“…Similar results to this study were also observed by Souza et al (2012), the researchers observed significant superiority in the recovery of wet digestion with a mixture of nitric and perchloric acids. In general, the nitric and hydrochloric methods showed efficient precision.…”
The objective of this study was to evaluate efficient analytical methods of wet digestion using the official method of analysis, a mixture of nitric acid and perchloric acid (HNO3 + HClO4), for the analysis of vinasse and also verify the effects of nutrients on stored vinasse. The analytical methods compared were: 1) Nitroperchloric (HNO3), 2) Nitric (HNO3); 3) Chloridric + Hydrogen Peroxide (HCl + H2O2); 4) Sulfuric + Hydrogen Peroxide (H2SO4 + H2O2) and 5) Solubilization with 1 molar Chloridric acid (HCl 1 Mol L-1). Phosphorus, potassium, calcium, magnesium and sulfur were determined over different storage periods, and these nutrients were analyzed at 5, 30, 90 and 150 days of storage, to verify the behavior of these nutrients over the time they are stored in laboratory conditions. The efficiency of the methods was evaluated by comparing the results of the nitroperchloric method obtained for each nutrient with the results obtained from the other methods. The results showed that the nitric (HNO3) and chloridric + hydrogen peroxide (HCl + H2O2) digestions presented good to excellent precision equivalent to the nitroperchloric digestion (HNO3) for the analyzed nutrients. The solubilization method with 1 molar chloridric acid (HCl 1 Mol L-1) presented a low accuracy and did not present the expected efficiency for quantification of any analyzed nutrient. With the exception of potassium contents, all the other nutrients analyzed in the study reduced at the end of the vinasse storage days.
“…Similar results to this study were also observed by Souza et al (2012), the researchers observed significant superiority in the recovery of wet digestion with a mixture of nitric and perchloric acids. In general, the nitric and hydrochloric methods showed efficient precision.…”
The objective of this study was to evaluate efficient analytical methods of wet digestion using the official method of analysis, a mixture of nitric acid and perchloric acid (HNO3 + HClO4), for the analysis of vinasse and also verify the effects of nutrients on stored vinasse. The analytical methods compared were: 1) Nitroperchloric (HNO3), 2) Nitric (HNO3); 3) Chloridric + Hydrogen Peroxide (HCl + H2O2); 4) Sulfuric + Hydrogen Peroxide (H2SO4 + H2O2) and 5) Solubilization with 1 molar Chloridric acid (HCl 1 Mol L-1). Phosphorus, potassium, calcium, magnesium and sulfur were determined over different storage periods, and these nutrients were analyzed at 5, 30, 90 and 150 days of storage, to verify the behavior of these nutrients over the time they are stored in laboratory conditions. The efficiency of the methods was evaluated by comparing the results of the nitroperchloric method obtained for each nutrient with the results obtained from the other methods. The results showed that the nitric (HNO3) and chloridric + hydrogen peroxide (HCl + H2O2) digestions presented good to excellent precision equivalent to the nitroperchloric digestion (HNO3) for the analyzed nutrients. The solubilization method with 1 molar chloridric acid (HCl 1 Mol L-1) presented a low accuracy and did not present the expected efficiency for quantification of any analyzed nutrient. With the exception of potassium contents, all the other nutrients analyzed in the study reduced at the end of the vinasse storage days.
“…The embryo and seed coat fractions were digested with concentrated perchloric/nitric acid (1/5, v/v) at 60 8C for 12 h, according to the method described by Souza et al (2012), with some modifications. The resultant solution was transferred to a volumetric flask, diluted 10 times with Milli-Q high purity water device (18.2 MV MV cm quality; Millipore, USA).…”
“…This is important, as it was experimentally observed that level change to a factor can alter other responses with synergistic or antagonistic effect, which it was not possible to assess with univariate studies (Weinert et al, 2008;Breitkreitz et al, 2014). Therefore, factorial design has been used in a diversified way such as in the analysis of metals (Pereira Filho et al, 2002), plants (Marques et al, 2012;Souza and Sena, 2012), and soils (Dolatto et al, 2012). Although there are few results of response surface application, using this tool, it was possible to find the optimum conditions for: (i) extrusion of soybean bran (Barros et al, 1987), (ii) spectrophotometric determination in pharmaceutical formulations (Weinert et al, 2008), and (iii) fruit productivity and quality because of the use of fertilizers (Mattos et al, 2004).…”
Soil organic matter (SOM) is important to fertility, since it performs several functions such as cycling, water and nutrient retention and soil aggregation, in addition to being an energy requirement for biological activity. This study proposes new trends to the Embrapa, Walkley-Black, and Mebius methods that allowed the determination of SOM by spectrophotometry, increasing functionality. The mass of 500 mg was reduced to 200 mg, generating a mean of 60 % saving of reagents and a decrease of 91 % in the volume of residue generated for the three methods without compromising accuracy and precision. We were able to optimize conditions for the Mebius method and establish the digestion time of maximum recovery of SOM by factorial design and response surface. The methods were validated by the estimate of figures of merits. Between the methods investigated, the optimized Mebius method was best suited for determining SOM, showing near 100 % recovery.
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