It has been established that condom traces are evidence to consider in sexual assaults and rape cases, but gaps in the interpretation of the evidence have been highlighted. Condom lubricants, more specifically silicone lubricants, are known to transfer in the vaginal matrix and can be easily recovered when analysed with infrared spectroscopy. The interpretation of condom evidence in forensic science requires a better understanding of mechanisms such as background, transfer, and persistence of the traces in a given matrix.

This work aimed to use Diffuse Reflectance Infrared Fourier Transform Spectroscopy (DRIFTS-FTIR) to provide an empirical dataset addressing the persistence of transferred silicone lubricants in the vaginal matrix. Swabs for condom traces were self-collected from volunteers at different post-coital intervals ranging up to 36 h post-coitus. The effect of the time elapsed between the intercourse and the time of sample collection was investigated, and a preliminary observation of the activity of the claimant as an influence factor is also discussed.

Silicones were easily detected up to 18 h post-coitus, while the vaginal matrix dominated the spectra after 36 h. At 24 h post-coitus, the results were not reproducible, which makes it difficult to assess a persistence at this time. The data were found to vary between the participants, but a similar trend was observed in the exponential decay. Finally, the activity of the volunteer was found to be one of the key parameters to the loss and differences in absorbance which were observed in the data. It was observed that when volunteers were taking a shower, which is likely to happen with real world cases, silicone persistence was also affected.

已经确定安全套痕迹是性侵犯和强奸案件中需要考虑的证据，但在解释证据方面的差距已被凸显出来。众所周知，避孕套润滑剂，更具体地说是硅酮润滑剂，会在阴道基质中转移，当用红外光谱分析时很容易回收。法医科学中对避孕套证据的解释需要更好地理解给定矩阵中痕迹的背景、转移和持久性等机制。

这项工作旨在使用漫反射红外傅里叶变换光谱 (DRIFTS-FTIR) 来提供经验数据集，以解决转移的有机硅润滑剂在阴道基质中的持久性。避孕套痕迹的拭子是从志愿者在不同的性交后间隔（最多可达性交后 36 小时）自行收集的。研究了性交时间与样本采集时间之间的影响，并初步观察了作为影响因素的索赔人的活动。

在性交后 18 小时内很容易检测到有机硅，而阴道基质在 36 小时后在光谱中占主导地位。在性交后 24 小时，结果不可重复，这使得此时难以评估持久性。发现参与者之间的数据有所不同，但在指数衰减中观察到类似的趋势。最后，发现志愿者的活动是数据中观察到的吸光度损失和差异的关键参数之一。据观察，当志愿者洗澡时（这在现实世界中很可能发生），有机硅的持久性也会受到影响。