Characterization of postmortem biochemical changes in rabbit plasma using ATR-FTIR combined with chemometrics: A preliminary study

Abstract

Postmortem interval (PMI) determination is one of the most challenging tasks in forensic medicine due to a lack of accurate and reliable methods. It is especially difficult for late PMI determination. Although many attempts with various types of body fluids based on chemical methods have been made to solve this problem, few investigations are focused on blood samples. In this study, we employed an attenuated total reflection (ATR)-Fourier transform infrared (FTIR) technique coupled with principle component analysis (PCA) to monitor biochemical changes in rabbit plasma with increasing PMI. Partial least square (PLS) model was used based on the spectral data for PMI prediction in an independent sample set. Our results revealed that postmortem chemical changes in compositions of the plasma were time-dependent, and various components including proteins, lipids and nucleic acids contributed to the discrimination of the samples at different time points. A satisfactory prediction within 48h postmortem was performed by the combined PLS model with a good fitting between actual and predicted PMI of 0.984 and with an error of ±1.92h. In consideration of the simplicity and portability of ATR-FTIR, our preliminary study provides an experimental and theoretical basis for application of this technique in forensic practice.

Application of FTIR spectroscopy for traumatic axonal injury: a possible tool for estimating injury interval

“…In the present study, the PLS model was established based on the calibration dataset and used to predict validation samples. Numerous studies have confirmed the efficiency of this supervised model in classifying or predicting different categories of biological tissues [ 41 , 42 , 14 ]. In Figure 5 A, the PLS score plot illustrates a straightforward separation amongst the four groups, where the control, 12, and 24h groups were distributed along LV1 accounting for 53.72% of total variance, while 24 h and the remaining groups were segregated along LV2 (18.90% of total variation).…”

“…Emerging evidence shows its great potential as a new promising diagnostic method to detect chemical changes from multiple macromolecules including proteins, lipids, carbohydrates, and nucleic acids, in biological tissues [ 12 , 13 ]. Combination with IR microscopy allows for spectral collection in complex and heterogeneous tissues with minimal sample preparation, and the acquired spectral fingerprints can yield subsequent classification of spectra into different categories using objective computational algorithms [ 14 , 15 ]. According to its numerous advantages, this spectroscopic technique has been widely used in various murine brain models, including ischemic brain injury [ 16 ], Alzheimer’s disease [ 17 ], brain tumors [ 18 ], and multiple sclerosis [ 19 ], but only a few attempts have been made to study TAI [ 20 – 22 ].…”

Identification of Skin Electrical Injury Using Infrared Imaging: A Possible Complementary Tool for Histological Examination

“…Therefore, this promote us to develop a FTIR-based method for auxiliary diagnosis in cases of electrocution, which could provide a more objective and intuitive identification of electrical mark than routine histological examination. In this study, the PLS model was chosen to process the spectral dataset because it has been demonstrated that this supervised pattern recognition method is powerful for distinguishing different sample categories[25–28]. The spectra in the calibration group were used to establish the initial PLS model.…”

Estimation of the age of human semen stains by attenuated total reflection Fourier transform infrared spectroscopy: a preliminary study

“…Moreover, FTIR has been used for the analysis, detection and identification of body fluids and biological tissues [14,15]. In our previous work, satisfactory results were achieved using attenuated total reflection-FTIR (ATR-FTIR) for the analysis of time-dependent changes in biological tissues, combining with chemometric methods which further improved the accuracy of the results [16][17][18][19][20]. In the field of semen research, FTIR has been used to characterize human sperm in clinical settings [21].…”