Organic%20Analysis - Organic Analysis Organic Organic...

Info iconThis preview shows page 1. Sign up to view the full content.

View Full Document Right Arrow Icon
This is the end of the preview. Sign up to access the rest of the document.

Unformatted text preview: Organic Analysis Organic Organic Compounds Are Simply Organic Carbon Containing Compounds Carbon (usually combined with H, O, N, S, P, (usually Cl, and/or Br) Cl, Inorganic compounds not based on C The Basics The Matter – has mass & occupies space Element – 89 naturally occurring elements Element + 21 lab made = 110 21 Periodic table –elements arranged Periodic according to atomic structure/properties according Symbols for elements (ex: C = carbon) Atom – smallest part of an element The Basics The Compound – 2 or more elements (89 elements = Compound more than 6 million combinations) more States of matter: Solid, Liquid, Gas Physical change vs. chemical change Immiscible liquids – phase difference (ex: oil & Immiscible water) water) “Like dissolves Like” Water is a polar substance while oil is non-polar Analytical Techniques Analytical Spectrophotometry – Identifies substances Spectrophotometry based on absorption of certain wavelengths of light (visible, ultraviolet or infrared usually) usually) Chromatography – separation of Chromatography components of a mixture using a stationary phase and a moving phase phase Gas Chromatography Gas Gaseous phase/liquid (stationary) phase- column Samples introduced as liquids Heated injection port vaporizes Inert gas (carrier gas) pressurizes the column, Inert forces vaporized sample onto column forces Liquid phase on column has attraction for the gas Liquid molecules dissolved in it molecules Different compounds (in gaseous form) vary in Different their degree of attraction to liquids their Henry’s Law: ratio of vapor to liquid state Henry’s constant for a given temperature Henry’s Law: At a given temperature, the ratio of vapor in air to vapor in liquid for a volatile substance dissolved in liquid will be constant in a closed system Air Liquid Gas chromatography Gas The greater the attraction between the The compound and the liquid phase, the longer the compound stays on column the “fastest” come out first (low molecular fastest” weight, low boiling point) weight, Detectors of various types register the exit Detectors of each component and an electrical impulse causes a recorder to produce a “peak” “peak” GC Procedure GC Known amt. sample is dissolved in a certain Known volume of volatile solvent such as chloroform (conc. = g/ml) chloroform A small amt. (0.5 ul) is injected small Portion of evidence is dissolved in some of Portion the solvent and small amt. injected If we have concentration of known and we If compare peak heights of known and unknown, we can determine conc. of unk. Typical Gas Chromatogram Typical Solvent Amphetamine ? Methamphetamine Time (minutes) Pyrolysis Gas Chromatography Pyrolysis Solids are pyrolyzed (heated to high temp.) Solids in the absence of oxygen in Pyrolysis of polymers results in Pyrolysis reproducible fragmentation reproducible Useful for the analysis of paint and other Useful polymers polymers HPLC: High Pressure Liquid Chromatography Chromatography Liquid phase is pumped through a column Liquid of small particles treated with a chemical of Sample is introduced onto the column and Sample different components attracted to different degrees to the particles degrees Over time the mixture is separated Over Takes place at room temperature Particularly useful for explosives analysis TLC: Thin-Layer Chromatography Chromatography A glass plate or a sheet of thin aluminum glass coated with silica coated Sample of mixture is dissolved in volatile Sample solvent and spotted onto plate or sheet solvent Plate is set into a tank with a liquid in the Plate bottom bottom Liquid moves up the plate by capillary Liquid action and mixture is separated action TLC TLC Q K Q Plate Glass Tank Liquid Phase Electrophoresis Electrophoresis Uses a gel coated plate as a stationary phase Electrical potential is used rather than a Electrical mobile (liquid or gas) phase mobile Useful for separation of enzymes Useful Enzyme mixtures separate on the basis of Enzyme differing electrical potentials differing Electrophoresis Electrophoresis + _ Spectrophotometry Spectrophotometry The electromagnetic spectrum X-rays UV Visible IR Microwave Radio Gamma wavelength Energy Wavelength Wavelength Frequency Frequency Wave #1 Wave #2 Frequency = C/λ Frequency C = the speed of light in a vacuum How are frequency and wavelength related? E = hf E = energy h = is a constant f = frequency How are energy and frequency related? Absorption of Electromagnetic Radiation Radiation Different elements and compounds absorb Different light of particular wavelengths light By varying the wavelength of light By projected through a substance and measuring what is absorbed and what is transmitted, substance may be identified transmitted, Electronic absorption Molecular absorption Spectrophotometer Spectrophotometer Source (produces electromagnetic radiation Source in either UV, Vis or IR range) in Slit, prism or grating – varies wavelength Sample holder (solid, liquid or gas) Detector – measures absorbance Recorder – produces chart of absorbance Recorder (spectrum) (spectrum) UV Spectrophotometer Sample Compartment Source Recorder Detector Reference UV Beams Source Sample IR Spectrophotometer Sample on KBr plate source detector IR Beam Sample on KBr window Recorder IR spectrum Fingerprint Region Fingerprint Region Mass Spectrometry Mass Usually coupled to a GC Sample is introduced into vacuum chamber and Sample bombarded with high energy electrons bombarded Positive ions are produced Positive ions fragment in particular patterns for a Positive given compound given No 2 compounds produce the same patterns Fragments separated by mass in an electric field Fragments (quadrupole) (quadrupole) Database used to compare Autosampler GC MSD Capillary column GC peak of interest Mass spectrum of selected component Comparison of Instrumental techniques techniques UV – electrons absorb energy; non-specifc IR – molecules absorb energy at bonds; specific IR identification (chemical fingerprint) (chemical GC – separates mixtures based on attraction to GC stationary phase; non-specific stationary HPLC – Separates mixtures based on attraction to HPLC stationary phase; non-specific stationary TLC – Separates mixtures based on attraction to TLC stationary phase; non-specific stationary MS – compounds are fragmented using high speed MS electrons; specific identification (chemical fingerprint) fingerprint) DART – direct analysis in real time mass spectrometer (no GC) mass Micro-spectrophotometer Micro-spectrophotometer ...
View Full Document

Ask a homework question - tutors are online