A: It responds to the flame tests for Sodium á191ñand Potassium á191ñ,to the oxalate test for Calcium á191ñ,and to the tests for Magnesium á191ñand Chloride á191ñ.

B: The retention time of the acetate peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparationobtained as directed in the Assay for acetate.

C: Where citrate is purported to be present,the retention time of the citrate peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparationobtained as directed in the Assay for citrate.

D: Where lactate is purported to be present,the retention time of the lactate peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparationobtained as directed in the Assay for lactate.

Internal standard solution,Potassium stock solution,Sodium stock solution,Stock standard preparation,and Standard preparation— Prepare as directed in the Assay for potassium and sodiumunder Potassium Chloride in Sodium Chloride Injection.

Assay preparation— Transfer 5.0mLof Injection to a 500-mLvolumetric flask,dilute with Internal standard solutionto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assay for potassium and sodiumunder Potassium Chloride in Sodium Chloride Injection.Calculate the quantity,in mg,of potassium (K)in each mLof the Injection taken by the formula: in which the terms are as defined therein.Each mg of potassium is equivalent to 0.02558mEq of potassium.Calculate the quantity,in mg,of sodium (Na)in each mLof the Injection taken by the formula: in which the terms are as defined therein.Each mg of sodium is equivalent to 0.04350mEq of sodium.

Lanthanum chloride solution,Dilute hydrochloric acid,Blank solution,Magnesium stock solution,and Standard preparations— Prepare as directed in the Assay for magnesiumunder Multiple Electrolytes Injection Type 1.

Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 20mg (1.65mEq)of magnesium,to a 1000-mLvolumetric flask containing 50.0mLof Lanthanum chloride solution.Dilute the contents of the flask with Dilute hydrochloric acidto volume,and mix.

Procedure— Proceed as directed for Procedurein the Assay for magnesiumunder Multiple Electrolytes Injection Type 1.Calculate the quantity,in µg,of magnesium (Mg)in each mLof the Injection taken by the formula: in which Vis the volume,in mL,of Injection taken to prepare the Assay preparation,and the other terms are as defined therein.

Lanthanum chloride solution,Dilute hydrochloric acid,and Blank solution— Prepare as directed in the Assay for magnesiumunder Multiple Electrolytes Injection Type 1.

Calcium stock solution— Transfer 499.5mg of primary standard calcium carbonate to a 200-mLvolumetric flask,and add 10mLof water.Carefully add 5mLof Dilute hydrochloric acid,and swirl to dissolve the calcium carbonate.Dilute with water to volume,and mix.This solution contains 1000µg of calcium (Ca)per mL.

Standard preparations— To three separate 100-mLvolumetric flasks,each containing 5.0mLof Lanthanum chloride solution,add 1.0,1.5,and 2.0mL,respectively,of Calcium stock solution.Dilute the contents of each flask with Dilute hydrochloric acidto volume,and mix.These three solutions contain 10.0,15.0,and 20.0µg,respectively,of calcium (Ca)per mL.

Assay preparation— Transfer an accurately measured volume of Injection,equivalent to about 20mg (1mEq)of calcium,to a 1000-mLvolumetric flask containing 50.0mLof Lanthanum chloride solution.Dilute the contents of the flask with Dilute hydrochloric acidto volume,and mix.

Procedure— Concomitantly determine the absorbances of the Standard preparationsand the Assay preparationat the calcium emission line at 422.7nm,with an atomic absorption spectrophotometer (see Spectrophotometry and Light-scattering á851ñ)equipped with a calcium hollow-cathode lamp and an air–acetylene flame,using the Blank solutionas the blank.Plot the absorbances of the Standard preparationsversus concentration,in µg per mL,of calcium,and draw the straight line best fitting the three plotted points.From the graph so obtained,determine the concentration,C,in µg per mL,of calcium in the Assay preparation.Calculate the quantity,in µg,of calcium in each mLof the Injection taken by the formula: in which Vis the volume,in mL,of Injection taken to prepare the Assay preparation.

Mobile phase,Standard preparation,andChromatographic system— Prepare as directed in the Assay for acetateunder Multiple Electrolytes Injection Type 1.

Assay preparation— Dilute an accurately measured volume of Injection quantitatively with water to obtain a solution containing about 0.0088mEq of acetate per mL.

Procedure— Proceed as directed for Procedurein the Assay for acetateunder Multiple Electrolytes Injection Type 1.Calculate the quantity,in mEq per liter,of acetate (C2H3O2)in the Injection taken by the formula: in which the terms are as defined therein.

Mobile phase— Prepare a filtered and degassed solution of 0.05Nsulfuric acid.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Standard preparations— Dissolve an accurately weighed quantity of anhydrous sodium citrate,previously dried at 180for 18hours,in water to obtain a stock solution having a known concentration of about 10mg per mL.Dilute accurately measured volumes of this stock solution quantitatively with water to obtain three Standard preparationshaving known concentrations of about 0.5,1.0,and 2.0mg,respectively,of anhydrous sodium citrate per mL.

Assay preparation— Where the labeled quantity is greater than 10mEq of citrate per liter,dilute an accurately measured volume of Injection quantitatively with water to obtain a solution containing about 0.01mEq of citrate per mL.Where the labeled quantity is 10mEq of citrate or less per liter,use the undiluted Injection as the Assay preparation.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 210-nm detector,a 7.8-mm ×4-cm guard column containing packing L17,and a 7.8-mm ×30-cm analytical column containing packing L17,and is maintained at about 60.The flow rate is about 0.8mLper minute.Chromatograph the Standard preparationcontaining 1mg of anhydrous sodium citrate per mL,and record the responses as directed for Procedure:the tailing factor for the analyte peak 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 20µL)of the Standard preparationsand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Plot the responses of the Standard preparationsversus concentration,in mg of anhydrous sodium citrate per mL,and draw the straight line best fitting the three plotted points.From the graph so obtained,determine the concentration,C,in mg of anhydrous sodium citrate equivalent per mL,in the Assay preparation.Calculate the quantity,in mEq per liter,of citrate (C6H5O7)in the Injection taken by the formula: in which 258.07is the molecular weight of anhydrous sodium citrate,Lis the labeled quantity,in mEq per liter,of citrate in the Injection,and Dis the quantity,in mEq per mL,of citrate in the Assay preparation,based on the labeled quantity and the extent of dilution.

Mobile phase— Prepare a solution in water containing about 1mLof formic acid and 1mLof dicyclohexylamine per liter,filter,and degas.Make adjustments if necessary (see System Suitabilityunder Chromatography á621ñ).

Resolution solution— Prepare a solution in water containing about 3mg of anhydrous sodium acetate and 3mg of USP Sodium Lactate RSper mL.

Standard preparation— Dissolve an accurately weighed quantity of USP Sodium Lactate RSin water to obtain a solution having a known concentration of about 2mg per mL.

Assay preparation— Where the labeled quantity of lactate is greater than 20mEq per liter,dilute an accurately measured volume of Injection quantitatively with water to obtain a solution containing about 0.02mEq of lactate per mL.Where the labeled quantity of lactate is 20mEq or less per liter,use the undiluted Injection as the Assay preparation.

Chromatographic system (see Chromatography á621ñ)—The liquid chromatograph is equipped with a 210-nm detector and a 4.6-mm ×10-cm column that contains packing L1.The flow rate is about 1mLper minute.Chromatograph the Resolution solution,and record the peak responses as directed for Procedure:the resolution,R,between the acetate peak and the lactate peak is not less than 2.Chromatograph the Standard preparation,and record the responses as directed for Procedure:the tailing factor for the analyte peak is not more than 2.0,and the relative standard deviation for replicate injections is not more than 2.0%.

Procedure— Separately inject equal volumes (about 20µL)of the Standard preparationand the Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mEq per liter,of lactate (C3H5O3)in the Injection taken by the formula: in which Cis the concentration,in mg per mL,of USP Sodium Lactate RSin the Standard preparation,112.06is the molecular weight of sodium lactate,Lis the labeled quantity,in mEq per liter,of lactate in Injection,Dis the quantity,in mEq per mL,of lactate in the Assay preparation,based on the labeled quantity and the extent of dilution,and rUand rSare the lactate peak responses obtained from the Assay preparationand the Standard preparation,respectively.