Loading...
7 results
Search Results
Now showing 1 - 7 of 7
- Multisyringe flow system: determination of sulfur dioxide in winesPublication . Segundo, Marcela A.; Rangel, António O. S. S.; Claderab, Andreu; Cerdà, VíctorA multisyringe flow system for the spectrophotometric determination of sulfur dioxide in wines is described. The methodology is based on the well-known reaction among SO2, formaldehyde and pararosaniline. The proposed manifold also includes a gas diffusion unit in order to prevent the colour interference of red wines in the spectrophotometric measurement. The proposed method was successfully applied to the determination of free SO2 (2–75 mg l21) and total SO2 (10–250 mg l21) in wines, just by changing a few operating parameters in the controlling software. A sampling-rate of 25–30 samples per hour was achieved with good repeatability for 10 consecutive injections of wine samples (RSD < 3.2%). The results obtained from 10 wine samples for each determination were statistically comparable to those obtained by the recommended procedure.
- Spectrophotometric determination of bromate in drinking water using a multi-syringe flow injection systemPublication . Oliveira, Sara M.; Segundo, Marcela A.; Lima, José L. F. C.; Cerdà, Victor; Rangel, António O. S. S.
- Avaliação comparativa da utilização de compostos da família das fenotiazinas para a determinação do ião bromatoPublication . Oliveira, Sara M.; Segundo, Marcela A.; Lima, José L. F. C.; Cerdà, Victor; Rangel, António O. S. S.
- Spectrophotometric determination of Bromate in water using multisyringe flow injection analysisPublication . Oliveira, Sara M.; Segundo, Marcela A.; Rangel, António O. S. S.; Lima, José L. F. C.; Cerdà, VíctorA multisyringe flow injection system for the spectrophotometric determination of bromate in water is proposed, based on the oxidation of phenothiazine compounds by bromate in acidic medium. Several phenothiazines were tested, including chlorpromazine, trifluoperazine, and thioridazine. Higher sensitivity and lower LOD were attained for chlorpromazine. Interference from nitrite, hypochlorite, and chlorite was eliminated in-line, without any changes in the manifold. The automatic methodology using chlorpromazine allowed the determination of bromate between 25 and 750 lgL 1, with LOD of 6 lgL 1, good precision (RSD<1.6%, n¼10), and determination frequency of 35 h 1.
- Automated solid-phase spectrophotometric system for optosensing of bromate in drinking watersPublication . Oliveira, Sara M.; Oliveira, Hugo M.; Segundo, Marcela A.; Rangel, António O. S. S.; Lima, José L. F. C.; Cerdà, VıctorAn automated method based on an optosensor included in a multisyringe flow injection system was developed for the determination of bromate in waters for human consumption. The optosensor was based on the formation of a colored radical cation after oxidation of chlorpromazine by bromate and its selective uptake in a mixed-mode cation exchanger sorbent (Discovery DSC-MCAX), placed on a flow-through spectrophotometric cell. In-line regeneration was attained by methanol + 5% (v/v) ammonia, fostering the application of the same sorbent portion up to 180 determinations. Parameters affecting the reaction development and uptake of the colored compound were studied and optimized, while in-line addition of sulfite ($0.100 g L 1) prevented interference from hypochlorite. The proposed methodology allowed the determination of bromate up to 50.0 mg L 1, with 0.9 mg L 1 as the limit of detection, meeting the requirements of current EU and USA legislation. Application to real drinking water samples was successful, with a mean recovery of 100.2 2.8% for spiked levels of 5.0, 10.0 and 25.0 mg L 1. Repeatability was good (RSD < 3.6%, n ¼ 10) with a determination throughput of 8 h 1, fostering the application to on-line control of water disinfection processes.
- Spectrophotometric determination of bromate in drinking water using a multi-syringe flow injection systemPublication . Oliveira, Sara M.; Segundo, Marcela A.; Lima, José L. F. C.; Cerdà, Victor; Rangel, António O. S. S.
- Avaliação comparativa da utilização de compostos da família das fenotiazinas para a determinação do ião bromatoPublication . Oliveira, Sara M.; Segundo, Marcela A.; Lima, José L. F. C.; Cerdà, Victor; Rangel, António O. S. S.