Two New Reference Materials Based on Tobacco Leaves: Certification for over a Dozen of Toxic and Essential Elements

Table 1

Homogeneity testing of the candidate reference materials: INCT-OBTL-5 (a) and INCT-PVTL-6 (b) for 100 mg sample by NAA using Fisher’s test and Student’s t-test.

(a)

Element; (γ line, keV)	𝑥1±𝑠1; mg kg^−1	n	𝑥2±𝑠2; mg kg^−1	m	F F 0.05	t t 0.05
Ce (145.4)	3.09±0.21	6	3.08±0.36	6	2.098<5.050	2.068<2.228
Co (1332.5)	0.962±0.028	6	0.991±0.019	6	2.098<5.050	2.068<2.228
Cs (795.9)	0.239±0.016	6	0.240±0.013	6	1.626<5.050	0.186<2.228
Eu (344.3)	0.057±0.004	6	0.058±0.002	6	3.959<5.050	0.527<2.228
Fe (1291.6)	1534±39	6	1572±27	6	2.053<5.050	1.911<2.228
Hf (482.2)	0.258±0.017	6	0.259±0.011	6	2.393<5.050	0.182<2.228
Rb (1076.6)	17.2±1.0	6	18.0±0.5	6	4.853<5.050	1.728<2.228
Tb (879.4)	0.041±0.011	6	0.032±0.008	6	1.762<5.050	1.645<2.228

(b)

Element; (γ line, keV)	𝑥1±𝑠1; mg kg^−1	n	𝑥2±𝑠2; mg kg^−1	m	F F 0.05	t t 0.05
Ba (216.1)	37.1±2.5	6	36.4±2.9	6	1.321<5.050	0.408<2.228
Co (1332.5)	0.144±0.005	6	0.145±0.005	6	1.165<5.050	0.103<2.228
Cs (795.9)	0.023±0.002	6	0.023±0.003	6	1.472<5.050	0.186<2.228
Eu (344.3)	0.013±0.002	6	0.013±0.003	6	1.671<5.050	0.017<2.228
Fe (1291.6)	251±8	6	257±13	6	2.668<5.050	1.165<2.228
Hf (482.2)	0.139±0.022	6	0.145±0.021	6	1.129<5.050	0.480<2.228
Rb (1076.6)	5.78±0.50	6	5.83±0.32	6	2.509<5.050	0.221<2.228
Sc (889.3)	0.058±0.004	6	0.059±0.002	6	3.313<5.050	0.306<2.228

𝐹=𝑠²¹⁽²⁾/𝑠²²⁽¹⁾, F _0.05—critical value of the Fisher’s test at significance level α = 0.05 and degrees of freedom 𝑓₁ = 𝑓₂ = 5.
𝑡=[|𝑥₁−𝑥₂|/(𝑛−1)𝑠²¹+(𝑚−1)𝑠²²]⋅√𝑛⋅𝑚(𝑛+𝑚−2)/(𝑛+𝑚), 𝑡_0.05—critical value of the Student’s t-test at significance level α = 0.05 and degrees of freedom f = n + m−2 = 10.