Determinação de Cu, Fe, Mn, Zn e do teor de proteína total em amostras de trigo e soja após procedimento de extração sequencial

A sequential extraction procedure was applied to wheat and soybean seed samples. The total protein content (determined by two distinct methods: Bradford and bicinchoninic acid-BCA) and distribution of Cu, Fe, Mn and Zn in each fraction was determined. The sequential extraction employed four different solutions: water, 0.5 mol L-1 NaCl, ethanol/water (70:30 v v-1) and 0.5 mol L-1 NaOH. For both samples, the highest concentration of metals was observed in those extracts associated with globulin-type proteins using NaCl solution. Regarding protein content, higher levels were obtained using the BCA method.

Determinação espectrofotométrica de cloreto em cimento após preparo de amostra por piroidrólise

A method based on pyrohydrolysis was proposed for cement sample preparation and further chloride determination by spectrophotometry using flow injection analysis. Analytical parameters were evaluated and, under the selected conditions, the calibration curve was linear in the range of 0.2 to 10.0 µg mL-1 with r2 = 0.998. The limit of detection was5 µg g-1 of chloride and the relative standard deviation was less than 7%. The proposed pyrohydrolysis method is relatively simple and can be used for sample preparation for further spectrophotometric determination of low concentrations of chloride in cement.