Element Alkaline Cleaning Treatment Acid/Oxidizer Cleaning Treatment XPS atom% XPS converted to ~atoms/cm2 ICP-MS, Acid Extract atoms/cm2 IC, DI- Water Extract atoms/cm2 XPS atom% XPS converted to atoms/cm2 ICP-MS, Acid Extract atoms/cm2 IC, DI- Water Extract atoms/cm2 Al 16.2 9.7 x 1015 1.2 x 1017 — 24 1.4 x 1016 2.6 x 1017 — Ca 0.5 3 x 1014 3.1 x 1014 1.4 x 1013 <0.1 <6 x 1013 2.6 x 1014 2.1 x 1013 Cr <0.1 <6 x 1013 4.7 x 1013 — <0.1 <6 x 1013 7.6 x 1013 — Cu <0.1 <6 x 1013 5.3 x 1013 — 0.1 6 x 1013 3.4 x 1014 — Fe <0.1 <6 x 1013 1.4 x 1014 — <0.1 <6 x 1013 3.5 x 1013 — Mg 1.8 1.1 x 1015 1.2 x 1015 — 0.1 6 x 1013 2.8 x 1015 — Ni <0.1 <6 x 1013 1.5 x 1012 — <0.1 <6 x 1013 2.0 x 1012 — K <0.1 <6 x 1013 3 x 1013 5 x 1012 <0.1 <6 x 1013 5.2 x 1013 <5 x 1012 Na <0.1 <6 x 1013 3.8 x 1012 5 x 1012 <0.1 <6 x 1013 <2.1 x 1012 <5 x 1012 Ti 0.2 1.2 x 1014 4.9 x 1013 — <0.1 <6 x 1013 1.2 x 1012 — Zn <0.1 <6 x 1013 1.6 x 1013 — <0.1 <6 x 1013 6 x 1012 — O 52.4 3 x 1016 — — 51.1 3 x 1016 — — C 24.2 1.5 x 1016 — — 22.1 1.3 x 1016 — — Si 0.9 5.4 x 1014 — — 0.7 4.2 x 1014 — — F1 2.1 1.3 x 1015 — 4.7 x 1012 1.5 9 x 1014 — <4 x 1012 N2 0.4 2.4 x 1014 — <2 x 1012 0.3 1.8 x 1014 — <2 x 1012 S3 <0.1 <6 x 1013 — <1 x 1012 0.2 1.2 x 1014 — <1 x 1012 Cl4 <0.1 <6 x 1013 — 3 x 1012 <0.1 <6 x 1013 — <3 x 1012 1 In IC, as fluoride. 2 In IC, as nitrate. 3 In IC, as sulfate. 4 In IC, as chloride.

Table II: Comparison of analytical methods used to detect elements on aluminum coupons cleaned with an alkaline or acid treatment.