The amount of source rock required depends upon its kerogen content, but ~5 g of clean rock should be sufficient.
Carbonate is removed from finely milled, solvent extracted, rock sample (2–3 tea-spoons) by treatment with 25–50 mL concentrated hydrochloric acid (approximately 60–70⁰C, ≥12 h). The samples are then washed with distilled water until pH 6.0–6.5 is obtained.
Dry samples are treated with 25–50 mL 40% hydrofluoric acid (approximately 60–70⁰C, ≥24 h, with regular agitation during the first 4 h). The residual kerogen is washed until pH neutral and isolated from aqueous solution by centrifuging.