Table 6.

Ions signals (cps) and signal-to noise (S/N) ratio for ⁵⁶Fe and ⁵²Cr isotopes obtained with H₂ and He CRI gases for blank (2% HNO₃), reagent blank (2% HNO₃ + 20 µL TEA), and 10 µg L⁻¹ Fe and Cr in the absence and presence of Mg matrix. Signal-to-noise (S/N) ratio is based on the ratio of average ion signals from 10 µg L⁻¹ Fe or Cr to that from 2% HNO₃ in the absence of matrix. In the presence of Mg matrix, S/N is the ratio of ion signals from 10 µg L⁻¹ Fe and Cr in 800 µg mL⁻¹ Mg + 20 µL TEA to that of reagent blank (2% HNO₃ + 20 µL TEA)

Solution/medium	56Fe		52Cr
	H2	He	H2	He
2% HNO3	2,630	62,262	45	823
2% HNO3 + 20 µL TEA	2,942	79,573	215	2,997
10 µg L−1 Fe and Cr	22,575 (S/N = 8.7)	112786 (S/N = 1.8)	6,004 (S/N = 133)	53,461 (S/N = 65)
10 µg L−1 Fe and Cr in 800 µg mL−1 Mg + 20 µL TEA	25,245 (S/N = 8.6)	142,121 (S/N = 1.8)	7,226 (S/N = 29)	54,804 (S/N = 18)