Assay for total citrate and total phosphate
Assay preparation for total citrate assay
Pipet 10 mL of Solution into a suitable volumetric flask, and proceed as directed for
Assay Preparation for Citric Acid/Citrate Assay under general chapter
345
.
Assay preparation for total phosphate assay
Pipet 5 mL of Solution into a suitable volumetric flask, and proceed as directed for
Assay Preparation for Phosphate 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 2; D is the dilution factor; and
rU and
rS are the citrate peak areas obtained from the
Assay preparation for total citrate assay and
Standard Preparation 2, respectively.
Calculate the quantity, in mg, of phosphate, expressed as monobasic sodium phosphate monohydrate (NaH2PO4·H2O), in the volume of Solution taken by the formula:
0.001(137.99/94.97)CS D(rU / rS)
in which 137.99 is the molecular weight of monobasic sodium phosphate monohydrate; 94.97 is the molecular weight of phosphate (PO4); CS is the concentration, in µg per mL, of phosphate in Standard Preparation 2; D is the dilution factor; and rU and rS are the phosphate peak areas obtained from the Assay preparation for total phosphate assay and Standard Preparation 2, respectively.
(Official April 1, 2009)
Assay for sodium
Lithium diluent solution
Transfer 1.04 g of lithium nitrate to a 1000-mL volumetric flask, add a suitable nonionic surfactant, then add water to volume, and mix. This solution contains 15 mEq of lithium per L.
Standard preparation
Transfer 8.18 g of sodium chloride, previously dried at 105

for 2 hours and accurately weighed, to a 1000-mL volumetric flask, dilute with water to volume, and mix. This solution contains 140 mEq of sodium per L. Transfer 50 µL of this solution to a 10-mL volumetric flask, dilute with
Lithium diluent solution to volume, and mix.
Assay preparation
Pipet 25 mL of Solution into a 50-mL volumetric flask, dilute with water to volume, and mix. Transfer 50 µL of this solution to a 10-mL volumetric flask, dilute with Lithium diluent solution to volume, and mix.
Procedure
Using a suitable flame photometer, adjusted to read zero with
Lithium diluent solution, concomitantly determine the sodium flame emission readings for the
Standard preparation and the
Assay preparation at the wavelength of maximum emission at about 589 nm. Calculate the quantity, in g, of Na in 1000 mL of Anticoagulant Citrate Phosphate Dextrose Adenine Solution taken by the formula:
2(8.18)(22.99/58.44)(RU/RS)
in which 8.18 is the weight, in g, of sodium chloride taken to make the
Standard preparation; 22.99 is the atomic weight of sodium; 58.44 is the molecular weight of sodium chloride; and
RU and
RS are the sodium emission readings obtained from the
Assay preparation and the
Standard preparation, respectively.
Assay for dextrose
Tare a clean, medium-porosity filtering crucible containing several carborundum boiling chips or glass beads. Pipet 50 mL of freshly mixed alkaline cupric tartrate TS into a 400-mL beaker. Add the boiling chips or glass beads from the tared crucible, 45 mL of water, and 5.0 mL of Solution to the beaker. Heat the beaker and contents over a burner that has been adjusted to cause boiling of the solution to start in 3.5 to 4 minutes. Boil the solution for 2 minutes, accurately timed, and filter immediately through the tared crucible, taking care to transfer all of the boiling chips or glass beads to the crucible. Wash the precipitate with hot water and 10 mL of alcohol. Dry the crucible and contents at 110

to constant weight. Perform a blank determination, and make any necessary correction. Each mg of cuprous oxide precipitate obtained is equivalent to 0.496 mg of C
6H
12O
6·H
2O.
Assay for adenine
Mobile phase
Dissolve 3.45 g of ammonium dihydrogen phosphate in 950 mL of water in a 1000-mL volumetric flask, add 10 mL of glacial acetic acid, dilute with water to volume, mix, pass through a membrane filter having a 1-µm or finer porosity, and degas.
Standard preparations
Dissolve accurately weighed quantities of
USP Adenine RS in dilute hydrochloric acid (1 in 120) in three separate volumetric flasks, dilute with the dilute hydrochloric acid solution to volume, and mix to obtain Standard preparations having known concentrations of about 0.25, 0.275, and 0.30 mg of adenine per mL, respectively. Protect from light.
Chromatographic system
(see
Chromatography
621
)The liquid chromatograph is equipped with a 254-nm detector and a 4-mm × 30-cm stainless steel column that contains packing L9. The flow rate is about 2.0 mL per minute. Prepare a solution containing
USP Adenine RS and purine, each at about 0.275 mg per mL, in dilute hydrochloric acid (1 in 120), and chromatograph not less than four injections (about 20 µL) of this solution: the relative standard deviation of the peak response of adenine is not more than 2.5%, the relative standard deviation of the retention time of adenine is not more than 2.0%, and the resolution of adenine and purine is not less than 3.0.
Procedure
Separately inject equal volumes (about 20 µL) of the Solution and the
Standard preparations, record the chromatograms, and measure the responses for the major peaks. Plot the responses against the concentrations, in mg of
USP Adenine RS per mL of the
Standard preparations. Calculate the quantity, in mg, of C
5H
5N
5 in each mL of the Solution taken as the value read directly from the Standard curve corresponding to the response obtained from the portion of the Anticoagulant Citrate Phosphate Dextrose Adenine Solution chromatographed.