Chemical Sensing Properties of BaF2-Modified hBN Flakes towards Detection of Volatile Organic Compounds

The application of BaF2-modified hBN flakes as rapid response and recovery as well as sensitive chemoresistive sensing device materials for detection of acetone and/or ethanol is presented in this study. Modification of the hBN flakes was achieved by using the modified polymer derived ceramics (PDCs) process through the use of 0–10 wt% BaF2 and 5 wt% Li3N. Upon exposure to individual acetone and ethanol vapours, room temperature sensing studies revealed high LoD values (−144–460 ppmacetone and −134–543 ppmethanol) with extremely compromised sensitivities of −0.042–0.72 × 10−2 ppm−1acetone and −0.045–0.19 × 10−2 ppm−1ethanol for the structurally improved 5–10 wt% BaF2-modified hBN flakes. Moreover, enhanced sensing for 0–2.5 wt% BaF2-modified hBN flakes, as shown by the low LoDs (−43–86 ppmacetone and −30–62 ppmethanol) and the high sensitivities (−1.8–2.1 × 10−2 ppm−1acetone and −1.5–1.6 × 10−2 ppm−1ethanol), was attributed to the presence of defects subsequently providing an abundance of adsorption sites. Overall, the study demonstrated the importance of structural properties of hBN flakes on their surface chemistry towards room temperature selective and sensitive detection of VOCs.

Improvement in the Analytical Capabilities of LA-ICP-MS for High Spatial Resolution U-Pb Dating of Zircon Using Mixed-Gas Plasma

In this work, a novel method for high spatial resolution U-Pb dating of zircon by laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) at 10–16 μm spot diameter has been proposed. This was achieved by introducing 2% (v/v) water-ethanol vapours into ICP in combination with the shielded torch system to increase the sensitivity and suppress the isotopic fractionation effect. Precise and accurate concordant U-Pb ages for Plešovice, GJ-1, and 91500 zircons were obtained using the proposed method, and the results agreed well with the isotope dilution-thermal ionization mass spectrometry (ID-TIMS) and LA-ICP-MS within 2σ, except for the ages obtained using dry plasma at 10 μm spot diameter. Additionally, the effects of plasma condition (dry plasma or 2% (v/v) ethanol plasma) and spot size (10, 16, 24, or 32 μm) on precision (RSD), accuracy (RE), and uncertainty (2σ) of the 206Pb/238U ages have been studied. The results indicated that increasing the spot diameter and introducing 2% (v/v) water-ethanol vapours into ICP significantly improved the precision, accuracy, and uncertainty for small spot diameters (10 and 16 μm), while it exhibited little influence for intermediate spot diameters (24 and 32 μm). Furthermore, the effects of spot size and plasma condition on the precision, accuracy, and uncertainty strongly depended on the sensitivity of analytes.

Neonatal ethanol exposure from ethanol-based hand sanitisers in isolettes

ObjectiveThe aims of this study is to measure the ethanol vapours in the isolette after use of hands cleaned with ethanol-based hand sanitiser (EBHS).MethodsTwo squirts (1.5 mL) of hand sanitiser were rubbed on hands for 10 or 20 s before inserting the hands in the isolette for 5 min. Ethanol vapours were measured in the isolette with photoionisation detector and alcohol breathalyser for 30 min.ResultsPeak ethanol concentration in the isolette was considerably higher with a 10 s hand rub (381±192 ppm) compared with a 20 s hand rub (99±50 ppm), and dissipated to ≤5 ppm within 30 min. Under routine care, EBHS use by care providers exposes neonates in isolettes to 3.7–7.3 or 1.4–2.8 mg/kg ethanol per day with 10 or 20 s hand rubs, respectively. The expected blood level from average single exposure is 0.036 mg/dL with 10 s hand rub and may increase further with multiple exposures in a short period.ConclusionPreterm neonates in the isolette are at risk of inadvertent exposure to ethanol. The expected blood alcohol level from this exposure is small and below 1 mg/dL level recommended by European Medicines Agency to limit the ethanol exposure in children. The unintended ethanol exposure can be avoided by rubbing hands for at least 20 s after applying EBHS.

Magnesium ferrite nanostructures for detection of ethanol vapours - a first-principles study

The adsorption behaviour and electronic properties of ethanol vapour on MgFe2O4 ceramic nanostructures are studied using density functional theory technique. The structural stability of MgFe2O4 nanostructure is determined with the help of formation energy. The adsorption behaviour of ethanol molecules on MgFe2O4 base material is analysed in terms of average energy gap variation, Mulliken charge transfer, band gap and adsorption energy. The most prominent adsorption sites of ethanol vapours on MgFe2O4 nanostructure are investigated at atomistic level. The density of states spectrum reveals the clear picture about the electronic properties of MgFe2O4 nanostructure. The density of states and electronic band gap confirmed the adsorption of ethanol vapours on MgFe2O4 nanostructure. The changes in the energy band gap and density of states are observed upon adsorption of ethanol vapour molecules on MgFe2O4 nanostructure. The density of states spectrum also confirms the changes in peak maxima due to the transfer of electrons between MgFe2O4 nanostructure and ethanol vapours. The adsorption of oxygen atom from ethanol vapour on iron in MgFe2O4 is found to be more prominent rather than other adsorption sites. The findings show that MgFe2O4 nanostructure can be utilized to sense the presence of ethanol vapour in the atmosphere.