TWO BENZALKONIUM HOMOLOGUES IN RABBIT EYE
MALDI imaging offers new insights into ocular pharmaceutical research, especially for high precision distribution and quantification studies. This is exemplified by the localization of two benzalkonium salt (BAK) species in different ocular structures. The aim of this study was the quantification of two BAKs species at the micrometer level after deposition of 2,5-DHB as MALDI matrix. The SunCollect spraying system preserves the spatial resolution of different compounds in fine tissue areas.
This study of benzalkonium salt distributions in the eye demonstrates MALDI Imaging’s pertinent application in ophthalmology, an area that has recently gained a lot of interest. The quantification of compounds directly from small histological structures of the eye provides knowledge of the molecules’ local effects. MSI presents a powerful tool to investigate the distribution of compounds such as BAK which are known to have adverse effects and is therefore useful in preclinical studies in pharmacology and toxicology.
(Courtesy of ImaBiotech, MS Imaging Department, Lille, France; https://www.imabiotech.com)
MALDI IMAGING – TWO PROCEDURES IN ONE
Fingerprint analysis plays an important role in crime investigation. Fingermarks can not only be used for the identification of subjects, in addition, MALDI Imaging methods provide the possibility to analyze chemical substances the owner of the fingermark has been in contact with.
In a simple experiment, a test person touched with his finger the inner wall of a vial which had included cocaine (Mr=303.36 g/mol). After that, the person made a fingermark on a stainless steel MALDI sample plate. This fingermark was covered with MALDI matrix by spraying with the SunCollect instrument and subsequently analyzed with a MALDI mass spectrometer.
Additional fingermarks were taken 4 and 24 hours after contamination with cocaine and analyzed in the same way. During that time, the test person washed his hands several times.
While the analyte is highly concentrated at the beginning, the intensity of the signal decreases over the time, especially when comparing the signal intensity to the matrix signals. But even after 24 hours and hand washing, cocaine could be identified. By addition of an internal standard to the matrix solution, a quantitative analysis could be possible.
Advantageously this method is combining two procedures: the identification of a person with his fingermark and the proof of the presence of illegal substances.
Fingermark analysis with MALDI Imaging
Contamination with cocain analyzed with a MALDI mass spectrometer
It has to be admitted that a fingermark which was taken and analyzed before contamination showed no signal from cocaine. This is very important especially considering that people who frequently handle banknotes may find their hands become contaminated with cocaine.