Clases, D, de Vega, RG, Funke, S, Lockwood, TE, Westerhausen, MT, Taudte, RV, Adlard, PA & Doble, PA 2020, 'Matching sensitivity to abundance: high resolution immuno-mass spectrometry imaging of lanthanide labels and endogenous elements in the murine brain', JOURNAL OF ANALYTICAL ATOMIC SPECTROMETRY, vol. 35, no. 4, pp. 728-735.View/Download from: Publisher's site
Lockwood, TE, Talebi, M, Minett, A, Mills, S, Doble, PA & Bishop, DP 2019, 'Micro solid-phase extraction for the analysis of per- and polyfluoroalkyl substances in environmental waters.', Journal of chromatography. A, vol. 1604.View/Download from: Publisher's site
Growing concern over the environmental and health impacts of per- and polyfluoroalkyl substances (PFASs) has led to the development of increasingly stringent regulatory guidelines. To meet these guidelines for the determination of PFASs in surface-water, solid-phase extraction (SPE) is commonly implemented for clean-up and pre-concentration of samples. In this paper a micro-SPE method for the clean-up and pre-concentration of PFASs from surface-water was developed. A micro-SPE packing phase was created to retain 13 long and short chain PFAS after examining combinations of four 3 µm particle size sorbents, with the optimal phase consisting of a 50:50 mixture of C18 and aminopropyl silica. Micro-SPE achieved similar results to conventional SPE methods while reducing sample preparation time to 5 min and using only 2 mL of sample. The method was validated using spiked recoveries (100 ng L-1) from PFAS contaminated surface-water samples with recoveries ranging from 86% to 111% and relative standard deviations below 18%. Concentrations of the PFASs in the samples ranged from below the limit of quantification to 898 ± 15 ng L-1. Automation of sample preparation, including the micro-SPE extraction, was also demonstrated. These results show the potential for automated micro-SPE to replace conventional SPE, with the decreases in sample preparation time, sample and solvent volumes crucial for incorporation into routine analyses in commercial laboratories.
Westerhausen, MT, Lockwood, TE, Gonzalez de Vega, R, Röhnelt, A, Bishop, DP, Cole, N, Doble, PA & Clases, D 2019, 'Low background mould-prepared gelatine standards for reproducible quantification in elemental bio-imaging.', The Analyst, vol. 144, no. 23, pp. 6881-6888.View/Download from: Publisher's site
Standard preparation for elemental bio-imaging by laser ablation-inductively coupled plasma-mass spectrometry is confounded by the chemical and physical differences between standard and sample matrices. These differences lead to variable ablation, aerosol generation and transportation characteristics and must be considered when designing matrix-matched standards for reliable calibration and quantification. The ability to precisely mimic sample matrices is hampered due to the complexity and heterogeneity of biological tissue and small variabilities in standard matrices and sample composition often negatively impact accuracy, precision and robustness. Furthermore, cumbersome preparation protocols may limit reproducibility and traceability. This work presents novel facile methods for the preparation of gelatine standards using both commercial and laboratory-made moulds. Surface roughness, thickness and robustness of the mould-prepared standards were compared against cryo-sectioned gelatine and homogenised brain tissue standards. The mould-prepared standards had excellent thickness accuracy and signal precision which allowed robust quantification, were easier to prepare and therefore easier to reproduce. We also compared gelatine standards prepared from a variety of animal sources and discuss their suitability to calibrate low level elemental concentrations. Finally, we present a simple method to remove background metals in gelatine using various chelating resins to increase the dynamic calibration range and to improve limits of analysis.