrothermal atomic absorption spectrometry; ppm: µg/g; ppb: ng/g.