Simultaneous quantification of seven glycols in antifreeze liquids using direct liquid injection gas chromatography coupled with mass spectrometry.

Glycol-based antifreeze liquids, commonly composed of ethylene glycol or propylene glycol, have important uses in automotive cooling, but they should be handled with care due to their toxicity. Ethylene glycol is highly toxic to humans and animals. A fast, accurate, precise, and robust method was developed for the simultaneous quantification of seven most important glycols and their isomers. METHODS: Glycols were analyzed from diluted sample solution of coolants using gas chromatography coupled with mass spectrometry (GC-MC) in single ion monitoring mode. RESULTS: The method was developed and validated for seven individual glycols (ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, propylene glycol, dipropylene glycol, and tripropylene glycol). Limits of detection (1-2 µg/mL) and limits of quantification (10 µg/mL) obtained were appropriate. The present method was applied for the determination of glycols in 10 different antifreeze liquids commercially available on the Romanian market, proving to be reliable. CONCLUSIONS: A method that requires only a two-step dilution of antifreeze samples combined with direct liquid injection GC-MS was validated for the simultaneous quantification of seven glycols (and their isomers) in 10 different types of antifreeze liquids. The results obtained in the validation procedure proved that the GC-MS method is sensitive and precise for the quantification of glycols.

In-Depth Comparative Assessment of Different Metallic Biomaterials in Simulated Body Fluid.

Invitro experiments have been conducted on metallic biomaterials used for orthopedic implants in order to determine their behavior when immersed in simulated body fluid (SBF). Thus, 3Ti-based metallic biomaterial samples already available on the marked were purchased and immersed in simulated blood plasma, and kept at 37 °C for 4 months. In-depth characterization consisted of a wide series of structural characterizations of both the samples and SBF. Sample analysis consisted of the following: optical (OM) and scanning electron microscopy (SEM) in order to establish the surface and deep corrosion, mass gain/loss assessment for determining the metallic ions loss and/or protective layer formation, and X-ray diffraction in order to establish if and what kind of layers are formed. SBF analysis consisted of using inductively coupled plasma mass spectroscopy (ICP-MS) in order to establish if and/or how many metallic ions have dissociated from the metallic samples into the SBF, and measurements of pH and electrical conductivity. The key findings of the research are as follows: during the four months while kept in SBF, the samples show surface corrosion degradation and protective layer generation. Also, the amount of metallic ions dissociated into the SBF is making them suitable for use. Taking into account that it is highly improbable for such a large area of metal as the one considered within this work to be exposed to real body fluids and that all the samples have developed protective oxide films, the overall conclusion is that they are appropriate for implant use.

An Experimental Investigation to Use the Biodiesel Resulting from Recycled Sunflower Oil, and Sunflower Oil with Palm Oil as Fuels for Aviation Turbo-Engines.

The paper is presenting the experimental analysis of the use of biodiesel from waste sunflower oil and a blend of sunflower oil with palm oil as fuel for aviation turbo-engines. A comparative analysis for fuel mixtures made of Jet A + 5% Aeroshell 500 Oil (Ke) with 10%, 30%, and 50% for each bio-fuel type has been performed and Ke has been used as reference. Firstly, the following physical and chemical properties were determined: density, viscosity, flash point, freezing point, calorific power. Then, elemental analysis and Fourier transform infrared spectroscopy (FTIR) analysis were conducted for Ke, biodiesel obtained from recycled sunflower oil (SF), biodiesel obtained from blending recycled sunflower oil, and recycled palm oil (SFP), and for each fuel blend. Secondly, experimental tests of the blends have been conducted on the Jet Cat P80® micro-turbo engine (Gunt Hamburg, Barsbüttel, Germany). The tests have been conducted at different engine working regimes as follows: idle, cruise, intermediate, and maximum. For each regime, a one-minute testing period was chosen, and the engine parameters have been monitored. The turbo engine instrumentation recorded the temperature after the compressor and before the turbine, the fuel consumption and air flow, pressure inside the combustion chamber, and generated thrust. The burning efficiency and the specific consumption have been calculated for all four above-mentioned regimes and for all fuel blends. Two accelerometers have been installed on the engine's support to register radial and axial vibrations allowing the assessment of engine stability.