Synthetic Paraffin
»Synthetic Paraffin is synthesized by the Fischer-Tropsch process from carbon monoxide and hydrogen,which are catalytically converted to a mixture of paraffin hydrocarbons;the lower molecular weight fractions are removed by distillation,and the residue is hydrogenated and further treated by percolation through activated charcoal.This mixture may be fractionated into its components by a solvent separation method,using a suitable synthetic isoparaffinic petroleum hydrocarbon solvent.It may contain not more than 0.005percent of a suitable antioxidant.
Packaging and storage— Preserve in well-closed containers.
Labeling— The labeling indicates its congealing temperature,viscosity,and needle penetration range under specified conditions.
Identification— Infrared Absorption á197ñ—Athin film of it,cast from a melt onto a cesium bromide plate,exhibits a pair of very strong IRabsorption peaks between 2840cm-1and 3000cm-1,a pair of moderately strong peaks between 1430cm-1and 1490cm-1,a pair of medium peaks between 720cm-1and 750cm-1,and only weak peaks at any other wave numbers.
Absorptivity (see Spectrophotometry and Light-scattering á851ñ)— Transfer 50to 100mg,accurately weighed,to a 100-mLvolumetric flask.Dissolve in decahydronaphthalene at 88,dilute with the same solvent at this temperature to volume,and mix.Using the same solvent in a matched cell as the blank,determine the absorbance of the solution in a 10-cm jacketed cell at 290nm,with a suitable spectrophotometer,both cells being maintained at 88.Calculate the absorptivity:it is not greater than 0.01.
Oil content: not greater than 0.5%,as determined by following ASTM Method D721-68,“Standard Test Method for Oil Content of Petroleum Waxes”(Reapproved 1987).*
*  Available from the American Society for Testing and Materials,1916Race St.,Philadelphia,PA19103.
Auxiliary Information— Staff Liaison:Catherine Sheehan,B.Sc.,Scientist
Expert Committee:(EMC)Excipients:Monograph Content
USP28–NF23Page 3046
Phone Number:1-301-816-8262