Extraction induced by emulsion breaking for determination of Ba, Ca, Mg and Na in crude oil by inductively coupled plasma optical emission spectrometry

Ionic liquid assisted extraction induced by emulsion breaking for extraction of trace metals in diesel, gasoline and kerosene prior to ICP-OES analysis

This study describes a novel and greener ionic liquid assisted extraction induced by emulsion breaking (ILA-EIEB) method for extraction of As, Ba, Cd, Cr, Ni Pb, Sb, Sn, Tb, Te and V in fuel oils. The most influential extraction parameters were ionic liquid concentration [(1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl)], HNO3 concentration, Triton X-100 concentration, and sample mass and were optimised by using full factorial and Box-Behnken designs. The optimum conditions obtained were 0.035 % 1-Ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) concentration, 18 % v/v HNO3 concentration, 15 % w/v Triton X-100 concentration, and 0.1 g sample mass. The emulsions were fully broken by using a controlled heating water bath at temperature of 80 ± 2 °C for 30 ± 4 min, followed by centrifugation at 3500 rpm for 15 min. Under the optimum conditions, the proposed ILA-EIEB method was accurate (80.1-101 %) and precise (1.9-4.7 %) for all the investigated metals. The method detection limits were 0.107, 0.013, 3.494 and 0.560 μg/g for Ba, Na, Ni and V, respectively. The optimised ILA-EIEB method was then applied in real fuel samples and metal concentration levels ranged from 0.072 to 8.610 μg/g, which were consistent with other literature reported work. Therefore, this study suggests that the examined metal ions present in fuel oils commercialised in Johannesburg, South Africa are in tolerable concentration levels and are not a threat.

Extraction Induced by Emulsion Breaking for Ca, Cu, Fe, Mn, Ni, and Zn Determination in Chocolate by Flame Atomic Absorption Spectrometry

Background

Chocolate is a rich source of essential and non-essential elements. A new liquid–liquid extraction (LLE) approach, extraction induced by emulsion breaking (EIEB), is proposed in which the analyzed elements are transferred from the organic phase to the aqueous phase before measurement by flame atomic absorption spectrometry (FAAS).

Objective

To compare EIEB to microwave digestion (MWD) for extraction of elements from chocolate prior to FAAS.

Methods

EIEB parameters were varied to optimize the procedure. EIEB-FAAS was then compared to MWD-FAAS for the analysis of Ca, Cu, Fe, Mn, Ni, and Zn in milk and dark chocolate samples. A certified reference material (NIST 2384, baking chocolate) was analyzed to determine the recoveries of Ca, Cu, Fe, Mn, and Zn by the two methods.

Results

The optimized EIEB extraction method involves dilution of tempered chocolate with toluene, ultrasonic emulsification with acidified Triton X-114, breaking the emulsion by heating, and centrifugation to produce two well-defined phases. Analysis of dark and milk chocolate samples showed similar repeatability by EIEB-FAAS (RSDr 0.3 to 6.6% in dark and 0.5 to 8.7% in milk) and MWD-FAAS (RSDr 0.5 to 5.4% in dark and 0.7 to 10.2% in milk), with no significant difference detected between the methods for analysis of Ca, Cu, Fe, Mn, Ni, and Zn based on Student’s t-test. Analysis of NIST 2384 baking chocolate certified reference material for Ca, Cu, Fe, Mn, and Zn demonstrated recoveries of 98.6 to 99.5% for EIEB-FAAS compared to 95.8 to 98.6% for MWD-FAAS.

Conclusion

EIEB-FAAS was shown to provide high recovery and excellent repeatability for accurate determination of Ca, Cu, Fe, Mn, Ni, and Zn from dark and milk chocolates.

Highlight

The EIEB-FAAS method is simpler and requires fewer reagents compared to other sample preparation methods and allows the calibration to be carried out using aqueous calibration solutions.

Euendolithic Cyanobacteria and Proteobacteria Together Contribute to Trigger Bioerosion in Aquatic Environments

Shellfish, mussels, snails, and other aquatic animals, which assimilate limestone (calcium carbonate, CaCO3) to build shells and skeletons, are effective carbon sinks that help mitigate the greenhouse effect. However, bioerosion, the dissolution of calcium carbonate and the release of carbon dioxide, hinders carbon sequestration process. The bioerosion of aquatic environments remains to be elucidated. In this study, the bioerosion of Bellamya spp. shells from the aquatic environment was taken as the research object. In situ microbial community structure analysis of the bioerosion shell from different geographical locations, laboratory-level infected culture, and validated experiments were conducted by coupling traditional observation and 16S rRNA sequencing analysis method. Results showed that bioeroders can implant into the CaCO3 layer of the snail shell, resulting in the formation of many small holes in the shell, which reduced the shell’s density and made the shell fragile. Results also showed that bioeroders were distributed in two major phyla, namely, Cyanobacteria and Proteobacteria. Cluster analysis showed that Cyanobacteria sp. and two unidentified genera (Burkholderiaceae and Raistonia) were the key bioeroders. Moreover, results suggested that the interaction of Cyanobacteria and other bacteria promoted the biological function of “shell bioerosion.” This study identified the causes of “shell bioerosion” in aquatic environments and provided some theoretical basis for preventing and controlling it in the aquatic industry. Results also provided new insights of cyanobacterial bioerosion of shells and microalgae carbon sequestration.

Extraction Induced by Emulsion and Microemulsion Breaking for Metal Determination by Spectrometric Methods - A Review

This review focuses on extraction induced by the destabilization of emulsified systems combined with spectrometric techniques for metal analysis in oily samples. This approach is based on the formation and breaking of an emulsion (extraction induced by emulsion breaking - EIEB) or microemulsion (extraction induced by microemulsion breaking - EIMB) to transfer the analytes from the oil sample to the aqueous phase, which is separated in the process. Its simplicity, speed, and low cost have contributed to its growing popularity among researchers. However, the potential of EIEB and EIMB is far from being fully exploited. Therefore, this paper aims to provide relevant information to expand the applicability of these methods. The principle of the methods is discussed, and a brief description of emulsified systems is presented. The parameters affecting the extraction efficiency and calibration strategy are also critically discussed. Furthermore, the analytical applications of the methods are reviewed. Trends and opportunities in this field are also considered.

Extraction induced by emulsion breaking to assay Cr, Cu and Mn in asphalt samples by high-resolution continuum source atomic absorption spectrometry and its comparison with other sample preparation methods

This paper reports the development of a method based on the extraction induced by emulsion breaking (EIEB) for the determination of Cr, Cu and Mn in asphalt by high-resolution continuum source atomic absorption spectrometry. In optimized conditions, the extraction efficiency ranged from 88.6 for Cu to 104.5% for Mn. Measurements were carried out at the primary lines of the three analytes. The limits of detection were 0.02 μg g^-1 for Cr, 0.01 μg g^-1 for Cu and 7.11 ng g^-1 for Mn. The precision, expressed as the relative standard deviation, ranged from 1.0 for Cu to 9.1% for Cr. The performance of the proposed method was compared to previously reported sample preparation procedures, including microwave-assisted acid digestion (MW-AD), ultrasound-assisted acid extraction (USE), emulsification (E), and direct dilution in organic solvent (DD). The parameters evaluated were matrix effects, limits of detection and quantification, characteristic mass, precision, accuracy, sample stability and applicability for routine analysis. The methods most suitable for Cu determination were EIEB, MW-AD, USE and E. For Cr and Mn, the best results were obtained by EIEB, MW-AD and DD procedures.

Pre-concentration of microalga Euglena gracilis by alkalescent pH treatment and flocculation mechanism of Ca3(PO4)2, Mg3(PO4)2, and derivatives

BACKGROUND

Microalgae are widely be used in carbon sequestration, food supplements, natural pigments, polyunsaturated fatty acids, biofuel applications, and wastewater treatment. However, the difficulties incurred in algae cell separation and harvesting, and the exorbitant cost required to overcome these challenges, are the primary limitations to large-scale industrial application of microalgae technology.

RESULTS

Herein, we explore the potential of inducing flocculation by adjusting the pH for pre-concentrating Euglena gracilis. Our results demonstrate that flocculation can be induced by increasing the medium pH to 8.5; however, most of the algae cells were broken by increasing the pH > 10. Magnesium phosphate, calcium phosphate, and their derivatives precipitation jointly led to flocculation, although calcium phosphate and its derivatives precipitation had a greater effect.

CONCLUSIONS

This study demonstrates that pH treatment-induced flocculation is efficient and feasible for the pre-concentration of E. gracilis under a pilot-scale culture system. Moreover, it also maintained the microalgae cells' integrity, chlorophyll production, and increased paramylon production. These findings provide a theoretical basis for reducing the cost of large-scale E. gracilis harvesting; as well as provide a reference for harvesting other microalgae.

Traditional Calibration Methods in Atomic Spectrometry and New Calibration Strategies for Inductively Coupled Plasma Mass Spectrometry

Applications, advantages, and limitations of the traditional external standard calibration, matrix-matched calibration, internal standardization, and standard additions, as well as the non-traditional interference standard method, standard dilution analysis, multi-isotope calibration, and multispecies calibration methods are discussed.