1. Gas Chromatography
1.1. Gas used as mobile phase
1.2. Need organic analytes to be thermally stable
1.3. Columns
1.3.1. Packed
1.3.1.1. peaks wide
1.3.1.2. plate height low
1.3.1.3. load a lot of samples
1.3.2. Capillary
1.3.2.1. sharp peaks
1.3.2.2. much shorter analysis time
1.3.2.3. length about 100m
1.3.2.4. ID= 0.1mm-0.53mm
1.3.2.4.1. Smaller inner diameter better
1.3.2.5. Film thickness = 0.1-5 um
1.3.2.6. Wall Coated open Tubular (WCOT)
1.3.2.7. Support-Coated Open Tubular (SCOT)
1.3.2.8. Easily saturated
1.4. Injections
1.4.1. Split injection
1.4.1.1. have a gas flowing
1.4.1.2. most of sample goes to waste
1.4.1.3. push sample in and its heated up to gas
1.4.2. Splitless
1.4.2.1. most of sample goes onto column
1.4.2.2. small injection valve
1.4.3. On column
1.4.3.1. injects directly on column
1.5. Liquid Stationary Phase
1.5.1. Silicone
1.5.1.1. Different polarities
1.5.2. PEG
1.5.3. Based on the idea that like dissolves like
1.5.4. nonpolar columns for nonpolar solutes
1.5.5. Strongly polar columns for strongly polar compounds
1.5.6. Reduce bleeding
1.5.6.1. bond covalently to silica
1.5.6.2. covalently cross link to itself
1.6. Temperature programming
1.6.1. effects viscosity
1.6.2. lowest boiling point comes off first
1.6.3. ramp temp as function of time
1.7. Detectors
1.7.1. Flame ionization
1.7.1.1. Eluate is burned in H2 and air
1.7.1.2. Cations and electons produced change current between electrodes
1.7.1.3. good for detecting organics
1.7.1.4. Detection limit is 100 times lower than TC detector
1.7.2. Thermal Conductivity
1.7.2.1. Helium is often the carrier gas
1.7.3. GC-MS
1.7.3.1. MS is a detector
2. High Performance Liquid Chromatography (HPLC)
2.1. Need a stronger pump than in GC
2.2. Modes
2.2.1. Reversed Phase
2.2.1.1. Stationary Phase=Low Polarity
2.2.1.2. Mobile Phase=High polarity
2.2.1.3. Compatible with ESI-MS
2.2.1.4. C18 is popular
2.2.1.5. increase in water increases retention
2.2.1.6. Polar comes out first then nonpolar
2.2.2. Normal Phase
2.2.2.1. Stationary phase=High polarity
2.2.2.2. Mobile phase at low polarity
2.2.2.3. Not very compatible with ESI-MS
2.2.3. HILIC
2.2.3.1. Hydrophillic stationary phase
2.2.3.2. Reverse phase like mobile phase
2.3. Packing Particles
2.3.1. Need particle diameter to be small
2.3.2. Minimize A and Cm
2.3.3. Smaller particles mean higher overall peak efficiencies
3. Violates the 2nd Law of Thermodynamics
4. Theories
4.1. Plate Theory
4.1.1. More plates means better separation
4.1.2. static system in equilibrium
4.1.2.1. Each species in equilibrium between stationary phase and mobile phase
4.1.3. Measure column efficiency with H=L/N
4.1.3.1. L=length of column
4.1.3.2. H= Height of theoretical plate
4.1.3.2.1. H decreases= more separation steps possible
4.1.3.3. N=Number of plates
4.1.3.3.1. Can calculate with N= 16((tr-tm)^2)/wb
4.1.4. Resolution indicates how well separated and resolved each peak is
4.1.4.1. Rs = 0.589 (Delta tr/w(1/2))
4.1.4.2. Proportional to N^(1/2)
4.2. Rate Theory
4.2.1. Vandeemter Equation
4.2.1.1. Eddy Diffusion
4.2.1.1.1. Term A
4.2.1.1.2. molecules travel different paths
4.2.1.1.3. independent of flow rate
4.2.1.1.4. depends on size of stationary particles or coating
4.2.1.1.5. 2Ydp
4.2.1.2. Longitudinal Diffusion
4.2.1.2.1. Term B
4.2.1.2.2. ration at which the substance moves randomly from high to low concentration
4.2.1.2.3. 2yDm
4.2.1.2.4. Dominates at low flow rate
4.2.1.2.5. More important in GC than LC
4.2.1.3. Mass Transfer
4.2.1.3.1. C term
5. Mass Spectrometry
5.1. Analyte is ionized and the resulting ion is detected according to its mass-to-charge ratio (m/z)
5.1.1. Lose electron to make a positive ion
5.1.2. Lose a proton to make a negative ion
5.1.3. GC-MS and LC-MS
5.1.3.1. need to be MS compatible
5.1.3.1.1. GC--Gases that can be ionized
5.1.3.1.2. LC--Volatile solvents
5.1.3.1.3. Low salt
5.1.3.1.4. Ready to be ionized
5.1.3.2. Separates mixtures prior to MS
5.1.4. Three parts
5.1.4.1. Ionizer
5.1.4.1.1. Gas
5.1.4.1.2. Desorption and Electrospray (ESI)
5.1.4.1.3. General
5.1.4.1.4. Electron Ionization (EI)
5.1.4.1.5. Chemical Ionization (CI)
5.1.4.1.6. Atmospheric pressure chemical ionization (APCI)
5.1.4.1.7. Matrix-assisted laser desorption/ionization (MALDI)
5.1.4.2. Mass analyzer
5.1.4.2.1. Types
5.1.4.2.2. Resolution = m/deltam
5.1.4.2.3. Mass Accuracy
5.1.4.2.4. Mass analyzers separate ions based on mass-to-charge ratio
5.1.4.3. Detector
5.1.4.3.1. Faraday Collector
5.1.4.3.2. Electron Multiplier