Quantitative analysis is an important aspect of surface-enhanced Raman spectroscopy (SERS). However, due to changes in the enhancing performance of SERS substrates, it is difficult to obtain reliable analysis results. In this work, a reliable quantitative method is introduced to overcome this problem by an external standard method. To achieve the external standard method, a self-assembled film of activated carbon nanoparticles is first prepared at the air/liquid (KCl aqueous solution) interface. Next, the activated carbon film transferred onto the surface of a Teflon slice (extraction film) is dipped into a high concentration of analyte to achieve reliable saturated adsorption, and the extraction film under saturated adsorption is called the reference (external standard). The uniformity is very good in one extraction film and thus the extraction film is cut into halves (used to prepare the determinand and reference) to eliminate deviation of different batches. The saturated adsorption time of the extraction film is different for different concentrations of analyte and the concentration can be therefore quantified by saturated adsorption time. Because the enhancing performance of the SERS substrate is almost unchanged in a short time and all of the SERS measurements are conducted at a similar measurement condition (saturated adsorption), the SERS intensity of the determinand and reference is almost the same under saturated adsorption. The SERS intensity of the determinand normalized by the reference is therefore very stable and uniform (approximately equal to “1” under saturated adsorption). The preparation conditions of the determinand and the reference are the same except for the concentration of the analyte, thus the interference can be eliminated by an external standard method. Any perturbations caused by the performance change of colloid substrates can be therefore effectively overcome. Moreover, the saturated adsorption time of the extraction film for different concentrations of analyte has a large time margin. This method is very simple and the cost is very low. Based on this method, a concept of time-discretized quantitative SERS (TDQ-SERS) is introduced. Thus, a reliable, simple, and economic quantitative SERS technique can be achieved.

中文翻译：

---

自组装活性炭纳米颗粒，用于可靠的时间离散的定量表面增强拉曼光谱

定量分析是表面增强拉曼光谱（SERS）的重要方面。但是，由于SERS基板的增强性能的变化，因此难以获得可靠的分析结果。在这项工作中，引入了可靠的定量方法以通过外标方法克服此问题。为了实现外部标准方法，首先在空气/液体（KCl水溶液）界面处制备了活性炭纳米颗粒的自组装膜。接下来，将转移到聚四氟乙烯薄片表面上的活性炭膜（萃取膜）浸入高浓度的分析物中，以实现可靠的饱和吸附，并且将饱和吸附下的萃取膜称为基准（外标）。一个提取膜的均匀性非常好，因此将提取膜切成两半（用于准备确定和参考），以消除不同批次的偏差。对于不同浓度的分析物，萃取膜的饱和吸附时间是不同的，因此可以通过饱和吸附时间对浓度进行定量。由于SERS底材的增强性能在短时间内几乎没有变化，并且所有SERS测量都是在相似的测量条件（饱和吸附）下进行的，因此在饱和吸附条件下，测定分子和参比样品的SERS强度几乎相同。因此，由参考确定并归一化的SERS强度非常稳定且均匀（在饱和吸附下大约等于“ 1”）。测定物和参比物的制备条件除了分析物的浓度相同外，可以通过外标法消除干扰。因此，可以有效地克服由胶体基质的性能变化引起的任何扰动。而且，提取膜对于不同浓度的分析物的饱和吸附时间具有较大的时间余量。该方法非常简单并且成本非常低。在此方法的基础上，引入了时间离散量化SERS（TDQ-SERS）的概念。因此，可以实现可靠，简单且经济的定量SERS技术。因此，可以有效地克服由胶体基质的性能变化引起的任何扰动。而且，提取膜对于不同浓度的分析物的饱和吸附时间具有较大的时间余量。该方法非常简单并且成本非常低。在此方法的基础上，引入了时间离散量化SERS（TDQ-SERS）的概念。因此，可以实现可靠，简单且经济的定量SERS技术。因此，可以有效地克服由胶体基质的性能变化引起的任何扰动。而且，提取膜对于不同浓度的分析物的饱和吸附时间具有较大的时间余量。该方法非常简单并且成本非常低。在此方法的基础上，引入了时间离散量化SERS（TDQ-SERS）的概念。因此，可以实现可靠，简单且经济的定量SERS技术。