No abstract

An analytical method for sample preparation and subsequent determination of Cd, Pb and Se in beef using aerosol dilution by inductively coupled plasma-mass spectrometry was developed. The use of high matrix introduction technology allowed the introduction of a complex sample into the plasma with higher content of total dissolved solids a residual acidity of 4% and better tolerance to matrix effects. Trueness was verified by the analysis of two reference materials. At the 95% significance level, results were statistically equivalent to the certified or informed values. Analytical precision expressed as relative standard deviation was less than 9% in all cases. After validation, a total of 12 beef samples from Uruguay were analyzed. Obtained levels for Cd and Pb were far below the maximum limits established by international regulations in all samples. Also, results showed that beef from this region is a good source of Se in the range 0.120-0.870 mg kg −1 with an interesting contribution to the daily intake of this essential element.

Four methods for the efficient extraction of copper from bovine and ovine liver were optimized. Sample preparation consisted of extractions with dilute nitric acid or dilute tetramethyl ammonium hydroxide, assisted by an ultrasonic bath or an ultrasonic probe. Copper was determined by flame atomic absorption spectrometry. The experimental conditions were optimized using multivariate experiments. All methods were considered adequate for copper extraction, however, the two methods involving the probe turned out to be more efficient and faster, so they were selected for subsequent validation. Trueness was verified after the analysis of a certified reference material and the performance of a microwave-assisted extraction. Results were statistically equivalent, at the 95% significance level, to the values declared on the certificate. Precision (expressed as relative standard deviation) was better than 5% for all methods. Samples obtained from Uruguayan animals were analyzed. Obtained results agreed with previous results from sheep and cattle abroad. The proposed methods are simple alternatives for food surveillance and animal status monitoring, being straightforward and aligned with Green Chemistry principles, as it was demonstrated by performing the analytical Eco-Scale comprehensive approach. A discussion related to the particle size distribution obtained during the multivariate experiments was also included, to give some deeper insight into ultrasound effect on the biological tissue in different media. In addition, ultrasound-assisted extraction was compared to magnetic stirring to prove the effect of ultrasound.

Estudio del contenido de selenio en carne vacuna luego del proceso de cocción Study of the selenium content in beef after the cooking process Estudo do teor de selênio na carne bovina após o processo de cozimento

No abstract

Development and validation of an analytical method for the determination of cadmium in cocoa powder and cocoa powder prepared with milk. Application to products of the local market Desenvolvimento e validação de uma metodologia analítica para a determinação de cadmio em cacau em pó e preparado com leite. Aplicação em produtos do mercado local Nataly rodríguez (1) Javier silva (1) Fiorella iaquiNta (1)

No abstract

A simple and fast method for the simultaneous determination of chloride and lactic acid in artisanal Danbo cheese was developed and validated. The proposed methodology combined a sample treatment using only ultrapure water as an extracting agent and ion chromatography with suppressed conductivity for the detection of the analytes. One gram of sample exactly weighted is added to 40.0 mL of ultrapure water at 55 ºC. The suspension was stirred for 5 minutes and after centrifugation the supernatant obtained is ready to be used for the determination of both analytes. The performance of this method was evaluated by comparing the results obtained with those acquired after the analysis of the cheese samples using the AOAC reference methods using a t-student test of mean concentration values. At a 95% significance level, the means obtained by the different methods were comparable. Analytical precision expressed as relative standard deviation (RSD %) was less than 6. Artisanal cheese samples were analyzed (n=12) using the validated methodology, obtaining chloride levels between 0.6 and 1.1% w w-1 expressed in sodium chloride and levels of lactic acid between 1.1 and 2.1% w w-1. Additionally, a greenness analysis was presented, using three different metric tools, concluding that the developed method is significantly in better agreement with the principles of Green Analytical Chemistry than the official methods.