2 GAS CHROMATOGRAPHY (GC) GC is a technique used to separate , identify and quantify compounds in a sample mixture.Compounds are separated primarily by differences in their volatilities and structures.Compounds must vaporize into the gas phase below C and thermally stable.
3 How the GC Operating? Recorder/Data System Flow Controller Injection PortChromatogramDetectorColumn OvenCarrier GasColumnInjectionMigrationElutionPeak SignalColumn Operating
4 GC ? ● GC : Gas Chromatography ● Is an Analytical Instruments Technique used for Separating Chemical Mixtures● Column coated with non-Volatile is a Stationary Phase● Solutes are Carried through GC dissolved in Carrier gas is a Mobile Phase● Solutes must be in vapor state at GC Operating Temperature
7 SEPARATION OF SAMPLE IN THE COLUMN time(A)(B)(D)(C)
8 HOW SEPARATION OCCURSChromatography is a separation method achieved by the distribution of substances between two phases: a mobile phase and a stationary phase.Mobile Phase Stationary PhaseGas SolidChromatography Gas Solid(GSC)Gas LiquidChromatography Gas Liquid(GLC)
9 DETECTOR DATA SYSTEM GAS SUPPLY SAMPLE INTRODUCTION COLUMN OVEN GAS CHROMATOGRAPHSAMPLEINTRODUCTIONCOLUMNDETECTOROVENTEMPERATURECONTROLDATA SYSTEMGAS SUPPLYDATA OUTPUTCHROMATOGRAM
10 CARRIER AND DETECTOR GASES chosen with the consideration of the type of detector usedCarrier Gas: He, N2, H2InertDryPure
11 Gas for GC 1.Carrier 2.Fuel & 3.Oxidation Non Flammable Detector ECD,TCDFlammable DetectorFID,FPD,TSDCarrier Gas is He,N2,H2,Argon purity UHP >Fuel = H2 purity UHP >Oxidation = Air purity UHP >
12 การเลือกก๊าซพา (Carrier Gas) มีคุณสมบัติเฉื่อย (inert) ปราศจากความชื้น และบริสุทธิ์ (มีสิ่งปนเปื้อน <1 ppm)H2 เร็วที่สุดมีความหนืดต่ำที่สุด แต่ไม่เหมาะกับ GC/MS เนื่องจากยากต่อกับขับออกด้วย vacuum pumping systemN2 ดีกว่า H2 และHe เล็กน้อยที่ optimum carrier gas flow rateสำหรับ fast analysis: H2 ดีกว่า He และ He ดีกว่า N2คำนึงถึงเครื่องตรวจวัดที่ใช้ใช้ He เป็นก๊าซพาใน GC/MS
14 Gas-Clean FiltersUsing high-grade gases in analytical labs is considered critical for modern high-resolution gas chromatographyLeaks in the gas lines connecting the gas cylinders to the GC are sometimes inevitable.Oxygen, water moistures, hydrocarbons may enter into your GC system may result indamage to columnloss of sensitivitydamage to detectorHigh sensitivity indicatorsFast and simple replacementNo instrument down timeNo tools requiredWill fit the filter base of Agilent, SGE and Alltech
15 Sample IntroductionPurpose: To introduce the sample on to the column in the vapor state.Syringe InjectionManual injectionAuto-sampler injectionValve InjectionGas sampling valvesLiquid sampling valvesAuxiliary Sampling DevicesPurge and TrapHeadspace
16 TYPES OF INLET SYSTEMS Packed column inlet Septum - purged packed column inletSplit/splitless capillary inletSplit - only capillary inletDedicated on - column capillary inlet
18 flow controller or pressure regulator flow controller or needle valve septum purgevent3mL/min2mL/min30mL/min2mL/min1mL/min28mL/minpressure regulatoror needle valvemL/min27mL/minsplit ventsolenoil-closedsolenoil-open1mL/min1mL/minPURGE ONPURGE OFF
19 Ratio of amount of sample in the column and total sample split ratio = Fcolumn+ Fsplit vent / FcolumnRatio of amount of sample in the column and the amount leaving via the split linesplit ratio = Fsplit vent / FcolumnFsplit vent = Flow from split vent (mL/min)Fcolumn = Column flow (mL/min)
24 Efficiency, plates/m 2000-4000 1000-4000 600-1200 500-1000 Properties and Characteristics of Typical GC ColumnsType of ColumnFSOT WCOT SCOT PackedLength, mInside diameter,mmEfficiency, plates/mSample size,ngRelative pressure Low Low Low HighRelative speed Fast Fast Fast SlowChemical inertness Best PoorestFlexible Yes No No NoFSOT : Fused-silica, open tubular column.WCOT : Wall-coated, open tubular column.SCOT : Support-coated, open tubular column.
25 COLUMN SEPARATION CHARACTERISTICS Efficiency : Ability of the column to produce sharp peaks.Resolution : Ability of the column to separate two peaks from each other.Selectivity : Ability of the column to determine chemical and/ or physical difference in two peaks.
28 COLUMN TEMPERATURE OPERATION ISOTHERMALTEMPERATUREPROGRAMMED
29 GC DETECTORDefinition : A GC Detector is a device which senses the presence of a component different from the carrier gas, and converts that information to an electrical signal.
30 DETECTOR RESPONSE CHARACTERISTICS Sensitivity: The response per amount of sample, that is, the slope of the response / amount curve. The minimum amount on the curve is defined as the minimum detectable level (MDL).Selectivity: A measure of which categories of compounds will give a detector response.Dynamic Range : The range of sample concentrations for which the detector can provide accurate quantitation.
32 DetectorsTypes of Detectors Brief DescriptionTCD Filament temperature increases as analytes present in the carrier gas pass over it . Causing the resistance to increase.FID Components burn in a flame producing ions which are collected and converted into a currentECD As electronegative species pass through the detector , they capture low energy thermal electrons causing a decrease in cell current.
33 Detectors Types of Detectors Brief Description NPD Nitrogen and phosphorous compounds produce increased currents in a flame enriched with vaporized alkali metal salt.FPD Sulfur and phosphorous compounds burn in a flame producing chemiluminescent species which are monitored at selective wave lengths..
34 Detectors Types of Detectors Brief Description ELCD Halogens , sulfur , or nitrogen compounds are mixed with a reaction gas in a reaction tube . The products are mixed with a suitable liquid which produces a conductive solutionPID Molecule are ionized by excitation with photons from a UV lamp . The charged particles are then collected , producing a current.
35 Detectors Types of Detectors Brief Description MSD Molecules are bombarded with electrons producing ion fragments which pass into the spectrometers mass filter . The ions are filtered based on their mass / charge ratio.IRD Molecules absorb infrared energy , the frequencies of which are characteristic of the bonds within that molecule.
36 Detectors Types of Detectors Brief Description AED Molecules are energized by a plasma source and separated into excited atoms. As electrons return to their stable state , they emit light,which is element specific.
37 DETECTORS COMMONLY USED IN CAPILLARY GC Type Typical Sensitivity Carrier+Samples Range Makeup H AirFID Hydrocarbons pgC/s10 ppb - 99 %TCD General ng n.a n.a.10ppm - 100%ECD Organohalogens pg n.a n.a.Chlorinated 50ppt-1ppmsolvents & pesticides
38 DETECTORS COMMONLY USED IN CAPILLARY GC Type Typical Sensitivity Carrier+Samples Range Makeup H AirNPD Organonitrogen pg&organo ppt-0.1%phosphorus compoundsFPD Sulfur pg(393 nm) compounds 10ppb-00ppmFPD Phosphorus 1-10 pg(526nm ) compounds 1ppb-0.1%
39 DETECTORS COMMONLY USED IN CAPILLARY GC Type Typical Sensitivity Carrier+Samples Range Makeup H AirPID Compounds 2pg C/sec * n.a.ionized by UVELCD Halogens,N,S 0.5pg CI/sec n.a.2pg S/sec4pg N/ secFTIR Molecular 1000pg of n.a n.a.vibrations Strong absorber
40 DETECTORS COMMONLY USED IN CAPILLARY GC Type Typical Sensitivity Carrier+Samples Range Makeup H AirMSD Tunable for any 10pg to 10 ng ** n.a n.a.species (depending onSIM vs.Scan)AED Tunable for any pg/sec PRESET PRESETElement (depending on element)* Refer to Detector Manual** Dependent upon the type of interface
57 Summary Of Methods Injection size not critical detector response ADVANTAGES DISADVANTAGESAREA % No calibration required Must have uniformInjection size not critical detector responseAll components must eluteAll components must bedetected
58 Summary Of Methods ADVANTAGES DISADVANTAGES All peaks must be measured NORM % Injection size not critical All peaks must eluteAll peaks must be measuredMust calibrate all peaks
59 Summary Of Methods ADVANTAGES DISADVANTAGES ESTD Correct for detector response Injection size is criticalCalibrate peaks of interest Instrument stability required Not all peaks need elute Frequent recalibrationsNot all peaks need detectResults reported in unitsof choice
60 Summary Of Methods to both sample and standard to the sample ADVANTAGES DISADVANTAGESISTD Known component addaded Must add a componentto both sample and standard to the sampleInjection size not critical More complex sampleCalibrate peaks of interest and standard preparationCorrect for detector response stepsResults reported in units ofchoice
61 CHROMATOGRAM Column type , stationary phase Condition: temperature , flow rateCarrier gasDetectorInjection volumeSample
Your consent to our cookies if you continue to use this website.