Abstrait

Simultaneous determination of phosphate and silicate in complex unknown mixtures by H-point curve isolation method and H-point standard addition method

Maryam Abbasi Tarighat, Fereshteh Abasi Tarighat, Reza Sharafdini

The present work examine the capability of standard addition method to correct the matrix effect and the advantages of the curve isolation of data using H-point standard addition method (HPSAM) and H-point curve isolation method (HPCIM) for determination in unknownmixtures. By a successive standard addition of the analyte was performed. The average of the created spectra was calculated. The subtraction of obtained averaged spectrumfromthe initial solution spectrumgives constant cumulative spectrum for interferents. The proposed procedure was based on the formation of phosphate- and silico-molybdenum blue complexes in the presence of ascorbic acid. Molybdenum blue is not relatively free from the interferences caused by the other ions, therefore several cations and anions (such as As5+, V5+, Sn2+, Zn2+, Fe3+, S2-, Mn  4 O , F-, I-) can react with this reagent. It is also not necessary to condition carefully the medium to remove interfering species. Hence due to the standard addition of analyte in sample solution more accurate results will be produced. This method was validated for the determination of phosphate and silicate in sea water, river water, mineral water, waste water, urine, detergent and soft drink samples.