Sistema automático para determinação seqüencial de cianeto livre e total empregando eletrodo tubular íon-seletivo de membrana homogênea

• Main Authors: Marin Maria Angélica Bonadiman, Silva Reinaldo Carvalho da, Lehmkuhl Arilson, Silva José Bento Borba da, Ganzarolli Edgard Moreira, Queiróz Roldão Roosevelt Urzêdo de
• Format: Article
• Language: English
• Published: Sociedade Brasileira de Química 2000-01-01
• Series: Química Nova
• Subjects: cyanide; automation; ion-selective electrode
• Online Access: http://www.scielo.br/scielo.php?script=sci_arttext&pid=S0100-40422000000100006

This study presents an automated system for potentiometric determination of free and total cyanide which employs a homogeneous membrane tubular ion-selective electrode. After the electrode is assembled, it is connected to a system composed of 3 three-way solenoid valves, sample line, carrier line, acid stream, and gas diffusion chamber. A Turbo Pascal® computer program, developed specifically for this task, automatically performs all the steps involved in data acquisition and processing. The proposed analytical procedure offers operational simplicity, since detection is performed by a tubular electrode, whose assembly is fast and easy. The system has shown reproducibility (r.s.d. < 0.5%, n=6) and high speed (30 readings/hour); it is efficient for determination of free and total cyanide in waste waters of starch processing plants. The detection limit was 1.2x10-5 and 1.5x10-5 mol L-1, for determination of free and total cyanide, respectively. The linear response range was between 1.2x10-5 and 1.0x10-2 mol L-1 for free cyanide and between 1.5x10-5 and 1.0x10-2 for total cyanide.