Multivariate approach to on-line supercritical fluid extraction - supercritical fluid chromatography - mass spectrometry method development.

Coupling supercritical fluid extraction (SFE) on-line with supercritical fluid chromatography (SFC) - tandem mass spectrometry (MS/MS) provides a single platform for efficient extraction, separation, and detection in a chemical analysis. SFE-SFC-MS/MS requires consideration of many extraction and chromatographic variables to not only provide the most efficient extraction, but also to analytically transfer the extracted analytes to the column for separation. There is a fundamental lack of understanding of how the variables in SFE affect those in SFC. Typically, a univariate approach is taken in on-line SFE-SFC-MS/MS method development, but this provides little insight into the relative importance of variables and their potential interactions. Here, a multivariate approach was used to develop a better understanding of the synergistic relationship between the extraction and separation processes by focusing on the optimization of extraction parameters for target analytes with a wide range of physicochemical properties in matrices of variable retentivity. The methodology used a set of optimal on-line SFE-SFC-MS/MS extraction parameters for 18 analytes of variable physicochemical properties in three different silica gel-based sample matrices are presented.

Characterizing anecdotal claims of groundwater contamination in shale energy basins.

The increased societal monitoring of unconventional oil and gas development (UD) has brought forth tremendous scrutiny over the environmental stewardship and subsequent public health impacts of surface and sub-surface activities. Concerns over groundwater quality in shale energy basins have prompted concerned citizens into monitoring UD activities for a series of qualitative parameters, and even coordinating sampling efforts for chemical analysis. Here we present a list of analytical parameters, hierarchically structured to guide concerned citizens through an efficient and cost-effective monitoring program. Utilizing this multi-step testing regime, we assessed groundwater quality from 36 private water wells involved in 19 anecdotal claims of alleged UD-related contamination across the Barnett, Eagle Ford, Haynesville, and Marcellus Shale formations in the United States. Our analytical findings aligned with the landowners' accounts of their situation in only 5 of the 36 collected samples, with several cases revealing environmental abnormalities that were unbeknownst to the landowners but likely unrelated to UD activities. These data are some of the first to assess the relationship between landowner perception and analytical determination in a cohort of highly variable anecdotal cases of alleged groundwater contamination, revealing a notable disconnect that is likely attributable to a myriad of societal and environmental factors. The analytical modalities presented here also serve as a step-wise method in a weight of evidence approach to assess the presence or absence of anthropogenic contamination under the most variable hydrogeological conditions.

On-line supercritical fluid extraction-supercritical fluid chromatography-mass spectrometry of polycyclic aromatic hydrocarbons in soil.

On-line supercritical fluid extraction - supercritical fluid chromatography - mass spectrometry (SFE-SFC-MS) has been applied for the determination of polycyclic aromatic hydrocarbons (PAHs) in soil. The purpose of this study was to develop and validate the first on-line SFE-SFC-MS method for the quantification of PAHs in various types of soil. By coupling the sample extraction on-line with chromatography and detection, sample preparation is minimized, diminishing sample loss and contamination, and significantly decreasing the required extraction time. Parameters for on-line extraction coupled to chromatographic analysis were optimized. The method was validated for concentrations of 10-1500 ng of PAHs per gram of soil in Certified Reference Material (CRM) sediment, clay, and sand with R2 ≥ 0.99. Limits of detection (LOD) were found in the range of 0.001-5 ng/g, and limits of quantification (LOQ) in the range of 5-15 ng/g. The method developed in this study can be effectively applied to the study of PAHs in the environment, and may lay the foundation for further applications of on-line SFE-SFC-MS.

[Interdisciplinary position paper "Perioperative pain management"]. / Interdisziplinäres Positionspapier "Perioperatives Schmerzmanagement".

Despite many positive developments, postoperative pain and its treatment is still not always given the necessary attention. Severe pain after surgical procedures affects a significant proportion of patients. This very fact is not only detrimental to the immediate recovery process, but can also form the basis for the development of chronic pain conditions.An adequate and effective management of perioperative pain requires appropriate organizational structures. This multidisciplinary paper which was initiated by the Austrian Society for Anaesthesiology and Intensive Care and the Austrian Pain Society and developed together with numerous specialist and professional societies dealing with the subject aims at supporting the organization of perioperative pain management structures and to make best use of proven concepts. Additional recommendations describe specific interventions for selected types of intervention.

Characterization of methane plumes downwind of natural gas compressor stations in Pennsylvania and New York.

The extraction of unconventional oil and natural gas from shale energy reservoirs has raised concerns regarding upstream and midstream activities and their potential impacts on air quality. Here we present in situ measurements of ambient methane concentrations near multiple natural gas compressor stations in New York and Pennsylvania using cavity ring-down laser spectrometry coupled with global positioning system technology. These data reveal discernible methane plumes located proximally to compressor stations, which exhibit high variability in their methane emissions depending on the weather conditions and on-site activities. During atmospheric temperature inversions, when near-ground mixing of the atmosphere is limited or does not occur, residents and properties located within 1 mile of a compressor station can be exposed to rogue methane from these point sources. These data provide important insight into the characterization and potential for optimization of natural gas compressor station operations.

The tendon defect after anterior cruciate ligament reconstruction using the midthird patellar tendon--a problem for the patellofemoral joint?

Retrospective clinical and radiographic evaluation was performed on 41 patients seen at the Salzburg General Hospital Department of Traumatology on average 2 years following ACL reconstruction. In 26 patients (61%) clinical examination revealed pain trigger points over the donor site of the midthird patellar tendon and in the patellofemoral joint. Functional pain during kneeling activities was observed in 19 patients (46%). Objective measurement of the length of the patellar tendon in bilateral radiographs demonstrated exactly equal patellar tendon length in both knees in 11 patients (27%). The radiographs showed tendon shortening following harvesting of the midthird patellar tendon by 1-3 mm in 7 patients (17%), by 4-6 mm in 16 (39%), and by 6-9 mm in 7 (17%). Average length change in the patellar tendon on the donor side was -3 mm, representing a patellar tendon shortening of 9.8%. On the basis of the OAK score, however, good and very good results were recorded in 33 patients (80%). On the whole, these good overall results were compromised only be patellar tendon defect morbidity. In addition to the local scarring problems at the donor site, shortening of the patellar tendon was observed with changes to patella position and interference with the mechanics of the patellofemoral joint. Tendon shortening can be explained on the basis of cicatricial contraction in the process of autorepair to the tendon defect. The problems affecting the patellofemoral joint are inherent in the therapy and must be treated as a negative factor. In the case of patients whose work requires mainly a kneeling position and those who make significant functional demands of the extension system of the knee, a critical assessment is required of the use of the midthird patellar tendon for anterior cruciate ligament reconstruction.

Evaluation of ractopamine cross-reactivity in several commercially available beta-agonist enzyme immunoassay kits.

Several enzyme immunoassay test kits are commercially available for screening of matrices including cattle feed, tissues, faeces and urine for the presence of beta-agonists. The kits utilized for this evaluation offer sensitivity as low as 0.1 ng ml-1 (assay solution concentration, not test sample). Evaluation of ractopamine hydrochloride (LY31537) solutions at concentrations as high as 1000 ng ml-1, using six different kits from four different manufacturers, showed cross-reactivity of less than 0.5%.

The need for larger analytical samples with granulated feed additives.

Sampling an animal feed containing a granulated analyte is extremely difficult. A granulated feed additive, Tylan (Elanco, tylosin), was used to demonstrate how a granulated product can increase assay variability if steps are not taken to reduce and control this variability. The number of tylosin granules was determined for Granulated Tylosin Concentrate, the active ingredient of Tylan Premix. Multiple weighings of 3 lots of the concentrate were prepared, and the average number of granules per gram of concentrate was determined with the aid of image analyses. The total weight of Tylan Premix in varying analytical samples was calculated. Finally, the average number of tylosin granules per analytical sample was calculated based on the average number of granules per gram. A 10 g analytical sample obtained from an animal ration containing 8 ppm tylosin activity would contain an average of 1.16 granules of tylosin, and a 100 g analytical sample would contain 11.6 granules. These calculations demonstrate the need to increase the analytical sample size in analyzing an animal feed containing a granulated feed additive.

Substantive theorizing.

This paper outlines, for purposes of discussion and debate, an ecologically oriented approach to theory and research in psychology and related social sciences. This approach, labeled "substantive theorizing", is intended as a constructive response to recent critiqies of the logical positivism paradigm. Substantive theorizing is presented as the intersection of a series of choices by researchers, including decisions to focus on limited but socially important domains; to use multiple methods; to develop intimate familiarity with chosen domains; and to examine processes in their natural social and temporal contexts. The approach emphasizes the process, rather than the product, of conceptual framing and development. Among the projected benefits of substantive theorizing are development of new concepts and procedures, blurring of disciplinary boundaries, greater understanding of socially important domains, and increased utility of research for policy and practice. Projected costs include long-term research commitments and lack of support from academic departments and research funding agencies.