Standard calibration curves were prepared from 2 ml of mucin standard solutions (0.25, 0.5, 0.75 and 1mg/2 ml). After adding 0.2 ml of periodic acid reagent, the samples were incubated at 37°C, for 2 h, in a water bath. Then, 0.2 ml of Schiff reagent was added at room temperature. Thirty minutes later, the absorbance of the solution was recorded at 555 nm in a UV spectrophotometer. Duplicate samples were run. Samples were determined with the same procedure. The mucin content was calculated from the standard calibration curve.