title: Digital movie-based on automatic titrations.
abstract: This study proposes the use of digital movies (DMs) in a flow-batch analyzer (FBA) to perform automatic, fast and accurate titrations. The term used for this process is "Digital movie-based on automatic titrations" (DMB-AT). A webcam records the DM during the addition of the titrant to the mixing chamber (MC). While the DM is recorded, it is decompiled into frames ordered sequentially at a constant rate of 26 frames per second (FPS). The first frame is used as a reference to define the region of interest (ROI) of 28×13pixels and the R, G and B values, which are used to calculate the Hue (H) values for each frame. The Pearson's correlation coefficient (r) is calculated between the H values of the initial frame and each subsequent frame. The titration curves are plotted in real time using the r values and the opening time of the titrant valve. The end point is estimated by the second derivative method. A software written in C language manages all analytical steps and data treatment in real time. The feasibility of the method was attested by application in acid/base test samples and edible oils. Results were compared with classical titration and did not present statistically significant differences when the paired t-test at the 95% confidence level was applied. The proposed method is able to process about 117-128 samples per hour for the test and edible oil samples, respectively, and its precision was confirmed by overall relative standard deviation (RSD) values, always less than 1.0%.
authors.affiliation: Universidade Federal da Paraíba, CCEN, Departamento de Química, P. O. Box: 5093, Zip Code: 58051-970, João Pessoa, PB, Brazil. Electronic address: ricardo@quimica.ufpb.br.
authors.forename: Ricardo Alexandre C
authors.initials: RA
authors.lastname: Lima
authors.affiliation: Universidade Federal da Paraíba, CCEN, Departamento de Química, P. O. Box: 5093, Zip Code: 58051-970, João Pessoa, PB, Brazil.
authors.forename: Luciano F
authors.initials: LF
authors.lastname: Almeida
authors.affiliation: Universidade Federal da Paraíba, CCEN, Departamento de Química, P. O. Box: 5093, Zip Code: 58051-970, João Pessoa, PB, Brazil.
authors.forename: Wellington S
authors.initials: WS
authors.lastname: Lyra
authors.affiliation: Universidade Federal da Paraíba, CCEN, Departamento de Química, P. O. Box: 5093, Zip Code: 58051-970, João Pessoa, PB, Brazil.
authors.forename: Lucas A
authors.initials: LA
authors.lastname: Siqueira
authors.affiliation: Universidade Federal Rural de Pernambuco-Unidade Acadêmica de Serra Talhada, UAST, P. O. Box: 063, Zip Code: 56900-000, Serra Talhada, PE, Brazil.
authors.forename: Edvaldo N
authors.initials: EN
authors.lastname: Gaião
authors.affiliation: Universidade Federal Rural de Pernambuco-Unidade Acadêmica de Serra Talhada, UAST, P. O. Box: 063, Zip Code: 56900-000, Serra Talhada, PE, Brazil.
authors.forename: Sérgio S L
authors.initials: SS
authors.lastname: Paiva Junior
authors.affiliation: Universidade Federal Rural de Pernambuco-Unidade Acadêmica de Serra Talhada, UAST, P. O. Box: 063, Zip Code: 56900-000, Serra Talhada, PE, Brazil.
authors.forename: Rafaela L F C
authors.initials: RL
authors.lastname: Lima
keywords: Digital movies; End point detection; Flow–batch analyzer; Hue–saturation–intensity color system; Pearson correlation coefficient; Webcam