Teixeira Leonel Silva, Vieira Heulla Pereira, Windmöller Cláudia Carvalhinho, Nascentes Clésia Cristina
Instituto de Ciências Exatas, Departamento de Química, Universidade Federal de Minas Gerais, Avenida Presidente Antônio Carlos, 6627, Pampulha, PO Box 702, CEP 31270-901, Belo Horizonte, Minas Gerais, Brazil.
Laboratório de Química Agropecuária, Instituto Mineiro de Agropecuária (IMA), BR 040, Km 527, CEP 32145-900, Contagem, Minas Gerais, Brazil.
Talanta. 2014 Feb;119:232-9. doi: 10.1016/j.talanta.2013.11.018. Epub 2013 Nov 11.
A fast and accurate method based on ultrasound-assisted extraction in a cup-horn sonoreactor was developed to determine the total content of Cd, Co, Cr, Cu, Mn, Ni, Pb and Zn in organic fertilizers by fast sequential flame atomic absorption spectrometry (FS FAAS). Multivariate optimization was used to establish the optimal conditions for the extraction procedure. An aliquot containing approximately 120 mg of the sample was added to a 500 µL volume of an acid mixture (HNO3/HCl/HF, 5:3:3, v/v/v). After a few minutes, 500 µL of deionized water was added and eight samples were simultaneously sonicated for 10 min at 50% amplitude, allowing a sample throughput of 32 extractions per hour. The performance of the method was evaluated with a certified reference material of sewage sludge (CRM 029). The precision, expressed as the relative standard deviation, ranged from 0.58% to 5.6%. The recoveries of analytes were found to 100%, 109%, 96%, 92%, 101%, 104% and 102% for Cd, Cr, Cu, Mn, Ni, Pb and Zn, respectively. The linearity, limit of detection and limit of quantification were calculated and the values obtained were adequate for the quality control of organic fertilizers. The method was applied to the analysis of several commercial organic fertilizers and organic wastes used as fertilizers, and the results were compared with those obtained using the microwave digestion procedure. A good agreement was found between the results obtained by microwave and ultrasound procedures with recoveries ranging from 80.4% to 117%. Two organic waste samples were not in accordance with the Brazilian legislation regarding the acceptable levels of contaminants.
开发了一种基于杯形喇叭式声化学反应器中超声辅助萃取的快速准确方法，通过快速顺序火焰原子吸收光谱法（FS FAAS）测定有机肥料中镉、钴、铬、铜、锰、镍、铅和锌的总含量。采用多变量优化方法确定萃取过程的最佳条件。将含有约120mg样品的一份溶液加入到500μL的酸混合物（硝酸/盐酸/氢氟酸, 5:3:3, v/v/v）中。几分钟后，加入500μL去离子水，八个样品同时在50%振幅下超声处理10分钟，每小时可进行32次萃取。用污水污泥标准参考物质（CRM 029）评估该方法的性能。以相对标准偏差表示的精密度范围为0.58%至5.6%。镉、铬、铜、锰、镍、铅和锌的分析物回收率分别为100%、109%、96%、92%、101%、104%和102%。计算了线性、检测限和定量限，所得值适用于有机肥料的质量控制。该方法应用于几种商业有机肥料和用作肥料的有机废物的分析，并将结果与采用微波消解程序获得的结果进行比较。微波法和超声法获得的结果之间具有良好的一致性，回收率范围为80.4%至117%。两个有机废物样品不符合巴西关于污染物可接受水平的法规要求。
