Packed Column Sfc (Rsc Chromatography Monographs, Volume 2)

Excerpt. Reprinted By Permission. All Rights Reserved.Packed Column Sfcby T. A. Berger The Royal Society Of Chemistrycopyright 1995 The Royal Society Of Chemistryall Rights Reserved.Isbn: 9780854045006Contentschapter 1 Putting Packed Column Supercritical Fluid Chromatography Into Perspective, 1,Chapter 2 Practical Aspects Of Sfc Hardware, 22,Chapter 3 Physical Chemistry Of Mobile Phases Used In Packed Column Sfc, 43,Chapter 4 Physical Chemistry Of The Stationary Phase, 72,Chapter 5 The Effect Of Instrumental Parameters On Retention, Selectivity, And Efficiency, 97,Chapter 6 Concepts That Simplify Phase Selection, 113,Chapter 7 Systematic Method Development, 133,Chapter 8 Pharmaceutical Analysis By Packed Column Sfc, 151,Chapter 9 Chiral Analysis Of Drugs, 176,Chapter 10 Separation Of Agricultural Chemicals By Packed Column Sfc, 192,Chapter 11 Sfc And The Petroleum Industry, 212,Chapter 12 Miscellaneous Applications Of Packed Column Sfc, 227,Subject Index, 245,Chapter 1Putting Packed Column Supercritical Fluid Chromatography Into Perspectiveintroductionwhat Is Packed Column Sfc?Packed Column Supercritical Fluid Chromatography (Sfc Or Psfc) Is An Analysis Technique Similar To Liquid Chromatography (Lc) That Uses Supercritical Fluids (Sfs), Instead Of Liquids, As The Mobile Phase (Mp) (Supercritical Fluids Are Defined In The Next Section). The Mp Solvates The Solutes. The Stationary Phase (Sp) Consists Of A Bed Of Very Small Particles Packed In A Tube Capable Of Withstanding High Pressures. Some Sps Are The Surfaces Of Uncoated Particles. Some Are Organic Films Bonded To The Surface Of The Particles. Solutes Are Separated By Differential Attraction To The Sp.Compared With Lc, Packed Column Sfc Is Faster, More Efficient, Has A Wider Range Of Selectivity, And Detection Options, And Produces Less Toxic Waste. Not Surprisingly, The Fields Most Likely To Be Affected By Packed Column Sfc In The Future Are Traditional Lc Application Areas. In Particular, Pharmaceutical And Agricultural Chemical Development Will Derive Significant Benefits. Chiral Separations Will Likely Be A Major Application Area For Packed Column Sfc. This List Is Likely To Surprise Many Readers Since The Application Areas Most Often Associated With Capillary Sfc Have Involved Less Polar But Perhaps More Complex Solute Mixtures Such As Homologous Series, Of Surfactants, Polymers, And The Like.In Reality, The Characteristics Of Interest In 'Sfc' Have More To Do With Intermolecular Interactions In The Mp Than The Name Of The Fluid. Many Of The Characteristics That Make Sfs Interesting To Chromatographers (E.G., High Diffusivity, Low Viscosity) Are Also Available From Some Fluids Defined As Gases Or Liquids. Unfortunately, The Name Sfc Is Somewhat Misleading. Sfc Differs From Lc In That The Mp Is A Dense Compressed Fluid Which Will Dramatically Expand If External Pressure Is Removed.The Most Widely Used Supercritical Fluids (Like Carbon Dioxide, Nitrous Oxide, Or Chf3) Are Inorganic And Do Not Produce A Response In Some Gc Detectors, Like The Fid. This Combination Of Characteristics Allows Some Lclike Separations With More Gclike Figures Of Merit, Such As High Speed, High Resolution, And Multiple Detection Options.Several Modern Packed Column Sfc Chromatograms May Help Convey The Features That Make The Technique Desirable. In Figure 1.1, The 11 Carbamates Of Epa Method 531.1 Are Separated In 9 Minutes And Directly Detected Using Both A Uv And An Npd (Nitrogenphosphorus Detector).The Methanol/Carbon Dioxide (Meoh/Co2) Mp Flow Rate Is 2.5 Ml Min1, Producing Near Optimum Chromatographic Efficiency. This Is Approximately 3.5 Times The Optimum Flow Rate In Lc (On This Column) And Illustrates The Superior Diffusion Rate In Supercritical Fluids.The Standard Method Uses Gradient Elution Lc2 Followed By Two Postcolumn Reactions To Yield Fluorescent Products. Although The Separation Takes Ca. 40 Minutes, The Column Must Then Be Reequi