Application of the quartz crystal microbalance for determination of phenol in solution

Polymethylmetacrylate (PMMA) modified quartz crystal microbalance (QCM) has been tested for determination of phenol in solution. A solution casting method was used for modification of quartz crystal with a thin layer of PMMA. Determination was based on frequency shifts of PMMA modified quartz crystal electrode due to the adsorption of phenol at the surface of modified electrode. Measurements were carried out by exposure of PMMA modified electrode both directly to the phenol solutions and indirectly to the phenol vapors exist in the head space of phenol solutions (head space analysis). The frequency shifts were found to be linear against the concentration of phenol in the range between 0 and 10 ppm for direct exposure and 1–100 ppm for head space analysis. The sensitivity factors of 37.87 and 1.47 Hz ppm−1 were found for direct exposure and head space analysis, respectively. Treatment of phenol solutions by acidification with hydrochloric acid (pH∼3) and salt addition (saturation with sodium chloride) caused an increase of sensitivity of the sensor. Sensitivity factors of 49.7 and 6.5 Hz ppm−1 were found for direct and head space analysis, respectively, after solution treatment by acidification and salt addition.