Greening microwave-assisted acid digestion of animal feeding samples

Nowadays it is well-established that microwave-assisted digestion of organic matrices can be efficiently performed in closed vessels using dilute nitric acid solutions. In this work microwave-assisted sample preparation procedures compatible with green chemistry recommendations were developed for grains and cereals used to raise swine. Digestion efficiency was evaluated by determining the residual carbon content, which was lower than 3.5%. Residual acidity was also evaluated and was lower than 0.65 mol L−1. Calcium, Co, Cu, Fe, K, Mg, Mn, Mo, Na, P, Sr, and Zn were determined using either ICP OES or ICP MS depending on respective concentrations. Certified reference materials were evaluated and most determined concentrations were between 80 and 120% compared to certified values. Finally, after analytical measurements an apparatus for recovering nitric acid by sub-boiling distillation was used. To the best of our knowledge, this is the first application of sub-boiling distillation for recovering nitric acid of digests. Then, the purified acid could be reused in further digestions. This is a promising alternative for increasing the green chemistry attributes of trace inorganic analysis. The combination of these strategies, i.e. dilute nitric acid digestion followed by recovery of the acid digests, represents steps towards green chemistry approaches: “reduce the use, recycle and reuse”, strictly following the major green chemistry recommendations.Fil: Savio, Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; ArgentinaFil: Fialho, Lucimar L.. Universidade Federal do São Carlos; BrasilFil: Nobrega, Joaquim A.. Universidade Federal do São Carlos; Brasi

Avaliação da combinação da nebulização discreta e processos de microextração aplicados à determinação de molibdênio por espectrometria de absorção atômica com chama (FAAS)

Simple and sensitive procedures for the extraction/preconcentration of molybdenum based on vortex-assisted solidified floating organic drop microextraction (VA-SFODME) and cloud point combined with flame absorption atomic spectrometry (FAAS) and discrete nebulization were developed. The influence of the discrete nebulization on the sensitivity of the molybdenum preconcentration processes was studied. An injection volume of 200 µL resulted in a lower relative standard deviation with both preconcentration procedures. Enrichment factors of 31 and 67 and limits of detection of 25 and 5 µg L-1 were obtained for cloud point and VA-SFODME, respectively. The developed procedures were applied to the determination of Mo in mineral water and multivitamin samples

Qualitative and Quantitative Chemical Investigation of Orthopedic Alloys by Combining Wet Digestion, Spectroanalytical Methods and Direct Solid Analysis

<div><p>In this study, two laser-based techniques, laser-induced breakdown spectroscopy (LIBS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used for analytical signal evaluation of Ti, Al, and V and investigation of possible harmful elements eventually present as minor elements in Ti alloys. Due to the lack of certified reference materials, samples were also analyzed by wavelength dispersive X-ray fluorescence (WDXRF) and inductively coupled plasma optical emission spectrometry (ICP OES) after microwave-assisted digestion. To maximize the efficiency of LIBS and LA-ICP-MS, operational conditions were adjusted aiming to find optimal analytical performance. LIBS showed several Ti emission lines and few signals for Al and V. LA-ICP-MS was able to detect all three major constituents. For quantitative analysis, the correlation of intensity signals from LIBS analysis with reference values obtained by ICP OES was not successful, showing that there are still difficulties for quantification using solid samples. Measurements using ICP OES showed that additionally to major constituents, only Fe was present in concentrations around 0.2%. Analysis by WDXRF confirmed the presence of Fe. Results using both methods, i.e., ICP OES and WDXRF, were in good agreement.</p></div

Qualitative and Quantitative Chemical Investigation of Orthopedic Alloys by Combining Wet Digestion, Spectroanalytical Methods and Direct Solid Analysis

<div><p>In this study, two laser-based techniques, laser-induced breakdown spectroscopy (LIBS) and laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) were used for analytical signal evaluation of Ti, Al, and V and investigation of possible harmful elements eventually present as minor elements in Ti alloys. Due to the lack of certified reference materials, samples were also analyzed by wavelength dispersive X-ray fluorescence (WDXRF) and inductively coupled plasma optical emission spectrometry (ICP OES) after microwave-assisted digestion. To maximize the efficiency of LIBS and LA-ICP-MS, operational conditions were adjusted aiming to find optimal analytical performance. LIBS showed several Ti emission lines and few signals for Al and V. LA-ICP-MS was able to detect all three major constituents. For quantitative analysis, the correlation of intensity signals from LIBS analysis with reference values obtained by ICP OES was not successful, showing that there are still difficulties for quantification using solid samples. Measurements using ICP OES showed that additionally to major constituents, only Fe was present in concentrations around 0.2%. Analysis by WDXRF confirmed the presence of Fe. Results using both methods, i.e., ICP OES and WDXRF, were in good agreement.</p></div