Soares Sarah Adriana R, Costa Silvânio Silvério L, Araujo Rennan Geovanny O, Teixeira Leonardo Sena Gomes, Dantas Alailson Falcão
Universidade Federal da Bahia, Instituto de Geociências, Departamento de Oceanografia, Núcleo de Estudos Ambientais, Salvador, BA 40170-115, Brazil; Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Salvador, BA 40170-115, Brazil.
Universidade Federal da Bahia, Instituto de Química, Departamento de Química Analítica, Salvador, BA 40170-115, Brazil; Laboratório de Química Analítica Ambiental, Departamento de Química, Centro de Ciências Exatas e Tecnologia, Universidade Federal de Sergipe, São Cristóvão, SE 49100-000, Brazil.
J AOAC Int. 2018 May 1;101(3):876-882. doi: 10.5740/jaoacint.17-0154. Epub 2017 Sep 15.
Three spectrophotometric methods were developed for the determination of copper (Cu) in sugar cane spirit using the chromogenic reagents neocuproine, cuprizone, and bathocuproine. Experimental conditions, such as reagent concentration, reducer concentration, pH, buffer concentration, the order of addition of reagents, and the stability of the complexes, were optimized. The work range was established from 1.0 to 10.0 µg/mL, with correlation coefficients of >0.999 for all three optimized methods. The methods were evaluated regarding accuracy by addition and recovery tests at five concentration levels, and the obtained recoveries ranged from 91 to 105% (n = 3). Precision was expressed as RSD (relative standard deviation), with values ranging from 0.01 to 0.17% (n = 10). The method using the chromogenic reagent cuprizone presented the greatest molar absorptivity, followed by bathocuproine and neocuproine. The methods were applied for the determination of Cu in sugar cane spirit, and the results were compared with a reference method by flame atomic absorption spectrometry (FAAS). Calibration curve solutions for FAAS analysis were prepared in a 40% (v/v) alcohol medium in a range of concentrations from 0.5 up to 5 µg/mL. Measurements for Cu determination were carried out at a wavelength of 324.7 nm. The concentrations obtained for Cu in sugar cane spirit samples from Brazil were between 1.99 and 12.63 µg/mL, and about 75% of the samples presented Cu concentrations above the limit established by Brazilian legislation (5.0 µg/mL or 5.0 mg/L).
开发了三种分光光度法，使用显色剂新铜试剂、铜试剂和2,9-二甲基菲绕啉来测定甘蔗酒中的铜（Cu）。对试剂浓度、还原剂浓度、pH值、缓冲液浓度、试剂添加顺序和配合物稳定性等实验条件进行了优化。工作范围设定为1.0至10.0 µg/mL，三种优化方法的相关系数均>0.999。通过在五个浓度水平下的加标回收试验对方法的准确性进行了评估，获得的回收率在91%至105%之间（n = 3）。精密度用相对标准偏差（RSD）表示，值在0.01%至0.17%之间（n = 10）。使用显色剂铜试剂的方法具有最大的摩尔吸光率，其次是2,9-二甲基菲绕啉和新铜试剂。这些方法应用于甘蔗酒中铜的测定，并将结果与火焰原子吸收光谱法（FAAS）的参考方法进行了比较。FAAS分析的校准曲线溶液在40%（v/v）乙醇介质中制备，浓度范围为0.5至5 µg/mL。铜测定的测量在波长324.7 nm处进行。从巴西采集的甘蔗酒样品中铜的浓度在1.99至12.63 µg/mL之间，约75%的样品铜浓度高于巴西立法规定的限值（5. µg/mL或5.0 mg/L）。
