Potassium disposable optical sensor based on transflectance and cromaticity measurements

Use of digital reflection devices for measurement using hue-based optical sensors

“…The R 2 of the fit was 0.993 and using the IUPAC criteria to calculate the detection limit (3 s), a dynamic range of 5.5 × 10 −6 M to 1.0 × 10 −1 M was found. The limit of detection found is similar to that obtained working with transmission images using the same Boltzmann type equation transmission mode (from 0.14% to 0.75%) [1] and much better than using transflectance as analytical parameter (from 2.4% to 7.9%) [38].…”

Evaluation of analytical reflection scanometry as an analytical tool

“…Although the LODs obtained here are similar to those obtained from absorbance (2.28 Â 10 À5 M) 39 and transflectance (2.18 Â 10 À5 M) 49 measurements, when we used the calibrated scanner, applying the imaging acquisition protocol, we were able to reach the LOD using portable instrumentation (5.0 Â 10 À6 M) 50 or using those obtained with reflectance (4.52 Â 10 À6 M), h ab,10 colour coordinate (3.95 Â 10 À6 M) 7 or a black and white CCD camera (8.2 Â 10 À6 M). 45 Likewise, better precision was obtained using the scanner than that obtained with a DAD spectrophotometer (3.31-7.66%), 39 with a spectroradiometer (1.7-4.6%) using the colour coordinate h ab,10 (1.5-3.9%), 7 and even better than with a black and white CCD camera (2.27-3.35%).…”

Full-range optical pH sensor based on imaging techniques

“…with X being the analytical signal measured, which can be absorbance [51], fluorescence [52], reflectance [53], transflectance [54], refractive index [55], and even one RGB channel [49], for a given quantity of analyte X; and X HI and X I the values of the parameter at the fully protonated and deprotonated indicator, respectively.…”