Trace-level quantification of ethylene oxide and 2-chloroethanol in low-viscosity hydroxypropyl methylcellulose with solid phase microextraction and GC-MS.

Ethylene oxide (EtO) is naturally present in numerous food products but recently EtO and its degradation product of 2-chloroethanol (2-CE) have been reported in amounts exceeding the maximum residue limit in Europe. The reports include hard capsules for dietary supplements made from low viscous hydroxypropyl methylcellulose (HPMC). The European council (EC) has proposed a generalized method for spices, seeds, and capsules utilizing QuEChERS, solid phase extraction (SPE), and GC-MS/MS to accommodate the need for analyte specificity, trace-level analysis, and higher throughput. HPMC has unique solvation properties and, without care, can potentially be transferred to the instrument. The current work presents the development of two methods specific for EtO and 2-CE in low viscous HPMC using solid phase microextraction (SPME) and GC-MS. Method optimization for solvation, SPME settings, and GC-MS settings are presented along with validation based on standard addition. Both methods present a high degree of specificity and limits of detection (EtO 6.7 µg/kg and 2-CE 12 µg/kg), comparable to those obtained with the EC method. Apart from sampling, the methods were fully automated and rely on low cost GC-MS instrumentation, widely available. Analyzed samples did not contain EtO or 2-CE, and method development was done with spiked samples. Contamination from plastic containers and analytical carry-over are shown as possible sources of EtO and 2-CE.

Effects of α-pinene on life history traits and stress tolerance in the springtail Folsomia candida.

Volatile monoterpenes are emitted in large quantities to both air and soil by many plant species. While studies have addressed effects of monoterpenes on aboveground invertebrates, we have much poorer understanding of the possible effects of monoterpenes on soil invertebrates. Monoterpenes play a protective role in some plant species during heat and water stress, and therefore may provide similar protection against abiotic stress to soil invertebrates. The aim of the present study was to investigate the effects of the common monoterpene, α-pinene, on the soil living springtail, Folsomia candida (Collembola; Isotomidae). We hypothesized that exposure to α-pinene would lower the transition temperature of membranes, and thereby improve cold tolerance. Controlled exposure to α-pinene, which is a volatile liquid at room temperature, was made possible by passive dosing through the air-phase using a lipid donor. This lipid-based passive dosing approach also allows linking observed effects to concentrations in membrane when equilibrium is achieved. Equilibrium membrane concentrations above 116 mmol kg-1 caused springtails to become comatose, and coma recovery time was proportional to exposure concentration. Alpha-pinene delayed time to first egg laying, while the number of eggs laid and hatchability was unaffected. Springtails exposed to α-pinene showed increased survival of cold shock (-6 °C, 2 h), but no effects on heat (34 °C, 2 h) or drought tolerance (98.2% relative humidity, 7d) were observed. The present study has demonstrated that α-pinene has direct toxic effects to F. candida, but on the other hand can improve their cold tolerance considerably at membrane concentrations above 87 mmol kg-1.

Using design of experiments to optimize derivatization with methyl chloroformate for quantitative analysis of the aqueous phase from hydrothermal liquefaction of biomass.

Hydrothermal liquefaction is a promising technique for the production of bio-oil. The process produces an oil phase, a gas phase, a solid residue, and an aqueous phase. Gas chromatography coupled with mass spectrometry is used to analyze the complex aqueous phase. Especially small organic acids and nitrogen-containing compounds are of interest. The efficient derivatization reagent methyl chloroformate was used to make analysis of the complex aqueous phase from hydrothermal liquefaction of dried distillers grains with solubles possible. A circumscribed central composite design was used to optimize the responses of both derivatized and nonderivatized analytes, which included small organic acids, pyrazines, phenol, and cyclic ketones. Response surface methodology was used to visualize significant factors and identify optimized derivatization conditions (volumes of methyl chloroformate, NaOH solution, methanol, and pyridine). Twenty-nine analytes of small organic acids, pyrazines, phenol, and cyclic ketones were quantified. An additional three analytes were pseudoquantified with use of standards with similar mass spectra. Calibration curves with high correlation coefficients were obtained, in most cases R (2) > 0.991. Method validation was evaluated with repeatability, and spike recoveries of all 29 analytes were obtained. The 32 analytes were quantified in samples from the commissioning of a continuous flow reactor and in samples from recirculation experiments involving the aqueous phase. The results indicated when the steady-state condition of the flow reactor was obtained and the effects of recirculation. The validated method will be especially useful for investigations of the effect of small organic acids on the hydrothermal liquefaction process.