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  EXPERIMENT NO.5 MASS SPECTROMETRY  Name: Chariezza Le J. Sanglad Student No.: 2015-00925  Name: Erlindo Regala Student No.: 2015-01947  Name: Leziel Talpis Student No.: 2015-01076  ABSTRACT Mass Spectrometry is an analytical spectroscopic tool that can determine the molecular weight, molecular formula (HRMS), structure (from fragmentation fingerprint), isotopic incorporation / distribution and protein sequence (MS-MS). This experiment aimed to identify the compound or structure in the given mass spectrum and to be able to interpret the fragments of the spectrum. Based on the spectrum, given the fragments with m/z of 46, 45, 31,29, 15, the parent ion  peak which has a m/z of 46 did not match to 1-propanol, methanol and isopropanol. Therefore, it corresponds only either formic acid or ethanol. The peak with 46 m/z is the parent molecular ion. From this parent molecular ion, some of the fragments were formed by cleaving its particular  bonds. At 45 m/z, this is the molecular ion less with I hydrogen. At this fragmentation, the parent ion has lost its hydrogen as a form of ion forming the fragment of [CH 3 CH 2 O] +.  One of the  properties of alcohols is that it can easily lose a hydrogen. This cleavage of CH 3 was not possible for formic acid because it has no CH 3  group in its structure. At 29, this is the cleaving of the C-O  bond or the removal of the OH group forming the fragment [CH 3 CH 2 ] +. . At fragment 45, the removal of C-H bond occurred. At 29, the fragmentation for C-O bond and at 31, the removal of C-C bond. In general, the spectrum clearly shows that the fragments correspond to the structure of ethanol.  INTRODUCTION The determination of the structures of organic compounds is a vital part of chemistry in general and analysis in particular. Mass Spectrometry is an analytical spectroscopic tool that can determine the molecular weight, molecular formula (HRMS), structure (from fragmentation fingerprint), isotopic incorporation / distribution and protein sequence (MS-MS). It is primarily concerned with the separation of molecular (and atomic) species according to their mass. The purposes of of this experiment are, to be able to identify the compound or structure in mass spectrum and to be able to interpret the fragments of the spectrum. The mass spectrometer is used to measure the masses and abundances of naturally occurring isotopes. It is an instrument that generates ions from molecules and measures their masses. A measure of how well a mass spectrometer separates ions of different mass is known as resolution. In low resolution, it is capable of separating only ions that differ in nominal mass; that is ions that differ by at least 1 or more atomic mass units while in high resolution, it refers to instruments capable of separating ions that differ in mass by as little as 0.0001 atomic mass unit. Figure 1.Block Diagram for Mass Spectrometer Instrument When an atom or molecule is hit by high-energy electron, it will ionize. The electron is deflected but transfers much of its energy to the molecule. This energy-rich species ejects an electron forming a positively charged, odd-electron species called the molecular ion. Molecular INPUT IONISER ELECTRIC FIELD MAGNETIC FIELD ELECTRIC FIELD DETECTOR  ion passes between poles of a magnet and is deflected by magnetic field. If the only ion that is  present is the molecular ion, mass spectrometry provides a way to measure the molecular weight of a compound and is often used for this purpose. However, the molecular ion often fragments to a mixture of species of lower m/z. The molecular ion dissociates to a cation and a radical. Usually several fragmentation pathways are available and a mixture of ions is produced. mixture of ions of different mass gives separate peak for each m/z. Intensity of peak proportional to percentage of each ion of different mass in mixture. The separation of peaks depends on relative mass. A molecular ion (M) is a radical cation formed by removal of a single electron from a  parent molecule in a mass spectrometer. For some purposes, it does not matter which electron is lost; radical cation character is delocalized throughout the molecule; therefore, the molecular formula of the parent molecule is written in brackets with plus sign to show that it is a cation and a dot to show that it has an odd number of electrons. Fragment ions rationalize these in terms of the structure. It identifies as many as possible, in terms of the parent structure. Generally, simply derived from the molecular ion or, in a simple fashion from a significant higher mw fragment. Fragments will make chemical se nse   structure of the compound. Fragmentation are governed by  product ion stability consideration, octet rule, resonance delocalization, polarizability and hyperconjugation as well as electronegativity. The ionising electron beam can fragment the molecule by cleaving particular bonds. The molecular fragmentation peaks in the mass spectrum can give clues as to the sub-structure of the molecule. The peak height is the relative abundance of each species. The most intense peak (called the Base peak) is assigned a relative abundance of 100. The parent ion peak (i.e. the singly charged ion of the test molecule denoted by M + located at m/e of 114 in the spectrum above) is often too weak to be seen in the high energy spectra that are necessary to produce a fragmentation pattern.
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