Turbidimetric determination of orthophosphate in digested plant material by flow-injection analysis

Authors

  • Maria-Celeste T. Diniz,

    1. Universidade Federal de São Carlos, Centro de Ciências Exatas e de Tecnologia, Departamento de Química, Grupo de Química Analítica, Rod. Washington Luiz, km 235, Caixa Postal 676, CEP 13560–970,– São Carlos,– SP, Brazil
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  • André Fernando Oliveira,

    1. Universidade Federal de São Carlos, Centro de Ciências Exatas e de Tecnologia, Departamento de Química, Grupo de Química Analítica, Rod. Washington Luiz, km 235, Caixa Postal 676, CEP 13560–970,– São Carlos,– SP, Brazil
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  • Orlando Fatibello-Filho

    Corresponding author
    1. Universidade Federal de São Carlos, Centro de Ciências Exatas e de Tecnologia, Departamento de Química, Grupo de Química Analítica, Rod. Washington Luiz, km 235, Caixa Postal 676, CEP 13560–970,– São Carlos,– SP, Brazil
    • Universidade Federal de São Carlos, Centro de Ciências Exatas e de Tecnologia, Departamento de Química, Grupo de Química Analítica, Rod. Washington Luiz, km 235, Caixa Postal 676, CEP 13560–970,– São Carlos,– SP, Brazil
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Abstract

A simple, fast, and low-cost flow-injection system is proposed for the determination of orthophosphate in digested plant material. The determination is based on the precipitation reaction of orthophosphate with 0.05 mol L−1 zinc solution in 0.05 mol L−1 triethanolamine buffer (TEA/TEAH+, pH 6.0) solution containing 0.025% (w/v) poly-(vinylalcohol). The zinc orthophosphate suspension produced was directly measured at 410 nm. Under the best experimental conditions, orthophosphate was determinated in the concentration range from 5 to 60 mg P L−1, and the relative standard deviations were less than 1.6% for 10 and 20 mg P L−1 solutions (n = 9). The analytical frequency was 180 h−1. The results obtained using the proposed FIA procedure and those obtained using a standard spectrophotometric procedure agree at the 95% confidence level. © 2000 John Wiley & Sons, Inc. Lab Robotics and Automation 12:236–240, 2000

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