Assay for total citrate
Assay preparation
Pipet 5 mL of Solution into a suitable volumetric flask, and proceed as directed for
Assay Preparation for Citric Acid/Citrate Assay under general chapter
345
.
Procedure
Proceed as directed for
Procedure under general chapter
345
, and calculate the quantity, in mg, of anhydrous citric acid (C
6H
8O
7) in the volume of Solution taken by the formula:
0.001(192.12/189.10)CS D(rU / rS)
in which 192.12 is the molecular weight of anhydrous citric acid; 189.10 is the molecular weight of citrate (C
6H
5O
7);
CS is the concentration, in µg per mL, of citrate in
Standard Preparation 1; D is the dilution factor; and
rU and
rS are the citrate peak areas obtained from the
Assay preparation and
Standard Preparation 1, respectively.
(Official April 1, 2009)
Assay for dextrose
Determine the angular rotation of Solution in a suitable polarimeter tube (see
Optical Rotation
781
). Where the Solution is labeled to contain anhydrous dextrose, calculate the percentage (g per 100 mL) of C
6H
12O
6 in the portion of Solution taken by the formula:
(100/52.9)AR
in which 100 is the percentage; 52.9 is the midpoint of the specific rotation range for anhydrous dextrose, in degrees;
A is 100 mm divided by the length of the polarimeter tube, in mm; and
R is the observed rotation, in degrees. Where the Solution is labeled to contain dextrose monohydrate, calculate the percentage (g per 100 mL) C
6H
12O
6·H
2O in the portion of Solution taken by the formula:
(100/52.9)(198.17/180.16)AR
in which 100 is the percentage; 52.9 is the midpoint of the specific rotation range for anhydrous dextrose, in degrees; 198.17 and 180.16 are the molecular weights for dextrose monohydrate and anhydrous dextrose, respectively;
A is 100 mm divided by the length of the polarimeter tube, in mm; and
R is the observed rotation, in degrees.