Presentation on how to chat with PDF using ChatGPT code interpreter
Steve dye onsite oil analysis with astm compliant ftir intruments
1. Onsite Oil Analysis with ASTM
Compliant FTIR Instruments
Dr Steve Dye
Business Development Manager
Parker Kittiwake
2. Why use FTIR in Oil Analysis?
§ One of the most widely used laboratory tools for oil analysis
§ Fast - capable of detecting multiple oil analysis parameters simultaneously
§ e.g. water, glycol, soot, oxidation, nitration…
§ Easy to use - no extensive sample preparation or wet chemistry required
§ Inexpensive – after capital outlay, per measurement costs are minimal
§ Quick - replaces tedious and time-consuming physical and chemical methods
3. Infrared Radiation§ Part of the Electromagnetic Spectrum
§ Longer wavelength than Visible light – “heat” energy
§ Absorbed by molecules (not atoms)
§ Gives molecular information, not elemental
§ Absorption increases molecular vibrations and/or rotations
§ associated with the internal bonds between the atoms of the molecule
The Electromagnetic Spectrum
Visible
Light
Wavelength
(m)
Frequency
(Hz)
Wavenumber
(cm-1)
10-11 10-10 10-9 10-8 10-7 10-6 10-410-5 10-3 10-2 10010-1 101 102 103
1019 1018 1017 1016 1014 1013 1012
1011 1010 109 108 107 106 105
1Å 1nm 10nm 1μm 10μm 100μm 1mm 1cm
Hard
X-ray
Soft
X-ray
UV IR
Microwave
VHF Short Mid Long
Radiowave
Mid FarNear
Near
Far
Spectral Regions
Gamma
rays
1000 100 105000
4. Infrared Absorption
§ Molecules have several types of vibrations. (3n-5 for linear, 3n-6 for non-linear)
§ Associated with the internal bonds, some (not all) are IR active.
§ IR radiation absorbed at a characteristic energy (frequency / wavelength).
§ Qualitative analysis – “fingerprint” identifies which molecules are present
§ Amount of energy absorbed per unit volume depends on concentration.
§ Quantitative analysis – signal intensity reflects how much present (ppm or %)
H
O
H
H
O
HH
O
H
H
O
H
H
O
H
H
O
H
H
O
H
H H
O
H H
O
IR Radiation
Stretching
Bending,
In Plane
Bending,
Out of Plane
A
wavelength (µm)
An example; Water (H2O):
6. Traditional scanning IR spectroscopy
§ First developed in the 1950s
§ Step wise scanning of a dispersive element and recording of signal
§ Time consuming
§ Drift issues
§ Need a reference to obtain the “instrument function”
§ Virtually all instruments are now of the Fourier Transform Interferometer design
7. FTIR Spectroscopy
§ Development started in the late 1960s by analytical chemists borrowing from early work of
physicists.
§ Michelson Morley Interferometer was the classic example
§ First commercial FT instrument released in 1969.
§ Uses an interferometer to generate an interference pattern of infrared radiation.
§ Divide infrared radiation into two paths.
§ Vary the path length along one of the arms
§ Recombine the radiation.
§ Record signal intensity as a function of change in pathlength difference (speed, time)
§ Interference pattern (interferogram) is in the time domain.
§ We need frequency (wavenumber, Hz).
§ Conversion is by Fourier Transform.
§ Extremely quick these days with computer FFT1 algorithms
9. Principle of FTIR Spectroscopy
Sample Interferogram
Background Interferogram
Ratio
A = -logT
Data
Fast Fourier
Transform
Algorithm
Transmittance Spectrum
Transmittance Spectrum Absorbance Spectrum
Single Beam Spectra
10. Advantages of FTIR Spectroscopy
§ All wavelengths scanned simultaneously (Fellget’s Advantage)
§ Reduction in data collection time by a factor of N
§ Increase in signal-to-noise ratio (SNR) by a factor of N 1/2 by multiple scanning
§ Greater amount of source energy to detector (Jacquinot’s Advantage)
§ No rectangular slit aperture
§ Much greater throughput compared to conventional IR
§ Fixed internal wavelength reference source
§ Typically a small HeNe laser
§ Provides high wavelength accuracy
11. Transmission (Sample) Cell
§ Fixed pathlength: Typically between 50-200μm
§ Note: ASTM standard mandates 100µm cell pathlength
§ Other cell pathlengths allow for different concentrations
§ Short pathlengths for strong absorbers / high concentration
§ Longer pathlengths for weak absorbers / low concentration
§ Cell window material choices:
§ Water insoluble ZnSe or CaF2
§ Water soluble KBr, NaCl or KCl
Sample: Fixed Pathlength
IR Transparent Cell Windows
IR Radiation To Detector
12. FTIR Spectrum of an Oil Sample
§ Load cell with sample and collect sample spectrum
§ The FTIR oil sample spectrum will reflect the molecular composition of the oil
§ For example, an ester based oil:
Wavenumber (cm-1)
Absorbance
3500 3000 2500 2000 1500 1000
e.g. Ester Based Oil
C
-
H Stretch
C=O Stretch
C
-
O Stretch
CH
2
, CH
3
Bending
CH
2
Rocking
IR
13. How can I use FTIR for oil analysis?
§ Most commonly used as a screening tool
§ FTIR is a rapid method to identify samples that have problems
§ Provides general information about the identity and condition of the oil
§ Degradation by-products, additive depletion, contaminants
§ FTIR supplements other methods to help diagnose any problems
§ For example, elemental analysis methods, viscosity measurements, chemical analyses.
14. Collecting an FTIR Spectrum
§ Specify FTIR instrument parameters:
§ Resolution (usually 2, 4 or 8 cm-1)
§ Lower wavenumber means higher resolution
§ Number of scans
§ Increasing the scans improves the signal-to-noise ratio by a factor of N1/2
§ Apodization
§ Corrects for interferogram side lobes and affects spectral band shapes
§ Collect background single beam spectrum
§ Air or empty cell reference
15. Sampling Oil for FTIR Analysis
§ Oil should be filtered to remove large particles.
§ Shake well to give a representative sample.
§ Most common sample cell is a transmission cell
– Manual loading or continuous flow pumping system
16. Example of Used Oil FTIR Spectrum
0.1
0.2
0.3
0.4
0.5
0.6
0.7
Absorbance
100015002000250030003500
Wavenumber (cm-1)
Water
Soot
Oxidation
Nitration
Antiwear
Sulfate
Fuel
17. Qualitative or Quantitative?
FTIR measurements can be either:
§ Qualitative
§ Identify constituents
§ Observe changes in peak intensities or absorbance – better/worse assessment
OR
§ Quantitative
§ Obtain a definite result in units of concentration (ex: ppm, g/L, %w/v)
§ Calibration using standards of known concentrations of the constituent or
parameter of interest
§ Correlate concentrations with absorbance to obtain regression coefficients
§ Prediction of concentrations in unknown sample using these coefficients
18. Quantitative Analysis - Example
§ Concentration of water in crankcase lubricants:
0.10 0.20 0.30 0.40
0.0
0.1
0.2
0.3
0.4
0.5
Water (%w/w)
Absorbance
.1
0
.2
.3
3800 3600 3400 3200
0.5%
0.4%
0.3%
0.2%
0.1%
0.05%
0.0%
Wavenumber (cm-1)
Absorbance
19. Considerations of Quantitative Analysis
§ Some methods are considered semi-quantitative:
§ Difficult to obtain calibration samples with reliable concentration values
§ Reference method only gives approximate values
§ Sample to sample variability
§ Actual samples can differ from calibration samples
§ For example: For soot measurements, particle size may vary
§ For example: When measuring fuel, fuel composition may vary between locations
§ Interferences
§ Other oil sample constituents and parameters can interfere with the measurement
20. Interferences
§ Parameters with the same functional group will absorb at the same frequency,
interfering with one another
§ e.g. Water and Glycol
Water
Ethylene Glycol
Absorbance
Wavenumber (cm-1)
O-H O-H
21. Interferences from the Base Oil
§ The base oil or new oil additives may also interfere with the measurement of some
parameters, especially in the “fingerprint” region.
0.05
0.15
0.25
0.35
0.45
0.55
0.65
0.75
Absorbance
60080010001200140016001800
Wavenumber (cm-1)
Oxidation
Antiwear
Base Oil
Hydraulic Oil
Fuel
Sulfate
Fingerprint Region
Oil Additives
22. Spectral Subtraction
§ Spectral subtraction is used
to subtract out the
interferences from the base
oil and additives
§ The contaminants,
degradation by-products and
additive depletion can be
visualized and analyzed more
easily
Used Oil Spectrum
0.5
1.0
Absorbance
New Reference Oil Spectrum
0.5
1.0
Difference Spectrum
0.5
1.0
100015002000250030003500
Wavenumber (cm-1)
Water
Soot Oxidation
Sulfation
Antiwear
23. Considerations of Spectral Subtraction
§ There are several considerations to take into account when using the spectral subtraction
method:
§ New (reference) oil may not always be available
§ Batch to batch variation in both base oil and formulation for same oil brand
§ Need correct reference
§ Oil changes lead to dilution and/or carryover
§ Reference no longer good
§ Topping up with another batch or different brand
§ Again, reference is no longer good
24. Contamination/Blending with Different Oils
§ FTIR is also very useful for determining significant changes in oil chemistry
§ e.g. PAO mixed with an ester- or polyalkylglycol- (PAG) based oi
0.0
0.4
0.8
1.2
1.6
2.0
2.4
Absorbance
100015002000250030003500
Wavenumber (cm-1)
Ester
PAG
25. Parameter Frequency (cm-1) Traditional Method
Oxidation 1710 Acid number (AN) titration
Nitration 1630 None
Sulfation 1150 Base Number (BN) titration
Diesel Fuel 810 Flash Point, Gas Chromatography
Gasoline 750 Flash Point, GC
Water 3420 Karl Fisher
Glycol 1080,1040, 880 Colorimetry, GC
Soot 2000 Thermogravimetric
Antiwear 980 Elemental Analysis (Zn etc.)
(T)BN 1516,1152 BN by titration
Common Oil Parameters by FTIR
26. ASTM Standards for oil analysis
§ American Society for Testing and Materials (now ASTM International) defines standard
methods and practices for over 12,000 measurement methods for metals, petroleum,
construction, environmental and many more.
§ Seen by Industry as THE STANDARD that all measurements should be made in accordance
with.
§ ASTM have several published standards and work is ongoing to define more:
§ 1 Standard practice (E2412) which defines a total of 12 trend parameters for 3 types of
lubricating oils; Petroleum based, Extreme Pressure (EP) fluids and Synthetic Polyol
Esters.
§ 5 Standard methods – Oxidation (D7414), Nitration (7624), Phosphate Antiwear
(D7412), Sulphation (D7415), Oxidation in transmission oils (D7214)
§ Proposed methods (WIP) – Acid Number, Base Number, Water Content
27. ASTM Lubricant Practices & Methods
§ D7418-07 Standard Practice for Set-Up and Operation of Fourier Transform Infrared (FTIR)
Spectrometers for In-Service Oil Condition Monitoring.
§ E2412-10 Standard Practice for Condition Monitoring of in-service Lubricants by Trend Analysis
Using Fourier Transform Infrared (FT-IR) Spectrometry.
§ D7214-07a Standard Test Method for Determination of the Oxidation of Used Lubricants by FT-IR
Using Peak Area Increase Calculation.
§ D7414-09 Standard Test Method for Condition Monitoring of Oxidation in In-Service Petroleum
and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR)
Spectrometry.
§ D7412-09 Standard Test Method for Condition Monitoring of Phosphate Antiwear Additives in In-
Service Petroleum and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform
Infrared (FT-IR) Spectrometry.
§ D7415-09 Standard Test Method for Condition Monitoring of Sulfate By-Products in In-Service
Petroleum and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform Infrared
(FT-IR) Spectrometry.
§ D7624-10 Standard Test Method for Condition Monitoring of Nitration in In-Service Petroleum
and Hydrocarbon Based Lubricants by Trend Analysis Using Fourier Transform Infrared (FT-IR)
Spectrometry.
28. Field vs. Lab testing
§ Lab testing:
§ Lab testing can offer increased number of alternative tests on oil samples
(e.g XRF)
§ Expert advice may be offered on analysis
§ Time taken to ship samples from remote locations can be long
§ Ongoing cost per sample sent
§ Field Testing:
§ Immediate results available so action can be taken fast, before major
problems arise
§ No/Low ongoing costs after initial capital outlay
§ Some user intelligence required to set up parameters for alarm warning
levels etc
§ Subset of full lab tests available
31. Parker Kittiwake FTIR3 Oil Analyser
ASTM Compliant, field deployable, all in a small, portable instrument
§ Simple to use
§ Software pre-loaded onto Netbook
§ Multiple equipment records
§ Trending of multiple parameters
§ Multiple users
36. What will the FTIR3 Measure
§ Sulphation – TO ASTM D7415-09
§ Oxidation – To ASTM D7414-09
§ Nitration – To ASTM D7624-10
§ Phosphate Antiwear – To ASTM D7412-09
§ E2412:
• Soot Water
• Diesel
• Fuel Contamination
• Ethyl Glycol Coolant
• Antioxidant depletion
§ Future published ASTM methods can be readily added to the instrument.
§ Customer specific methods can be developed and also added to the instrument.
37. Advantages and Limitations
§ Advantages of FTIR spectroscopy in oil analysis:
§ Rapid analysis with no extensive sample preparation
§ Can give information on multiple parameters simultaneously
§ Provides quantitative and qualitative data
§ Accurate and repeatable results
§ Limitations of FTIR spectroscopy in oil analysis:
§ Different base oils and additives can interfere with the measurement of
different parameters
§ For spectral subtraction, sometimes it can be difficult to find a suitable
reference oil
§ Difficulty measuring some components that are less than 0.1% w/w
§ No elemental analysis
38. In Summary….
§ FTIR provides a quick and accurate test method to measure multiple parameters
on in service oils
§ Advances in recent years have allowed reduced size, field deployable devices to
be developed
§ ASTM ratification of test Methods is an ongoing process, providing end users with
confidence in reliable and repeatable measurement techniques and results
§ More ASTM agreed methods are on the way for additional parameters
§ Field deployable, ASTM compliant devices are now available
