Discipline of Physics, Indian Institute of Technology Indore, Khandwa Road, Simrol, Indore 453552, India; Laser Biomedical Applications Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India.
Laser Biomedical Applications Division, Raja Ramanna Centre for Advanced Technology, Indore 452013, India; Homi Bhabha National Institute (HBNI), Training School Complex, Anushakti Nagar, Mumbai 400094, India.
Spectrochim Acta A Mol Biomol Spectrosc. 2021 Feb 15;247:119144. doi: 10.1016/j.saa.2020.119144. Epub 2020 Nov 4.
Urine analysis is an important clinical test routinely performed in pathology labs for disease diagnosis and prognosis. In recent years, near-infrared Raman spectroscopy has drawn considerable attention for urine analysis as it can provide rapid, reliable, and reagent-free analysis of urine samples. However, one important practical problem encountered in such Raman measurements is the orders of magnitude stronger spectral background preventing one to utilize the full dynamic range of the detector which is required for the measurement of Raman signal with good signal-to-noise ratio (SNR). We report here the results of an exploratory study carried out on human urine samples to show that the photobleaching, which is a major disadvantage during the fluorescence measurement, could be utilized for suppressing the measured background to improve the SNR of the Raman peaks. It was found that once the photobleaching reached its plateau, there were improvements by ~67% and ~47% in the SNR and the signal to background ratio (SBR), respectively, of the Raman signals as compared to the spectra measured at the start of acquisition. Further, the reduced background also allowed us to utilize the full dynamic range of the detector at increased integration time without saturating the detector indicating the possibility of obtaining an improved detection limit.
尿液分析是病理实验室中常规进行的一项重要临床检测，用于疾病诊断和预后。近年来，近红外拉曼光谱技术在尿液分析中引起了相当大的关注，因为它可以提供快速、可靠且无需试剂的尿液样本分析。然而，在这种拉曼测量中遇到的一个重要实际问题是，光谱背景的强度要高出几个数量级，这使得无法利用探测器的全动态范围，而这是获得具有良好信噪比（SNR）的拉曼信号所必需的。我们在此报告了对人尿液样本进行的探索性研究的结果，表明在荧光测量中是主要缺点的光漂白，可以用于抑制测量背景，从而提高拉曼峰的 SNR。结果发现，一旦光漂白达到平台期，与采集开始时测量的光谱相比，拉曼信号的 SNR 和信号与背景比（SBR）分别提高了约 67%和 47%。此外，减少的背景还允许我们在不使探测器饱和的情况下利用探测器的全动态范围增加积分时间，这表明有可能提高检测限。
