Identification
A:
It responds to the flame tests for Sodium á191ñand for Potassium á191ñ,to the ammonium oxalate test for Calcium á191ñ,and to the tests for Chloride á191ñ.
B:
The retention time of the lactate peak in the chromatogram of the Assay preparationcorresponds to that of the Standard preparationas obtained in the Assay for lactate.
Assay for lactate
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 3mg per mL.
Assay preparation
Use undiluted Injection.
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 preparationsand the
Assay preparationinto the chromatograph,record the chromatograms,and measure the responses for the major peaks.Calculate the quantity,in mg,of lactate (C
3H
5O
3)in the Injection taken by the formula:
C(89.07/112.06)(rU/rS),
in which
Cis the concentration,in mg per mL,of
USP Sodium Lactate RSin the
Standard preparation,89.07and 112.06are the molecular weights of lactate (C
3H
5O
3)and anhydrous sodium lactate (C
3H
5NaO
3),respectively,and
rUand
rSare the lactate peak responses obtained from the
Assay preparationand the
Standard preparation,respectively.