Journal of Analytical Science and Technology

Table 2 Ar isotope analyses of representative aliquots of alunite

From: Improvement of ⁴⁰Ar/³⁹Ar age determinations for Quaternary basaltic rocks by eliminating the peak suppression effect

Sample ID	Previous protocol						Modified protocol
	427-10			427-11				619-12
	fAmp	± 1 sd	% sd	fAmp	± 1 sd	% sd	fAmp	± 1 sd	% sd
⁴⁰Ar	104.7595	1.3274	1.27	111.1220	1.5948	1.44	209.5691	0.1125	0.05
³⁹Ar	1.7986	0.2951	16.41	2.9216	0.2942	10.07	4.8741	0.0706	1.45
³⁸Ar	0.0952	0.1101	115.68	0.1788	0.1071	59.89	0.0869	0.0658	75.76
³⁷Ar	0.0481	0.0763	158.68	0.0304	0.0756	249.11	− 0.0705	0.0565	− 80.1
³⁶Ar	0.2541	0.0090	3.55	0.2423	0.0092	3.78	0.2232	0.0027	1.22
Moles (⁴⁰Ar)	3.48E-15			3.69E-15			6.96E-15
%⁴⁰Ar*	28.3			35.6			68.5
Ca/K	0.209			0.081			− 0.083
Age (Ma)	8.60			7.07			15.21
± 1 sd	1.30			0.73			0.23
% sd	15.12			10.32			1.48

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