Total dissolved iron and hydrogen peroxide determination using the PhotoMetrixPRO application: A portable colorimetric analysis tool for controlling important conditions in the solar photo-Fenton process

Simultaneous measurement of aqueous redox-sensitive elements and their species across the soil-water interface

“…Additionally, a microplate reader was used to measure the Fe profile in paddy soil with the 1, 10-phenanthroline method (λ = 510 nm) (Lumbaque et al, 2019). Before measurement, the O 2 -free colorimetric reagent was online mixed with the porewater sample in a 1:1 volume ratio driven by two injection pumps (Fig.…”

“…The HR samplers (e.g. DET, HR peeper, IPI samplers) designed for element profile mapping generally can only take less than 0.5 mL solution (Yuan et al, 2019), which is a bare minimum for one sample injection with most analytical techniques, like inductively coupled plasma mass spectrometry (ICP-MS) (Xu et al, 2017), ICP-optical emission spectrometry (Cheng et al, 2012), colorimetric method (Lumbaque et al, 2019). An alternative to collect more samples is to collect porewater repeatedly at different places or times, assuming the soil or sediment matrix is homogenous and stable over time.…”

PhotoMetrix and colorimetric image analysis using smartphones

“…Lumbaque et al 129 proposed the determination of dissolved iron and hydrogen peroxide during solar photo‐Fenton process through digital image analysis. Iron determination was performed by two methodologies, one employing 1,10‐phenantroline and the other with hydroquinone, and the determination of H 2 O 2 was performed with ammonium metavanadate.…”

“…Through the researches that used PhotoMetrix ® early presented, it is possible to visualize the versatility of this application, because it was used in different analysis, presenting significant results. It is possible to carry out direct analysis, 126,136 that is, without performing sample preparation, analysis of solid 120 and liquid samples, [131][132][133]135 with the use of chambers to store the samples, 121,124,125,129,134 or without lighting control accessories, 127 in addition to allowing the sample to be conditioned in different ways to capture images such as paper 122,123 and SDS-PAGE 128,130 for example. Figure 12 shows four different ways of acquiring images related to the previously presented articles that used Photo-Metrix app in their analysis, where in some works, chambers were made to capture images, and in others, the image acquisition was performed without light control.…”

Blue Ballpoint Pen Inks Differentiation using Multivariate Image Analysis of Digital Images Captured with PhotoMetrix PRO®

“…This app uses the mobile camera to capture digital images and, so that can proceed with multivariate image analysis, those images are decomposed into scores and loadings. This technique has been previously applied for environmental 26,27 and food analysis 28,29 .…”