Serology Lab Report Example | Topics and Well Written Essays - 500 words

Serology - Lab Report Example The specificity of this test lies on the fact that hemoglobin is only contained in blood. This change in pH is then detected by phenolphthalein, and the solution turns into pink quickly, or leuchomalachite green, which turns the solution into green (Houck and Siegel, 2010; Tobe et al., 2007). However, there are a few considerations in using these substrates. First, because phenolphthalein is a pH indicator, phenolphthalein reacts with any basic solution. It is thus important that the addition of LMG or PPT prior to the addition of hydrogen peroxide do not yield a color change. This ensures that any change in the solution results from the reaction of hemoglobin with hydrogen peroxide. Second, when the phenolphthalein is exposed too long in the solution, a spontaneous oxidation occurs causing the colorimetric reaction to occur (Houck and Siegel, 2010). The color change indicating presence of blood must thus be quick. Third, substances in fruits and vegetables may act like a peroxidase (Tobe et al., 2007). MATERIALS AND METHODS Sample FS-26-07 was tested for the presence of blood using leuchomalachite green (LMG) and phenolphthalein (PPT). Two set-ups were prepared. Each set-up consists of three spot plates each containing a strip of 1) positive control, 2) negative control, or 3) FS-26-07. The spot plates in the first set-up were added with two drops of LMG, while those of the second set-up were added with the same amount of PPT.