Accordingly,RSD values for different sample masses were 2.1–4.9% for Ca, 1–2.8% for Fe, 0.6–2.1% for Mg, and 2.2–3.2% for Mn in coffees pre-treated with procedure B and 1.2–3.9% (Ca), 1.7–5.9% (Fe), 1–2 (Mg) and 0.7–4.4% (Mn) in coffees pre-treated with procedure C.