Fare clic per modificare gli stili del testo dello schema,Secondo livello,Terzo livello,Quarto livello,Quinto livello,Fare clic per modificare lo stile del titolo dello schema,*,General Overview of Detector Systems,Daniela Cavagnino,General Overview of Detector S,D,etectors classification,Universal,They respond to everything eluting from the column,TCD,PDD,(FID),Selective,They may be element selective,structure/functional group selective or selective to other properties,FID,(very broad selectivity),ECD,PID,PDD,Specific,They are so selective to distinguish particular structures or elements,NPD,FPD,Detectors classificationUniver,Concentration vs Mass dependent response,Common conc.dependent:,TCD,PID,PDD,ECD,Common mass dependent:,FID,NPD,FPD,Non-Destructive vs Destructive,Common non-destructive:,TCD,PID,PDD,ECD,Common destructive:,FID,NPD,FPD,D,etectors classification,Concentration vs Mass dependen,Detector Response,Ch,aracteristics,Sensitivity,Detector efficiency to convert the sample in an electrical signal,Noise,Short term,:high frequency baseline fluctuation,Long term,:low frequency baseline perturbation,Dynamic Range,Range of sample concentration for which the detector can provide a detectable signal variation with analyte amount,Selectivity,The ratio of the detector sensitivities of a given compound over a potentially interfering compound,Minimum Detectability,Amount of sample in which the peak height is 3 times the noise height(S/N=3),Detector Response Characterist,Detector Response,Ch,aracteristics,Sensitivity and Minimum Detectability,FID sensitivity:,S=coulomb/g=,FPD sensitivity for sulfur:,S=*=uV/(gS/s),2,MDA=g/sec RF(Response Factor)=,MDA=gS/sec,peak area,sample weight,A*sec,g,peak area,S amount,PW,S amount,3N,S,A*g,A*sec,peak area,amount,3N,S,peak height,mass rate,n-1,Detector Response Characterist,Dynamic and Linear Range,Dynamic range:,over which an incremental change in the amount of compounds in the detector volume produces a measurable incremental change in the detector signal,Linear range:,over which the response deviation is less than 5%,Detector Response,Ch,aracteristics,Dynamic and Linear Range Dy,Flame Ionization Detector,Universal response,Ionization detection,Mass detector,Destructive,Flame Ionization Detector Univ,Flame Ionization Detector,Hydrogen is mixed with gas stream at bottom of jet and air or oxygen is supplied axially around the jet,Hydrogen flame burns at the tip,which also functions as cathode and it is electrically insulated from the body,Collector electrode is above the burner tip,Flame Ionization DetectorHydro,Flame Ionization Detector,Principle of operation,Combustion of organic compounds in a oxidizing flame,CH+O CHO,+,+e,-,Electric field betweenthe jet and the collectorelectrode,Voltage-300V,Collection of the ions generated into the flame,Current pA,A good combustion step is the prevailing factor to get the best performances,Flame Ionization DetectorPrinc,Flame Ionization Detector,It responds to all organic compounds except for formic acid,Response is greatest with hydrocarbons and decreases with substitution,Sensitivity high due to low noise level,No response to water,permanent gases,and inorganic compounds simplifies the resolution of components in analysis of aqueous extracts and in air pollution studies,Suitable for fast and ultrafast GC applications,Flame Ionization Detector It r,Flame Ionization Detector,Technical Specifications,Operating temperature limit 450C with ceramic jet,Linear rangebetter than 10,6,Minimum detectable amount 3 x 10,-12,gC/s,Input range 0 to 10,-6,A,Input attenuation 4 steps(10,0,-10,1,-,10,2,-,10,3,),Electrode polarization voltage -300 V,Time constant 6 ms 63.2%,Acquisition rate up to 300Hz,Flame Ionization DetectorTechn,Flame Ionization Detector,Standard Operating Procedure(SOP),C12,C14,C16,Area Counts 4 000 000,C12=6 877 493,C14=6 790 762,C16=6 988 181,Flame Ionization DetectorStand,Flame Ionization Detector,MDL Calculation(C12),C12,C14,C16,V=1.6uL 20ng/uL,Mass C12=32ng,%C=84.7%,Mass C=27.1ng,C12 A=6877493(0.1uV*s),MDL=3N/S,S=Area(uV*s)/mass,MDL=48(,uV,)*27.1(,ngC,)/687749.3(,uV*s,),=0.00189 ngC/s=1.89 pgC/s,Noise 16 uV,Flame Ionization DetectorMDL C,Electron Capture Detector,Selective response,Non-destructive,Ionization detector principle,Concentration-dependent detector,Radioactive source,63,Ni(10mCi activity),Displaced coaxial-cylinder geometry,Electron Capture DetectorSelec,Principles of detection,Electron Capture Detector,-,-,-,e,-,e,-,+,+,+,-,M,M,M,AB,AB,_,+,*+N,2,+N,2,+,+e,-,*+Ar +Ar,+,+e,-,+Ar*,Ar*+CH,4,Ar+e,-,+CH,4,+,dissociative-capture mechanism,AB+,e,-,A,+B,-,nondissociative mechanism,AB+,e,-,AB,-,side reactions,C+e,-,C,-,N,2,+,+e,-,neutrals,AB,-,+N,2,+,neutrals,Principles of detection Electr,Electron Capture Detector,Pulsed voltage,e,-,V,50,0,T,Time (,s),w=0.1,1 s,PULSE voltage,DC voltage,Electron Capture DetectorPulse,Electron Capture Detector,Constant current method,I=K,e,-,f,+,-,I,f,f,=const,I=const,Electron Capture Det