» Hexachlorophene contains not less than 98.0 percent and not more than 100.5 percent of C13H6Cl6O2, calculated on the dried basis.
Packaging and storage Preserve in tight, light-resistant containers.
B: To a solution of about 5 mg in 5 mL of alcohol add 1 drop of ferric chloride TS: a transient purple color is produced immediately.
Melting range 741: between 161 and 167.
Loss on drying 731 Dry it at 105 for 4 hours: it loses not more than 1.0% of its weight.
Residue on ignition 281: not more than 0.1%.
Limit of 2,3,7,8-tetrachlorodibenzo-p-dioxin [CautionSince 2,3,7,8-tetrachlorodibenzo-p-dioxin is an extremely toxic substance, exercise all necessary precautions in the conduct of this procedure. ] Dissolve 10.0 g of Hexachlorophene in 50 mL of methanol, transfer to a 1-Liter separator with the aid of 25 mL of methanol, add 25 mL of 2.5 N lithium hydroxide and 225 mL of water, and extract with two 200-mL portions of freshly distilled n-hexane. Dry the combined n-hexane extracts over anhydrous sodium sulfate, filter, and evaporate to a volume of about 15 mL on a rotary evaporator at a bath temperature not exceeding 40. Transfer this solution in portions to a 12-mL centrifuge tube, concentrating each time to a volume of 1 mL in a gentle stream of nitrogen in a warm water bath. Rinse the flask with 15 mL of n-hexane, and evaporate similarly. Wash down the walls of the tube with 10 mL of n-hexane, and again evaporate to a volume of 1.0 mL. Cool, and transfer to a micro-column that has been prepared in the following manner. Place a small plug of glass wool in a 5- × 15-mm pipet, add a small amount of sand and 1.0 g of basic alumina, tap several times to pack down the alumina, and heat in a vacuum oven at 110 for 3 hours. Store under vacuum.
Elute the column with 10 mL of a mixture of n-hexane and methylene chloride (9:1), using a portion to rinse the tube. Collect the eluate in a 12-mL graduated centrifuge tube, and concentrate in a gentle stream of nitrogen in a warm water bath to a volume of 1.0 mL.
Inject 2.0 µL of the concentrated eluate into a suitable gas chromatograph connected to a mass spectrograph equipped with a multiple-ion detector (see Chromatography 621 and Mass Spectrometry 736). The gas chromatograph is fitted with a 2-mm × 1-m glass column containing liquid phase G1 on support S1. The carrier gas is helium, flowing at the rate of 40 mL per minute. The column temperature is maintained at 250 and the injection port is maintained at 300. Similarly inject 2.0 µL of a Standard solution of 2,3,7,8-tetrachlorodibenzo-p-dioxin containing 0.01 µg per mL.* The sum of the peak heights at mass values of 320, 322, and 324 obtained from the solution under test is not greater than the sum of the peak heights at the same mass values obtained from the Standard solution. The limit is 1 ppb.
Assay Accurately weigh about 1.5 g of Hexachlorophene, dissolve in 25 mL of alcohol, and titrate with 0.1 N sodium hydroxide VS, determining the endpoint potentiometrically. Perform a blank determination, and make any necessary correction. Each mL of 0.1 N sodium hydroxide is equivalent to 40.69 mg of C13H6Cl6O2.
* A solution in anisole is available commercially from KOR Isotopes, Div. of ECO, Inc., 56 Rogers St., Cambridge, Mass. 02142. This solution may be diluted with a mixture of n-hexane and methylene chloride (9:1) to the required concentration.
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USP32NF27 Page 2554
Chromatographic columns text is not derived from, and not part of, USP 32 or NF 27.