Quality Of Chemical Data Research Articles

High-Performance Data Processing Workflow Incorporating Effect-Directed Analysis for Feature Prioritization in Suspect and Nontarget Screening.

Effect-directed analysis (EDA) aims at the detection of bioactive chemicals of emerging concern (CECs) by combining toxicity testing and high-resolution mass spectrometry (HRMS). However, consolidation of toxicological and chemical analysis techniques to identify bioactive CECs remains challenging and laborious. In this study, we incorporate state-of-the-art identification approaches in EDA and propose a robust workflow for the high-throughput screening of CECs in environmental and human samples. Three different sample types were extracted and chemically analyzed using a single high-performance liquid chromatography HRMS method. Chemical features were annotated by suspect screening with several reference databases. Annotation quality was assessed using an automated scoring system. In parallel, the extracts were fractionated into 80 micro-fractions each covering a couple of seconds from the chromatogram run and tested for bioactivity in two bioassays. The EDA workflow prioritized and identified chemical features related to bioactive fractions with varying levels of confidence. Confidence levels were improved with the in silico software tools MetFrag and the retention time indices platform. The toxicological and chemical data quality was comparable between the use of single and multiple technical replicates. The proposed workflow incorporating EDA for feature prioritization in suspect and nontarget screening paves the way for the routine identification of CECs in a high-throughput manner.

Assessment of the efficacy of six field cleaning protocols for hydrocarbon quantification.

The defensibility of field sampling data collected in support of natural resource damage assessments and other environmental investigations depends on rigorous quality assurance and control both in the field and laboratory. One important step in field procedures is the cleaning of sampling equipment between samples to minimize the carryover of contaminants. Large-scale sampling efforts during the Deepwater Horizon oil spill event have highlighted the importance of understanding how multiple equipment cleaning protocols affect interstation cross-contamination and the resulting chemical data quality. In this study, six field cleaning techniques were tested on metal sampling equipment using two different sediment types spiked with crude oil in order to understand their relative and absolute effectiveness in reducing chemical carryover. The complexity of the cleaning protocols ranged from a simple water and scrub brush application to protocols that included soap and/or solvent. In this study, percent residual hydrocarbon transfer, relative to total loading in sediments, never exceeded 0.032%. The least labor-intensive protocol, water and scrub brush application, had the highest potential for hydrocarbon transfer (0.011-0.032%). Statistical differences were observed among treatments, and it was found that protocols containing a solvent step were more effective than protocols without solvents. Depending on the data quality objectives, the differences may not be meaningful, and choosing a cleaning technique should be governed by health, safety, and environmental factors. The residual hydrocarbons measured after equipment cleanings for all techniques in this study were negligible when compared with other variables that occur during routine sampling and laboratory activities.

Lessons from practice in the assessment and remediation of contaminated ground water

The famous American humorist Mark Twain once wrote “don’t let school interfere with your education”. This paper builds on this theme by examining important lessons that come from work on practical problems of ground-water contamination and remediation in Canada and the United States. We draw lessons from the interesting features of the studies, and mistakes in execution, which have had important consequences. The first case study from Edmonton, Alberta Canada examines a problem of ground-water contamination due to leakage of water contaminated by 2,4-D and other contaminants from a small storage pond. This study highlights the problems related to an inadequate geologic understanding of a site, misunderstandings concerning the advantages and limitations of key tools for site investigation, and how projects can benefit from early and ongoing peer reviews. The second case study examines a problem of sewage contamination related to a deep tunnel system in Milwaukee Wisconsin. This system is designed to store surface-water overflows from an old, combined sewer system. This case study highlights the difficulties in working on unique problems without an effective conceptual hydrogeologic model, the need to always be concerned about the quality of chemical data, and the necessity of being alert to behaviors beyond typical experience. The lessons coming from these case studies have important implications for remedial work being undertaken in Korea and regulatory agencies with oversight of the projects.

Our future resources, groundwater

for site investigation, and how projects can benefit from early and ongoing peer reviews. The second case study explains difficulties in working on unique problems without an effective conceptual hydrogeologic model, the need to always be concerned about the quality of chemical data, and the need to be alert to behaviors that are beyond typical experience. Sudicky et al. (2008) present large-scale surface-subsurface hydrodynamic model that was applied to a 17 km 2 subcatchment of the Laurel Creek Watershed in Southern Ontario, Canada. A steady-state condition was achieved in the model by calibrating the subsurface flow field to 16 observation wells where long-term hydraulic head data were available. The model was then subjected to several hundred hours of rainfall data and the resulting discharge hydrographs were compared with the measured hydrographs. The calculated subsurface hydraulic head distribution and surficial rainfall-runoff responses, respectively, were shown to agree moderately well with those observed in the system during this period. These results suggested that the model is capable of reproducing surface and subsurface hydrodynamic processes at the subcatchment scale although the results could be better through improved parameterization of the subcatchment and the manner in which the model simulates evapotranspiration processes. Koo and Kim (2008) perform numerical simulations to demonstrate variability in local groundwater recharge in response to monsoon rainfall in Korea. Monsoon in the summer provides more than 50% of the total precipitation in Korea, thus important for recharge to shallow aquifers. This paper specifically examines impact of monsoon precipitation on the water flux and thermal diffusivity in the vadose zone and variability of precipitation recharge in relation to the monsoon rainfall by applying heat transport and infiltration models to 22-year time series soil temperature and meteorological data. The results demonstrate that the annual recharge is linearly proportional to the annual precipitation with varying degrees of the correlation coefficients depending on soil types. Nordstrom (2008) reports results of recent investigation to determine the pre-mining groundwater quality at a molybdenum mine in northern New Mexico, USA. The pre-mining groundwater quality was inferred by studying a

Preparation of twelve candidate agricultural reference materials

A cost-effective approach to monitoring and maintaining reliability of analytical procedures is by the incorporation of appropriate, compositionally similar reference materials into the scheme of analysis. Agricultural and food commodities represent an extremely wide range of composition, in respect of the sought-for analyte and the supporting material (matrix), not fully reflected in currently available biological reference materials (BRM's). With the view to attempting to fill some of the gaps in the world repertoire of reference materials and to have suitable products for our laboratories' use, preparation has been completed of twelve candidate agricultural reference materials. These products, representing a number of food classes, include bovine muscle powder, hard red spring wheat flour, soft winter wheat flour, durum wheat flour, wheat gluten, corn bran, corn starch, potato starch, whole egg powder, whole milk powder, microcrystalline cellulose, and sugar. Preparative steps included, as required, freeze drying, grinding or ball milling, X-ray sterilization, sieving, blending and packaging to yield sizeable quantities of each material in finely powdered form. Cooperative analytical effort is expected to lead to characterization in respect of concentrations of a number of nutritionally, toxicologically and environmentally-pertinent, major, minor, and trace chemical elements. These materials will then be available for analytical chemical data quality control for inorganic constituents in a range of agricultural commodities.