In present work, a novel
quartz crystal microbalance (QCM) sensor array has been developed for prompt identification of primary
aldehydes in human body odor.
Molecularly imprinted polymers (MIP) are prepared using the
polyacrylic acid (PAA)
polymer matrix and three organic
acids (propenoic
acid,
hexanoic acid and
octanoic acid) as template molecules, and utilized as QCM surface coating layer. The performance of MIP films is characterized by 4-element QCM sensor array (three coated with MIP layers and one with pure PAA for reference) dynamic and static responses to target
aldehydes:
hexanal,
heptanal, and
nonanal in single, binary, and tertiary mixtures at distinct concentrations. The target
aldehydes were selected subsequent to characterization of
body odor samples with solid phase-micro extraction gas chromatography mass spectrometer (
SPME-GC-MS). The
hexanoic acid and
octanoic acid imprinted PAA exhibit fast response, and better sensitivity, selectivity and reproducibility than the propenoic
acid, and non-imprinted PAA in array. The response time and recovery time for
hexanoic acid imprinted PAA are obtained as 5 s and 12 s respectively to typical concentrations of binary and tertiary mixtures of
aldehydes using the static response. Dynamic sensor array response matrix has been processed with principal component analysis (PCA) for visual, and support vector machine (SVM) classifier for quantitative identification of target odors.
Aldehyde odors were identified successfully in principal component (PC) space. SVM classifier results maximum recognition rate 79% for three classes of binary odors and 83% including single, binary, and tertiary odor classes in 3-fold cross validation.