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Solvent— Prepare a mixture of n-hexane and dehydrated alcohol (5:2).

Mobile phase— Prepare a filtered and degassed mixture of acetonitrile,tetrahydrofuran,and water (55:40:5).Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparation— Dissolve an accurately weighed quantity of USP Ubidecarenone RSin Solventto obtain a solution having a known concentration of 1.0mg per mL.Dilute a portion of this solution with dehydrated alcohol to obtain a solution having a known concentration of about 40µg per mL.

Resolution solution— Dissolve an accurately weighed quantity of coenzyme Q9in Solventto obtain a solution having a concentration of 1.0mg per mL.Dilute a portion of this solution with dehydrated alcohol to obtain a solution having a concentration of about 40µg per mL.Mix equal volumes of this solution and the Standard preparation.

Assay preparation 1(for soft gelatin Capsules)— Using a suitable cutting instrument,open an accurately counted number of Capsules,equivalent to about 200mg of ubidecarenone.Quantitatively transfer the shells and contents to a suitable container,add 100mLof Solvent,and shake by mechanical means for 30minutes.Using small portions of Solvent,quantitatively transfer this mixture to a 200-mLvolumetric flask,dilute with Solventto volume,and mix.Centrifuge a portion of this solution,transfer 1.0mLof the supernatant to a 25-mLvolumetric flask,add 2.5mLof a 0.1%solution of anhydrous ferric chloride in alcohol,dilute with alcohol to volume,USP28and mix.

Assay preparation 2(for hard gelatin Capsules)— Empty and thoroughly mix the contents of not fewer than 20Capsules.Transfer an accurately weighed portion of the powder,equivalent to about 100mg of ubidecarenone,to a 100-mLvolumetric flask,add 60mLof Solvent,and shake by mechanical means for 30minutes.Dilute with Solventto volume,and mix.Centrifuge a portion of this solution,transfer 1.0mLof the supernatant to a 25-mLvolumetric flask,add 2.5mLof a 0.1%solution of anhydrous ferric chloride in alcohol,dilute with alcohol to volume,and mix.

Chromatographic system (see Chromatography á621ñ)— The liquid chromatograph is equipped with a 280-nm detector and an 8-mm ×10-cm column that contains packing L1.The flow rate is about 2.5mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the resolution,R,between ubidecarenone and coenzyme Q9is not less than 2.5.Chromatograph the Standard preparation,and record the peak responses as directed for Procedure:the tailing factor is not more than 1.5;and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 15µL)of the Standard preparationand Assay preparation 1or Assay preparation 2into the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of ubidecarenone (C59H90O4)in each soft gelatin Capsule taken by the formula: in which Cis the concentration,in mg per mL,of USP Ubidecarenone RSin the Standard preparation;Nis the number of Capsules taken to prepare Assay preparation 1;and rUand rSare the peak responses obtained from Assay preparation 1and the Standard preparation,respectively.Calculate the quantity,in mg,of ubidecarenone (C59H90O4)in the portion of hard gelatin Capsules taken by the formula: in which rUis the peak response obtained from Assay preparation 2;and the other terms are as defined herein.