太赫兹时域光谱技术测定淀粉中的丙烯酰胺

Determination of Acrylamide in Starch Based on Terahertz Time-domain Spectroscopic Technique

目的:利用太赫兹时域光谱(terahertz time-domain spectroscopy,THz-TDS)技术对丙烯酰胺、淀粉及两者混合物进行定性、定量检测。方法:通过采集时域光谱数据,获得丙烯酰胺、淀粉及两者混合物在THz波段的吸收谱与折射率谱;采用偏最小二乘法(partial least squares,PLS)对淀粉中丙烯酰胺的低浓度含量进行回归拟合分析。结果:丙烯酰胺在1.33 THz处有一个明显的特征吸收峰,可用于物质识别;随着混合物中丙烯酰胺质量的增加,样品的吸收系数和折射率都呈现逐渐下降的趋势。由回归模型分析可得,混合物中丙烯酰胺质量含量与吸收系数、折射率都有良好的线性关系,其中基于折射率的PLS模型相关系数可达0.9994,标准误差0.1335%,检出极限0.4402%,定量限1.334%,最大绝对偏差小于0.2497%。结论:THz-TDS技术具有检测结果可靠的优点,可用于淀粉中丙烯酰胺含量的快速、无损检测,为太赫兹光谱检测食品中的有害添加物提供了理论基础。

Objective： Terahertz time-domain spectroscopy （THz-TDS） technology was utilized for the determination and analysis in the quantity and quality of acrylamide, starch and its mixtures. Methods： The refractive index and absorption spectrum of the acrylamide, starch and its mixtures were obtained by terahertz time-domain spectroscopy （THz-TDS）; Partial least squares （PLS） regression was taken to regressively analyse the low concentrations of acrylamide in starch. Result： experimental results showed that there was distinct absorption feature for acrylamide at around 1.33 THz, which can be used as fingerprint for its material recognition. Furthermore, absorption coefficient and refractive index of mixtures is gradually increased with fewer acrylamide in mixture. The result showed that there was a good linear relation- ship between the content of acrylamide in the mixture and both parameters of absorption coefficient and refractive index. The correlation factor from PLS model based on refractive index was 0.9994, and the root mean square error was 0.1335%. The detection limit of acrylamide concentration in mixture was 0.4402%, while limit of quantitation was 1.334% and the maximum absolute deviation error was less than 0.2497%. Conclusion： THz-TDS technique, as a quick and non-damaging measurement, can be used to detect the content of food additives like acrylamide in food fields with incredible testing result. This work also provides a experimental and theoretical basis for terahertz spectroscopy detection of harmful materials in the areas such as food.