Abstract Quantitative detection for nanomolar analytes is a challenge for surface-enhanced Raman scattering (SERS). In this report, a SERS method which combined with an internal standard method and a two-step centrifugation method was established for trace analysis of two drugs using a portable Raman spectrometer. Metformin hydrochloride was used as an internal standard for phenformin hydrochloride to increase the linearity of SERS detection, while, streptomycin sulfate was used for tigecycline. The two-step centrifugation method for sample preparation increased the density of hot spots and the concentration of analyte by accumulating silver nanoparticles. Therefore, the detection sensitivity was significantly improved. Furthermore, the repeatability of SERS signals was increased by adding 200 µL of the sample solution into a slit-type quartz cuvette to make the excitation light transmit through a heavy thickness sample solution. The RSDs of SERS signal intensity ratio of phenformin hydrochloride and tigecycline to internal standard were 1% and 1.6%, respectively. Finally, phenformin hydrochloride and tigecycline exhibited a good linearity in the range of 1–500 nM (R2 = 0.9976) and 10–750 nM (R2 = 0.9926), respectively. In a word, this method greatly improved the lower limit of quantitation of SERS, and laid foundation for rapid and convenient quantitative detection of low concentration drug in biological samples.

中文翻译：

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表面增强拉曼散射结合内标法和两步离心法定量检测纳摩尔药物

摘要 纳摩尔分析物的定量检测是表面增强拉曼散射 (SERS) 的一项挑战。在本报告中，建立了一种结合内标法和两步离心法的 SERS 方法，用于使用便携式拉曼光谱仪对两种药物进行痕量分析。盐酸二甲双胍用作盐酸苯乙双胍的内标以增加SERS检测的线性，而硫酸链霉素用于替加环素。用于样品制备的两步离心法通过积累银纳米粒子来增加热点的密度和分析物的浓度。因此，检测灵敏度显着提高。此外，通过将 200 µL 样品溶液加入狭缝型石英比色皿中，使激发光透过厚厚的样品溶液，提高了 SERS 信号的可重复性。盐酸苯乙双胍和替加环素的 SERS 信号强度比与内标的 RSD 分别为 1% 和 1.6%。最后，盐酸苯乙双胍和替加环素分别在 1–500 nM (R2 = 0.9976) 和 10–750 nM (R2 = 0.9926) 范围内表现出良好的线性。总之，该方法大大提高了SERS的定量下限，为快速方便地定量检测生物样品中的低浓度药物奠定了基础。盐酸苯乙双胍和替加环素的 SERS 信号强度比与内标的 RSD 分别为 1% 和 1.6%。最后，盐酸苯乙双胍和替加环素分别在 1–500 nM (R2 = 0.9976) 和 10–750 nM (R2 = 0.9926) 范围内表现出良好的线性。总之，该方法大大提高了SERS的定量下限，为快速方便地定量检测生物样品中的低浓度药物奠定了基础。盐酸苯乙双胍和替加环素的 SERS 信号强度比与内标的 RSD 分别为 1% 和 1.6%。最后，盐酸苯乙双胍和替加环素分别在 1–500 nM (R2 = 0.9976) 和 10–750 nM (R2 = 0.9926) 范围内表现出良好的线性。总之，该方法大大提高了SERS的定量下限，为快速方便地定量检测生物样品中的低浓度药物奠定了基础。