Recommendations for the advancement of oil-in-water media and source oil characterization in aquatic toxicity test studies

During toxicity testing, chemical analyses of oil and exposure media samples are needed to allow comparison of results between different tests as well as to assist with identification of the drivers and mechanisms for the toxic effects observed. However, to maximize the ability to compare results between different laboratories and biota, it has long been recognized that guidelines for standard protocols were needed. In 2005, the Chemical Response to Oil Spills: Ecological Effects Research Forum (CROSERF) protocol was developed with existing common analytical methods that described a standard method for reproducible preparation of exposure media as well as recommended specific analytical methods and analyte lists for comparative toxicity testing. At the time, the primary purpose for the data collected was to inform oil spill response and contingency planning. Since then, with improvements in both analytical equipment and methods, the use of toxicity data has expanded to include their integration into fate and effect models that aim to extend the applicability of lab-based study results to make predictions for field system-level impacts. This paper focuses on providing a summary of current chemical analyses for characterization of oil and exposure media used during aquatic toxicity testing and makes recommendations for the minimum analyses needed to allow for interpretation and modeling purposes.publishedVersio

Reusable Solid-Phase Microextraction Coating for Direct Immersion Whole-Blood Analysis and Extracted Blood Spot Sampling Coupled with Liquid Chromatography–Tandem Mass Spectrometry and Direct Analysis in Real Time–Tandem Mass Spectrometry

Three different biocompatible polymers were tested and evaluated in order to improve the whole-blood biocompatibility of previously developed C18–polyacrylonitrile (C18–PAN) thin-film solid-phase microextraction (SPME) coating. Among all methods of modification, UV-dried thin PAN-over C18–PAN provided the best results. This coating presented reusable properties and reproducible extraction efficiency for at least 30 direct extractions of diazepam from whole blood [relative standard deviation (RSD) = 12% using external calibration and 4% using isotope dilution calibration]. The amount of absolute recovery for direct immersion analysis and based on the free concentration of diazepam in blood matrix was about 4.8% (desorption efficiency = 98%). The limit of quantitation (LOQ) for the developed solid-phase microextraction liquid chromatography–tandem mass spectrometry (SPME-LC–MS/MS) method for direct whole-blood analysis was 0.5 ng/mL. The optimized modification of the coating was then used for an extracted blood spot (EBS) sampling approach, a new sampling method which is introduced to address the limitations of dried blood spot sampling. EBS was evaluated using LC–MS/MS and direct analysis in real time (DART)–MS/MS, where, for a 5 μL blood spot, LOQs of 0.2 and 1 μg/mL, respectively, were achieved for extraction of diazepam

Microextraction versus exhaustive extraction approaches for simultaneous analysis of compounds in wide range of polarity

This article discusses comparison of microextraction versus exhaustive extraction approaches for simultaneous extraction of compounds in wide range of polarity at low and high volumes of sample by comparing solid phase extraction (SPE) and solid phase microextraction (SPME). Here, both systems are discussed theoretically and evaluated based on experimental data. Experimental comparisons were conducted in terms of extraction recovery, sensitivity, and selectivity for the extraction of doping agent compounds (logP: 0.14-4.98), using C18 as the extraction phase. The extraction recovery of both systems was studied at different volumes of phosphate buffered saline (PBS). The distribution constant of SPME in thin-film geometry (i.e., thin-film microextraction/TFME) as well as the retention factor and breakthrough volume for the SPE system were evaluated for the simultaneous extraction of polar and non-polar compounds. Using 1 mL of sample, the extraction recovery and sensitivity of the SPE system (100 mg sorbent) was comparable with that of TFME format of SPME (15 mg sorbent) for all analytes, with the exception of most polar compounds, due to the smaller amount of the extraction phase in SPME. Breakthrough in the SPE system was observed for more polar compounds in a 25 mL sample; however, this situation did not affect the quantitation of TFME, as this technique operates in equilibrium mode. Experimental values for breakthrough volume were in good match with the calculated theoretical values. Results indicate that the microextraction approach is more suitable for untargeted determinations, where the breakthrough volume cannot be determined prior to the experiment. In addition, when both methods are at optimum conditions, findings suggest that, despite the smaller volume of the extraction phase in TFME, the sensitivity of TFME can exceed that of SPE for samples where the target analytes vary substantially in polarity