accurately dissolving
about 30 mg of pentacosane (Supelco, Bellefonte, PA,
USA) in 50 mL of isooctane (2,2,4-trimethylpentane; Mallinckrodt)
and diluted for use by pipetting 3 mL to 50 mL isooctane in
a volumetric flask. These solutions were stable 2e3 years under
refrigeration