Solutions— Prepare a solution of Nicotine in water having a concentration of about 1 mg per mL. Transfer 1.0 mL of this solution to a 50-mL volumetric flask, dilute with 0.1 N hydrochloric acid to volume, and mix to obtain the test solution. Transfer an amount of USP Nicotine Bitartrate Dihydrate RS, equivalent to about 50 mg of nicotine, to a 25-mL glass-stoppered tube. Add 5 mL of 6 N ammonium hydroxide, 2 mL of 1 N sodium hydroxide, and 20 mL of n-hexane. Shake for 5 minutes, allow the phases to separate, transfer the upper n-hexane layer to a vial, and evaporate with a stream of nitrogen gas. [note—Avoid excessive drying to prevent loss of nicotine.] Dissolve the residue of the nicotine so obtained in water to obtain a solution having a concentration of about 1 mg per mL. Dilute 1.0 mL of this solution with 0.1 N hydrochloric acid to 50.0 mL, and mix to obtain the Standard solution.

Test solution: 20 mg per mL, in alcohol.

Test solution— Dissolve about 0.13 g of Nicotine, accurately weighed, in dichloromethane, dilute with dichloromethane to 25.0 mL, and mix.

Reference solutions— Dilute accurately measured volumes of the Test solution quantitatively, and stepwise if necessary, with dichloromethane to obtain Reference solution A and Reference solution B having concentrations of about 26 µg per mL and 52 µg per mL, respectively.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector maintained at 270 and a 0.53-mm × 30-m fused silica column bonded with a 1.5-µm layer of phase G1. Helium is used as the carrier gas at a flow rate of 20 mL per minute. The column temperature is maintained at 50 for 6 seconds, then programmed to rise from 50 to 250 at 6 per minute, and finally held isothermally at 250 for 3 minutes.

Procedure— Separately inject equal volumes (about 1 µL) of the Test solution, Reference solution A, and Reference solution B into the chromatograph, and allow the Test solution to elute for not less than 2.5 times the retention time of nicotine. Record the chromatograms, and measure all of the peak responses. The sum of the peak responses, excluding that of nicotine, from the Test solution is not more than that of the nicotine response from Reference solution B (1.0%), and no single peak response is greater than that of the nicotine response from Reference solution A (0.5%).