Elemental, My Dear Watson Paul Middlestead University of Ottawa, G.G. Hatch Laboratory For 19th Continuous Flow Conference, Calgary, 2013

 This talk is for new users  We will touch the basics on Elemental analysers  A mix bag of tricks and advices  Refer to manufacturer’s instruction manuals  Only endorsed products are: Rickards Red and Rickards White Who/what is this talk for?

Meet my family Combustion EA NCHS TC/EA Pyrolysis HO Large capacity S onlyTOCStable isotopes C C

 Leco is the most popular manufacturer of elemental analysers. Every department has one or two of those accumulating dust.  Static combustion using oxygen: not suitable for IRMS Meet Grand Pa

Elemental Analyser as an…instrument Schematics Autosamplers Flash combustion Chemicals & Configurations Gas Chromatography Thermal Conductivity Detector Typical run Common problems EA-IRMS Let’s touch on

 Simultaneous determination of Nitrogen, Carbon, Hydrogen, Sulfur, Oxygen  Measuring range: 100 ppm to 100%  Sample size: 0.1 to 1000 mg / 0.1 to 25 ul  Detection limit: 10 ppm  Accuracy: 0.3% % absolute EA as an …. instrument

 CE instruments (Carlo Erba) models 1108, 1110, NA 1500, NA 2100, Flash 1112  Costech Model ECS4010  Elementar cube family  Eurovector models EuroEa3028-HT, Ea3024- IRMS, pyrolysis model  Sercon-Integra  TC\EA Thermo  … Manufacturers, models blablabla

EA : Bulk analysis of NCHS/O  Organic compounds  Pharmaceuticals  Organometallics  Petrochemicals  Gasoline & fuels  Graphite  Carbides & nitrides  Metals & alloys  Polymers  Explosives  Hydrocarbons  Soils  Coal & coke  Liquids In short, you can combust your grandmother!

Ref gas 1 Elemental Analyser (CNS) (OH) Interface Isotope Ratio Mass Spectrometer He Ref gas 2 2 m Typical EA setup with IRMS

EA picture

Elemental Analyser Schematic TCD Combustion Chemicals 1020C Reduction Chemicals 650C Gas chromatography Column in oven Thermal Conduc- tivity Detector Autosampler N2 H2O CO2 SO2 He O 2 Water Trap EA line out

Found the problem with the previous slide? A beer if you do… (5 seconds)

Elemental Analyser Schematic TCD Combustion Chemicals 1020C Reduction Chemicals 700C Gas chromatography Column in oven Thermocouple Detector Autosampler N2 H2O CO2 SO2 He O 2 Water Trap EA line out

A cold Rickard’s Red for me please.

1. Sample/Std is weighed and wrapped in tin foil, placed in culture tray/autosampler 2. Sample drops is flash-combusted in O 2 in He stream, causing rapid cracking and oxidation of gases stoichiometrically equivalent to their elemental components, some gas oxides need to be reduced before obtaining final products (N 2, CO 2, H 2 O, SO 2 ) i.e. oxidation and reducing reactions involved Typical Analysis Procedure for EA

3.Separation of gases by gas chromatography or chemical column traps 4.Detection by thermal conductivity detector (TCD) or IRMS. 5.Curve made from weighing certified stds (for isotope and/or quantitative measurements)

Some torture tools…

Well well, got culture?

Super size meSuper size meSuper size meSuper size me

MAIS C’EST IMPOSSIBLE!

C’EST FANTASTIQUE! Filters? Careful!

Not flat please

Autosamplers (AS128)

Autosamplers (AS200)

Zero Blank

Zero Blank modified

Special tools required ECS 4010

Take 20 minutes to study the gas schematics of your instrument Be good to yourself

Loop concept (a) OXYGEN OUT He SAMPLE LOOP 10, 5, 3 ML O TO AUTOSAMPLER He only

Loop concept (b) He SAMPLE LOOP 10, 5, 3 ML O2O2 TO AUTOSAMPLER He + O 2 + He OXYGENOUT

Sample dropping START Sample drops Combustion starts Injected O 2 Flash should occur within 2-3 seconds of being dropped 20 seconds

PLATINUM: Absorbs much of the heat of the reactor before passing it on to the sample, slowing down reaction PLATINUM: Absorbs much of the heat of the reactor before passing it on to the sample, slowing down reaction ALUMINIUM: Supplies good oxidation flash and prime sample ignition but does not melt or mix with the sample thus does not promote inner oxidation ALUMINIUM: Supplies good oxidation flash and prime sample ignition but does not melt or mix with the sample thus does not promote inner oxidation SILVER: Melts at C, does not take part in the combustion, retains trace of carbon when in molten state SILVER: Melts at C, does not take part in the combustion, retains trace of carbon when in molten state TIN: Inexpensive & takes active part in process. Melts at C with very low enthalpy, intermixes with organic and inorganic substances, expedites the final oxidation reaction TIN: Inexpensive & takes active part in process. Melts at C with very low enthalpy, intermixes with organic and inorganic substances, expedites the final oxidation reaction Why you Tin man?

 Increases local temperature from C to C, accelerating combustion  Cancels the endothermic effects of tin melting (0.14 calories required for melting vs calories given off during flash)  Equalizes the thermal degradation of any substance  Uses available oxygen immediately and requires less Dynamic Flash Combustion Oxidation of TIN gives a tremendous enthalpy reaction Sn + O 2 SnO cal C C

 Ensures that sample oxidation is performed in gaseous phase (95%) rather than in the catalytic reactions  Breaks down any matrix without combustion aid  Converts the sample into a homogenous, quantitative combustion gas mixture (unfractionated)  Provides a gaseous plug for the entry into the GC column  Forms tin oxide, an oxidation catalyst  Provides visual indication of the reaction Dynamic Flash Combustion Oxidation of TIN gives a tremendous enthalpy reaction

C CO 2 CO 2 C CO 2 CO 2 Let’s get cracking H H 2 OH 2 O S SO 2 + SO 3 SO 2 Combustion tube Reduction tube N N 2 + NxOx N 2

Chemicals and Configurations System should be optimized for element(s) to be analyzed One-tube system: both oxidant catalyst and reducing chemicals in one tube; usually used if S is to be analyzed Two-tube system: one tube for oxidant, one tube for reducing chemicals; usually used for N, NC or NCH Chemical traps: Mg Perchlorate or Anhydrone will trap H 2 O, and Carbosorb will trap CO 2 (and SO 2 )

Configuration CN

Configuration S

Small is beautiful

Using grinding tools and diluted Nitric acid, one can re-use combustion and reduction tubes More torture tools

 Gas chromatographic columns will separate different components according to their polarity and molecular size.  Factors influencing the quality of the chromatography: column length, size of packing, tube diameter, stationary phase type, flow rate, temperature.  Packed column: packed polymer beads, different sizes available. High capacity, low resolution.  Capillary column: small capillary with polymeric film on inner wall. High resolution, low capacity.  Deactivated fused silica is free of adsorption problems encountered with most packings or capillaries columns. Gas Chromatography

Gas Separation/ GC He + N 2, CO 2, H 2 O, SO 2 + He He + SO 2 + H 2 O + CO 2 + N 2 + He INCREASING POLARITY OF GASES

What after we separate? He + SO 2 + H 2 O + CO 2 + N 2 + He DETECTOR TIME DETECTOR N2N2 CO 2 SO 2 H20H20

Gas Separation / Purge & Trap TCD SO 2 H2OH2O CO 2

Thermal conductivity detector (TCD) Heated filament from which heat is removed at a constant rate by He gas stream. Change in heat transfer is caused by presence of analyte molecules with different thermal conductivities than He. Relatively low sensitivity, excellent range and linearity. Non-destructive. Electron capture detector (ECD) Electrons are captured by organic species in ionized carrier; used for trace sulfur determination. Isotope Ratio Mass Spectrometer (IRMS) Detectors

TCD schematic

Typical output of EA, text book N2 CO2 H2O SO2

Balance: Get the best A 0.01mg readability translates in an error of 0.25% on a 2 mg sample (say on 100% carbon) A 0.01mg readability translates in an error of 0.25% on a 2 mg sample (say on 100% carbon) Balance

IAEA (and NIST) standards Links available on Isogeochem

 Best : %N, 15 N, %C, 13 C  Test different materials and pray  Make your own:  Caffeine  L-glutamic acid  Mixtures such as sucrose + potassium nitrate  Mix in solution of natural + enriched/depleted material then dried, powdered, sieved STD: Making it on your own…

STD: Not making it on your own…

Can also contact other university labs to buy or obtain their internal standards. STD: Not making it on your own…

Calculation Methods 1. K-Factor ( Single point calibration with blank substraction) Calculated % = K * (Area unk – Area blk) Weight unk Where K = Weight std * Theor std % Area std - Area blk

Calculation Methods 2. Linear Fit (Least square linear regression) Calculated % = m * Area unk + b Weight unk Peak Area Wt * Th std %

Calculation Methods 3. Quadratic Fit (Least square quadratic regression) Calculated % = a * Area unk 2 + b * Area unk + c Weight unk Peak Area Wt * Th std %

An update… Most elemental analysers manufacturers have considerably refined their calculation methods, with more complex algorithms, low-high ranges and statistical tools.

Common Problems (I) CO2 Blank Unreproducible blank Contaminated capsules Wash or change batch Memory effect due to ashes Remove ashes N2 Blank Increasing blank values Copper exhausted Repack reduction tube High mass 30 Repack reduction tube

Common Problems (II) Very high blank values Autosampler purge off Very high mass 28 Switch on!! High & constant blank Impure oxygen High mass 28 Replace O2

Common Problems (III) No signal Detector off Switch on! Broken filament Call engineer Low carrier flow Check flow rate & blockage MS valve closed, open split problem Ghost/double peaks Leak Find and fix CO2 or H2O trap exhausted Replace packing of trap N2 ? CO2?

Common Problems (IV) Peak broadening Presence of dead volume Check trap(s) or packing Incomplete combustion Remove ashes, check drop time (flash), exhausted chemicals Baseline drift Leak Find and fix Carrier flow fluctuating Check GC oven temperature Outgassing of chemicals

Leak check or check leaks (1) EA Pressure check Cap exit port Increase P of He to 1.3 bar, wait 3 minutes Close regulator Pressure gauge should not move for 5 minutes EA Flow check (requires electronic mass flow controller) Cap exit port Monitor flow for 3 minutes Flow should drop to 0 ml/min

Leak check or check leaks (2) EA Inter- face Leak check with IRMS EA has been leak checked EA chemicals have outgassed (12 hours) Tune to Ar (mass 40) Should meet manufacturer’s requirements Use Ar cylinder to hunt MS Ar

Elemental Analyser Schematic for IRMS TCD Combustion tubeReduction tube Water trap Gas chromatography Column Thermocouple Detector Autosampler To MS N2 CO2 Interface Diluter & ref gas

Did you find the small error in the last slide? WAKE UP!

Elemental Analyser Schematic for IRMS TCD Combustion tubeReduction tube Water trap Gas chromatography Column Thermocouple Detector Autosampler To MS N2 CO2 Interface Diluter & ref gas

 Water is removed via Mg Perchlorate/sicapent trap ---water and mass spectrometer do not mix----  Configuration should be optimized for gas of interest  Leak free (mass 28 & 40, use Argon as leak probe)  Low and stable background (mass 28, 18, 40, 44)  Dynamic range must be respected, do use target beam  Best sequence is carefully planned ie known concentration of samples  Garbage in……Garbage out Considerations for EA-IRMS

Some useful info Lab No.Sample typeNitrogenCarbonHydrogenSulphurC/NComments Adult mysids10,2050,97na 5,00Whall JD, Trent U Amphipods 6,8133,205,660,004,88Pastershank G., U of O/ Biology Chironomids8,9837,23na 4,15Whall JD, Trent U Clam12,3048,91na 3,98Whall JD, Trent U Clam muscle 11,2643,416,771,103,85Pastershank G., U of O/ Biology Clam shell 0,0511,910,190,00 231,6 3 Pastershank G., U of O/ Biology Cragon (shrimp) 10,0337,225,910,003,71Pastershank G., U of O/ Biology Diatom 0,000,740,090,00N.A.Bad trace Egg white 11,8545,836,931,143,87Pastershank G., U of O/ Biology Egg yolk 5,4162,699,730,0011,59Pastershank G., U of O/ Biology Fish bone 6,4319,533,510,003,04Pastershank G., U of O/ Biology Fish eye 12,9048,707,052,133,77Pastershank G., U of O/ Biology Fish fin 10,0134,365,350,003,43Pastershank G., U of O/ Biology Fish gill 13,2847,107,060,003,55Pastershank G., U of O/ Biology Fish gut content 9,5644,887,071,134,69Pastershank G., U of O/ Biology

 Best are quartz filters; they are stable. However they are more expensive and offer less choice.  Silver filters are great too.  Mostly glass filters, cheap, huge choice.  How much to use? Filters, we can do that!

Area =  *R 2 In this case, a punch is about 16mm 2 and our whole filter is about 1490mm 2. Our punch hole is roughly 1% of the filter.

Sediment contamination Inorganic Carbon Average  13 C: 0‰ = Total CarbonOrganic Carbon Average  13 C: -25‰ 0%+ 100%=-25 ‰ 1%+ 99%= ‰ 5%+ 95%= ‰ 10%+ 90%= ‰ 50%+ 50%= ‰

Honey, you think I’m fat? % NitrogenWt required mg 101.0mg 55mg 27mg 110mg mg 0.001Yeah, right! Optimal amount of Nitrogen: 0.1mg

Open split, magical stuff He + CO 2 + N 2 + He EA 100 ml/min Fused silica capillary 100 um, 2m, inserted about 30cm in EA line, 0.4 ml/min going into source of IRMS 2mm or 1/16” SS line from EA

In real life…Open split EA IRMS Ref 1 Ref 2 He Ref 3 Ref 4 Ref 5 Ref 6 Ref 7 Ref 8 Ref 9 Ref 10 Ref 11 Ref 12

In real life…Open split EA IRMS Ref 1 Ref 2 He Ref 3 Ref 4 Ref 5 Ref 6 Ref 7 Ref 8 Ref 9 Ref 10 Ref 11 Ref 12

The joy of sniffing EA only Mass spectrometer output TCD output from EA MagnetPeakjump N2N2 CO 2 Mass 28, 29 Mass 44,45,46

The joy of sniffing, total Mass spectrometer output TCD output from EA MagnetPeakjump N2N2 CO 2 Mass 28, 29 Mass 44,45,46 Masses 28 & 29Masses 44, 45 & 46

To dilute or Not to dilute?

Second last suggestion I strongly recommend that you create a basic document for your users explaining the limits and pitfalls of EA-IRMS analysis, this will save you (and your users) an enormous amount of time.

 Removing inorganic carbon is not trivial  Alkalies (Sodium, Potassium, Calcium) are difficult to combust, catalist is definitively required to bind and help with oxydation.  Oxygen contribution to  34 S is still a problem. Some unresolved issues with EA

Last suggestion and only Official Endorsement The only product fully and officially endorsed by the author is: Rickard’s Red

Thank you for not snoring My thanks to: Wendy Abdi, Nik Binder, Fred Longstaffe, Scott Hughes, Gilles St-Jean, Peter Stow and Patricia Wickham for the use of material, brain power and time …