Utilize este identificador para referenciar este registo: http://hdl.handle.net/10400.14/2819
Título: A multi-commuted flow injection system with a multi-channel propulsion unit placed before detection: Spectrophotometric determination of ammonium
Autor: Oliveira, Sara M.
Lopes, Teresa I.M.S.
Tóth, Ildikó V.
Rangel, António O.S.S.
Palavras-chave: Multi-commuted flow system
Gas diffusion
Waters
Trace levels of ammo
Spectrophotometry
Data: 2007
Editora: Elsevier
Citação: "Analytica chimica acta". ISSN 0003-2670. 600 (2007) 29–34
Resumo: A flow system with a multi-channel peristaltic pump placed before the solenoid valves is proposedto overcome some limitations attributed to multi-commuted flow injection systems:the negative pressure can lead to the formation of unwanted air bubbles and limits the useof devices for separation processes (gas diffusion,dialysis or ion-exchange). The proposed approach was applied to the colorimetric determination of ammonium nitrogen. In alkaline medium, ammonium is converted into ammonia, which diffuses over the membrane,causing a pH change and subsequently a colour change in the acceptor stream (bromothymol blue solution). The system allowed the re-circulation of the acceptor solution and was applied to ammonium determination in surface and tap water, providing relative standard deviations lower than 1.5%. A stopped flow approach in the acceptor stream was adopted to attain a low quantification limit(42ugL−1) and a linear dynamic range of 50–1000ugL−1 with a determination rate of 20h−1.
URI: http://hdl.handle.net/10400.14/2819
Versão do Editor: http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6TF4-4MV0MBP-B&_user=2460358&_coverDate=09%2F26%2F2007&_alid=1493592657&_rdoc=1&_fmt=high&_orig=search&_origin=search&_zone=rslt_list_item&_cdi=5216&_st=13&_docanchor=&view=c&_ct=1&_acct=C000057417&_version=1&_urlVersion=0&_userid=2460358&md5=a951e76b8082c13f33e68190691cdf22&searchtype=a
Aparece nas colecções:ESB - Artigos em revistas internacionais com Arbitragem / Papers in international journals with Peer-review

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