<![CDATA[High phosphate concentrations in aquatic environments can cause algal bloom that canresult serious problem in aquatic ecosystems. As such, the determination techniques ofphosphate which reflect its bioavailability need to be available in order to know the levelof phosphate concentration in aquatic ecosystem. One of effective method that is currentlyused in the determination of phosphate bioavailability in aquatic environments is aDiffusive Gradient in Thin Films (DGT) technique with TiO2 as a binding layer. In thisresearch, the crosslinking modification of polyacrylamide gel was used as a diffusive gelsin DGT system to improve the selectivity of the orthophosphate adsorption. Thecrosslinker that used for modification is N, N'-methylenebisacrylamide (MBA). Diffusioncoefficient with concentration of crosslinking degree of variation was found that thediffusion coefficient is inversely proportional to the concentration of cross linker. Test ofselectivity DGT diffusive gels with crosslinking MBA done through the calculation of totalphosphate levels in both systems with a competing organic phosphorus compound in theform of phytic acid anions and humic acids. The calculation is done using the systemdeployment within 24 hours and the concentration of crosslinking variation MBA (0,05%,0,2% and 0.3%). Obtained through these calculations show that the diffusive gelcrosslinking MBA with a concentration of 0.3% gave the best selectivity towardsorthophosphate anion. This has been proven through experimental research by usingorganic phosphate as competing species. Concentration of phytic acid and humic acidadsorbed on these systems tend to stagnate despite its concentration increases. This provesthat the diffusive gel MBA 0,3% have skipped a certain threshold in both the organic acids; was only of 28,753μg for phytic acid and 33,177 μg for humic acid. Based on this study itcan be concluded that the degree can be used as a crosslinking on diffusive polyacrylamidegels in DGT system. The use of crosslinked diffusive material can also provide phosphatebioavailability concentration measurements that are more accurate because it is moreselective towards amount of orthophosphate and limting organic phosphate diffused asphytic acid and humic acid which can interfere with analysis of the levels oforthophosphate.]]>
