Formaldehyde Solution
CH2O 30.03

Formaldehyde.
Formaldehyde [50-00-0].
»Formaldehyde Solution in bulk containers contains not less than 37.0percent,by weight,of formaldehyde (CH2O),with methanol added to prevent polymerization.Formaldehyde Solution in small containers (4liters or less)contains not less than 36.5percent,by weight,of formaldehyde (CH2O),with methanol present to prevent polymerization.
Packaging and storage— Preserve in tight containers,and preferably store at a temperature not below 15.
Labeling— The label of bulk containers of the Solution directs the drug repackager to demonstrate compliance with the USPAssaylimit for formaldehyde of not less than 37.0%,by weight,immediately prior to repackaging.
Identification—
A: Dilute 2mLwith 10mLof water in a test tube,and add 1mLof silver-ammonia-nitrate TS:metallic silver is produced either in the form of a finely divided,gray precipitate,or as a bright,metallic mirror on the sides of the test tube.
B: Add 2drops to 5mLof sulfuric acid in which about 20mg of salicylic acid has been dissolved,and warm the liquid very gently:a permanent,deep-red color appears.
Acidity— Measure 20.0mLinto a flask containing 20mLof water,add 2drops of bromothymol blue TS,and titrate with 0.1Nsodium hydroxide VS:not more than 10.0mLof 0.1Nsodium hydroxide is consumed.
Assay— Transfer about 3mLof Solution to a tared flask containing 10mLof water,insert the stopper in the flask tightly,and accurately determine the weight of the Solution taken.Slowly and quantitatively add a mixture of 50.0mLof 1Nsodium hydroxide VSand 50mLof hydrogen peroxide TSthat has been previously neutralized to bromothymol blue TSwith 1Nsodium hydroxide.Heat the contents of the flask cautiously on a steam bath for 15minutes,shaking it occasionally with a rotary motion.Allow the mixture to cool,rinse the funnel and the inner wall of the flask with water,and after allowing it to stand for 30minutes,add 2to 5drops of bromothymol blue TS,and titrate the excess alkali with 1Nsulfuric acid VS.Perform a blank determination (see Residual Titrationsunder Titrimetry á541ñ).Also make a correction based upon the acidity found in the test for Acidity.Each mLof 1Nsodium hydroxide is equivalent to 30.03mg of CH2O.
Auxiliary Information— Staff Liaison:Tina S.Morris,Ph.D.,Senior Scientist
Expert Committee:(VVI)Vaccines,Virology,and Immunology
USP28–NF23Page 871
Phone Number:1-301-816-8397