三磷酸铝的傅里叶变换红外光谱分析

摘要

Fourier transform infrared spectrometry (FT-IRS) was applied to assaying of aluminum rntriphosphate (AlH2P3O10·2H2O) in the presence of the main impurities, aluminum metaphosphate and aluminum dihydrogen phosphate, produced during its preparation. As shown in the IR absorption spectra, absorption maxima of aluminum triphosphate (Al-TP) and aluminum metaphosphate (Al-MP) were found at the wavenumbers of 986 cm-1 and 740 cm-1 respectively, while no absorption peak of aluminum dihydrogen phosphate was observed in this wavelength region. It was proposed that aluminum metaphosphate was used as the internal standard, and a plotting of ratio of values o{ peak height of Al-TP to Al-MP against ratio of values of concentration of Al-TP to Al-MP was made to obtain a linear calibration curve by method of curve-fitting or minimum baseline calculation. Ratio of contents of Al-TP to Al-MP of the sample was found in this way with elimination of the interference of aluminum metaphosphate. Contents of aluminum dihydrogen phosphate and moisture of the sample were determined individually by methods given in the standards 浙 B/HG 204-88 and GB/T 1714-1979. Finally, the content of aluminum triphosphate in the sample was calculated by substraction as given by the formula given.%提出了应用傅里叶变换红外光谱法,在由生产中产生的偏磷酸铝和磷酸二氢铝杂质存在下测定三磷酸铝(AlH2P3O10·2H2O).从红外吸收光谱可见,三磷酸铝(Al-TP)及偏磷酸铝(Al-MP)分别在波数为986 cm-1及740 cm-1处存在特征吸收峰,而磷酸二氢铝在此波段无吸收峰.据此提出,用Al-MP作内标,以Al-TP与Al-MP的峰高比值与两者相应的浓度比值图,并采用曲线拟合或最低基线计算法制得工作曲线.由此可求得试样中Al-TP与Al-MP的含量比值.由于采用了Al-MP作内标,其干扰也得到消除.同时用标准(浙B/HG 204-88及GB/T 1714-1979)中所述方法对样品中磷酸二氢铝及水分的含量分别予以测定.按文中所给的公式,计算样品中三磷酸铝的含量.