collecting a target sample suspected of containing the at least one taggant;

introducing the target sample to a portable interferometric system;

mixing the target sample with a buffer solution to form a test sample composition;

initiating interferometry on the test sample composition;

determining whether the test sample composition includes at least one taggant;

processing any data resulting from the interferometry of the test sample composition; and

transmitting the data to a user such that a positive or negative indication is given to indicate whether at least one suspected taggant is present or absent in the target sample,

the interferometric system including:

a cartridge system comprising: (i) an interferometric chip including one or more waveguide channels having a sensing layer thereon, the sensing layer adapted to selectively bind or otherwise be selectively disturbed by the at least one taggant within the test sample composition; (ii) a flow cell wafer; and (iii) a cartridge housing enclosing the interferometric chip and flow cell wafer; and

an alignment means for aligning the cartridge system within a cartridge recess in an optical assembly unit of the portable interferometric system upon insertion thereby providing optical and microfluidic alignment of the interferometric chip and flow cell wafer.