Dynamics of potassium and nitrate ions release from polycarboxylate cement with 5% KNO3

Release of potassium and nitrate ions from polycarboxylate-cement blocks containing 5% KNO3, with different exposure in extragent aqua redestillata was studied. Using flame photometry we found increased concentration of eliminated potassium ions into the extragent after the 24th hour (0.90 +/- 0.03 mg/cm3) while the maximum quantity of released potassium ions was measured after the 14th day (336 h)--1.50 +/- 0.02 mg/cm3 (t = 60, P < 0.001). The concentration of the released nitrate ions was determined by spectrophotometry at l = 410 nm. The degree of extraction of nitrate ions from the model cement blocks progressively increased with time, but their concentration in the cement decreased after the 14th day too, demonstrating a statistically significant difference: from 4.50 mg on the 20th minute to 2.60 mg on the 14th day (t = 115, P < 0.001).