Appendices 5-13 - Nautilus Cares - Nautilus Minerals

2. An aliquot(s) of sample after centrifugation (2,500 rpm for 15
minutes) was taken for pH, Eh, temperature, conductivity,
alkalinity, sulfide and dissolved oxygen measurements prior to
filtration.
3. The remaining solution was filtered through a 0.45 !m acid-
2.4 Analytical methods:
pH
washed filter to remove particulates prior to chemical analysis.
Chemical analysis of the supernatant included: organic carbon,
sulfate, Au, Ag, Al, As, Ca, Cd, Co, Cr, Cu, Fe, Hg, K, Mg, Mn,
Na, Ni, Pb, Sr and Zn.
pH was measured with a TPS Aqua pH meter and Ionode pH electrode. The system
was calibrated at pH 7 and 9 in accordance with the instrument manufacturer’s
instructions.
Redox (Eh)
Redox was measured with an Ionode ORP combination electrode and Aqua
conductivity/pH meter. The system was calibrated in accordance with the
manufacturer’s instructions.
Dissolved oxygen
Dissolved oxygen was measured with a WP 82Y dissolved oxygen meter with a YSI
Model 5739 dissolved oxygen probe. The system was calibrated in accordance with
the manufacturer’s instructions.
Conductivity
Conductivity was measured with a Cyberscan 200 conductivity meter and a Eutech
Instruments conductivity probe. The system was calibrated in accordance with the
manufacturer’s instructions.
Alkalinity
Centrifuged samples (25 mL) were analysed by potentiometric titration with
0.01 M HCl to pH 2.5. A CyberScan pH 300 meter (Eutech Instruments) was used to
monitor pH changes. Gran function plots of the titration data were used to determine
alkalinity.
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