Optimization and validation of ultrasound-assisted extraction for the determination of micro and macro minerals in non-centrifugal sugar by F AAS.

In this work, the ultrasound-assisted extraction was employed for the first time as a sample treatment in the determination of Mn, Zn, Fe, Mg and Ca in non-centrifugal sugar by F AAS. Parameters that influence the extraction, such as composition of the extraction solvent, sample mass and sonication time were optimized in this work. The optimum condition for the extraction was the proportion of 60:40% (v/v) of HNO3:H2O2 as an extraction solution, 0.100 g of non-centrifugal sugar and 60 min of sonication. Analytical curves were built in an aqueous solution. Low quantification limits for Mn (0.021), Zn (0.008), Fe (0.030), Ca (0.389) and Mg (0.009) mg L-1 were determined, suggesting a good detectability of the methodology. Estimates of repeatability and intermediate precision demonstrated that the precision observed was within the limits recommended in the literature. Good accuracy of the method was verified through the high recovery rates (91-108%).

Fast and direct analysis of Cr, Cd and Pb in brown sugar by GF AAS.

A simple and fast analytical method for the determination of Cr, Pb and Cd in brown sugar by GF AAS using slurry sampling was developed and in house validated for the first time. Analytical curves were prepared by external standardization for Cr, and by matrix simulation for Pb and Cd and they were linear. Low limits of quantification for Cr (32.8 ng g-1), Pb (49.3 ng g-1) and Cd (4.5 ng g-1) were found. Repeatability and intermediate precision estimates (<10% and <15%, respectively) and recovery rates (95-103%) demonstrated a good precision and accuracy. The levels in brown sugar samples ranged from <32.8 to 160 ng g-1 for Cr, from <49.3 to 211.0 ng g-1 for Pb and from <4.5 to 7.0 ng g-1 for Cd and they may be assigned to anthropogenic activities and the adoption of inadequate practices of production and processing.

In house validation from direct determination of 5-hydroxymethyl-2-furfural (HMF) in Brazilian corn and cane syrups samples by HPLC-UV.

In this work the development and in house validation of the HMF direct determination in corn and cane syrups by HPLC-UV was carried out for the first time. The separation was done with isocratic elution of a mobile phase comprising water (with 0.5% formic acid) and acetonitrile (90:10, v/v) on Phenomenex C18 column (5.0 µm, 4.6 × 150 mm), at 30 °C, flow rate of 0.8 mL min(-1) and detection at 285 nm. The validated method showed excellent performance with low limits (LOD and LOQ of 0.09 and 0.26 mg L(-1), respectively), good accuracy (recovery rates between 100% and 104%) and precision (RSD's for repeatability and intermediate precision between 0.57% and 6.43%). Good selectivity and linearity were also observed. HMF contents in both foods were very high (406.6-2121.3 mg kg(-1) for corn syrup and 109.2-893.1 mg kg(-1) for cane syrup), which arouses concern about food safety of these products.

Development and in house validation of a new thermogravimetric method for water content analysis in soft brown sugar.

Recently the use of brown sugar has increased due to its nutritional characteristics, thus requiring a more rigid quality control. The development of a method for water content analysis in soft brown sugar is carried out for the first time by TG/DTA with application of different statistical tests. The results of the optimization study suggest that heating rates of 5°C min(-1) and an alumina sample holder improve the efficiency of the drying process. The validation study showed that thermo gravimetry presents good accuracy and precision for water content analysis in soft brown sugar samples. This technique offers advantages over other analytical methods as it does not use toxic and costly reagents or solvents, it does not need any sample preparation, and it allows the identification of the temperature at which water is completely eliminated in relation to other volatile degradation products. This is an important advantage over the official method (loss on drying).