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- Determination of mercury in fish by cold vapor atomic absorption spectrophotometry using a multicommuted flow Injection analysis systemPublication . Silva, M. Fátima; Tóth, Ildikó V.; Rangel, António O. S. S.A flow system was developed for the determination of total mercury concentration in fish samples by cold vapor atomic absorption spectrophotometry (CVAAS), based on the multicommuted flow injection analysis (MCFIA) approach. The system uses independently controlled solenoid valves for the introduction of reagents and samples. When not injected, solutions were recirculating to the reservoir bottles, in this way reducing the waste produced by the analytical system and also the sample consumption. Results were compared to those obtained by the reference flow injection procedure. Accuracy was also assessed by recovery studies using a certified reference material as well as spiked samples; recovery percentages in the range of 90.7% to 99.8% were found. The repeatability of the method was better than 6.0% (RSD, n = 10). A limit of detection of 4.8 μg of mercury per kg of fresh fish sample was achieved. The total waste produced was reduced to 30% of that from the reference flow injection CVAAS procedure.
- A multicommuted flow injection system with a multi-channel propulsion unit: spectrophotometric determination of N-NH4+Publication . Oliveira, Sara M.; Lopes, Teresa I. M. S.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Novas tendências na automatização das técnicas de geração de hidretos e vapor frio em espectrofotometria de absorção atómicaPublication . Silva, Fátima M.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Miniaturization of enzymatic assay based on the LOV-sequential injection system: application to the determination of ethanol in alcoholic beveragesPublication . Vidigal, Susana S. M. P.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Sistema de fluxo com célula de percurso óptico longo para a determinação de ferro em águasPublication . Páscoa, Ricardo N. M. J.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Development of a flow method for monitoring cell membrane damage: application to the study of phosphate release from wine lactic acid bacteriaPublication . Torres, André F.; Mesquita, Paulo A. R.; Tóth, Ildikó V.; Campos, Francisco M.; Couto, José A.; Hogg, Tim; Rangel, António O. S. S.
- A double-line sequential injection system using a long pathlength liquid waveguide capillary flow cell for the spectrophotometric iron determination in watersPublication . Páscoa, Ricardo N. M. J.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Sequential injection-LOV format for peak height and kinetic measurement modes in the spectrophotometric enzymatic determination of ethanol: Application to different alcoholic beveragesPublication . Vidigal, Susana S. M. P.; Tóth, Ildikó V.; Rangel, António O. S. S.The objective of this work was to make a contribution to study the potential of the sequential injectionlab-on-valve (SI-LOV) format for the miniaturization of enzymatic assays, by using different measurement modes (peak height and initialrate-based measurement). A LOV system was developed for the enzymatic assay of ethanol in beverages, based on the conversion of ethanol to acetaldehyde by alcohol dehydrogenase, using spectrophotometric detection. The use of the kinetic-based approach permits the applicability of the enzymatic determination to samples with intrinsic absorption, with a higher determination throughput. A linear dynamic application range up to 0.040% (v/v)was achieved for both initial rate and for the peak height measurement, with good repeatability (R.S.D. < 5.0% and <1.0%, respectively). Enzyme, NAD+, buffer and sample consumption per assay were 0.12U, 0.066 mg, 150 and 15µL, respectively. The determination rate achieved was 37 and 27 determinations h−1 for the initial rate and for the peak height measurement, respectively. The results obtained for several alcoholic beverages, including a certified sample material, were not statistically different from those obtained by the reference procedures.
- Novas tendências na automatização das técnicas de geração de hidretos e vapor frio em espectrofotometria de absorção atómicaPublication . Silva, Fátima M. B.; Tóth, Ildikó V.; Rangel, António O. S. S.
- Exploiting the multicommutation approach for calibration using a single standard solution: application to the determination of mercury by CVAASPublication . Silva, Fátima; Tóth, Ildikó V.; Rangel, António O. S. S.