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The Simplified Molecular Input Line Entry System (SMILES) is a specification in the form of a line notation for describing the structure of chemical species using short ASCII strings. SMILES strings can be imported by most molecule editors for conversion back into two-dimensional drawings or three-dimensional models of the molecules.
A gas detector is a device that detects the presence of gases in an area, often as part of a safety system. A gas detector can sound an alarm to operators in the area where the leak is occurring, giving them the opportunity to leave.
The mass spectrometry process normally requires a very pure sample while gas chromatography using a traditional detector (e.g. Flame ionization detector) cannot differentiate between multiple molecules that happen to take the same amount of time to travel through the column (i.e. have the same retention time), which results in two or more ...
When alkyl groups are attached to the ring, a favorable mode of cleavage is to lose a H-radical to form the tropylium cation (m/z 91). [2] [11] Benzylic cleavage. Alkyl substituted benzenes can fragment via the kinetic controlled process to form C 6 H 5 +, C 6 H 6 + ions. [11] Benzene derivatives' fragmentation process
Reaction is only possible if energetically allowed, i.e. if the proton affinity of R is higher than the proton affinity of H 2 O (691 kJ/mol [3]).As most components of ambient air possess a lower proton affinity than H 2 O (e.g. N 2, O 2, Ar, CO 2, etc.) the H 3 O + ions only react with VOC trace components and the air itself acts as a buffer gas.
The detection limit for electron capture detectors is 5 femtograms per second (fg/s) and the detector commonly exhibits a 10,000-fold linear range. [ citation needed ] This made it possible to detect halogenated compounds such as pesticides and CFCs , even at levels of only one part per trillion ( ppt ), thus revolutionizing our understanding ...
The photoionization detector was applied to gas chromatography (GC) three years later, in 1976. [5] A PID is highly selective when coupled with a chromatographic technique or a pre-treatment tube such as a benzene-specific tube. Broader cuts of selectivity for easily ionized compounds can be obtained by using a lower energy UV lamp.
In the United States, most state and federal agencies have adopted the Gas Piping and Technology Committee (GPTC) standards for grading natural gas leaks. A Grade 1 leak is a leak that represents an existing or probable hazard to persons or property, and requires immediate repair or continuous action until the conditions are no longer hazardous ...