Forensic chemistry is an important
and rapidly growing branch of
analytical chemistry. As a part of forensic practices, phenotype profiling
is beneficial to help narrow down suspects. The goal of this study
is to identify a person’s age range using dried bloodstains.
Attenuated total reflection Fourier transform-infrared (ATR FT-IR)
spectroscopy is the technique used to acquire information about the
total (bio)chemical composition of a sample. For the purpose of this
proof-of-concept study, a diverse pool of donors including those in
newborn (<1), adolescent (11–13), and adult (43–68)
age ranges was used. Different donor age groups were found to have
different levels of lipids, glucose, and proteins in whole blood,
although the corresponding spectral differences were minor. Therefore,
the collected data set was analyzed using chemometrics to enhance
discrepancy and assist in donors’ classification. A partial
least squares discriminant analysis (PLSDA) was used to classify ATR
FT-IR spectra of blood from newborn, adolescent, and adult donors.
The method showed a 92% correct classification of spectra in leave-one-out
cross-validation (LOOCV) of the model. Overall, ATR FT-IR spectroscopy
is nondestructive and can be an infield method that can be used for
a variety of forensic applications. In general, the developed approach
combining ATR FT-IR spectroscopy and advanced statistics shows the
great potential for classifying (bio)chemical samples exhibiting significant
intra-class variations.