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Sequential injection kinetic flow assay for monitoring glycerol in a sugar ferm...
Hueso Domínguez, Karina B.; Tóth, Ildikó V.; Souto, M. Renata S.; Mendes, Filipa; García De María, Cándido; Vasconcelos, IsabelA sequential injection system to monitor glycerol in a Saccharomyces cerevisiae fermentation process was developed. The method relies on the rate of formation of nicotinamide adenine dinucleotide in its reduced form (NADH, measured spectrophotometrically at 340 nm) from the reaction of glycerol with NAD+ cofactor, catalysed by the enzyme glycerol dehydrogenase present in solution. This procedure enables the de...
Spectrophotometric flow system using vanadomolybdophosphate detection chemistry...
Neves, M. Sofia A. C.; Souto, M. Renata S.; Tóth, lldikó V.; Victal, Sérgio M. A.; Drumond, M. Cláudia; Rangel, António O. S. S.reactive phosphorus in water samples is described. The system includes a liquid waveguide long pathlength cell connected to a charge coupled device (CCD) spectrophotometer. Calibration was linear up to 500 µgPL−1, with a detection limit of 17 µgPL−1 and a quantification limit of 56 µgPL−1. An injection throughput of 60 determinations h−1 and repeatability (R.S.D.) of 2.2% were achieved. Potential interference f...
Flow-through solid-phase based optical sensor for the multisyringe flow injecti...
Morais, Inês P.A.; Miró, Manuel; Manera, Matias; Estela, José Manuel; Cerdà, Víctor; Souto, M. Renata S.; Rangel, António O.S.S.In this work, a novel flow-through solid-phase based chemiluminescence (CL) optical sensor is described for the trace determination of orthophosphate in waters exploiting the multisyringe flow injection analysis (MSFIA) concept with multicommutation. The proposed time-based injection flow system relies upon the in-line derivatisation of the analyte with ammonium molybdate in the presence of vanadate, and the tr...
Use of a single air segment to minimise dispersion and improve mixing in sequen...
Morais, Inês P. A.; Souto, M. Renata S.; Lopes, Teresa I. M. S.; Rangel, António O. S. S.In this work, we propose the use of an air segment in a sequential injection system to simultaneously improve the overlapping of the stacked zones and minimise dispersion. This strategy was developed for the determination of sulphate in natural and wastewaters. Barium chloride was used as a precipitating agent and the turbidity of the suspension formed was measured at 420 nm. Analysis was performed without samp...
Turbidimetric flow-injection determination of total nitrogen and potassium in v...
Lima, José L.F.C.; Rangel, António O.S.S.; Souto, M.Renata S.; Zagatto, Elias A.G.A turbidimetric flow-injection system was developed for the determination of total nitrogen and potassium in vegetable samples using a single spectrophotometer as detector. As a precipitating agent, 3.0% (w/v) sodium tetraphenylboron solution prepared in 2.0% (w/v) poly(vinyl alcohol) was used. A gas diffusion process was included in the manifold to separate ammonium ions from the rest of the sample and to allo...
Flow injection system with gas diffusion for the sequential determination of to...
Lima, José L.F.C.; Rangel, António O.S.S.; Souto, M. Renata S.A flow injection system was developed for the sequential determination of total nitrogen and phosphorus in digests of vegetables using potentiometric and spectrophotometric detection systems, respectively. A tubular ammonium selective electrode with a sensor system composed of nonactin/monactin in tris(2-ethylhexyl) phosphate was used. The selectivity limitations of this electrode were overcome by the inclusion...
Potentiometric determination of chloride in vegetables by flow injection analysis
Lima, José L. F. C.; Rangel, António O. S. S.; Souto, M. Renata S.A flow injection system for the potentiometric determination of chloride (Cl) in vegetables is reported. A tubular chloride ion-selective electrode based on a homogeneous crystalline membrane without inner reference solution was used as indicator electrode. A methodology to minimize the influence of the sample matrix on the electrodes response is described. The results obtained with the developed flow injection...
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