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{{Short description|Chemical test for monosaccharides}}Barfoed's test is a chemical test used for detecting the presence of monosaccharides. It is based on the reduction of copper(II) acetate to copper(I) oxide (Cu2O), which forms a brick-red precipitate.JOURNAL

(Disaccharides may also react, but the reaction is much slower.) The aldehyde group of the monosaccharide which normally forms a cyclic hemiacetal is oxidized to the carboxylate. A number of other substances, including sodium chloride,JOURNAL, William H. Welker, J. Am. Chem. Soc., 1915, 10.1021/ja02174a036, 2227–2230, A Disturbing Factor in Barfoed's Test, 37, 9,weblink may interfere.Its autor is the Danish chemist Christen Thomsen Barfoed and is primarily used in botany.{{Citation needed|date=April 2009}}The test is similar to the reaction of Fehling's solution to aldehydes.

Composition

Barfoed's reagent consists of a 0.33 molar solution of copper (II) acetate in 1% acetic acid solution.WEB, Barfoed Reagent Safety Data Sheet,weblink Broward Central Science, Carolina Biological Supply Company, 10 September 2020, 14 February 2020,weblink" title="web.archive.org/web/20200214175228weblink">weblink dead, The reagent does not keep well and it is therefore advisable to make it up when it is actually required.BOOK, Bowen, Graham and Williams, A Students' Handbook of Organic Qualitative Analysis, University of London Press, 1957, 73,

Procedure

1 drops of Barfoed's reagent is added to 2 mL of given sample in a test tube and boiled for 3 minutes and then allowed to cool. If a red precipitate occurs, a monosaccharide is present.

References

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