A method of quantifying an antimicrobial coatings using a handheld XRF analyzer is disclosed. The method provides an estimate of the expected level of antimicrobial efficacy for a thin film comprising silicon and/or titanium by obtaining a 14Si or 22Ti peak intensity using XRF spectroscopy and converting the obtained 14Si or 22Ti peak intensity to the expected level of efficacy using a calibration curve. A properly calibrated handheld XRF analyzer allows a user to assess the viability of antimicrobial coatings in the field, such as in a hospital where various fomites may be coated with silane and/or titanium compositions.