Hydrazine solution— Transfer 1.0 g of hydrazine sulfate to a 100-mL volumetric flask, dissolve in and dilute with water to volume, and mix. Allow to stand 4 to 6 hours before use.

Methenamine solution— Transfer 2.5 g of methenamine to a 100-mL glass-stoppered flask, add 25.0 mL of water, insert the glass stopper, and mix to dissolve.

Primary opalescent suspension— [note—This suspension is stable for 2 months, provided it is stored in a glass container free from surface defects. The suspension must not adhere to the glass and must be well mixed before use.] Transfer 25.0 mL of Hydrazine solution to the Methenamine solution in the 100-mL glass-stoppered flask. Mix, and allow to stand for 24 hours.

Opalescence standard— [note—This suspension should not be used beyond 24 hours after preparation.] Transfer 15.0 mL of the Primary opalescent suspension to a 1000-mL volumetric flask, dilute with water to volume, and mix.

Reference suspensions— Transfer 5.0 mL of the Opalescence standard to a 100-mL volumetric flask, dilute with water to volume, and mix to obtain Reference suspension 1. Transfer 10.0 mL of the Opalescence standard to a second 100-mL volumetric flask, dilute with water to volume, and mix to obtain Reference suspension 2.

Test solution— Dissolve 2.0 g of Benzyl Alcohol in 60 mL of water, and mix.

Procedure— Transfer a sufficient portion of the Test solution to a test tube of colorless, transparent, neutral glass with a flat base and an internal diameter of 15 mm to 25 mm, to obtain a depth of 40 mm. Similarly transfer portions of Reference suspension 1, Reference suspension 2, and water to separate matching test tubes. Compare the Test solution, Reference suspension 1, Reference suspension 2, and water in diffused daylight, viewing vertically against a black background (see Visual Comparison under Spectrophotometry and Light-Scattering 851). [note—The diffusion of light must be such that Reference suspension 1 can readily be distinguished from water, and that Reference suspension 2 can readily be distinguished from Reference suspension 1.] The Test solution shows the same clarity as that of water, or its opalescence is not more pronounced than that of Reference suspension 1.

Test solution— Use the Test solution prepared in the test for Clarity of solution.

Procedure— Transfer a sufficient portion of the Test solution to a test tube of colorless, transparent, neutral glass with a flat base and an internal diameter of 15 mm to 25 mm, to obtain a depth of 40 mm. Similarly transfer a portion of water to a separate matching test tube. Compare the color of the Test solution with that of water in diffused daylight, viewing vertically against a white background (see Visual Comparison under Spectrophotometry and Light-Scattering 851). The Test solution has the color of water.

Test solution— Use the Benzyl Alcohol specimen under examination.

Ethylbenzene solution— Transfer 100 mg of ethylbenzene, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with Test solution to volume, and mix. Transfer 1.0 mL of this solution to a 10-mL volumetric flask, dilute with Test solution to volume, and mix.

Dicyclohexyl solution— Transfer 2.0 g of dicyclohexyl to a 10-mL volumetric flask, dissolve in and dilute with Test solution to volume, and mix. Transfer 1.0 mL of this solution to a 10-mL volumetric flask, dilute with Test solution to volume, and mix.

Standard solution 1— Transfer 750 mg of benzaldehyde, accurately weighed, and 500 mg of cyclohexylmethanol, accurately weighed, to a 25-mL volumetric flask, dissolve in and dilute with Test solution to volume, and mix. Transfer 0.5 mL of this solution to a 10-mL volumetric flask, add 1.0 mL of Ethylbenzene solution and 1.5 mL of Dicyclohexyl solution, dilute with Test solution to volume, and mix.

Standard solution 2 (where the Benzyl Alcohol under test is intended for use in the manufacture of injectable dosage forms)— Transfer about 250 mg of benzaldehyde, accurately weighed, and about 500 mg of cyclohexylmethanol, accurately weighed, to a 25-mL volumetric flask, dissolve in and dilute with Test solution to volume, and mix. Transfer 0.5 mL of this solution to a 10-mL volumetric flask, add 1.0 mL of Ethylbenzene solution and 1.0 mL of Dicyclohexyl solution, dilute with Test solution to volume, and mix.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector and a 0.32-mm × 30-m column coated with a 0.5-µm film of G16. Helium is used as the carrier gas flowing at a rate of 1.2 mL per minute at 50. The injection port and detector temperatures are maintained at about 200 and 310, respectively. The column temperature is programmed to increase linearly from 50 to 220 at a rate of 5 per minute, and is maintained at 220 for 35 minutes. Chromatograph the appropriate Standard solution, and record the peak responses as directed for Procedure: the relative retention times are about 0.28 for ethylbenzene, 0.59 for dicyclohexyl, 0.68 for benzaldehyde, 0.71 for cyclohexylmethanol, and 1.0 for benzyl alcohol; and the resolution, R, between benzaldehyde and cyclohexylmethanol is not less than 3.0.

Procedure— Separately inject equal volumes (about 0.1 µL) of the appropriate Standard solution and the Test solution into the chromatograph, record the chromatograms, and measure the areas for the major peaks. [note—Disregard any peak having an area less than 0.01 times the area of the ethylbenzene peak in the chromatogram of the appropriate Standard solution. In the chromatogram of the Test solution, verify that there are no peaks with the same retention times as those of ethylbenzene or dicyclohexyl.]

10.81N(VB VU)/W