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2400 Series 2 CHNS/O Analyser

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Presentation on theme: "2400 Series 2 CHNS/O Analyser"— Presentation transcript:

1 2400 Series 2 CHNS/O Analyser
Paul Gabbott PETA

2 Page 2

3 Organic 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 types Capable of operating in 3 modes; CHN, CHNS and Oxygen Page 3

4 Organic Elemental Analysis
The 2400 is an organic elemental analyser It is designed to analyser organic materials such as those produced in a chemical laboratory It is not designed for inorganics eg carbon in steel Nor 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 seawater Page 4

5 How 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 TC Page 5

6 2400 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 Zone Gas Control Zone Separation Detection Page 6

7 Combustion Process Static and Dynamic 4 steps to combustion
Completely combusting a weighed sample is critical to obtaining accurate results Static and Dynamic 4 steps to combustion Sample introduced into oxygen environment Additional oxygen introduced Allowed to sit and burn Operator programmable Page 7

8 CHN Combustion Tube

9 Combustion Tube Oxidizing & Removes interferences
Ultra high gases and pure quality reagents are required Oxidizing & Removes interferences i.e.,halogens and sulfur Aids in the combustion of the sample Prevents unwanted elements from interfering with the analysis and keeps the system cleaner Page 9

10 CHN Reduction Tube

11 Combustion and Reduction Packing
Combustion Tube Silver Vanadate Silver Tungstate EA-1000 Reduction Tube Copper mesh Pack the Copper as tight as you can Cuprox Copper Plug Leave about ¼ inch space from top of copper plug and the top of the tube

12 Reduction Tube Removes excess oxygen Reduces NOX to Nitrogen
Copper oxide at the end converts any CO to CO2 Operates at about 640°C (the best temp is often debated)

13 Consumables N241-0680 CHN Combustion Kit N241-0681 CHN
Consumables are supplied individually or in kits N CHN Combustion Kit 2 Combustion tubes & Chemicals 2000 runs N CHN Reduction tube Kit 2 tubes 500 runs total

14 Gas Control Zone Homogenous mixture of product gases will achieve the highest precision Constant temperature, volume and pressure maintained in the mixing chamber Environmental conditions such as changes in barometric pressure do not affect results Achieve highest precision Separates the combustion area from the separation area , so we can change the amount of O2 without change in retention times Mechanical mixing Ensures a homogenous mixture of product gases Also unique to PerkinElmer Page 14

15 Separation Frontal Chromatography Steady State Signal
Simple difference calculation determines signal Easier to calculate a small step change than a small peak Page 15

16 Frontal Chromatography
Page 16

17 Modes 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

18 Sulphur CHNS is determined in a similar manner to CHN
Sulphur separates after water so gives a step after water This gives a longer analysis time However the combustion tube is completely different

19 Sulphur Tube Operating temperature around 975°C

20 Sulphur tube Sulphur burns to SO3 and SO2
The SO3 must be removed (reduced) immediately because of its reactivity This is achieved by adding copper to the combustion tube Normal catalysts are replaced with EA 6000 because they scrub for sulphur Dynamic combustion conditions are required, and this restricts the use of the ability to extend combustion time or add extra oxygen CHNS does not use a separate reduction tube

21 Oxygen Analysis Oxygen 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 CO Acid gases are scrubbed in a trap installed on the side of the analyser

22 Oxygen Tubes

23 Trap used with oxygen

24 Oxygen detection

25 Oxygen applications Often involve coals or fuels
Note that coals must be demineralised for which procedures exist, but it is not as simple.

26 CHNS and O2 CHNS Tubes Copper EA-6000 Oxygen Tubes

27 Analysis 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 low Analytical Element Range (mgs) detector range C S H O N Page 27

28 Capabilities of EA 2400 Data Manager
Collect and store complete run information Search stored runs Create reports 21 CFR part 11 compliant option audit trail signature points permissions Complete analyzer history stored Instrument messages Leak test output Timing events Monitored components Advanced calculations Statistics Recalculation capabilities Archive data Before we step through the SW I’d like to describe a typical analysis Page 28

29 EA 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 instrument Run Query and Diagnostic buttons and icons on the toolbar– before we move to Queries Page 29

30 Queries Specify your search using AND/OR statements on sample ID date
operator project run type mode Set limits like is contains does not contain starts with between before after on Select your limit – Add, edit – see from the list that it provides a high degree of flexibility to search on numerous parameters SEARCH Results show below Further select – View Result – Details shown for the highlighted run Opens more capability to perform advanced calculations, statistics, recalculation - ICONs Page 30

31 Advanced calculations and Statistics
Advanced calculations provide additional information on results Statistics can be preformed on a set of runs View results, icons, adv calculations, report Page 31

32 Printing reports and exporting data
Table Report template Save to a file RTF TXT PDF Export formats Excel CSV Print – not the dot matrix printer – more details later – printer on the computer Main run window for exporting – Excel or CSV (comma separated valve) Icon to diagnostics Page 32

33 Diagnostics For confidence in instrument performance and for easy evaluation of instrument history the operator can send vital information to the database, including Instrument status temperatures pressures detector signals voltages Leak test results Parameter settings Purge times Operator can send instrument status information to the Diagnostics area Here 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 graph Multiple user, confidence that your instrument is performing, service person easily evaluate Page 33

34 21 CFR part 11 compliance Included 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 Manager Page 34

35 EA 2400 CHNS/O Analyzer Unique technology features and newest most modern Data Manager Software Page 35

36 EA 2400 CHNS/O Analyzer Operating the system Purging the analyser
Blanks Conditioners K-Factors Samples Page 36

37 CHNS and CHN Purge Gases
Gases : Helium and % N2 or Air for the to 99.99%

38 Purging prior to analysis
The analyser uses helium as a purge gas and oxygen as a combustion gas Purge 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 times Oxygen is used only as required so the oxygen lines are more prone to contamination when the system is unused Page 38

39 System Purging Helium purge Oxygen Purge Gas Lines
Use as long as found necessary to purge the analyser Afterwards a series of helium blanks can be performed to ensure the analyser is free of contaminants Oxygen Purge Oxygen purging will pass through the copper tube and can cause a significant loss in lifetime of the copper Oxygen purging should be kept to a minimum The end of the combustion tube may be loosened to allow oxygen escape before the reduction tube. Gas Lines These 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

40 Leak tests Leak Tests #1 Mixing Volume #2 Combustion /Auto-Injector
#3 Column/Detector Must pass Leak test 1 Pressure 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 mm If this fails Check for Cracked tubes, Auto-injector o-rings

41 Leak 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

42 Blanks Blanks 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 sample They use up copper at a high rate so should be kept to a minimum Helium 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

43 Conditioners Blanks decondition the system by removing adsorbed water from internal surfaces A series of blanks will therefore continuously reduce the hydrogen background value Any 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 standard It 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

44 Blank Values Blank values are determined from a running average of three blanks interspersed with conditioners. The system automatically averages the results unless blanks are run sequentially The manual makes the following comments

45 K Factors K 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

46 K Factors K factors are determined from the running average of three or more values. Typical values as given by the manual are shown below.

47 K-factors K-Factors Standards used
should be run periodically to account for any drift or instability in the system. Standards used Should be appropriate to the samples being run Eg if a 5% nitrogen standard is run with a 50% sample any error will be magnified 10 times Different standards can be used for different elements if required. Page 47

48 Typical Sart-up Sequence
Check Leak tests 5 Helium blanks Conditioner Blank 3 K-Factors Samples Page 48

49 Samples Solid samples are encapsulated in tin foil capsules which are folded manually using a pair of tweezers Care must be taken not to tare the foil or lose sample in this process This is one of the most important and time consuming aspects of analysis Page 49

50 Weighing Samples Samples need to be weighed to at least six figures (microgram) level weighing accuracy of a 1mg sample weighed to 6 figures is +/- 0.1% weighing accuracy of a 1mg sample weighed to 5 figures is +/- 1%

51 Weight range specification
Total weight of each element must not exceed the analytical range below

52 Homogeneity Since samples are small they must be representative of the material they are from Inhomogeneous samples should be ground and a small amount of the resulting fines taken Potentially Inhomogeneous samples include Polymers and Composites Coals and minerals Solis and biological materials Page 52

53 Liquid Samples Volatile 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 combustion Non 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 crack Viscous volatile liquids use ‘volatile’ aluminium pans more frequently associated with DSC Page 53

54 Liquid samples If 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

55 Handling Samples N Standard tin capsules. For solids and viscous, non-volatile liquids N 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

56 Accuracy Specifications

57 Optimise Combustion

58 Optimise Combustion For most CHN work the extended combustion time can be set to 10 – 20 seconds Increased oxygen usage should be avoided if not needed since it reduces the life of the copper tube.

59 High carbon containing samples
POLYNUCLEAR AROMATICS These 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.

60 Incomplete combustion
Quite rare but may occur with very high carbon containing materials or if the combustion tube needs to be changed How is this evident Increasing 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 carbon Extend combustion time and amount of available oxygen for future runs or reduce sample weight.

61 High carbon containing samples
Carbon Fibre Increase combustion furnace to 980°C Max weight around 2mg

62 Low combustible (carbon) content
SOILS Soils 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

63 Coal Actually it does not burn easily
Needs time and available oxygen, but 20 secs extended combustion and typically 2 secs extra oxygen are sufficient Homogeneity is always an issue and how well it is ground Moisture content is another, usually it is analysed after drying Usually analysed for its calorific content which is calculated from its elemental composition

64 Particulate matter in water or air
This is an increasingly common requirement Applications include air quality exhaust emissions Plankton in seawater Material is collected on filter discs which can be analysed completely in the 2400

65 Rolling up a glass fibre filter disk

66 Filters Use a sacrificial quartz liner
Do not drop furnace temps in case of wetting Extend combustion times Calculate C/N ratios

67 Silicon 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.

68 Refractory carbides

69 Organometallic 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.

70 Mercury 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 produced REPLACE TUBE AFTER THE ANALYSIS HAS FINISHED Use a similar approach with other potentially hazardous metal complexes most will produce stable oxides The tube catalysts and the copper tube are actually very good at scrubbing for these products It is therefore good practice to replace the combustion tube regularly before any unwanted elements pass through the system

71 Varying H content The equilibration effect of water during blanks has already been noted It also has an effect as samples are run High 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 material All results are should still be within specification but these effects are easily noticeable.

72 Effect of a hydrate Water content has a significant effect on results as shown in this example of a hydrate. Solvates also have a significant effect.

73 Effect 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

74 Effect of moisture It is no surprise that moisture has a similar effect If a sample is not dry then accurate CHN data is difficult It can be back calculated but again this is not ideal Impure (wet) samples give inaccurate results

75 Sulphur CHNS determination works but the system is not as optimised as for CHN Additionally the separation of water and sulphur is not complete This makes determination of low levels of sulphur difficult unless the water is removed using an in-line trap.

76 Final practical comments

77 Drying the catalysts The 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 temps Store in a dessicator Damp material leads to high hydrogen blanks that drift down and the water evolved can also promote devitrification of the quartz

78 Diagnostics-Signal Timing
Make sure signals are properly timed Signal Timing We are looking at the signal timing which was recorded

79 Filter Disks Install Filter disks on both sides of the cross-over and at the top of the Reduction tube This will help in keeping the cross-over and the parts after the reduction tube clean Place filters on both side of the cross-over and the top of the reduction tube

80 CHN Reduction Tube Copper reduction tube with support for filling
If not properly filled this is the main cause of drift in an analyser Wire form copper is easier to pack but is less efficient Copper powder gives the longest life but often settles in use


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