Basic Gas Chromatography History 1850 - Separation of

Basic Gas Chromatography History 1850 - Separation of

Basic Gas Chromatography History 1850 - Separation of dyes by Runge 1906 - Separation of plant pigments by Tswett 1941 - Theoretical gc (Martin & Synge) 1952 - First gc 1954 - TC detector Process

Sample is vaporized (if it is not already a vapor) Passes through a column where interaction occurs - does analyte move with gas phase or stay with stationary phase (column coating) Separation occurs Detection - many types of detectors High purity! Source of mobile phase - He or H

Detector gases - none or air/H (Flame ionization detector) Gas flow regulators Pressure regulators - stainless steel parts not welding quality! Flow regulators - Determine gas flow rates through system (sensitive precision instruments) Injection port

Introduce sample Vaporize sample Split sample (?) Injection ports - many versions Split - only a portion of injection goes on column Splitless - all material injected goes on column On-Column - cold injection (sensitive materials)

Programmed temperature - sensitive materials (more durable method than OC) Large volume - Can inject 1 ml - solvent removal Columns Packed (hard to find) Capillary (generally open tubular but can be a wall coated PLOT type)

Columns Generally fused silica - strong and inert Inner diameters - 0.10 - 0.53 mm Length - 1 - 60 m Coatings - several - range in thickness from 0.1 5 um Common Stationary Phase Coatings Similar Temperature Composition

Polarity 1. 100% Dimethyl Nonpolar Polysiloxane (Gum) Applicatiom Phenol, hydroc. amines, sulfur cpds pesticides, PCBs

Reynolds Constants OV-1 SE-30 Limits 60C to 325C 2. 100% DimethyL Polysiloxane (Fluid)

Nonpolar Amino Acid Der. Essential oits OV-101, SP-2100 OC to

280C 3. 5% Diphenyl to 95% Dimethyl Nonpolar Fatty Acids, Me Est

SE-52 -60C Alkaloids, Drugs, Halogenated Cpds OV-23, SE-54

325C 7% Cyanopropyl Intermediate 7% Phenyl Polysiloxane Drugs. steroids, Pesticides OV-1701

5. 50% Phenyl, Intermediate 50% Me.Polysiloxane Drugs, Steroids, Pesticides, Glycols

OV-17 60C to 240C 6. 50% Cyanopro. Intermediate me 50% Phenyl

ethyl Polysiloxane 50% Trifluoropro Intermediate Polysiloxane Fatty Acids, Me Est Alditol Acetates OV-225 60C to

240C Halogenated Cpds Aromatics OV-210 45 to 240C

8. Polyethylene Polar Glycol-TPA modified Acids, Alcohols, Acrytates, Nitrites, Aldehydes, Ketones

OV-351, SP-1000 60 to 240C 9. Polyethylene Gly

Free Acids, Alc Carbowax 20M Ethers,Essential Oils, Glycols, Solvents 4. 7. Polar

-20 to 280C 60C to 220C Phase selection PUBLISHED INFORMATION Kovats indices compilations Journal articles

Internal work INTUITION like structures NO IDEA? Sample information Nonpolar column Change to polar if needed Separation theory 1.Adsorption

2.Molecular exclusion 3. Partition 4. Vapor pressure Adsorption chromatography Interaction with a granular support e.g. Tenax, charcoal, silica gel, Molecular exclusion

Used for the separation of permanent gases e.g. Zeolites, Linde molecular sieves Partition chromatography Partitioning between mobile phase and carrier gas vapor pressure SEPARATION BASED ON THE BOILING PT

Column coatings (stationary phases) Polar to nonpolar Polar - Carbowax Non Polar - silicone based phases Column ovens Usually heat ovens to help in separations Ovens can be controlled from about -60 400C

Detectors Many types varying in sensitivity and selectivity Discuss most common types Thermal conductivity detector Characteristics of TC detector Specificity - very little - will detect almost

anything including H2O - called the universal detector. Sensitivity to 10-7 grams/sec - this is poor varies with thermal condition of the compound. Linear dynamic range; 104 - this is poor response easily becomes nonlinear. Flame ionization detector

Characteristics of a Flame Ionization Detector (FID) Specificity - most organics. Sensitivity - 10-12 g/sec for most organics -this is quite good. Linear range 106 - 107 -- this is good. A special type of FID is called an alkali flame (AFID). Rubidium sulfate is burned in the flame

and the detector becomes specific for N and P. Organics are not detected. Used for amines and nitrosoamines. (more commonly called the NPD) Electron Capture Detector Characteristics of an ECD Specificity - sensitive to halogens, conjugated

carbonyls, nitriles, and a few others - no response with ordinary organics or H2O. Sensitivity 5 x 10-14 g/sec - excellent Linear range 104 The radioactive detectors have definite temperature limits. Separation - terms RESOLUTION

SELECTIVITY = relative interaction of column stationary phase with both compounds to be separated = tr2 tr1 CAPACITY = retention time of compounds to be separated k = tr - tm = tr tm

tm THEORETICAL PLATES = column EFFICIENCY n = 5.545 (tr/Wh)2 Optimizing Gas Chromatography Key factors influencing efficiency in gas chromatography are column phase (nonpolar are most efficient) and column diameter.

Carrier gas type and velocity Phase thickness: Capacity and Efficiency influenced by column diameter and phase thickness Thick phase capacity Thin Phase less capacity Column length Longer means better separations but longer

analysis times Time proportional to length Separation proportional to sq root of length Poor means of getting separation costs too much in time. Use diameter, phase thickness or phase type What do you need?

Recently Viewed Presentations

  • Focus Lesson: Complete this REVIEW Complete the final

    Focus Lesson: Complete this REVIEW Complete the final

    The tree of life is divided into 3 domains and within the domains are 6 kingdoms. Domain Bacteria - corresponds to the Kingdom Eubacteria. Domain . Archaea - corresponds to the Kingdom Archaebacteria. Domain . Eukarya - composed of the...


    The overview of the impact tourism has on the state's economy - how it is used as a business tool. Tourism's impact on state / local tax revenue and employment. Tourism's relationship with marketing and how the two work together...
  • Definisi Manajemen Strategik - Directory UMM

    Definisi Manajemen Strategik - Directory UMM

    Internal Struktur, Budaya Industri Shareholders Pemerintah Pihak Istimewa Konsumen Masyarakat Asosiasi Dagang Kompetitor Karyawan Supplier Kreditur V a r i a b e l L i n k u n g a n Lingkungan Sosial Dorongan Socioculture Dorongan Legal -...
  • Dealing with the Angry Public - Pennsylvania Department of ...

    Dealing with the Angry Public - Pennsylvania Department of ...

    Dealing with Angry People. Bureau of Workers' Comp . PA Training for Health & Safety (PATHS) Each day our interactions with clients or coworkers may result in dealing with unhappy persons. During these exchanges, the result may run the extremes;...
  • Particles, Strings and Fields

    Particles, Strings and Fields

    Particle Theory. about 5 students for 5 faculty. historically paid our students 10 hour RA for 3 years; students TA at least 10 hours throughout. year 1: take the graduate classes, do reading, attend particle theory journal club on Fridays...
  • Cahit Sıtkı Tarancı - Turkceci.Net

    Cahit Sıtkı Tarancı - Turkceci.Net

    Aynı kurumda üç yıl İstanbul üniversitesi Edebiyat Fakültesi Felsefe Bölümü'nde okuduktan sonra Ankara'da D.T.C.F.'de öğrenimini tamamlayan Cavidan Hanım da çalışmaktadır. Cahit Sıtkı aynı büroda çalışan bir kıza aşık olmaktan dolayı işine daha çok sarılmaktadır.
  • Safety in the Science Classroom - Deer Valley Unified School ...

    Safety in the Science Classroom - Deer Valley Unified School ...

    SWBAT Demonstrate safe behavior and appropriate procedures in all science inquiry activities.Enter SilentlyGrab Materials, Notebooks, FoldersBegin Do Now1.Make an observation: look at the green cups in the front of the room (on the lab desk). Write down everything you see...
  • CONFUCIANISM  With no clergy or gods - Confucianism

    CONFUCIANISM With no clergy or gods - Confucianism

    Confucius's principles - based on common Chinese tradition and belief. Believed in: strong family loyalty - ancestor worship - respect of elders . by their children and of husbands by their wives . His principle "Do not do to others...