On-line digestion in a focused microwave-assisted oven for elements determination in orange juice by inductively coupled plasma optical emission spectrometry

Abstract

Um sistema de fluxo acoplado a um forno de microondas focalizadas foi utilizado para digestão em linha de amostras de suco de laranja para a determinação de Ca, Cu, Fe, K, Mg, Mn, Na, P e Zn por espectrometria de emissão ótica com plasma indutivamente acoplado. Uma bobina de reação de PTFE (4,0 m de comprimento e 1,6 mm de diâmetro interno) foi posicionada no interior da cavidade de vidro do forno de microondas focalizadas. Alíquotas de 500 µL de amostra e de 1000 µL de reagente (80% v/v HNO 3 ) foram misturadas em uma confluência e conduzidas para a bobina de reação utilizando ar como carregador. O desvio padrão relativo para cinco determinações da mesma amostra usando o método proposto foi inferior a 5,0%. Boas recuperações variando de 91 a 111% foram obtidas para adições de quantidades conhecidas dos elementos de interesse. Os resultados obtidos, utilizando o sistema de digestão proposto, foram concordantes a um nível de confiança de 95% com aqueles obtidos por digestão total. Com este método de digestão foi possível processar 12 amostras h -1 , minimizando contaminações, consumo de amostra e reagentes e gerando pequena quantidade de resíduos.A flow injection system coupled to focused microwave-assisted oven was used for on-line orange juice sample digestion for determination of Ca, Cu, Fe, K, Mg, Mn, Na, P, and Zn by inductively coupled plasma optical emission spectrometry. The reactor coil was a PTFE tube (4.0 m long and 1.6 mm i.d.) positioned into the commercial glass tube of the focused microwave oven. Aliquots of 500 µL of sample and 1000 µL of reagent (80% v/v HNO 3 ) were mixed in a confluence and carried out to the reactor coil by air carrier. The relative standard deviation for five replicates of sample was lower than 5.0%. Good recoveries varying from 91 to 111% were obtained for added concentrations of the interest elements. The results obtained using the proposed digestion system are in agreement with those obtained for total digestion at the 95% confidence level. With this on-line digestion system was possible to carry out 12 samples h -1 , minimizing contamination, saving consumption of samples and reagent and low residue generation.

Development of efficient method for preconcentration and determination of copper, nickel, zinc and iron ions in environmental samples by combination of cloud point extraction and flame atomic absorption spectrometry

“…The real samples were treated according to our previous publication [23][24][25][26][27] as following. The certified liver sample was also digested in the manner described below.…”

Development of an orange juice surrogate for the study of dental erosion

“…Even though this makes it difficult to find a single standard similar to all juices, we targeted for a formulation that would be representative of most orange juices. This was the rationale behind creating a synthetic formula using the average mineral composition of orange juices made with oranges from Australia, Brazil and Florida (15)(16)(17).…”

“…The SJ composition was based on an average composition of natural orange juices made with oranges from different locations (15)(16)(17), with special attention to the mineral compounds. An average composition of the major chemical compounds was determined (Table 1), and the formula used for preparation of SJ was determined based on this information ( Table 2).…”

PVC Coated with an Indole Derivative-Loaded Triton X-100: a New Sorbent for Cu, Zn and Mn Ions

“…The apple, soil and tomato samples were treated according to a reported procedure [40]. Fenne, spearmint and water samples were prepared as we previously reported [41][42][43].…”