formaldehyde - Sciencemadness Dot Org

DETECTIOX OF FORMALDEHYDE 253
spirits, beer, and solid foods. In general, the test is best applied to 25 *;•,
30 ec of distillate. In the ease of solid foods, an aqueous suspension in
water or dilute sulfuric acid may be st earn -distilled to obtain a *ui:abit
solution for analysis.
Detection of Formaldehyde in Products which have been Subjected to
Formaldehyde Treatment
Formaldehyde that is combined with hydroxy compounds in the form of
formal or methylene ethers can be liberated by heating with dilute solutions
of strong acids. Methylene derivatives of amino and arnido cornpounds
may also be hydrolyzed in the same manner. As a result, formaldehyde
solutions suitable for analytical tests can usually be readily obtained
from such varied products as textiles and paper which have been treated
with formaldehyde and urea-formaldehyde condensates, polyvinyl formal*,
protein products which have been hardened or insolubilized by formaldehyde
treatment, formaldehyde-tanned leather, etc. In general, the material
to be examined is heated with a solution of a strong mineral acid and
then subjected to distillation or steam distillation. Sulfuric acid is nsuaily
preferable because of its non-volatile nature and a 10 to 20 per cent solution
h generally satisfactory. In carrying out such distillations the condenser
outlet should dip below the level of a little distilled water which is first
placed in the receiver so that any gaseous formaldehyde will be dissolved.
A solution obtained in this way will naturally contain any free formaldehyde
originally present in the sample material. At low concentrations (less than
approximately 10 per cent), formaldehyde can be quantitatively distilled
from aqueous solutions usually coming over in the first 10 to 60 per cent of
the distillate- Just how much distillate must be collected to secure all the
formaldehyde for quantitative studies depends on the amount and concentrations
involved. It is best to determine the size of this fraction by a tiiai
analysis in which successive fractions of distillate are subjected to Deiuges 1
test, until a negative result is obtained.
References
1. "Allen's Commercial Organic Analysis," 5tix Ed., Vol. L, p. 302, Philadelphia, P. Blaktetoa's Soa , Vol, IX, pp. 92-3.
4. Aioy, J., and Yaldiguie, A., J. pharm. chim. .;s.r 1, -390-3 (1936); C. Ait 21* 235S-S.
5. Bamberger, E.a Ber., 32, IS07 C1SS9).
6. Barnes, E. C, and Spriober, H. W„ J. Ind. Hug., 24, 10 (1942).
7. Bonnet, F., Jr., J. Am. Clem. $oc.> 27. 601 £1905).
8. Boyd, 11, J., and B&mbach, K., 7ud. Eng. Chem., Anal. Ed.r 15> 314-5 (l$43\
9. Boyd, M. J., and Logan, M. A., J. Biol. Clem., 146, 279 (1942).
10. Bryant, W. M. D., J". Am. Chem. Soc., H, 3760 .1932). ,
1L Campbell, N. It., Analyst, 61, S92 (1636).
12. Cohn, IL, CMm. Ztg., 45, 997-S (1921); C. A„ it, 222.
13. Denigfe, G., J. pharm. chim. (4), 6* 193 '1806^