Glutaral Concentrate
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C5H8O2 100.12

Pentanedial.
Pentanedial [111-30-8].
» Glutaral Concentrate is a solution of glutaraldehyde in Purified Water. It contains not less than 100.0 percent and not more than 104.0 percent of the labeled amount, the labeled amount being 50.0 g of C5H8O2 per 100 g of Concentrate.
Packaging and storage— Preserve in tight containers, protected from light, and avoid exposure to excessive heat.
Labeling— The label states that this article is not intended for direct administration to humans or animals.
Clarity of solution— Transfer 5.0 mL of Concentrate to a glass-stoppered, 100-mL graduated cylinder, add water to obtain 100 mL of mixture, insert the stopper, and mix by inverting the graduated cylinder several times. Allow the bubbles to rise, and view downward through the solution against a dark background: the solution is clear.
Identification—
2,4-Dinitrophenylhydrazine reagent— Add 4 mL of sulfuric acid to 0.8 g of 2,4-dinitrophenylhydrazine, then add 6 mL of water, dropwise, with swirling. When dissolution is essentially complete, add 20 mL of alcohol, mix, and filter. The filtrate is the 2,4-Dinitrophenylhydrazine reagent.
Procedure— Add 0.4 mL of Concentrate to 20 mL of 2,4-Dinitrophenylhydrazine reagent, mix by swirling, and allow to stand for 5 minutes. Collect the precipitate on a filter, and rinse thoroughly with alcohol. Dissolve the precipitate in 20 mL of hot ethylene dichloride, filter, and cool the filtrate in an ice bath until crystallization occurs. Collect the precipitate on a filter. Redissolve the precipitate by refluxing with 30 mL of acetone, filter, and cool the filtrate in an ice bath until crystallization occurs. Collect the precipitate on a filter: the 2,4-dinitrophenylhydrazone so obtained melts between 185 and 195, within a 3 range (see Melting Range or Temperature 741).
Specific gravity 841: between 1.126 and 1.135 at 20.
Acidity— Transfer 60.0 g to a conical flask, add phenolphthalein TS, and titrate with 0.10 N alcoholic potassium hydroxide to a pink endpoint that is permanent for not less than 15 seconds: not more than 40 mL of 0.10 N potassium hydroxide is consumed, corresponding to not more than 0.4% (w/w) of acid, calculated as acetic acid.
pH 791: between 3.7 and 4.5.
Heavy metals 231: 0.001%.
Assay—
Hydroxylamine hydrochloride solution— Dissolve 35 g of hydroxylamine hydrochloride in 150 mL of water in a 1000-mL volumetric flask, add isopropyl alcohol to volume, and mix.
Triethanolamine solution— Transfer 65 mL of triethanolamine to a glass-stoppered, 1000-mL volumetric flask, add water to volume, and mix.
Procedure— To 500 mL of Hydroxylamine hydrochloride solution add 15 mL of a solution of bromophenol blue in alcohol (1 in 2500), and add Triethanolamine solution from a buret to obtain a neutralized solution that appears greenish blue by transmitted light. Transfer 65.0 mL of the neutralized solution to a glass-stoppered, 500-mL conical flask, add 50.0 mL of Triethanolamine solution, purge with nitrogen, and insert the stopper. Add about 1.2 g of Concentrate, accurately weighed, by means of a suitable weighing pipet, insert the stopper, and allow to stand for 60 minutes, swirling the flask occasionally. Titrate with 0.5 N sulfuric acid VS to a greenish blue endpoint, and perform a blank determination (see Residual Titrations under Titrimetry 541). Calculate the percentage, by weight, of C5H8O2 in the Glutaral Concentrate taken by the formula:
[N(B – A)(0.05006) / W]100
in which N is the normality of the sulfuric acid; B and A are the volumes, in mL, of 0.5 N sulfuric acid VS consumed by the blank and specimen solution, respectively; 0.05006 is the mEq weight, in g per mEq, of glutaraldehyde; and W is the weight, in g, of Concentrate taken.
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