2.3.2. Metal CaCl2 Extraction

For the extraction of soluble metals from soil, air-dried soil aliquots (10 g) were placed in 250 mL high density polyethylene (HDPE) plastic bottles. Calcium chloride (100 mL, 0.01 M) was then added to each bottle [26]. The bottles were vortexed for 2 h at 20 ◦C. The suspension was decanted into a 100 mL centrifuge tube and centrifuged for 10 min at 1800 rpm. A 10 mL aliquot of the supernatant was filtered using a 0.45 μm syringe filter. The filtered supernatant was acidified with 4% HNO3 at a ratio of 1:2 ratio before metal analysis.
