Octane R

n-Octane; C₈H₁₈; CAS Reg. No. 111-65-9.

Contains not less than 99% of C₈H₁₈.

Octanoic acid R

Caprylic acid, C₈H₁₆O₂.

Description. A colourless, oily liquid.

Boiling temperature. About 237 °C.

Mass density. ρ₂₀ = about 0.92 kg/L.

Olive oil R

A commercially available reagent of suitable grade.

Opalescence standard TS1

Procedure. Dilute 15 mL of Opalescence stock standard TS with sufficient water to produce 1000 mL.

Shelf-life. Use within 24 hours after preparation.

Opalescence standard TS2

Procedure. Dilute 5.0 mL of Opalescence standard TS1 with sufficient water to produce 100 mL. Mix well and shake before use.

Note: Opalescence standard TS2 must be freshly prepared.

Opalescence standard TS3

Procedure. Dilute 10 mL of opalescence standard TS1 with sufficient water to produce 100 mL. Mix well and shake before use.

Note: Opalescence standard TS3 must be freshly prepared.

Opalescence stock standard TS

Procedure. Dissolve 1.0 g of hydrazine sulfate R in sufficient water to produce 100 mL and allow to stand for 4–6 hours. To 25.0 mL of this solution add a solution of 2.5 g of methenamine R dissolved in 25.0 mL of water, mix well and allow to stand for 24 hours.

Storage. Store in a glass container free from surface defects.

Shelf-life. Use within 2 months after preparation.

Oracet blue B R

Solvent blue 19; a mixture of 1-methylamino-4-anilinoanthraquinone (C₂₁H₁₆N₂O₂) and 1-amino-4-anilinoanthraquinine (C₂₀H₁₄N₂O₂).

Oracet blue R/acetic acid TS

Procedure. Dissolve 0.5 g of oracet blue B R in sufficient glacial acetic acid R1 to produce 100 mL.

Osmium tetroxide R

OsO₄.

Caution. The fumes are corrosive to the eyes, the mucous membranes and the skin.

Description. Yellow, needle-shaped crystals or a yellow, crystalline mass; hygroscopic; light sensitive; odour, pungent.

Solubility. Soluble in water, ethanol (~750 g/L) TS and ether R.

Ox brain, acetone-dried, R

Procedure. Cut into small pieces a fresh ox brain previously freed from vascular and connective tissue. Place in acetone R for preliminary dehydration. Complete the dehydration by pounding in a mortar 30 g of the material with successive quantities, each of 75 mL of acetone R, until a dry powder is obtained after filtration. Dry at 37 °C for 2 hours or until the odour of acetone is no longer perceptible.

Oxalic acid (0.05 g/L) TS

A solution of oxalic acid R containing 0.05 g of C₂H₂O₄ in 1000 mL.

Procedure. Dissolve 0.07 g of oxalic acid R in sufficient water to produce 1000 mL.

Oxalic acid R

C₂H₂O₄,2H₂O (SRIP, 1963, p. 131).

Oxalic acid/sulfuric acid TS

Procedure. Dissolve 5 g of oxalic acid R in a sufficient quantity of a cooled mixture of equal volumes of sulfuric acid (~1760 g/L) TS and water to produce 100 mL.

Oxibendazole R

Oxibendazole of a suitable quality should be used.

Oxytetracycline hydrochloride R

Oxytetracycline hydrochloride of a suitable quality should be used.