Cost-Effective Condition Monitoring The SPECTRO GENESIS Petrochem ICP-OES

Transcription

1 Cost-Effective Condition Monitoring The SPECTRO GENESIS Petrochem ICP-OES CONDITION ANALYSIS - INTRODUCTION The elemental analysis of used lubricating oil has become an essential part of condition monitoring, the use of physical and chemical techniques to measure the condition of plant and equipment with the objective of preventing equipment failure and optimizing maintenance programs. Specialist service laboratories and major plant operators analyze hundreds of oil samples per day for a wide range of elements to detect component wear and the presence of foreign matter that may accelerate wear. The systematic analysis of lubricating oils in service can result in lower operating costs, reduced downtimes, extended plant and equipment lifetimes and more effective maintenance programs. There are many techniques for elemental analysis, but Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES) has become the technique of choice in most service laboratories. There are two main types of ICP-OES instrument: sequential ICP-OES spectrometers measure each element in turn by scanning from one element to the next, whereas simultaneous instruments measure all the programmed elements at one time. The latter approach offers considerable speed advantages and hence faster sample throughput, but simultaneous instruments have traditionally been significantly more expensive than sequential systems. The SPECTRO GENESIS Petrochem is a simultaneous instrument that offers a real economic alternative to sequential ICP and Atomic Absorption spectrometers. The latest detector technology combined with remarkably low running costs provide an effortless introduction to simultaneous ICP-OES for those unfamiliar with the technique and a powerful and efficient tool for routine used oil analysis. The SPECTRO GENESIS Petrochem is available with a complete set of factory methods for used oil analysis - truly plug & analyze without needing to first develop a method. This paper describes the SPECTRO GENESIS Petrochem in some detail and illustrates its suitability for elemental analysis in condition monitoring. Lubricating oil analysis has been used to monitor the condition of engines and other machinery for over 50 years. It has been likened to the use of blood tests by a clinician in determining the condition of a patient. This analogy is quite useful, as it suggests the main object of the exercise: to assess the condition of the mechanical system that the oil is lubricating, rather than that of the oil itself. It can be applied to most lubricated mechanical systems, such as engines, gear transmissions, hydraulics and the like, and has wide application in areas such as construction machinery, power generation and transportation, including aviation, fleet operations and public transport. One of the most powerful arguments for condition analysis is that it can trigger preventive maintenance before component wear leads to potentially catastrophic failure. Early detection of foreign matter in the oil, perhaps due to an air filter failure, can prevent wear and costly repairs. There are several causes of wear, such as friction between moving surfaces, abrasion by contaminants such as grit, corrosion processes and so on, but most give rise to the presence of microscopic metallic particles in the lubricant as components wear away. Quantitative measurement of metallic elements in the oil can therefore be a useful indicator of wear. Furthermore, as different metals are used to manufacture different components, elemental analysis can

2 often provide a clue as to which components are subject to wear. Analysis can also detect the presence and possibly the origin of foreign matter in the oil, such as dust that may have entered an engine via a defective filter. Many other changes can occur in oils under fault conditions, such as dilution by fuels, or contamination by water or anti-freeze. Processes such as oxidation can lead to changes in lubricant properties like viscosity, leading to accelerated wear rates. Not all these processes can be detected by elemental analysis, so several different physical and chemical measurement techniques are necessary for comprehensive condition monitoring, but elemental analysis has become the essential tool for wear detection. Interpretation of the analytical results from oil analysis is itself a complex and specialized task. Many lubricating oils contain additives to improve their properties that are themselves metallic compounds, and some of these metals may occur in the wearing components themselves. Therefore the presence of a particular element does not necessarily indicate wear. Indeed, these additives are used to improve or extend the lubricant properties of the oil, and may be consumed over time. This is known as additive depletion, and unless the oil is changed or the additives replenished, the oil itself may lead to increased wear, so the level of additives needs to be monitored. Mechanical systems and engines are often subjected to a running in period during which wear can be quite rapid but is actually beneficial. For these reasons, system management decisions are rarely made on the basis of single oil analysis measurements or against predetermined limit values, but by following trends established by regular sampling regimes. Software packages designed to assist in the interpretation of measurement data are commercially available. Unless wear is severe, metallic particles entering the lubricant are usually very finely divided (10 microns or less) and remain largely suspended in the oil without settling out. Oil samples like this can be treated essentially as solutions and are amenable to analy- sis by several well established laboratory techniques. In more severe wear, larger particles can be produced that settle out and require a different approach. Large metallic particles in any lubricating oil are a cause for concern, and one popular technique is the use of magnetic sump plugs to harvest such particles for subsequent analysis aimed at identification of their origin. The following table indicates the possible significance of some elements found in used oil: it is by no means exhaustive. Table 1 Element Aluminum Barium Boron Calcium Copper Iron Lead Magnesium Molybdenum Nickel Phosphorus Potassium Silicon Silver Sodium Tin Titanium Zinc Possible Origin Pistons, bearings Oil additive Coolant contamination, additive Additive, contaminant from dust Bearings, bushings, additive Many sources, the element most frequently found Bearings, bushings, solders Additive Additive, piston rings, coolant contamination Bearings, turbine blades Additive Coolant, contaminant Airborne dust, seals, coolants, additive Bearings, silver solders Coolant, additive, salt water in marine engines Bearings, piston rings, solders Turbine blades (aircraft engines) Additive, brass components ANALYTICAL CONSIDER- ATIONS AND TECHNIQUES As mentioned above, fine wear metal particles remain suspended in the oil. Additive elements are usually in solution. Under these circumstances the oil sample can be regarded as homogeneous and analyzed by solution techniques. Typical concentration levels for wear metals lie in the range from 1 to 500 parts per million, and some additive elements can be at several thousand ppm. For most elements, these concentrations are well within the scope of spectroscopic techniques such as Inductively Coupled Plasma Optical Emission Spectrometry (ICP-OES), Atomic Absorption Spectrometry (AAS) and Energy Dispersive X-ray Fluorescence (EDXRF). The requirement for speed and the need to measure many elements in each sample means that sequential techniques (including sequential ICP-OES) are usually considered too slow for high throughput applications, so when high sample throughput is required, the relatively high speed of simultaneous ICP-OES has made it the technique of choice in service laboratories, particularly as the sample preparation required is usually limited to a simple dilution with a solvent such as kerosene. ICP-OES spectrometers usually require a laboratory environment and some logistical support. Sometimes distance or the need for a rapid response - aviation or motor racing might be examples - requires more portable or rugged instrumentation. Even quite sophisticated EDXRF systems such as the SPECTRO XEPOS can be used in these situations, and small hand-held instruments such Page 2/9

3 Page 3/9 as the SPECTRO xsort are useful for screening measurements. However the relatively long measurement times usual in EDXRF mean that ICP-OES is still preferred in the routine laboratory when high sample throughput is required. Another approach is to use small optical emission spectrometers equipped with a rotating disc electrode (RDE), or Rotrode. Rotrode instruments are typically operated manually and do not offer the sensitivity or stability of ICP-OES systems. AAS was a popular oil analysis technique for many years but compares unfavorably with ICP-OES. When solid particles are present in the oil, the air/acetylene flames normally used may not be hot enough to dissociate them, and the pneumatic concentric nebulizers conventionally used can be prone to blocking. Indeed AAS may require time-consuming acid sample digestion to completely dissolve these particles prior to analysis. Also with AAS, hotter and potentially more hazardous nitrous oxide/acetylene flames are needed to determine refractory elements such as Si and Al, and its inability to determine S and P directly also makes ICP-OES the more attractive option. ICP-OES has a significantly wider linear dynamic range, which makes it better able to cope with wide concentration ranges and avoids multiple sample dilutions. The safety implications of flames, flammable solvents and pressurized flammable gases mean that unlike an ICP system, an AAS instrument should not be left to run unattended. There are several national and international standard methods that describe or recommend the use of ICP-OES for the analysis of fuels and lubricating oils by ICP-OES. These include: ASTM D4951 ASTM D5708 ASTM D5185 ASTM D7111 ASTM D7260 ASTM D7691 ASTM D5184 ASTM D7040 ASTM D7303 EN EN ICP-OES spectrometers from SPECTRO Analytical Instruments are widely used for oil analysis. The SPECTRO GENESIS Petrochem is an affordable, compact but high performance instrument that was specially developed for routine analysis and provides a perfect entrée to the ICP-OES technique. Weighing less than 150 Kg, the SPECTRO GENESIS Petrochem can be easily accommodated on a standard laboratory bench. ICP-OES - BASIC PRINCIPLES ICP-OES is a technique of Optical Emission Spectrometry (OES) that uses an Inductively Coupled Plasma as an emission source. Every element has a unique atomic structure, with a massive positively charged nucleus and a number of electrons surrounding it. Each of these electrons exists at a defined energy level and under normal conditions, with no external influences, this is known as the ground state. If, however, the atom is subjected to energy, perhaps in the form of heat e.g. in an electrical discharge, that energy can be absorbed and the electron(s) excited to a higher or excited state. This is an unstable condition, and the electrons quickly return to the ground state, at which point the energy is re-emitted. The energy changes involved in the transition between ground and excited states are different for each electron in every element, so the characteristics of the energy absorbed and emitted will also be different for each element. If enough energy is absorbed, an electron can be driven out of the atom completely, in which case the atom is said to be ionized. Fig 1: Excitation and Emission Because of the relationship between energy and wavelength (frequency), and since the energy emitted when the electrons returns to the ground state can be in the form of electromagnetic radiation, each transition is giving rise to radiation at a discrete and precisely defined wavelength, so each element generates a unique set of emission wavelengths. The intensity of this radiation is proportional to the number of atoms present (i.e. the concentration), which is the basis of quantitative analysis by Optical Emission Spectrometry. For practical analysis, the wavelengths usually employed lie in the ultra-violet and visible regions of the optical spectrum. Because of the large number of transitions possible in most elements, their emission profiles (spectra) can be very complex. Over 4000 different emission wavelengths (referred to by spectroscopists as emission lines) have been identified for iron alone. Multi-element spectra can be very complex indeed, and ionized atoms give rise to emission spectra of their own, to further complicate the issue.

4 For practical analysis with OES, several essential components have to be provided: An excitation generator (source) to provide the energy to excite the atoms in the test sample. In ICP-OES Spectrometry this is an Inductively Coupled Plasma A sampling system to introduce the sample into the plasma Optics to isolate the specific wavelengths for the elements to be measured A detector system to measure the intensity of the light emissions Electronics to acquire the detector signals and to control the functions of the spectrometer A computer with software for calculation and display of emission spectra and concentration values We can now consider these components in turn: The ICP Source In ICP-OES, the excitation source is an Inductively Coupled Plasma, electrically powered, into which the sample is introduced as an aerosol. In the plasma the sample is thermally atomized and the atoms are excited to emit elementspecific radiation as described above. When a gas is heated to a certain point, the thermal energy becomes high enough to ionize atoms in it, to form what is known as a plasma. The ions and free electrons in the plasma cause it to become electrically conducting and it is then possible to inductively couple radio frequency energy into the plasma to maintain it continuously. A typical configuration has the argon plasma supported in a quartz torch and powered through an induction coil. The ICP Torch A significant advantage of ICP-OES for oil analysis is that the very high temperatures reached in the analytical zone of the plasma ( K) can vaporize and atomize even solid metallic particles in the oil elements must be present as free atoms or ions to be excited and emit their characteristic radiation. The energy needed to maintain the plasma is provided by a radio frequency generator typically operating at 27 or 40 MHz. International regulations permit limited radiation at these frequencies whereas the use of other frequencies would require expensive shielding. The radio frequency generator must be extremely stable and able to sustain the plasma when its electrical properties change because of sample introduction. This is especially important with organic samples and solvents, as the presence of organics places a heavy load on the plasma. Indeed some ICP-OES systems suffer from instability when attempting to analyze organic samples and in extreme cases the plasma may even be extinguished. TCP/IP Interface TCP/IP CCD Readout Instrument Controller 27 MHz RF Generator PC with Instrument Software 17 Detector Arrays rating g/mm Entrance Slit SPI Gas Flow Side-On Plasma Interface (SPI) ng 3 g/mm 5 Detector Arrays Plasma Torch RF Load Coil 7 Detector Arrays Coolant Gas Flow K Array Li Array Na Array Grating g/mm Optical System (ARCOS) Auxiliary Gas Flow Nebulizer Gas Flow Spray Chamber Peristaltic Pump Sample Fig 2: Schematic Diagram of an OES Spectrometer Page 4/9 Fig 3: Schematic View of ICP Torch

5 A convenient way of reacting to changing sample load is for the RF generator to adjust the resonant frequency so that the effective plasma power remains constant. This is termed a free-running generator. The generator used in SPECTRO ICP- OES instruments is an air-cooled freerunning RF generator running at a nominal frequency of MHz with a power output range from 0.7 to 1.7 kw MHz is chosen in preference to MHz because the permitted bandwidth over which the frequency can be adjusted is wider at MHz, giving more range for adjustment and thus better control. Fig 4: Permitted RF Emission Bandwidths at MHz and MHz Sample Introduction Liquid sample introduction in ICP-OES is usually via a pumped nebulizer/ spray chamber system, with argon used as a carrier gas to transport the aerosol produced by the nebulizer into the plasma. The pumped nebulizer is capable of handling quite viscous solutions, suspensions or even slurries, which makes it very suitable for used oil analysis. Only a relatively small proportion of the total sample reaches the plasma: the larger sample droplets produced by the nebulizer tend to fall out of the gas stream and are lost. The same may happen to a proportion of the particulates in the original sample, which are relatively heavy and also tend to fall out of the gas stream. It is generally considered that while particles of 10 microns or smaller will reach the plasma, any larger probably will not. Nebulizer efficiency is another factor, as sample surface tension and viscosity also come into play. This means that there should be a degree of matrix matching between samples and any standards used. For oil analysis a single dilution of the sample with kerosene is normally sufficient to overcome viscosity effects. Furthermore, because of the wide dynamic range of ICP- OES, this one dilution will normally bring all the elemental concentrations within the range of a single multi-element measurement. AAS will often require several different dilutions to bring different elements within the linear measurement range. The design of the GENESIS sample introduction system provides a very short sample pathway to the plasma, so signals stabilize quickly and very short flush times are achieved between samples. The GENESIS can be integrated with an autosampler/ dilutor system under full computer control. With the combination of the inherent speed of the spectrometer and optimized sampling routines, high sample throughput rates are possible. Optics and Detectors for ICP-OES The optical system is the heart of the spectrometer, as this is where the individual emission lines are separated and selected for measurement. The ability of the optical system to discriminate between adjacent wavelengths is described as its resolving power or resolution. A reflecting diffraction grating is used to separate (disperse) the radiation from the ICP source. The diffraction grating is a device with multiple angled parallel grooves across its surface. These grooves are very narrow - typically 1800 to 3600 per millimeter for a UV-visible grating. Light passing through or reflected from such a surface (almost all gratings used in spectroscopy are reflection gratings) will undergo diffraction, where essentially each groove acts as an individual source of light, with a very small path difference between them. Under these conditions, there will be interference between light from adjacent grooves, and reinforcement (maxima) and cancellation (minima) will occur at certain angles to the grating depending on the wavelength. For an incident light beam normal to the grating surface, the wavelength maxima for each wavelength λ will occur at an angle θ according to the grating equation: n λ = d sinθ where d is the grating constant given by the groove spacing and n is an integer. This is for illumination normal to the surface; when the grating is illuminated at an incident angle θi, the equation becomes n λ = d (sinθ + sinθi) As every wavelength leaves the grating at a different angle the spectrum is now dispersed. For a given geometry it is straightforward to calculate at which angle a particular wavelength (i.e. emission line) will occur. There are many different designs of optical systems in spectroscopy. In most sequential instruments, the grating is rotated until the selected emission line falls on a single exit slit and through it onto a detector. This means that to cover many elements the spectrum has to be scanned. This can be very time consuming, as the instrument has to pause at each wavelength to take a measurement. A simultaneous spectrometer, like the SPECTRO GENESIS Petrochem, measures all the chosen wavelengths Page 5/9

6 Page 6/9 at once, giving much higher speed and productivity. The SPECTRO GENESIS Petrochem is a simultaneous spectrometer, but at a price comparable to many sequential systems. In the GENESIS optical system, a concave reflection grating is used that not only disperses the radiation but brings each wavelength to a focus on an arc defined by the physical geometry of the system and called the Rowland Circle. In traditional simultaneous ICP-OES instruments, derived from classical arc/ spark emission designs, emission lines were selected by slits positioned around the Rowland Circle, passing through them to fall on detectors (usually photomultiplier tubes or PMT s) placed behind the slits. This arrangement has several limitations when dealing with ICP spectra, not least because of the difficulty of placing slits and detectors sufficiently close to isolate closely adjacent lines. It is also time-consuming to set up. From the analyst s perspective it is inflexible, as the choice of analytical lines is limited to those installed by the manufacturer. More recent instruments like the SPECTRO GENESIS Petrochem use more flexible detectors called CCD s, or Charge Coupled Devices that completely overcome this problem. These semiconductor devices are constructed as arrays of very narrow strips, or pixels, each an independent detector that effectively acts as its own exit slit. Such arrays can be placed around the entire arc over which the spectrum falls, giving effectively continuous coverage of the spectrum and a virtually unlimited choice of spectral lines for analysis. The CCD arrays in the SPECTRO GENESIS Petrochem differ from those used in many other ICP-OES Fig 6: Linear CCD Array Detector Fig 5: ORCA Polychromator instruments in that they require no special sub-ambient cooling. In the SPECTRO GENESIS Petrochem, a series of 15 CCD detector arrays is used to give coverage of the spectrum from 175 to 770 nm. This proprietary design has been named ORCA, or Optimized Rowland Circle Arrangement. The high-speed readout system can read all 15 CCD detectors and calculate the complete emission spectrum in only three seconds. With its minimum number of optical components, the ORCA is very energy efficient, and this contributes to analytical sensitivity and detection limits. Argon Purged Optics The analytical lines for several important elements in used oil analysis, such as P, S and Sn, lie below 190 nm, where atmospheric oxygen absorbs UV radiation. To use these lines, most modern ICP spectrometers have an argon purge system (argon is transparent to UV radiation) to exclude oxygen from the optical path. In some instruments, the running cost of this facility can be a major proportion of the total running costs. The ORCA polychromator is designed and constructed to have a very low internal volume, which means that the amount of argon required to purge the optics and maintain an oxygen-free optical path is minimized only 0.5 l/min for normal operation and zero on standby. Compared to a competitive instrument, the SPECTRO GENESIS Petrochem used one tenth of the volume of purge gas overall, reducing the annual operating costs by 30%. SPECTRO Analytical Instruments has produced a cost calculator for ICP-OES that is available on the company s website at that allows easy cost comparison with any other instrument. Interference Effects There are several interference effects that could lead to incorrect results when analyzing oil samples. Most of them can be dealt with by judicious choice of instrument parameters, sample treatment or calibration technique. A full discussion is outside the scope of this White Paper, but the main ones are: Spectral Interferences. As mentioned above, the emission spectra from the plasma can be very complex. This means that in some situations the spectrometer could have difficulty discriminating between closely adjacent lines from different elements. This could introduce an error, particularly if the interfering element were present in high concentration and the analyte as a trace. While using very high resolution optics may improve the situation, this has implications for the size and cost of the instrument that may be hard to justify considering that spectral interferences are rarely encountered in used oil analysis - the elements that are usually present do not interfere in this

7 way. A much better solution if it does occur is to choose an analytical line that has no potentially interfering lines close to it. This may be difficult or impossible with pre-selected fixed wavelengths. Thus, this is where the CCD detector array used in the SPECTRO GENESIS Petrochem, with complete spectral coverage and total flexibility of line selection, has real advantages. Physical Sample Effects. Sample viscosities can vary widely, so the efficiency of nebulization could vary from sample to sample, or between synthetic standard and sample. While modern pumped nebulizers are less affected than older types, and diluting the sample also improves the situation, the internal standard technique can be used to overcome this problem. In this technique, an element not found in the sample is added to it in known and constant concentration. Any variations in the measurement due to sample introduction will be reflected in the values obtained for the internal standard, and can be used to correct the measurements. Other Matrix Effects. As mentioned above, the sample matrix can have a significant effect on the efficiency of excitation in the plasma. This is particularly pronounced with organic samples. The ability of an ICP-OES system to cope with variations in sample type and plasma loading is described as its robustness. An approach to quantifying robustness was developed by the French spectroscopist J.M. Mermet and relies on measuring the relative intensities of ionic and atomic emission lines. The relative abundances of atoms and ions in the plasma, and hence their emissions, is heavily influenced by the efficiency of energy transfer, excitation and other parameters such as residence time in the plasma. Thus the sensitivity of the instrument to changes in sample type will be indicated by changes in the ratio of the atom/ion emissions. A recognized way of measuring this is to use the atomic and ion lines of magnesium at nm and nm respectively. Table 2 shows the result of such an experiment using a SPECTRO ICP-OES system and shows its relative resilience to changes in solvent composition, comparing results in aqueous solution with those in iso-propanol solutions. Table 2: Robustness Test Solvent MgII:MgI ratio Normalized to Aqueous Aqueous % IPA % IPA One aspect of ICP-OES that has been the subject of much debate is the way the plasma is viewed, i.e. axially, from the end (EOP) or radially, from the side (SOP). It is generally accepted that with aqueous solutions EOP achieves better ultimate detection limits than SOP, perhaps by a factor of up to 4-6 depending on the element. With organic solvents such as kerosene, however, this advantage reduces dramatically, and at the same time interference effects are more pronounced. Axial observation views the plasma end-on, along the center channel, so that the entire emission zone is visible to the optical system. Because of the higher viewing volume, sensitivity is enhanced, but the optics can also see the cooler zones at the base of the plasma, where matrix effects are more evident. Since the plasma bottom is also visible, the amount of noise on the signal increases as well. If the plasma is viewed radially, on the other hand the optics only sees a selected region that is free from interferences and emits less background radiation and noise, hence better stability and precision. The linear dynamic range is also increased. The SPECTRO GENENESIS Petrochem is equipped with a radial interface, the clear choice for petrochemical applications. Fig 7: Radial Plasma Observation Page 7/9

8 DESIGNED FOR CONVENIENCE AND CONFIDENCE Page 8/9 As can be seen from the above, ICP- OES is a complex technique, with many potential variables to be taken into account for successful analysis. The basic concept of the SPECTRO GENESIS Petrochem, however, was to provide the analyst with a routine tool that would exploit the many advantages of ICP-OES but at the same time eliminate or minimize potential sources of error, ensure accurate results and make the introduction of the instrument into a busy laboratory as trouble-free and straightforward as possible. This objective has been realized in a number of ways: The SPECTRO GENESIS Petrochem can be supplied with pre-evaluated factory methods. In addition to Wear Metals in Oil and Additives in Oil, Diesel Fuel, Bio Diesel and Crude Oil, methods are available for other common industrial applications like Industrial Waste Water, Soil and Sewage Sludge. They are delivered ready for use with, sample preparation instructions and method documentation. If workload increases methods can be transferred from instrument to instrument or even from laboratory to laboratory. System stability is essential to ensure accurate results and avoid time consuming and expensive repeat measurements: SPECTRO s proprietary ical logic continuously and automatically monitors the state of the optical system. In the case of changes the measurement of just one ical sample corrects all spectrum variables. The sample introduction system and ICP torch are factory-aligned for optimum plasma observation. No user adjustments are needed. The SMART ANALYZER VISION software for the SPECTRO GENESIS Petrochem gives the user clear, structured and easy to understand control of all instrument functions, with 1-click routine operation. Software assistants are available for less frequently used operations. Used Oil Analysis with the SPECTRO GENESIS Petrochem The achievable limits of detection can give an indication of the performance of an analytical instrument. Many manufacturers give this data on aqueous solution samples, and as suggested above, these can be significantly different in an organic matrix. The GENESIS Limits of Detection (LODs) given below were obtained using organometallic standards, made up to constant volume with pure oil and then diluted as necessary with kerosene: Table 3: Limits of Detection λ [nm] LOD (3σ) [μg/kg] Ag Al B Ba Ca Ca Ca Cd Cd Cr Cu Fe Mg Mg Mn Mo Na Ni P Pb S Si Sn Ti V Zn While these LODs show that the SPECTRO GENESIS Petrochem has more than enough sensitivity to detect and measure the required elements in used oil, the accuracy and precision of the measurements is equally, if not more, important. Table 4 shows the certified and measured values obtained on a certified reference material, NIST Standard Reference Material 1084a Wear Metals in Lubricating Oil : Table 4: Analysis of NIST SRM 1084a Certified Conc. Measured Conc. Recovery [%] [mg/kg] [mg/kg] Al (104) Ag ± Cr 98.3 ± Cu 100 ± Fe 98.9 ± Mg 99.5 ± Mo ± Ni 99.7 ± Pb ± Sn 97.2 ± Ti ± V 95.9 ± S (1700) Si (103) Fig 8: The SPECTRO GENESIS

9 There is excellent agreement between certified and measured values. Results for some elements not in this certified standard, but encountered in oil additives were obtained on a commercially available standard material (Fluxana): Table 5: Analysis of FLX ASTM- P Certified- Conc. Measured Recovery [%] [mg/kg] Conc. [mg/kg] Ca P S Zn Another interesting application of ICP-OES in the oil laboratory is the analysis of biodiesel, in which different elements are important. The concentration of phosphorus is regulated to be below 10 mg/kg. Monitoring of Na, K, Ca and Mg is necessary due to their ability to form undesirable compounds in engines. European Norm EN 14214, the standard for FAME, the commonest form of biodiesel, states that the sum of Na and K and the sum of Ca and Mg are limited to 5 mg/kg. The LODs for these elements, determined in biodiesel with the SPECTRO GENESIS Petrochem, are well within these limits: Table 6: LODs in Biodiesel Line [nm] LOD in biodiesel [μg/kg] Na Na K Mg Mg Ca P P These results show that the SPECTRO GENESIS Petrochem has more than enough performance headroom for routine oil analysis for condition monitoring. For research, or for those needing to measure elements such as the halogens, an even more powerful system could be needed. Such an instrument is the SPECTRO ARCOS, probably the most advanced ICP- OES system currently available. The ARCOS has a very high resolution optical system with a wavelength range extended into the deep ultraviolet region, down to 130 nm where the analytical lines for the halogens are found. This top-of-therange instrument, however, builds on the same proven design principles used in the SPECTRO GENESIS Petrochem, with a powerful 27 Mz generator, CCD detection, low argon consumption and the ical instrument monitoring system. CONCLUSIONS ICP-OES has many advantages for the analysis of used oils and other petroleum products. Direct measurement of oil samples is possible with a simple kerosene dilution, avoiding the complex and time-consuming digestions and multiple dilutions needed with some other techniques. The SPECTRO GENESIS Petrochem concept is optimized to eliminate many of the variables and uncertainties associated with using a new technique or instrument for the first time, and includes factory method packages and SPECTRO s ical facility that continuously monitors system performance. The SPECTRO GENESIS Petrochem is simple to commission and operate, and is a cost-effective tool for elemental analysis in any oil service laboratory. GERMANY SPECTRO Analytical Instruments GmbH Boschstrasse 10, D Kleve Tel: Fax: spectro.sales@ametek.com U.S.A. SPECTRO Analytical Instruments Inc. 91 McKee Drive Mahwah, NJ Tel: Fax: spectro-usa.sales@ametek.com Hong Kong (Asia-Pacific) SPECTRO Analytical Instruments (Asia-Pacific) Ltd. Unit 1603, 16/F., Tower III Enterprise Sq. No. 9 Sheung Yuet Road Kowloon Bay, Kowloon Tel: Fax: spectro-ap.sales@ametek.com Subsidiaries: u CHINA: Tel , Fax , spectro-china.info@ametek.com, u FRANCE: Tel , Fax , spectro-france.sales@ametek.com, u GREAT BRITAIN: Tel , Fax , spectro-uk.sales@ametek.com, u INDIA: Tel , Fax , sales.spectroindia@ametek.com, u ITALY: Tel , Fax , spectro-italy.sales@ametek.com, ujapan: Tel , Fax , spectro-japan.info@ametek.co.jp, u SOUTH AFRICA: Tel , Fax , spectro-za.sales@ametek.com, u SWEDEN: Tel , Fax , spectro-nordic.info@ametek.com. uspectro operates worldwide and is present in more than 50 countries. For SPECTRO near you please visit AMETEK Inc.,all rights reserved, subject to technical modifications A-14 Rev. 1 Photos: SPECTRO and thinkstock Registered trademarks of SPECTRO Analytical Instruments GmbH : USA (3,645,267); EU ( ); SPECTRO : EU ( ); ical: USA (3,189,726), EU ( ); SPECTRO GENESIS : USA (3,170,644), EU: ( ). Page 9/9