Advances in structure elucidation of small molecules using mass spectrometry

The structural elucidation of small molecules using mass spectrometry plays an important role in modern life sciences and bioanalytical approaches. This review covers different soft and hard ionization techniques and figures of merit for modern mass spectrometers, such as mass resolving power, mass accuracy, isotopic abundance accuracy, accurate mass multiple-stage MS(n) capability, as well as hybrid mass spectrometric and orthogonal chromatographic approaches. The latter part discusses mass spectral data handling strategies, which includes background and noise subtraction, adduct formation and detection, charge state determination, accurate mass measurements, elemental composition determinations, and complex data-dependent setups with ion maps and ion trees. The importance of mass spectral library search algorithms for tandem mass spectra and multiple-stage MS(n) mass spectra as well as mass spectral tree libraries that combine multiple-stage mass spectra are outlined. The successive chapter discusses mass spectral fragmentation pathways, biotransformation reactions and drug metabolism studies, the mass spectral simulation and generation of in silico mass spectra, expert systems for mass spectral interpretation, and the use of computational chemistry to explain gas-phase phenomena. A single chapter discusses data handling for hyphenated approaches including mass spectral deconvolution for clean mass spectra, cheminformatics approaches and structure retention relationships, and retention index predictions for gas and liquid chromatography. The last section reviews the current state of electronic data sharing of mass spectra and discusses the importance of software development for the advancement of structure elucidation of small molecules

Application of Flame RefluxerTM Concept to ISB – Experimental Results of 5 Field Trials in Mobile, Alabama

A new in situ burning (ISB) method, capable of enhanced combustion of oil slicks in containment booms, is analyzed. The concept named Flame RefluxerTM is based on the use of immersed thermally conductive objects to transfer heat generated by the combustion back to the fuel to create a feedback loop. The resulting enhanced heat transfer from flame back to the fuel helps to sustain a significantly increased burning rate. The project spanned a period of two years ranging from bench scale to large-scale experiments in the laboratory and culminating in outdoor field experiments. Five large-scale field experiments were performed at the United States Coast Guard (USCG) test facility at Little Sand Island in Mobile Bay, Alabama. A confined liquid pool (1.4 m diameter) was continuously fed to maintain a constant oil layer thickness of 1 cm floating over water. A 0.5 cm thick copper blanket, 94% porous, was immersed in the oil and served as a heater for the oil slick. Conical shaped copper coils extending out into the fire were attached to the blanket and were used to collect the heat from the flame. Experiments resulted in three major outcomes: i) Additional heat transfer to the fuel lateral dissipation through the copper blanket increased mass loss rate by 6 times ii) Heat stored in the blanket facilitated burning of the heavier components of crude oil such as tar, resulting in negligible residue (15 times less than baseline). iii) Black smoke was reduced by 50%. The Flame RefluxerTM is robust, easy and cheap to construct and has no moving parts. The field experiments demonstrated the feasibility of the technology to be used in efficient clean up of oil spills using ISB