Liquid Chomatography 1液相色谱法1.ppt

Typical IC Results Example: an isocratic method for monovalent cations in ammonium nitrate based explosives Detection limits 50-100 ppb, max working range 40 ppm Method: Sample Loop Volume: 50 μL Columns: IonPac? CS3 Analytical, IonPac CG3 Guard Eluent: 25 mM HCl, 0.1 mM DAP?HCl, 4% Acetonitrile Eluent Flow Rate: 1.0 mL/min Suppressor: Cation MicroMembrane? Suppressor (CMMS) Regenerant: 100 mM Tetrabutylammonium Hydroxide Detector: Conductivity, 30 μS full scale Injection Volume: 50 μL From Dionex Application Note 121R Mobile Phases in LC Mobile phases differ for each LC mode Normal phase solvents are mainly nonpolar Reversed-phase eluents are usually a mixture of water with some polar organic solvent such as acetonitrile. Size-exclusion LC has special requirements for mobile phases Must dissolve polymers Must also suppress all possible interactions of the sample molecule with the surface of the packing material The type and composition of the mobile phase (eluent) is one of the variables influencing LC separations Desirable properties: Purity Detector compatibility Solubility of the sample Low viscosity Chemical inertness Reasonable price Figure from Phenomenex technical literature Isocratic elution: the eluent composition remains constant as it is pumped through the column during the whole analysis. Gradient elution: the eluent composition (and strength) is steadily changed during the run. Control of Eluent Polarity time % mobile phase where k* is the k at the midpoint of the column LC Instrumentation Pumps, Mixers and Injectors Column Detector(s) Computer LC Instrumentation The Agilent 1100, a typical modern LC system Solvent reservoirs Solvent degasser Pump Autosampler Column oven DAD Review: The Purpose of Key LC Components column separation chemistry detector signal transduction amplification/scaling filtering A/D data acquisition digitization tubing to detector flow cell analog output digital output chromatogram digital processing data analysis The