Fibrous g-C3N4@Tio2 Nanocomposites-Based Dispersive Micro-Solid Phase Extraction for Chromium Speciation in Cow Milk by ICP-MS after Digestion Treatment with Artificial Gastric Juice

Background Chromium is an interesting element because its toxicity depends on its speciation. Thus, knowledge of Cr speciation in cow milk is essential to human health. Objective This study aims to achieve real bioaccessible species in cow milk, including Cr(III), Cr(VI), residual, digestible, and total Cr. Methods Samples were treated with artificial gastric juice, followed by dispersive micro-solid phase extraction (DMSPE) combined with ICP-MS for Cr speciation. Fibrous g-C3N4@TiO2 nanocomposites (FGCTNCs) were used as a novel adsorbent for DMSPE. Results The method detection limits were 110 pg/g (Cr(III)) and 260 pg/g (Cr(VI)) for milk powder (0.1 g), and 5.1 pg/g (Cr(III)) and 13 pg/g (Cr(VI)) for liquid cow milk (2 mL). The relative standard deviations (RSDs), obtained by analyzing the standard solutions containing 1.0 ng/mL of the analytes in sequence for nine times, were 4.3% and 5.1% for Cr(III) and Cr(VI), respectively. Linearity was observed over the range of 4 magnitude orders with correlation coefficients better than 0.9961. The enrichment factor of 100 was obtained. The majority of Cr in the samples was transferred into digestion solution. The content of Cr(III) is much higher than that of Cr(VI) in the digestion solution. Conclusions This method has the advantages of reduced solvent consumption, less adsorbent dosage, and high extraction efficiency. It may become a valuable strategy for elemental species in food samples. Highlights The samples were treated with artificial gastric juice to avoid the inter-conversion of species. FGCTNCs exhibit the merits of N-rich functional groups and selective adsorption for the analytes.

Preparation of ZnO Powder from Clinker Digestion Solution of Zinc Oxide Ore

The ZnO powder was successfully obtained by calcining the basic zinc carbonate, which was synthesized from clinker digestion solution of zinc oxide ore using analytical Na2CO3. The factors of mol ratio of Na2CO3to ZnSO4and reaction temperature were discussed at stirring intensity 400 rpm. Both the obtained basic zinc carbonate and ZnO powders were characterized using XRD, EDS and SEM. The thermal decomposition of basic zinc carbonate was also investigated below 600°C. The results show that the ZnO powder was wurzite hexagonal structure and the well-crystallized ZnO powder was uniformly spherical particles and distributed in a narrow range.

The Removal of Interference from Microwave Digestion Solution of Industrial Wastewater on the Determination of Arsenic

In existing literature ,there is no unified time for the evaporating excessive acid to microwave digestion solution of different samples. a new method was developed .The interference from nitrite ion and volatile nitrogen oxides which were generated during digestion were quickly removed by the adding urea and heating with boiling water. The interference from nitrate was studied. Optimized conditions of determination of arsenic with hydride generation atomic absorption spectrometry. The detection limit was 0.3μg·L-1 and minimum quantitative detection limit was 1.0μg·L-1, the relative standard deviation of standard addition method in sample was 1.1% and recovery from 98 % to 102%.