Add the following:

Change to read:

A: Infrared Absorption 197F.

B: The retention time of the major peak in the chromatogram of Acetone corresponds to that in the chromatogram of USP Acetone RS, as obtained in the Assay.NF27

Change to read:

Standard preparation— Transfer 0.50 mL of water to a dry 100-mL volumetric flask, dilute with dehydrated isopropyl alcohol to volume, and mix.

Chromatographic system— Under typical conditions, the gas chromatograph is equipped with a thermal conductivity detector, maintained at about 250, and a 0.32-mm × 50-m capillary column coated with a 5.0-µm layer of support S2. The carrier gas is helium, flowing at a rate of 11 mL per minute, with a split rate of 50 mL per minute. The column is maintained at 100, then the temperature is increased at a rate of 25 per minute to 190. The injection port temperature is maintained at 250.NF27

Procedure— Inject about 1.0 µLNF27 of the Standard preparation into a suitable gas chromatograph, and determine the area under the water peak. Similarly inject about 1.0 µLNF27 of NF27 dehydrated isopropyl alcohol to provide a blank, and determine the area under the water peak. Identify the components based on their relative retention times, which are 1.0 for water, and about 1.9 for isopropyl alcohol.NF27 Similarly inject about 1.0 µLNF27 of Acetone. The area under the water peak for Acetone is not greater than that from the Standard preparation corrected for the area under the water peak in the blank chromatogram (0.5%).

Change to read:

System suitability solution— Dilute 1.0 mL of USP Methyl Alcohol RS and 1.0 mL of USP Acetone RS with tetrahydrofuran to 50 mL.

Chromatographic system (see Chromatography 621)— The gas chromatograph is equipped with a flame-ionization detector, maintained at about 280, and a 0.32-mm × 30-m fused-silica capillary column coated with a 1.8-µm layer of phase G43. The carrier gas is helium with a linear velocity of about 35 cm per second and a split ratio of 1:400. The column is maintained at 40 for the first 5 minutes, then the temperature is increased at a rate of 20 per minute to 240. The injection port temperature is maintained at 200. Chromatograph the System suitability solution, and record the peak responses as directed for Procedure: the relative retention times are 1.0 for acetone, about 0.6 for methyl alcohol, and about 1.9 for tetrahydrofuran; and the resolution, R, between the methyl alcohol and acetone peaks is not less than 15.

Procedure— Inject a suitable volume, typically about 1 µL, of Acetone into the chromatograph, and record the chromatogram. Calculate the percentage of C3H6O in the portion of Acetone taken, on the anhydrous basis, by dividing the area under the acetone peak by the sum of the areas under all of the peaks, and multiplying by 100. [note—No separate correction is applied for water content, because water does not respond to the flame-ionization detector.]NF27