自动检测技术样品准备概要.pptx

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1、CEE 772#22 1 Pretreatments to LLE n nAcidify to 2 Acidify to 11)then acidify(11)then acidify(2)n n8250&8270:GC/MS for Semivolatiles 8250&8270:GC/MS for Semivolatiles n nDrying is sometimes necessary Drying is sometimes necessary n n10 cm column of anhydrous Na10 cm column of anhydrous Na2 2SOSO4 4 n

2、 nAddition of powdered anhydrous MgSOAddition of powdered anhydrous MgSO4 4第1页/共36页CEE 772#22 2 Soxhlet Extractionn nGood for soils,sediments&sludges n nUsed with thimbles n nOr glass wool plugs Or glass wool plugs n nTypical extraction solvents n nToluene/methanol(10:1)Toluene/methanol(10:1)n nAcet

3、one/hexane(1:1)Acetone/hexane(1:1)n nMethylene chlorideMethylene chloride第2页/共36页第3页/共36页第4页/共36页第5页/共36页CEE 772#22 6 Distillation Theory第6页/共36页CEE 772#22 7 Kuderna Danish Concentratorsn nIdeal for concentrating ether extracts Ideal for concentrating ether extracts n nCommon procedures Common proce

4、dures n nUse with heated water bath Use with heated water bath n nBoiling chips Boiling chips n nGood to pre-wet snyder column by adding Good to pre-wet snyder column by adding 1 mL of solvent to top 1 mL of solvent to top n nBalls should“chatter”,but chambers Balls should“chatter”,but chambers shou

5、ld not be flooded should not be flooded n nMay take 10-20 minutes May take 10-20 minutes n nStop at apparent volume of 1 mL Stop at apparent volume of 1 mL n nExchange solvent may be added at this Exchange solvent may be added at this time&concentration continuedtime&concentration continued第7页/共36页第

6、8页/共36页第9页/共36页第10页/共36页第11页/共36页CEE 772#22 12 Rotary Evaporationn nRotary evaporators(also called rotavaps Rotary evaporators(also called rotavaps in lab slang)are used to remove solvents in lab slang)are used to remove solvents from reaction mixtures and can from reaction mixtures and can accommod

7、ate volumes as large as 3 liters.accommodate volumes as large as 3 liters.n nA typical rotary evaporator has a heatable A typical rotary evaporator has a heatable water bath to keep the solvent from water bath to keep the solvent from freezing during the evaporation process.freezing during the evapo

8、ration process.The solvent is removed under vacuum,is The solvent is removed under vacuum,is trapped by a condenser and is collected for trapped by a condenser and is collected for easy reuse or disposal.Most labs use a easy reuse or disposal.Most labs use a simple water aspirator vacuum on their si

9、mple water aspirator vacuum on their rotavaps,so a rotavap can not be used for rotavaps,so a rotavap can not be used for air and water-sensitive materials unless air and water-sensitive materials unless special precautions are taken.special precautions are taken.n n 第12页/共36页CEE 772#22 13 Use of Rot

10、avaps1.1.Empty and then replace the solvent collection flask on the unit.Empty and then replace the solvent collection flask on the unit.2.2.Place your flask on the rotary evaporator.Place your flask on the rotary evaporator.3.3.Use the speed control to rotate the flask.A typical rotavap uses a vari

11、able Use the speed control to rotate the flask.A typical rotavap uses a variable speed sparkless induction motor that spins at 0-220 rpm and provides high speed sparkless induction motor that spins at 0-220 rpm and provides high constant torque.constant torque.4.4.Turn on the aspirator vacuum.On mos

12、t models,the vacuum on/off control is Turn on the aspirator vacuum.On most models,the vacuum on/off control is managed by turning a stopcock at the top of the condenser.managed by turning a stopcock at the top of the condenser.5.5.Lower your flask into the water bath.On most models,a convenient hand

13、le Lower your flask into the water bath.On most models,a convenient handle(with height locking mechanism)moves the entire condenser/motor/flask(with height locking mechanism)moves the entire condenser/motor/flask assembly up and down.You can also adjust the tilt of the condenser assembly up and down

14、.You can also adjust the tilt of the condenser assembly.Be sure not to put the flask into a water bath that exceeds the assembly.Be sure not to put the flask into a water bath that exceeds the boiling point of your solvent!For small amounts of common solvents you boiling point of your solvent!For sm

15、all amounts of common solvents you dont need to turn on the bath heater.dont need to turn on the bath heater.6.6.The solvent should start collecting on the condenser and drip into the The solvent should start collecting on the condenser and drip into the receiving flask.Some solvents(such as ether o

16、r methylene chloride)are so receiving flask.Some solvents(such as ether or methylene chloride)are so volatile that they will also evaporate from the receiving flask and be volatile that they will also evaporate from the receiving flask and be discharged down the drain.To prevent this you can place a

17、 cooling bath on discharged down the drain.To prevent this you can place a cooling bath on the receiver or(on some models)use a dry ice condenser.the receiver or(on some models)use a dry ice condenser.7.7.Once all your solvent has evaporated,release the vacuum,raise the flask out Once all your solve

18、nt has evaporated,release the vacuum,raise the flask out of the water bath and turn off the rotation.Remove your flask.of the water bath and turn off the rotation.Remove your flask.第13页/共36页CEE 772#22 14 Rotavap tipsn nAlways use distilled water in your heating bath.Otherwise,scale Always use distil

19、led water in your heating bath.Otherwise,scale will build up in the bath and coat the thermistor and heating will build up in the bath and coat the thermistor and heating coils.This is very difficult to remove and reduces the efficiency coils.This is very difficult to remove and reduces the efficien

20、cy of the bath.In addition,regular tap water will promote the growth of the bath.In addition,regular tap water will promote the growth of spectacularly disgusting algae colonies,particularly during the of spectacularly disgusting algae colonies,particularly during the summer months.summer months.n n

21、To reduce the amount of evaporation from your water bath,To reduce the amount of evaporation from your water bath,simply add some small plastic balls to the water bath.This simply add some small plastic balls to the water bath.This reduces the surface area for evaporation and therefore the rate redu

22、ces the surface area for evaporation and therefore the rate at which the water level drops.at which the water level drops.n nThe ground glass joint holding your flask does not need to be The ground glass joint holding your flask does not need to be greased,but on rare occasions it(or the bump bulb)m

23、ay get greased,but on rare occasions it(or the bump bulb)may get frozen.Some companies sell special joint clips that can free frozen.Some companies sell special joint clips that can free frozen joints simply by screwing them in one direction.frozen joints simply by screwing them in one direction.第14

24、页/共36页CEE 772#22 15 第15页/共36页David Reckhow CEE 772#22 16 Freeze Dryers in EVEn nManifold Dryer Manifold Dryer n nLabconco Freeze Dryer 8 Labconco Freeze Dryer 8 n n8 liter 8 liter n nMarcus 5c Marcus 5c n nTray Dryer Tray Dryer n nLabconcoLabconco FreeZone 6 FreeZone 6 n n6 liter 6 liter n nMarston

25、24Marston 24第16页/共36页CEE 772#22 17 Freeze Drying In nThree stages Three stages n nPre-freezing at atmospheric pressure(A)Pre-freezing at atmospheric pressure(A)n nSlow cooling produces large crystals,which improves sublimation Slow cooling produces large crystals,which improves sublimation n nFast c

26、ooling better preserves biological samples Fast cooling better preserves biological samples n nPrimary Drying Primary Drying n nPressure is lowered in sample compartment(C)to 0.06 mBar or Pressure is lowered in sample compartment(C)to 0.06 mBar or below below n nSample pressure drops(B)and sample wa

27、rms leading to removal of Sample pressure drops(B)and sample warms leading to removal of ice by sublimation ice by sublimation n nRate depends on difference between vapor pressure of the product Rate depends on difference between vapor pressure of the product(B)compared to the vapor pressure of the

28、condenser(D)(B)compared to the vapor pressure of the condenser(D)n nCondenser is usually 20 C cooler than product(e.g.,-50 to 80C)Condenser is usually 20 C cooler than product(e.g.,-50 to 80C)第17页/共36页CEE 772#22 18 Freeze Drying IIn nSecondary Drying Secondary Drying n nRemoval of last 5-10%of moist

29、ure Removal of last 5-10%of moisture n nHigher temp:isothermal Higher temp:isothermal desorption desorption n n30-50%of primary drying time 30-50%of primary drying time n nSource of heat during drying Source of heat during drying n nAmbient(room)heat Ambient(room)heat n nManifold drying(Model 8)Mani

30、fold drying(Model 8)n nMay be increased with a water May be increased with a water bath bath n nThermal conductor shelf Thermal conductor shelf n nTray drying(FreeZone 6)Tray drying(FreeZone 6)第18页/共36页CEE 772#22 19 Tray Dryersn nTypical Sublimation CycleShelf TemperatureProduct Temp.Condenser Tempe

31、ratureTemperaturePressureTimeWhen primary drying is complete,product temperature equals shelf temperatureAs drying proceeds,product temperature Remains below shelf temperatureABCD第19页/共36页CEE 772#22 20 Manifold Dryersn nExternal valve第20页/共36页CEE 772#22 21 Manifold Dryersn nFlasks第21页/共36页CEE 772#22

32、 22 Manifold Dryersn nPre-freezing n nEither shell freeze or angle Either shell freeze or angle flask to avoid breakage flask to avoid breakage n nWater expands when frozenWater expands when frozen第22页/共36页CEE 772#22 23 Purge&Trapn nA.purge&simultaneous trap B.thermal desorption第23页/共36页CEE 772#22 2

33、4 P&Tn nEPA purging vessel design n n5 mL sample 5 mL sample n nRoom temp.Room temp.n nUse NUse N2 or He or He n n20-40 mL/min 20-40 mL/min n n10-15 min10-15 min第24页/共36页CEE 772#22 25 P&Tn nExample Trap Example Trap n nDesorb 180 C Desorb 180 C n n20-60 mL/min20-60 mL/minbackflush backflush n n1.5-4

34、 min 1.5-4 min n nTenax Tenax n n2,6-diphenylene oxide polymer 2,6-diphenylene oxide polymer n nOV-1 OV-1 n nMethyl silicone polymer Methyl silicone polymer n nUsed for EPA methods#Used for EPA methods#n n8010:Halogenated VOCs 8010:Halogenated VOCs n n8015:Nonhalogenated VOCs(high temp):Ether,Ethano

35、l,MEK 8015:Nonhalogenated VOCs(high temp):Ether,Ethanol,MEK n n8020:Aromatic VOCs(BTEX,chlorobenzenes)8020:Aromatic VOCs(BTEX,chlorobenzenes)n n8030:(high temp)Acrolein,Acetonitrile,Acrylonitrile8030:(high temp)Acrolein,Acetonitrile,AcrylonitrileFrom CFR Title 40第25页/共36页CEE 772#22 26 Purge and Trap

36、n nCommercial Unit n nVarian LSC-Varian LSC-20002000第26页/共36页CEE 772#22 27 Closed Loop Stippingn nBrechbuhler Brechbuhler unit unit n nMarston 5 Marston 5 n nHigh High concentration concentration factor factor n n1 liter of 1 liter of sample down sample down to 0.010 mL to 0.010 mL extractextract第27

37、页/共36页CEE 772#22 28 CLSAn nPurge and Adsorb on Purge and Adsorb on 1.5 mg activated 1.5 mg activated carboncarbonn nExtract into carbon Extract into carbon disulfidedisulfide第28页/共36页CEE 772#22 29 Solid Phase Extractionn nSteps n n1.Addition of1.Addition of solvent to solvate solvent to solvate the

38、functional the functional groups groups n n2.Adsorption of sample 2.Adsorption of sample(Loading step):1 mL to 1 L(Loading step):1 mL to 1 L n n3.Sample clean-up 3.Sample clean-up n n4.Elution4.ElutionFrom:Solid Phase Extraction by Thurman&Mills第29页/共36页CEE 772#22 30 SPE cont.n nThree formats:disks,

39、cartridges&syringe barrelFrom:Solid Phase Extraction by Thurman&Mills第30页/共36页CEE 772#22 31 SPE cont.n nCut-away of a syringe barrelFrom:Solid Phase Extraction by Thurman&Mills第31页/共36页CEE 772#22 32 SPE cont.n nSyringe barrel method with vacuum manifoldFrom:Solid Phase Extraction by Thurman&Mills第32

40、页/共36页CEE 772#22 33 SPE cont.n nOther methods of sample application to syringe barrelsFrom:Solid Phase Extraction by Thurman&Mills第33页/共36页CEE 772#22 34 SPE cont.n nDisk methodsFrom:Solid Phase Extraction by Thurman&Mills第34页/共36页CEE 772#22 35 SPE cont.n nManifold assembly for disk extractionsFrom:Solid Phase Extraction by Thurman&Mills第35页/共36页感谢您的观看！第36页/共36页