油脂低场核磁(LF-NMR)检测参数的优化试验

Determination of Oil Quality by LF-NMR:Optimization of Measurement Parameters

适当的低场核磁共振(LF-NMR)检测条件对于保障数据的可靠性具有重要意义。该文研究了大豆油LF-NMR检测过程中仪器参数、样品温度及体积等对检测结果稳定性及重现性的影响。结果表明,将2.5 mL油脂样品置于核磁试管中,并在32℃恒温10 min,采样前稳定1 min,在TR=2 000 ms,τ=200μs,EchoCount=5 000个,NS=4次,TD=500 050,SW=250 kHz参数条件下采集信号,可保证检测结果稳定可靠。研究结果可为后期应用LF-NMR技术进行油脂品质检测提供适当的检测条件参考。

In order to get reliable results, the measurement parameters of low field NMR（LF-NMR） should be optimized. In this paper, effects of instrument parameter, temperature and volume of the sample on the stability and reproducibility of the results were investigated, by using soybean oil as the object. The results indicated that good stability and reproducibility can be guaranteed if the following parameters such as TR = 2 000 ms, r = 200 p,s, EchoCount = 5 000, NS = 4, TD = 500 050 and SW = 250 kHz are chosen. Before the measurement, a sample of 2. 5 mL should be stabilized at 32 ℃ for 10 min, and subsequently transferred to the probe and tested after 1 min stabilization. The results can provide appropriate detection conditions for the latter application of LF-NMR technique in the determination of oil quality.