Effect of sample preparation on the characterization of crude oil and its complex fractions by high resolution mass spectrometry

Die Abhängigkeit der modernen Gesellschaft auf verfügbare Energie-Ressourcen wächst. Gleichzeitig, der rasante Anstieg der Preise auf den weltweiten Öl-Märkte in den letzten Jahren zeigt deutlich, dass eine bessere Ausnutzung der restlichen Quellen deutlich wichtiger wird. Trotz der eher teuren chemischen Aufarbeitungsmethoden, um saubere und nützliche Energieversorgung zu erzielen, wird die Aufarbeitung von unkonvetionellen Rohölen notwendig. Anderseites, haben höher siedenden Fraktionen von Standard Rohöle und schwere Rohöle erhöhten Konzentrationen von Heteroatomen, z. B. Schwefel-, Stickstoff-, Sauerstoff-oder Metall-Verbindungen. Viele dieser Verbindungen haben nachteilige Auswirkungen auf die Verarbeitung sowie auf die Leistung der Endprodukte. Die Optimierung der katalytischen Raffinierungsverfahren ist daher stark abhängig von der Qualität der chemischen Charakterisierung der Rohstoffe. In diesem Zusammenhang hat Fourier-Transform-Ionenzyklotronresonanz-Massenspektrometrie (FT-ICR MS) als analytische Methode bewiesen, dass die resultierenden Daten von ausreichender Genauigkeit und Auflösung sind. Dennoch, auch mit der letztlich hohen Auflösungsstärke des FT-ICR MS, beruht die genaue massenspektrometrische Analyse von Rohölkomponenten auf geeigneten Ionisationsmethoden und Trennverfahren. Die Rolle der Probenvorbereitung ist immens in dieser Hinsicht. Ohne Vereinfachung der komplexen Rohöl Probe ist es praktisch unmöglich, die Probe auch mit hochauflösender Massenspektrometrie einer einzelnen Messung zu analysieren. FT-MS Geräte arbeiten am besten, wenn eine kleinere Anzahl von Ionen bei jedem Transient verfügbar ist. Dies kann nicht in die Analyse von Rohöl Proben ohne Vereinfachung der Probe durchgeführt werden. Diese Studie basiert auf der Untersuchung der Probenvorbereitungsmethoden, die die Komplexität von Rohöl Proben vereinfacht und zur gleichen Zeit die Selektivität gegenüber Rohöl Klassen zeigt. Die Kombination dieser analytischen Ansätze mit höchster Auflösung der Massenspektrometrie gibt unverzichtbare Daten, die zur elementaren Zusammensetzung der Bestandteile der Probe führen. Dementsprechend werden statistische Informationen, die die Charakterisierung der Verbindungen ermöglicht, gewonnen. Vor allem, werden mit Hilfe hoch auflösende FT-MS Instrumente Extraktionsverfahren und Chromatographische Trennung in dieser Studie eingesetzt, damit komplexe Erdölproben analysiert und charakteriziert werden können.The dependency of the modern society on affordable energy resources, which fuels the economy and social development, is growing. The rapid rise of prices on the world’s oil markets in the last years clearly demonstrates that a better exploitation of the remaining supplies becomes distinctively more valuable. Despite the rather expensive chemical work-up procedures to yield clean and useful energy supplies, higher oil prices push the exploitation of non-conventional oils. Heavier crude oils and the higher boiling fractions of standard crude oils have thus become important resources to the expense of significantly elevated impurities levels, e.g., sulfur-, nitrogen-, oxygen- or metal-compounds. Many of these compounds have adverse effects on processing as well as on performance of the final products. The optimization of catalytic refinement processes is thus heavily dependent on the quality of the chemical characterization of the raw material. In this regard, Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) has proven to provide analytical data of sufficient accuracy and resolution. Nevertheless, even with the ultimately high resolving power of FT-ICR MS, the accurate mass spectrometric analysis of crude oil components relies on appropriate ionization and separation methods. The role of sample preparation is immense in this regard. Without simplification of the complex crude oil sample it is practically impossible to analyze the sample even with high resolution mass spectrometry by one-shot-measurement approach. FT-MS instruments operate best when smaller number of ions is present during each transient. This cannot be accomplished in the analysis of crude oil samples without simplification of the sample. This study is focusing on the investigation of sample preparation methods which simplify the complexity of crude oil samples and at the same time show selectivity towards crude oil classes. Combining these analytical approaches with ultrahigh resolution mass spectrometry gives indispensable data that lead to the elemental composition of the sample components. Accordingly, statistical information that allows characterization of the compounds is gained. Extraction methods and chromatographic separations are applied in this study to analyze and characterize complex crude oil samples using high resolution FT-MS instruments

Direct Coupling of Normal-Phase High-Performance Liquid Chromatography to Atmospheric Pressure Laser Ionization Fourier Transform Ion Cyclotron Resonance Mass Spectrometry for the Characterization of Crude Oil

The high complexity of crude oil makes the use of chromatographic separation an important tool especially for sample simplification. The coupling of normal-phase high-performance liquid chromatography (HPLC) using a polar aminocyano column to a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer offers the best attributes of good separation prior to ultrahigh resolution mass spectrometry (MS) detection. Atmospheric pressure laser ionization (APLI) was used as an ionization technique to analyze the nitrogen-containing aromatic compounds in a deasphalted crude oil due to its unique selectivity toward aromatic compounds and also due to its sensitivity. Two main chromatographic peaks were observed during this separation indicating a class-based separation. Mass spectra obtained from fractions were collected along the entire retention time and compared with each other to assign the unique constituents. By coupling the HPLC system directly to the FTICR mass spectrometer, comparable ion and UV chromatograms were obtained, reflecting the scan-to-scan sensitivity of the coupling system. The results show that it is possible to calculate reconstructed class chromatograms (RCC), allowing differences in class composition to be traced along the retention time. As an example, radical and protonated nitrogen species generated by APLI were detected along the retention time which enabled a differentiation between basic and nonbasic species in the same polar peak, thus overcoming the limitation of chromatographic resolution. This report represents the first online LC–FTICR MS coupling in the field of crude oil analysis

Thromboprophylaxis using combined intermittent pneumatic compression and pharmacologic prophylaxis versus pharmacologic prophylaxis alone in critically ill patients: study protocol for a randomized controlled trial

Abstract Background Venous thromboembolism (VTE) remains a common problem in critically ill patients. Pharmacologic prophylaxis is currently the standard of care based on high-level evidence from randomized controlled trials. However, limited evidence exists regarding the effectiveness of intermittent pneumatic compression (IPC) devices. The Pneumatic compREssion for preventing VENous Thromboembolism (PREVENT trial) aims to determine whether the adjunct use of IPC with pharmacologic prophylaxis compared to pharmacologic prophylaxis alone in critically ill patients reduces the risk of VTE. Methods/Design The PREVENT trial is a multicenter randomized controlled trial, which will recruit 2000 critically ill patients from over 20 hospitals in three countries. The primary outcome is the incidence of proximal lower extremity deep vein thrombosis (DVT) within 28 days after randomization. Radiologists interpreting the scans are blinded to intervention allocation, whereas the patients and caregivers are unblinded. The trial has 80 % power to detect a 3 % absolute risk reduction in proximal DVT from 7 to 4 %. Discussion The first patient was enrolled in July 2014. As of May 2015, a total of 650 patients have been enrolled from 13 centers in Saudi Arabia, Canada and Australia. The first interim analysis is anticipated in July 2016. We expect to complete recruitment by 2018. Trial registration Clinicaltrials.gov: NCT02040103 (registered on 3 November 2013). Current controlled trials: ISRCTN44653506 (registered on 30 October 2013)

Statistical analysis plan for the Pneumatic CompREssion for PreVENting Venous Thromboembolism (PREVENT) trial: a study protocol for a randomized controlled trial

Abstract Background The Pneumatic CompREssion for Preventing VENous Thromboembolism (PREVENT) trial evaluates the effect of adjunctive intermittent pneumatic compression (IPC) with pharmacologic thromboprophylaxis compared to pharmacologic thromboprophylaxis alone on venous thromboembolism (VTE) in critically ill adults. Methods/design In this multicenter randomized trial, critically ill patients receiving pharmacologic thromboprophylaxis will be randomized to an IPC or a no IPC (control) group. The primary outcome is “incident” proximal lower-extremity deep vein thrombosis (DVT) within 28 days after randomization. Radiologists interpreting the lower-extremity ultrasonography will be blinded to intervention allocation, whereas the patients and treating team will be unblinded. The trial has 80% power to detect a 3% absolute risk reduction in the rate of proximal DVT from 7% to 4%. Discussion Consistent with international guidelines, we have developed a detailed plan to guide the analysis of the PREVENT trial. This plan specifies the statistical methods for the evaluation of primary and secondary outcomes, and defines covariates for adjusted analyses a priori. Application of this statistical analysis plan to the PREVENT trial will facilitate unbiased analyses of clinical data. Trial registration ClinicalTrials.gov, ID: NCT02040103. Registered on 3 November 2013; Current controlled trials, ID: ISRCTN44653506. Registered on 30 October 2013

Additional file 2: of Statistical analysis plan for the Pneumatic CompREssion for PreVENting Venous Thromboembolism (PREVENT) trial: a study protocol for a randomized controlled trial

SPIRIT 2013 Checklist. (PDF 238 kb

Additional file 1: of Statistical analysis plan for the Pneumatic CompREssion for PreVENting Venous Thromboembolism (PREVENT) trial: a study protocol for a randomized controlled trial

Online supplement. (DOCX 63 kb