3Organic Elemental Analysis The PE 2400 CHNS/O Elemental Analyzer is a combustion technique that determines weight percent carbon, hydrogen, nitrogen, sulfur or oxygen in a variety of sample typesCapable of operating in 3 modes; CHN, CHNS and OxygenPage 3
4Organic Elemental Analysis The 2400 is an organic elemental analyserIt is designed to analyser organic materials such as those produced in a chemical laboratoryIt is not designed for inorganics eg carbon in steelNor is it a TOC analyser (total organic carbon). In some instances the 2400 could act as a TOC but it is not designed to continuously handle applications such as TOC in seawaterPage 4
5How does it work ? Combustion technique – Typically a sample is weighed into a tin capsule and placed in the autosampler carousel.Information is entered into the instrument (ID & wt) and the run started.The sample is combusted into simple gases, CO2, H2O and N2, collected in the mixing chamber, separated by frontal chromatography and measured by TCPage 5
62400 Design Schematic Combustion Zone Gas Control Zone Separation Combustion technique - a sample is weighed into a tin capsule and placed in the autosampler carousel. Information is entered into the instrument (ID & wt) and the run started. The sample is combusted into simple gases, CO2, H2O and N2, collected in the mixing chamber, separated by frontal chromatography and measured by TC – more detail on this in the competitive section.Combustion ZoneGas Control ZoneSeparationDetectionPage 6
7Combustion Process Static and Dynamic 4 steps to combustion Completely combusting a weighed sample is critical to obtaining accurate resultsStatic and Dynamic4 steps to combustionSample introduced into oxygen environmentAdditional oxygen introducedAllowed to sit and burnOperator programmablePage 7
9Combustion Tube Oxidizing & Removes interferences Ultra high gases and pure quality reagents are requiredOxidizing & Removes interferencesi.e.,halogens and sulfurAids in the combustion of the samplePrevents unwanted elements from interfering with the analysis and keeps the system cleanerPage 9
11Combustion and Reduction Packing Combustion TubeSilver VanadateSilver TungstateEA-1000Reduction TubeCopper meshPack the Copper as tight as you canCuproxCopper PlugLeave about ¼ inch space from top of copper plug and the top of the tube
12Reduction Tube Removes excess oxygen Reduces NOX to Nitrogen Copper oxide at the end converts any CO to CO2Operates at about 640°C (the best temp is often debated)
13Consumables N241-0680 CHN Combustion Kit N241-0681 CHN Consumables are supplied individually or in kitsN CHNCombustion Kit2 Combustion tubes & Chemicals 2000 runsN CHNReduction tube Kit2 tubes 500 runs total
14Gas Control ZoneHomogenous mixture of product gases will achieve the highest precisionConstant temperature, volume and pressure maintained in the mixing chamberEnvironmental conditions such as changes in barometric pressure do not affect resultsAchieve highest precisionSeparates the combustion area from the separation area , so we can change the amount of O2 without change in retention timesMechanical mixingEnsures a homogenous mixture of product gasesAlso unique to PerkinElmerPage 14
15Separation Frontal Chromatography Steady State Signal Simple difference calculation determines signalEasier to calculate a small step change than a small peakPage 15
17Modes of Operation CHN mode is the most universal of the analysis CHN mode has the best reagent design and allows use of the Optimize Combustion control parameters.Interfering elements (halogens and sulphur) are removed.CHNS mode designed to include sulphur, which reduces universality. This includes limiting the range of sample types and sample size (1 to 2 mgs recommended). Metal cations are excluded.Special care must be used in calibration and blanks for lower levels of sulphur.The Oxygen mode where oxygen in a sample is converted to carbon monoxide over platinised carbon.This mode excludes compounds containing phosphorous, fluorine, silicon and metal cations. Samples containing mineral matter must be demineralised prior to analysis.Upgradeability The user may choose any or all modes. The 2400 Series II may be freely upgraded at any time to add additional mode capability to suit the needs of the laboratory.Page 17
18Sulphur CHNS is determined in a similar manner to CHN Sulphur separates after water so gives a step after waterThis gives a longer analysis timeHowever the combustion tube is completely different
20Sulphur tube Sulphur burns to SO3 and SO2 The SO3 must be removed (reduced) immediately because of its reactivityThis is achieved by adding copper to the combustion tubeNormal catalysts are replaced with EA 6000 because they scrub for sulphurDynamic combustion conditions are required, and this restricts the use of the ability to extend combustion time or add extra oxygenCHNS does not use a separate reduction tube
21Oxygen AnalysisOxygen is converted to carbon monoxide over platinised carbon in a helium gas stream using silver capsules.Helium / hydrogen (approx 5%) gas stream enhances conversion to CO and allows the use of tin capsules.Copper is used to convert any CO2 formed back to COAcid gases are scrubbed in a trap installed on the side of the analyser
27Analysis Times Analysis times CHN: 6 min, CHNS: 8 min, Oxygen: 4 min Sample size 0 to 3 mgs typically depending on sample type. Small samples will generally be limited by weighing errors, but may be used. Large samples may be used if the combustible content is lowAnalytical Element Range (mgs)detector rangeC SH ONPage 27
28Capabilities of EA 2400 Data Manager Collect and store complete run informationSearch stored runsCreate reports21 CFR part 11 compliant optionaudit trailsignature pointspermissionsComplete analyzer history storedInstrument messagesLeak test outputTiming eventsMonitored componentsAdvanced calculationsStatisticsRecalculation capabilitiesArchive dataBefore we step through the SW I’d like to describe a typical analysisPage 28
29EA 2400 Data Manager Main Run Window Modern Outlook Design - Current data generated (Run results) come in here. Flexibility with our view of these columns. Run detail information to the right and complete run information is easily viewed in the detail pane.Runs are separated by project folders via bases on a field input on the instrumentRun Query and Diagnostic buttons and icons on the toolbar– before we move to QueriesPage 29
30Queries Specify your search using AND/OR statements on sample ID date operatorprojectrun typemodeSet limits likeiscontainsdoes not containstarts withbetweenbeforeafteronSelect your limit – Add, edit – see from the list that it provides a high degree of flexibility to search on numerous parametersSEARCHResults show belowFurther select – View Result – Details shown for the highlighted runOpens more capability to perform advanced calculations, statistics, recalculation - ICONsPage 30
31Advanced calculations and Statistics Advanced calculations provide additional information on resultsStatistics can be preformed on a set of runsView results, icons, adv calculations, reportPage 31
32Printing reports and exporting data TableReport templateSave to a fileRTFTXTPDFExport formatsExcelCSVPrint – not the dot matrix printer – more details later – printer on the computerMain run window for exporting – Excel or CSV (comma separated valve)Icon to diagnosticsPage 32
33DiagnosticsFor confidence in instrument performance and for easy evaluation of instrument history the operator can send vital information to the database, includingInstrument statustemperaturespressuresdetector signalsvoltagesLeak test resultsParameter settingsPurge timesOperator can send instrument status information to the Diagnostics areaHere we see a graphical view of the detector signals during the separation of the product gases - frontal chromatography – view to be assured the read is being taken on the plateau - before with the only the printer you has several pages of numbers and you had to imagine the graphMultiple user, confidence that your instrument is performing, service person easily evaluatePage 33
3421 CFR part 11 complianceIncluded as standard. Has the same high standard of compliance as our other ES packages – like Pyris.Both use the same global security component.Note – Any ES program requires a dedicated computer since the GSC is monitoring and recording actions – conflicts can occur when 2 such programs are loaded on the same computer. Not specific to EA 2400 Data ManagerPage 34
35EA 2400 CHNS/O AnalyzerUnique technology features and newest most modern Data Manager SoftwarePage 35
36EA 2400 CHNS/O Analyzer Operating the system Purging the analyser BlanksConditionersK-FactorsSamplesPage 36
37CHNS and CHN Purge Gases Gases : Helium and %N2 or Air for the to 99.99%
38Purging prior to analysis The analyser uses helium as a purge gas and oxygen as a combustion gasPurge gases contain amounts of carbon, hydrogen and nitrogen which need to be determined.In addition contaminants from the atmosphere get into the instrument and gas lines, particularly overnight and when the system is left unused.Purging is required to make sure the analyser and gas lines are free of contamination before starting.The longer the gas lines the longer the purge timesOxygen is used only as required so the oxygen lines are more prone to contamination when the system is unusedPage 38
39System Purging Helium purge Oxygen Purge Gas Lines Use as long as found necessary to purge the analyserAfterwards a series of helium blanks can be performed to ensure the analyser is free of contaminantsOxygen PurgeOxygen purging will pass through the copper tube and can cause a significant loss in lifetime of the copperOxygen purging should be kept to a minimumThe end of the combustion tube may be loosened to allow oxygen escape before the reduction tube.Gas LinesThese must be copper or steel and completely free of leaks. Any leaks will seriously compromise performance. As a result gas lines must be connected straight to a cylinder and not used by any other equipment whatsoever.Page 39
40Leak tests Leak Tests #1 Mixing Volume #2 Combustion /Auto-Injector #3 Column/DetectorMust pass Leak test 1Pressure should get to 760 mm, you will here a click around 730mm. Pressure will hold for mm.Test 2 will pressure around 780 to 800 mm, you may get a small drop in pressure +/- 2 mmIf this fails Check for Cracked tubes, Auto-injector o-rings
41Leak Tests Leak test 3 adds the detector and column Cap sensing vent Sensing vent is the peek tubing a yellow heat shirk tubing on it
42BlanksBlanks consist of running the system without any sample to determine background levels of contamination. These are then subtracted from the sample values.Tin (and all other) capsules contain levels of impurities which must be measured so need to be included.Full oxygen blanks contain everything except a sampleThey use up copper at a high rate so should be kept to a minimumHelium blanks are run without oxygen or a capsule and are used to make sure the system is purged, stable and ready to be used. They do not use up chemicals so can be used freely.Page 42
43ConditionersBlanks decondition the system by removing adsorbed water from internal surfacesA series of blanks will therefore continuously reduce the hydrogen background valueAny sample run afterwards will show lower levels of hydrogen than it should because some of the water will be used to re-establish the adsorbed water equilibrium.As a result a conditioner must be run after a blank.Normally this is a sample of the reference standardIt does not have to be weighed because no use will be made of the result, but normally this is good practice to make sure a sensible amount is used, (eg – 2mg similar to a sample)Page 43
44Blank ValuesBlank values are determined from a running average of three blanks interspersed with conditioners. The system automatically averages the results unless blanks are run sequentiallyThe manual makes the following comments
45K FactorsK Factors are the calibration factors determined for each element by running known standards.The step height of the signal for each element is measured in microvolts per microgram (or whatever units the software uses) of element present.Sample response divided by the K Factor allows the amount of each element to be determined. This is converted to a weight percent when the weight is known.Page 45
46K FactorsK factors are determined from the running average of three or more values. Typical values as given by the manual are shown below.
47K-factors K-Factors Standards used should be run periodically to account for any drift or instability in the system.Standards usedShould be appropriate to the samples being runEg if a 5% nitrogen standard is run with a 50% sample any error will be magnified 10 timesDifferent standards can be used for different elements if required.Page 47
49SamplesSolid samples are encapsulated in tin foil capsules which are folded manually using a pair of tweezersCare must be taken not to tare the foil or lose sample in this processThis is one of the most important and time consuming aspects of analysisPage 49
50Weighing SamplesSamples need to be weighed to at least six figures (microgram) levelweighing accuracy of a 1mg sample weighed to 6 figures is +/- 0.1%weighing accuracy of a 1mg sample weighed to 5 figures is +/- 1%
51Weight range specification Total weight of each element must not exceed the analytical range below
52HomogeneitySince samples are small they must be representative of the material they are fromInhomogeneous samples should be ground and a small amount of the resulting fines takenPotentially Inhomogeneous samples includePolymers and CompositesCoals and mineralsSolis and biological materialsPage 52
53Liquid SamplesVolatile free flowing liquids can be syringed into small aluminium capsules (which contain around 2mg material) sealed, and weighed.These are then inserted into tin capsules since tin aids the combustionNon volatile liquids can be inserted into thicker walled tin capsules.It is always good to minimise the amount of aluminium put into the combustion tubes – it can wet quartz and cause the tube to crackViscous volatile liquids use ‘volatile’ aluminium pans more frequently associated with DSCPage 53
54Liquid samplesIf a lot of aluminium is used then the quartz tube may need to be protected. This can be done using zirconia cloth, or a sacrificial quartz inner tube.Do not cool the furnaces overnight and replace the vial receptacle more frequently
55Handling SamplesN Standard tin capsules. For solids and viscous, non-volatile liquidsN Large tin capsules. For larger sample weights of solids with inert material (soil, silica beads) and lower carbon.N Volatile tin pans and covers. Requires sealer, For volatile viscous liquids i.e. urea formaldehyde.l aluminum capsules. Requires sealer B For volatile, non- viscous liquids i.e. gasoline.microliter aluminum capsules. Requires sealer B For volatile, slightly viscous liquids.N Tin disks. For particulate material collected on a glass filter.N241-xxxx Thick walled tin capsules for liquids
58Optimise CombustionFor most CHN work the extended combustion time can be set to 10 – 20 secondsIncreased oxygen usage should be avoided if not needed since it reduces the life of the copper tube.
59High carbon containing samples POLYNUCLEAR AROMATICSThese are quite demanding materials due to high Carbon content and difficult to burn structure. Typically limit max sample size to about 2.5mg, add extra combustion time and extra oxygen if incomplete combustion is found.
60Incomplete combustion Quite rare but may occur with very high carbon containing materials or if the combustion tube needs to be changedHow is this evidentIncreasing carbon background (blank)Production of methane (shows as a high nitrogen / low carbon result)Remove residue by running some oxygen blanks or Purge with oxygen to burn any remaining carbonExtend combustion time and amount of available oxygen for future runs or reduce sample weight.
61High carbon containing samples Carbon FibreIncrease combustion furnace to 980°CMax weight around 2mg
62Low combustible (carbon) content SOILSSoils work well on the 2400 because higher wts can be used and the furnace conditions can be optimised to burn them. Samples should be well dried first.I typically work with approx 20mg samples thought weights can be higher if required, add 20 seconds to combustion and add a second to oxyfill and oxyboost1
63Coal Actually it does not burn easily Needs time and available oxygen, but 20 secs extended combustion and typically 2 secs extra oxygen are sufficientHomogeneity is always an issue and how well it is groundMoisture content is another, usually it is analysed after dryingUsually analysed for its calorific content which is calculated from its elemental composition
64Particulate matter in water or air This is an increasingly common requirementApplications include air qualityexhaust emissionsPlankton in seawaterMaterial is collected on filter discs which can be analysed completely in the 2400
66Filters Use a sacrificial quartz liner Do not drop furnace temps in case of wettingExtend combustion timesCalculate C/N ratios
67Silicon containing compounds May form a stable silane or the extremely stable silicon carbide. The general approach to analysis of this type of material is to add vanadium pentoxide to the capsule if required. Tin also promotes combustion of this type of material , one reason for using it.
69Organometallic compounds As with silicon containing compounds these are susceptible to the formation of stable carbides, eg boron carbide which is a stable glass. The tin capsule acts as a combustion aid but if difficulties emerge then vanadium pentoxide should be added to the capsule.
70Mercury containing complexes If mercury compounds are in use then as a precaution add pelleted gold to the combustion tube to trap any potentially volatile mercury producedREPLACE TUBE AFTER THE ANALYSIS HAS FINISHEDUse a similar approach with other potentially hazardous metal complexesmost will produce stable oxidesThe tube catalysts and the copper tube are actually very good at scrubbing for these productsIt is therefore good practice to replace the combustion tube regularly before any unwanted elements pass through the system
71Varying H contentThe equilibration effect of water during blanks has already been notedIt also has an effect as samples are runHigh H followed by low H will result in a higher value for the low H material than it should have.Low H followed by high H will result in a low value for the latter materialAll results are should still be within specification but these effects are easily noticeable.
72Effect of a hydrateWater content has a significant effect on results as shown in this example of a hydrate. Solvates also have a significant effect.
73Effect of Solvate / Hydrate Calculations exist that allow the operator to fit the data to a known solvate. However the material may not be fully solvated which causes difficulties
74Effect of moistureIt is no surprise that moisture has a similar effectIf a sample is not dry then accurate CHN data is difficultIt can be back calculated but again this is not idealImpure (wet) samples give inaccurate results
75SulphurCHNS determination works but the system is not as optimised as for CHNAdditionally the separation of water and sulphur is not completeThis makes determination of low levels of sulphur difficult unless the water is removed using an in-line trap.
77Drying the catalystsThe EA 1000 and silver tungstate on magnesium oxide are best dried before use.Use a muffle furnace at 900°C for 30 minutes, longer at lower tempsStore in a dessicatorDamp material leads to high hydrogen blanks that drift down and the water evolved can also promote devitrification of the quartz
78Diagnostics-Signal Timing Make sure signals are properly timedSignal TimingWe are looking at the signal timing which was recorded
79Filter DisksInstall Filter disks on both sides of the cross-over and at the top of the Reduction tubeThis will help in keeping the cross-over and the parts after the reduction tube cleanPlace filters on both side of the cross-over and the top of the reduction tube
80CHN Reduction Tube Copper reduction tube with support for filling If not properly filled this is the main cause of drift in an analyserWire form copper is easier to pack but is less efficientCopper powder gives the longest life but often settles in use