Gas Chromatography (GC) Description Stationary Phase: Gel coated solid Mobile Phase: Gas A sample is injected into a column with a carrier gas. The components of the sample travel through the column at different rates to a flame. Basic Theory Components of a sample move at different rates through a column. Qualitative results based on r t.. Once the components have been separated a quantitative results can be obtained based on the flame responds to the material.
Gas Chromatography (GC) Major Uses Provides both qualitative and quantitative analysis of compounds with a molar mass of less than 300. Compounds must be easily vapourised, without decomposing. Used for analysis of blood and urine for the presence of drugs Typical Analyte: Low molecular mass compounds Typical Sample: Foods, drugs, biological samples Advantages: Highly sensitive and precise Disadvantages: Moderately expensive
High Performance Liquid Chromatography (HPLC) Description Stationary Phase: Gel covered solid Mobile Phase: Solvent A sample is injected into a column under high pressure, The components of the sample travel through the column at different rates. Basic Theory Components of a sample move at different rates through a column. Qualitative results based on r t..
High Performance Liquid Chromatography (HPLC) Major Uses Provides both qualitative and quantitative analysis of large molecular substances. Ideal for identifying compounds that do not vaporise or will decompose. Used for the analysis of proteins and organic compounds. Typical Analyte: Medium to high mass organic compounds Typical Sample: Foods, drugs, biological samples Advantages: High sensitivity and precision Disadvantages: Moderately expensive
Ultra-Violet Visible Spectroscopy Description UV light of a complimentary colour to the colour of the substance tested is passed through the substance to a receiver. Basic Theory Light is absorbed by some molecules. The amount of light absorbed is proportional to concentration of the molecule, allowing in quantitative results being obtained.
Ultra-Violet Visible Spectroscopy Major Uses Generally used as a quantitative analysis to determine the concentration of organic compounds and metal ions in urine, blood, plastics or water. Can be used as qualitative using the unique spectra as a fingerprint Typical Analyte: Low mass organic compounds Typical Sample: Liquid and gas samples Advantages: Simple to operate Disadvantages: Not suitable for low concentrations
Atomic Absorption Spectroscopy (AAS) Description A light of a specific wavelength is passed through a flame which contains a vaporised sample. The light passes through a wavelength selector to a detector Basic Theory When a metal atom absorbs energy its electrons will jump to higher energy states. The wavelength of the light absorbed identifies the element, the intensity of the light absorbed identifies the concentration.
Atomic Absorption Spectroscopy (AAS) Major Uses Used in quantitative analysis to determine the concentration of metals in blood, urine, air, soil, water and foods. May by used qualitatively to determine the presence of metals. Typical Analyte: Metals Typical Sample: Low viscosity solutions Advantages: Highly sensitive and precise Disadvantages: Moderately expensive
Infrared Spectroscopy (IR) Description Infrared light is passed through a sample to a detector. The percentage absorption and wavelength is measured, resulting ina unique IR spectrum. Basic Theory Functional groups absorb infrared light at specific wavelengths. Based on the was the sample responds to IR light the functional groups and overall structure can be identified
Infrared Spectroscopy (IR) Major Uses Used for qualitative analysis to determine the types of bonds and functional groups present. Typical Analyte: Organic molecules Typical Sample: Solids, liquids or gases Advantages: Huge range of analytes Disadvantages: Moderately expensive
Nuclear Magnetic Resonance Spectroscopy (NMR) Description A sample is placed in a test tube that spins between a powerful magnet. A radio transmitter coil produces a short powerful pulse of radio waves, a radio then detects the radio frequencies emitted from the nuclei as they relax to a lower energy level Basic Theory Any atom with an odd number of protons or neutrons will absorb energy, resulting in being in a state of resonance. Atoms in different configurations result in different energy shifts. The resulting shift in energy can be used to identify the configuration of the atom.
Nuclear Magnetic Resonance Spectroscopy (NMR) Major Uses Used in qualitative analysis to provide information in the determination of the structure of the carbon-hydrogen backbone of organic compounds Typical Analyte: Organic molecules Typical Sample: Liquid or solids Advantages: Highly sensitive and precise Disadvantages: Very expensive
Mass Spectroscopy Description A gaseous sample is injected into the chamber, where it is ionised. Positive ions are accelerated in a magnetic field. Ions move in a curved path depending on their mass/charge ratio. The detector measures the relative abundance of each m/e ratio. Basic Theory Charged particles move in a curved path relative to the mass/charge ratio. Using an ion collector we can detect the amount of ions in each mass/charge ratio. The mass/charge ratios can be compared to a book of data to identify fragments.
Mass Spectroscopy Major Uses Used in qualitative analysis to determine the structure and identity of a compound. Can be used in quantitative analysis as a detector for Atomic Emissions Spectroscopy, Gas Chromatography and Liquid Chromatography Typical Analyte: Any elements/compounds that can be volatised Typical Sample: Anything that can be volatised Advantages: Highly sensitive and precise for wide range of analytes Disadvantages: Expensive and requires training to operate