牙膏中可溶性/游离氟化物快速定量分析方法研究OACSTPCD

Low-field nuclear magnetic resonance(LF-NMR)and high-field solid-state nuclear magnetic resonance(SS-NMR)were effectively combined to systematically study the fluoride in toothpastes,and a rapid LF-NMR method for quantitative analysis of soluble/ionic fluoride in toothpastes was established.The results showed that the relative standard deviations(RSDs)of LF-NMR in 6 parallel tests were all within 2%,indicative of high precision.In the actual sample test,117 toothpaste samples were selected,and the relative deviation between LF-NMR data and national standard test data was within±5%for the 110 toothpaste samples therein.For the other 7 samples,the quantitative data of LF-NMR were significantly different from that of the national standard method.Combined with the analysis results of SS-NMR,it was found that the difference was due to the existence of insoluble fluoride substances in the system,which affected the relaxation time of the whole system and therefore the results of LF-NMR were lower than that of the national standard method.Nevertheless,LF-NMR could still be used as a fast screening method to reflect the quality of toothpaste in time.The LF-NMR method was a very fast quantitative analysis method,the toothpaste samples could be directly tested without any pre-treatment,and the whole test process was approximately 5 min.In addition,combined with SS-NMR technology,the systems which were applicable to be measured with LF-NMR quantitative test were further defined.