Statistics from Altmetric.com
We have all faced the dilemma. The laboratory receives a universal container in which a tissue sample is immersed in a clear liquid. The tissue is still pink and blood stained. So has the sample been placed in saline in error or is it in formalin and simply not yet fixed? In time honoured fashion, the laboratory technician or pathologist removes the lid of the container and gingerly inhales. Regrettably, by the time the characteristic odour of formalin is recognised, its noxious and irritant properties have already inflicted their damage upon the teary eyed investigator. It need no longer be this way!
An easily and rapidly applied technique can establish the presence or absence of formalin without placing the investigating staff in harm's way.
Place a few drops of reticulin solution in a beaker and add small drops of your test solution. If the test solution is formalin, the reticulin solution will turn black. A similar effect can be produced by adding the test solution to Schiff's solution. In this case, adding drops of formalin will turn the combination a deep magenta colour. The addition of a test solution of saline (the most frequently encountered alternative) will produce no colour change to Schiff's solution and will turn reticulin solution white. Because all laboratories will have both reagents already prepared on their shelves, the test may be done in a matter of seconds.
Good old fashioned chemistry to the rescue!