Loss on drying
(see Thermal Analysis 891)
In this procedure, perform weighings rapidly with minimum exposure of the substances to air.]
Determine the percentage of volatile substances by thermogravimetric analysis on an appropriately calibrated instrument, using about 10 mg of Vinblastine Sulfate, accurately weighed. Heat the specimen at the rate of 5
per minute between ambient temperature and 200
in an atmosphere of nitrogen at a flow rate of 40 mL per minute. From the thermogram, determine the accumulated loss in weight between ambient temperature and a point on the plateau before decomposition is indicated (at about 160
): it loses not more than 15.0% of its weight.
, System suitability preparation
, and Chromatographic system
Prepare as directed in the Assay
High load test preparation
Prepare as directed for Assay preparation
in the Assay
Low load test preparation
Pipet 1 mL of High load test preparation into a 25-mL volumetric flask, dilute with water to volume, and mix.
Separately inject 200 µL of the Low load test preparation
and of the High load test preparation
into the chromatograph, and record the chromatograms. Measure the peak responses, ri
, of any related substances appearing after the solvent peak in the chromatogram of the High load test preparation
. Calculate the total percentage of responses due to related substances taken by the formula:
100rt / (rt + 25rv),
in which rt
is the sum of the ri
responses; and rv
is the vinblastine peak response in the chromatogram of the Low load test preparation
. Not more than 3.0% is found. Calculate the percentage response of each related substance taken by the formula:
100ri / (rt + 25rv).
Not more than 1.0% of response due to any individual related substance is found.
Mix 14 mL of diethylamine with 986 mL of water, and adjust with phosphoric acid to a pH of 7.5 (Solution A). Mix 200 mL of acetonitrile with 800 mL of methanol (Solution B). Mix 380 mL of Solution A with 620 mL of Solution B, pass through a 0.5-µm filter, and degas under vacuum. The ratio of Solutions A and B may be varied to meet system suitability requirements and to provide a suitable elution time for vinblastine sulfate.
Dissolve an accurately weighed quantity of USP Vinblastine Sulfate RS
in water to obtain a solution having a known concentration of about 0.4 mg per mL.
Transfer about 4 mg of Vinblastine Sulfate, accurately weighed, to a 10-mL volumetric flask, dissolve in and dilute with water to volume, and mix.
System suitability preparation
Dissolve an amount of USP Vincristine Sulfate RS
in a portion of Standard preparation
to obtain a solution having concentrations of about 0.4 mg of each Reference Standard per mL.
(see Chromatography 621
)The liquid chromatograph is equipped with a 262-nm detector, a pre-column packed with porous silica gel installed between the pump and the injector, and a 4.6-mm × 15-cm analytical column that contains packing L1. The Mobile phase
is maintained at a pressure and flow rate (about 2 mL per minute) capable of producing the required resolution and a suitable elution time. Chromatograph replicate injections of the Standard preparation
, and record the peak responses as directed for Procedure:
the relative standard deviation is not more than 2.0%. Similarly chromatograph 20 µL of the System suitability preparation
, and record the peak responses: the resolution, R,
between the vincristine and vinblastine is not less than 4.0. [NOTE
For a particular column, the resolution may be increased by increasing the proportion of Solution A
in the Mobile phase
Separately inject equal volumes (about 20 µL) of the Standard preparation
and the Assay preparation
into the chromatograph, record the chromatograms, and measure the responses for the major peaks. Calculate the quantity, in mg, of C46
in the portion of Vinblastine Sulfate taken by the formula:
10C(rU / rS),
in which C
is the concentration, in mg per mL, of USP Vinblastine Sulfate RS
(corrected for loss in weight) in the Standard preparation;
are the peak responses obtained from the Assay preparation
and the Standard preparation