Astm stp 1468 2005

STP 1468 Elemental Analysis of Fuels and Lubricants: Recent Advances and Future Prospects R A Kishore Nadkarni, editor ASTM Stock Number: STP 1468 ASTM International 100 Barr Harbor Drive PO Box C700 West Conshohocken, PA 19428-2959 INTERNATIONAL Printed in the U.S.A Library of Congress Cataloging-in-Publication Data Elemental analysis of fuels and lubricants: recent advances and future prospects/R.A Kishore Nadkarni, editor p c m ~ S T P ; 1468) Includes bibliographical references and index ISBN 0-8031-3494-0 (alk paper) Fuel Analysis Lubrication and lubricants Analysis I Nadkami, R.A II Series: ASTM special technical publication; 1468 TP321.E46 2005 665.5'38 -dc22 2005022779 Copyright 2005 ASTM International, West Conshohocken, PA All rights reserved This material may not be reproduced or copied, in whole or in part, in any printed, mechanical, electronic, film, or other distribution and storage media, without the written consent of the publisher Photocopy Rights Authorization to photocopy items for internal, personal, or educational classroom use, or the internal, personal, or educational classroom use of specific clients, is granted by ASTM International provided that the appropriate fee is paid to the Copyright Clearance Center, 222 Rosewood Drive, Danvers, MA 01923; Tel: 978-750-8400; online: http://www.copyright.com/ Peer Review Policy Each paper published in this volume was evaluated by two peer reviewers and at least one editor The authors addressed all of the reviewers' comments to the satisfaction of both the technical editor(s) and the ASTM Committee on Publications To make technical information available as quickly as possible, the peer-reviewed papers in this publication were prepared camera-ready as submitted by the authors The quality of the papers in this publication reflects not only the obvious efforts of the authors and the technical editor(s), but also the work of the peer reviewers In keeping with long-standing publication practices, ASTM maintains the anonymity of the peer reviewers The ASTM Committee on Publications acknowledges with appreciation their dedication and contribution of time and effort on behalf of ASTM Printed in Baltimore,MD September2005 Foreword This publication, Elemental Analysis of Fuels and Lubricants: Recent Advances and Future Prospects, contains selected papers presented at the symposium of the same name held in Tampa, Florida, on 6-8 December 2004 The symposium was sponsored by Committee D02 on Petroleum Products and Lubricants The symposium chairman and editor was R A Kishore Nadkarni Contents Overview vii Zen and the Art (or is it Science) of a Perfect Analysis R A K NADKARNI i A T O M I C EMISSION SPECTROSCOPY Analysis of Gasoline and Diesel Fuel Samples by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES), Using Pneumatic Nebulizer and Standard Spray Chamber -c c ONYESO 17 Elemental Analysis of Lubricating Grease by Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-AES) B s FOX 24 The Use of Microwave Digestion and ICP to Determine Elements in Petroleum Samples J D HWANG,M HORTON,AND D LEONG 33 Advances in ICP-MS Technologies for Characterization and Ultra-Trace Speciation as a Tool for the Petroleum Industry J PASZEK,K J MASON, A, S MENNITO, AND F C MCELROY 42 Direct Trace and Ultra-Trace Metals Determination in Crude Oil and Fractions by Inductively Coupled Plasma Mass Spectrometry-S DREYFUS C PECHEYRAN, C MAONIER, A PRINZHOFER C P LIENEMANN AND O F X DONARD 51 Fuel Analysis by Filter Furnace Electrothermal Atomic Absorption Spectrometry P TII~rARELLL M PRIOLA S RICCHIUTO, D A KATSKOV, AND 59 P NGOBENI Rotrode Filter Spectroscopy: A Recently Improved Method to Detect and Analyze Large Wear and Contaminant Particles in Fluids M LUKAS R J YURKO AND D P ANDERSON 71 S U L F U R D E T E R M I N A T I O N AND X - R A Y FLUORESCENCE Trace Levels of Sulfur in the Fuels of the Future: Analytical Perspective-R A K NADKARNI 85 vi CONTENTS Analysis of Fuels, Lubricants, and Greases Using X-Ray Fluorescence Spectrometry J WOLSKA, B VREBOS, AND P BROUWER 98 Determination of Sulfur Content in Crude Oil Using On-Line X-Ray Transmission Technology s FESS 108 Low-Level Sulfur in Fuel Determination Using Monochromatic W D X R F ASTM D 7039-04 z w CHEN, F WEI, I RADLEY,AND B BEUMER 116 Latest Improvements on Using Polarized X-Ray Excitation EDXRF for the Analysis of Low Sulfur Content in Automotive Fuel D WISSMANN 128 Rapid Determination of Sulfur in Liquid Hydrocarbons for At-Line Process Applications Using Combustion/Oxidation and UV-Fluorescence Detection s TARKANICAND J CRNKO 137 Pyro-Electrochemicai On-Line Ultra Low Sulfur Analyzer J R RHODES 152 DP-SCD and LTMGC for Determination of Low Sulfur Levels in Hydrocarbons R L GRAS,J C LUONG R V MUSTACICH,AND R L SHEARER 164 MERCURY DETERMINATION Sampling and Analysis of Mercury in Crude Oil s M WILHELM D A KIRCHGESSNER L LIANG, AND P H KARiHER 181 Determination of Total Mercury in Crude Oil by Combustion Cold Vapor Atomic Absorption Spectrometry (CVAAS) B s Fox K J MASON.AND 196 F C MCELROY Mercury Measurements in Fossil Fuels, Particularly Petrochemicals-P B STOCKWELL, W T CORNS, AND D W BRYCE 207 OTHER HETEROATOMS Recent Advances in Gas Chromatographic/Atomic Emission Hetero-Atom Selective Detection for Characterization of Petroleum Streams and eroducts F, p DISANZO AND J W DIEHL 221 Improvements in the Determination of Fluorine in Fuel and Lubricants by Oxidative Combustion and Ion-Selective Electrode Detection L J NASH 232 Phosphorus Additive Chemistry and its Effects on the Phosphorus Volatility of Engine Oils T w SELBY, R J BOSCH AND D C FEE 239 Analysis of the Volatiles Generated During the Selby-Noack Test by 31p NMR Spectroscopy R J BOSCH, D C FEE, AND T W SELBY 255 Index 275 Overview In spite of being a mature science, elemental analysis continues to play a vital role in product manufacturing and quality characterization in many sectors of all industries Research divisions in both industry and academia continue devising new ways of lowering the elemental detection limits so that even the minutest amounts of elements in products could be determined in as accurate and precise a fashion as possible The ASTM International D02 Committee on Petroleum Products and Lubricants through its Subcommittee on Elemental Analysis has played a large and crucial role in the last several decades in standardizing numerous elemental analysis methods used in the oil industry Currently there are about 75 standard test methods under the jurisdiction of SC 3, and additionally at least more are under active development and moving towards standard designations I have no doubt that this activity will continue in the future These standards comprise virtually all known modem techniques for elemental analysis of petroleum products and lubricants The first ASTM D02 symposium on this subject was held in New Orleans in December 1989 at which 20 papers were presented Of these, 13 were published as a book, Modern Instrumental Methods of Elemental Analysis of Petroleum Products and Lubricants, ASTM STP 1109 The current and second "quindecennial" (i.e., every 15 years) was held in Tampa, Florida in December 2004 This was attended by over 120 people Thirty papers were presented on diverse subjects from 64 authors from nine different countries: Brazil, France, Germany, Italy, the Netherlands, South Africa, Switzerland, U.K., and U.S Of these, 12 papers were from the oil industry, 15 from the instrument manufacturers, l0 from national research organizations, and from the universities The objective of this symposium and this book is to acquaint the readers with the latest advances in the field of elemental analysis and to focus on what avenues of future research to explore in this area The subjects included are various elemental analysis techniques such as atomic absorption spectrometry, inductively coupled plasma emission and mass spectrometry, isotope dilution mass spectrometry, X-ray fluorescence, ion chromatography, gas chromatography-atomic emission detection, other hyphenated techniques, hetero-atom microanalysis, sample preparation, reference materials, and other subjects related to matrices such as petroleum products, lubricating oils and additives, crude oils, used oils, catalysts, etc Of the 30 papers presented at the symposium, 23 papers were published in the Journal of ASTM International (JAI), and are included in this ASTM publication As far as possible, the papers have been arranged by analytical techniques used, although in some cases there is some overlap: ICP-AES, XRF, sulfur, mercury, other hetero-atoms The first article is from the plenary lecture given at the symposium by the symposium chairman Kishore Nadkarni It covers total quality management practices advocated for obtaining a "perfect" analysis Proper staff training, sampling, calibration and quality control practices, adherence to test method details, participation in proficiency testing, accreditation from national bodies, benchmarking, etc., are some of the critically important approaches that need to be taken to achieve the ideal state of analytical Zen perfection Atomic Spectroscopy Among the seven atomic spectroscopy papers in this book, five concern various aspects of ICP-AES, a technique widely used for the determination of metals in petroleum products vii viii ELEMENTALANALYSIS OF FUELS AND LUBRICANTS and lubricants Onyeso (Ethyl Corporation) presents an ICPAES method for the determination of additive elements and wear metals, principally manganese, in gasoline and diesel fuels, with simple dissolution in kerosene and using yttrium internal standard Accessories such as direct injection nebulizer, ultrasonic nebulizer, chilled spray chamber, etc., were not necessary for this analysis Fox (ExxonMobil Research and Engineering) presents an ICPAES method for the determination of additive elements and wear metals in lubricating greases Since such samples cannot be directly nebulized in the ICP plasma, alternate sample dissolution techniques were employed: dry sulfated ashing, microwave assisted dry ashing, microwave assisted acid digestion with both open and closed vessels This method is being developed into an ASTM standard test method and is expected to be published by YE05 Hwang and Leong (ChevronTexaco) also discuss the use of microwave acid digestion for sample preparation before ICPAES measurements Elemental speciation using mass spectrometry in conjunction with ICPAES is a latest advance in atomic spectroscopy, which is becoming popular in analytical research labs Mason et al (ExxonMobil Research and Engineering) show how linking ICP-MS to various liquid chromatographic techniques has enabled determination of ppm levels of metals in hydrocarbons to ppb level measurements in refinery effluent streams Hyphenated ICP-MS techniques were used to provide speciation information on nickel and vanadium in crude oils and assist in development of bioremediation options for selenium removal in wastewater treatment plants Similar ICP-MS technique without sample demineralization was used by Lienemann, et al (lnstitut Francais du Petrole) to determine the trace and ultra-trace amounts of metals in crude oils and fractions Lukas et al (Spectro Inc.) describe an improvement made in rotating disc electrode atomic emission technology by incorporating a filter device in the rotrode, which enables to detect particles greater than 10 i~m size Tittarelli et al (SSC, Milan) employed a transverse heated filter atomizer with atomic absorption spectrometry to determine a number of trace elements in automotive and jet fuels Sub-ppm detection limits were obtained The use of filter furnace reduces the risk of elemental loss during drying and pyrolysis steps, and decreases the interferences due to molecular absorption and light scattering X-Ray Spectroscopy Similar to atomic emission spectroscopy, equally widely used technique for elemental analysis in the oil industry is X-ray fluorescence (XRF) There are four papers in this book using this technique, three of which deal with the determination of sulfur in gasoline and diesel Wolska et al (Panalytical BV) compared performance of three XRF technologies: high power and low power WDXRFs and a bench top EDXRE There are large differences in the sensitivities and hence varying lower limits of detection or qualification and sample throughput, for these technologies Sulfur Analysis One of the most important analyses done today on petroleum products, particularly gasoline, reformulated gasoline, and diesel, is for low levels of sulfur Government regulations on sulfur emissions from automobiles and other combustion sources have steadily increased; hence, the increasing interest in devising precise and accurate methods for trace and ultra- OVERVIEW ix trace amounts of sulfur in fuels of the future as evident from seven papers on this subject published in this book Nadkarni (Symposium Chairman) reviewed the alternate methods available for sulfur determination in fuels Out of about 20 ASTM standard test methods available, only about five (D 2622 WDXRF, D 3120 microcoulometry, D 5453 UV-fluorescence, D 6920 pyroelectrochemical, D 7039 MWDXRF) are appropriate for ultratrace amounts of sulfur in gasoline or diesel However, in their actual industrial use only D 2622 and D 5453 predominate Chen et al (XOS Inc.) describe a newly developed technology instrument based on monochromatic WDXRF for low sulfur analysis of fuels The instrument has a significant advantage over existing WDXRF instruments in terms of increased sensitivity and improved signal to noise ratio This technique has been recently given the ASTM designation D 7039 Another new instrument recently developed for sulfur by XRF determination is described by Wissmann (Spectro, Inc.) This method uses polarized EDXRF, considerably reducing background scatter, and achieving detection limit comparable to that of WDXRF Recent developments in detector technology and in closed coupled static geometry have resulted in further improvement of sensitivity for this application This method is also in the developmental stage for ASTM method designation Shearer et al (Ionic Instruments and Dow Chemicals) describe a novel technique developed tbr low levels of sulfur in hydrocarbon matrices using a low thermal mass temperature programmable and dual plasma chemiluminiscence detector The method with appropriate modification can measure individual sulfur species similar to ASTM method D 5623 On-line Sulfur Analysis Increasingly refineries, plants, and pipeline operators are focusing on obtaining quick turnaround for sulfur analysis rather than wait ['or time-delayed laboratory analysis A large number of such installations are being operated in the industry around the world Three papers in this book discuss applications of such on-line technology for sulfur determination in fuels In an on-line application of X-ray transmission technology, Fess (Spectro, Inc.) describes the basis of this technology and its application to classification and blending of crude oils that contain between 0.1 and 3.3 m % sulfur Commercial instruments based on this technology are being used in the field In a second on-line application paper, Tarkanic and Crnko (Antek/PAC) describe an online instrument based on ASTM Test Method D 5453, UV-Fluorescence Detection The latter is a widely used method in the oil industry for low and ultra-low levels of sulfur The online instrument appears to be very stable and fast (< per analysis) over extensive periods of field operations In a third on-line application paper tbr sulfur analysis, Rhodes (Rhodes Consulting), ASTM Test Method D 6920 is applied for on-line application This method uses pyro-combustion followed by electrochemical detection Mercury Determination Although adverse effects of mercury emissions on environment and humans has been known lbr decades, in recent years there has been concern regarding the mercury content of crude oils, and its emission through petroleum refining process There are three articles in this book discussing this issue Wilhelm et al (Mercury Technology Services/EPA et al.) provide a review of the presence of mercury in various parts of the world, its speciation, and alternate methods of determining X ELEMENTALANALYSIS OF FUELS AND LUBRICANTS low ppm and sub-ppm levels Fox et al (ExxonMobil Research and Engineering) describe a method for the determination of ppb levels of mercury in crude oils and distillation cuts using combustion cold vapor atomic absorption spectrometry technique Stockwell et al (PS Analytical Ltd.) describe the technique of atomic fluorescence spectrometry for the determination of mercury both before and after mercury removal from petrochemicals The technique has been used for on-line measurements in installations operating around the clock for at least years Other Heteroatoms DiSanzo and Diehl (ExxonMobil Research and Engineering) used GC-AED for the determination of elements such as carbon, nitrogen, sulfur, oxygen, and phosphorus in fuels and petroleum fractions A simplified version of comprehensive GC x GC is coupled with atomic emission detector to reduce the hydrocarbon matrix interference using simple and rugged modulation along with rugged wide bore capillary columns The technique together with other spectroscopic techniques such as GC-MS can provide information on many selected elements and compounds that may be present in fuels as additives or contaminants In a pair of papers, Selby et al (Savant, hzc and Astaris LLC) describe using phosphorus as an indicator of volatility of engine oils Phosphorus is volatilized during Noack volatility test (ASTM D 5800) The volatile material is trapped and analyzed for total phosphorus using ICP-AES, and for phosphorus species using 3~p NMR spectroscopy An oxidative combustion followed by ion selective electrode detection method is proposed by Nash (Antek/PAC) for the determination of fluorine in fuels and lubricants An ASTM method based on this technique is in development stage Unpublished Symposium Papers Some papers were presented at the Symposium; however, they were not submitted for publication by the authors Nevertheless, they represent interesting approaches to some specific elemental analysis issues in the petrochemical industry It would be useful if the authors eventually publish these articles for the benefit of others in the industry These presentations include the following: I Kelly et al (NIST) describe an isotope dilution thermal ionization mass spectrometry method for the determination of sulfur in fossil fuels The method is being used in NIST for certification of a number of liquid fuels at low sulfur concentration levels Kelly et al (NIST) also describe a "designer" calibration standard method for sulfur determination in fossil fuels for users to prepare NIST traceable working standards with known concentrations and uncertainties Manahan and Chassaniol ( Cosa Instruments and Dionex) describe an oxidative combustion followed by ion chromatographic conductometric method for the determination of a number of nonmetallic elements such as sulfur and halogens in liquid and gaseous hydrocarbons A standard based on this technique is under development in ASTM for designation as a standard method Long et al (NIST) describe another method for mercury determination in crude oils using isotope dilution-cold vapor-inductively coupled plasma-mass spectrometry technique The method has very high sensitivity, very low blank and high accuracy The technique is being used to determine mercury in a large number of crude oil samples from Department of Energy strategic petroleum reserve in the mercury concentration range of 0.02-10 ng/g 262 ELEMENTAL ANALYSIS OF FUELS AND LUBRICANTS Sample750, 10 and ISO mln -I/'~ SO Volatiles lat,~ I SO mill Residue ~W,.~] r ] i ~,-L,, 1,,~ , , A.L, L Ld.,.,la ,, i[i xalR I I , ,1 ~,.r, e ill iii :, ,; g, ,', ; ;i, ' p,' t0 rain Volatlles [[ ,L ~ j ~]L&,.I t ;;": ?V ??L"~" "; 'Y ?.~ "? T[.tlZ"Y77.' 7.77": "T',Z"." : Y;" Y .';", ~ 77 ~ 7: T ~ "?TE" ~"l', Y,~ ' "~' .'~ ,'7: ' ': '! Y' 7!'~"Y~, 10mln.Res due t - r , FIG -R0-780, t = 10 volatiles and residue and t = 50 volatiles and residue TABLE Summary of 31 P NMR results for R0-780, 10 and 50 runs Sample: RO-780 oil Selby - Noaek PEI, Chemical shifts (ppm) Volatility mg/L Original oil (from Table 5) 100 (broad), 93.8, 84.3, 83.7, 83.6, 83.5, 82.8, 74.6, 67.9 Volatiles, T=10 4.03 % 103.0, 102.4, 94.4, 94.0, 93.8, 93.3, 88.9, 83.2, 67.6, 54.1 Residue, T=10 54.1, (broad) 13.62 % 95.1, 94.6, 93.9, 83.0, 54.1 Volatiles, T=50 rain Residue, T=50 (broad) Fourth Study Effects of ZDDP Chemistry and Formation Four Z D D P samples were prepared in the Astaris labs The alcohols employed were 2Ethylhexanol, a primary alcohol, and 4-Methyl-2-pentanol, a secondary alcohol Two P2S5 samples were employed, one with a phosphorus content o f 27.77 % (Low Phos P2S5) and the second with a phosphorus contend o f 28.07 % (High Phos PzSs) These four Z D D P s were blended into a typical GF-3 oil at Savant using a non-ZDDP-containing version o f RO 780 provided b y Chevron Oronite C o m p a n y LLC ZDDP ZDDP ZDDP ZDDP A B C D 2-Ethylhexanol 2-Ethylhexanol 4-Methyl-2-pentanol 4-Methyl-2-pentanol Low Phos P2S5 High Phos P2S5 Low Phos P2S5 High Phos P2S5 These samples were subjected to a series o f Selby-Noack tests in which the runs were terminated at 10, 20, 30, and 50 m i n progressively The resulting volatiles and residues, along with the starting oil samples, were subjected to 3~p N M R analyses BOSCH ET AL ON PNMR SPECTROSCOPY 263 Figures 10-14 contain the most relevant 31p NMR spectra; however, Tables 9-12 contain summaries of the results of all of the NMR spectra The 31p NMR spectra for the experiments involving the two 2-Ethylhexyl ZDDPs were integrated, which are summarized in Tables 13 and 14 Original OII FIG 10 -ZDDP A, Original Oil and t = 10 volatiles and residue ! Sample ZDDP A 50 mln Volatltes l , FIG 11 ~ u Is -1 -t, p, ZDDP A, Original Oil, and t = 50 volatiles and residue 264 ELEMENTAL ANALYSIS OF FUELS AND LUBRICANTS T A B L E Summary Of 31 P NMR results for Sample: ZDDP A Selby - Noack Volatility Oil Volatiles, T=10 3.31% Volatiles, T=20 rain 7.09 % Volatiles, T=30 8.43 % Volatiles, T=50 11.82 % Residue, T=10 Residue, T=20 Residue, T=30 n'fin Residue, T=50 rain Sample ZDDP B ZDDP A (2-Ethylhexanol + Low Phos P2S5) PEI, mg/L 13 14 19 - Chemical shifts (ppm) 104, 98.1, 69.5, 65 104, 96.7, 84.4, 69.0, 29.6 103.3, 97.2, 84.2, 69.5, 29.9 103.2, 97.2, 69.6, 30.0 103.5, 97.2, 69.6, 30.0 97.3, 69.6, 29.7, 97.2, 69.6, 29.7, 97.3, 69.7, 29.7, 97.3, 69.7, 65, I t ,, , " " i 50 MIn Residue ~ a 7* le , Wl ,J * ~ ' ~ ' Zl ~X , - i* " " - ~l Pm ' FIG 12 ZDDP t?, Original Oil, and t = 50 volatiles and residue T ABLE lO Summary of 31P NMR results for ZDDP B (2-Ethylhexanol + High Phos P2S5) Sample: ZDDP - B Selby - Noack PEI, Chemical shifts (ppm) Volatility mg/L Oil 104.1, 103.5, 98.5, 69.7, 65 Volatiles, T=10 rain 3.59 % 103.9, 96.8, 84.3, 69, 29.6 Volatiles, T=20 rain 5.97 % 10 103.3, 97.2, 84.2, 70, 29.9 Volatiles, T=30 8.55 % 13 103.5, 97.1, 69.4, 29.8 Volatiles, T=50 rain 13.72 % 18 103, 97.3, 69.6, 30.0 Residue, T=10 rain 97.2, 69.6, 65.3, 29.6, Residue, T 20 97.3, 69.7, 65.2, 29.7, Residue, "1" 30rain 97.2, 69.6, 65.3, I Residue, "I" 50min 97.3, 69.7, 65.4, BOSCH ET AL ON PNMR SPECTROSCOPY 265 SampleZDDPC mln.VolMlkll 20 ' ' " " " ~ '' F~'I rl''' 'r] ~- p ", ~ " , ' " r r - ' ,']l' ,, i,p,~ H I ' , - -1[~1 I, , r I ~ I' 1' '~"1,' FIG 13 ZDDP C Original Oil and t = 20 volatiles and t = 10 residue TABLE, X Summary of3'P NMR results for ZDDP C (4-Methyl-2-1aentanol+Low Phos PeSs) Sample: ZDDP-C Selby - Noack PEI, Chemical shitts (ppm) Volatility m~/L 99.2, 93.1, 77.3 Oil Volatiles, T=10 rain 4.28 % 103, 97, 94.1, 89.1, 83.2, 66.4 Volatiles, T=20 rain 6.23 % 102.7, 101.6, 95.0, 94.5, 94.2, 93.5, 90.2, 89.2, 89.1, 88.1, 85.3, 83.1, 66.6, 26.5 Volatiles, T=30 rnin 9.80 % 102.5, 101.5, 94.3, 93.5, 89.3, 88.1, 83.1, 66.7, Volatiles, T=50 rain 15.29% 102.3, 101.2, 95.3, 94.7, 94.4, 93.7, 93.5, 83.1, 66.8, 26.8 Residue, T=10 rain (broad) Residue, T=20 rain (broad) Residue, T=30 rain (broad) Residue, T=50 rain Ibroad) SIl~pleZDDPD / ,ir.l~-ir Hi ~ "r ['" i,i- ~ 1~- U,, ,.[r,T i 1.~.,rni ,p~ ,], ~ ,n ,n , l~li?vl'" T Orlgln~O~OII FIG 14 -ZDDP D - Original Oil and t = 10 volatiles and residue 266 ELEMENTALANALYSIS OF FUELS AND LUBRICANTS T A B L E 12 Summary of31P NMR results for ZDDP D(4-Methyl-2-pentanol+High phos PeSs) Sample: ZDDP D Selby - Noack PEI, Chemical shiRs (ppm) Volatility mg/L 100.4, 93.1, 77.3, 5.5 Oil Volafiles, T=10 rain 3.98 % 102.9, 101.9, 94.2, 93.9, 83.2, 66, 26,5, 5.9, 5.5 Volatiles, T=20 rain 5.83 % 102.4, 101.3, 83.1, 67.5, 66.7, 26.6, 5.9, 5.4, 4.8 Volatiles, T=30 rain 8.65 % 102.6, 94.5, 83.1, 67.8, 66.7, 5.5, 4.8, Volatiles, T=50 13.99% 102.2, 95.4, 94.5, 83.1, 66.8, 5.9, 5.4, 4.8 Residue, T=10 rnin (broad) Residue, "1" 20rain (broad) Residue, T=30 rain (broad) (broad) Residue, T=50 rain ,7 TABLE - - I n t e g r a l s of the 31p NMR results for ZDDP A (2-Ethylhexanol + Low Phos PeSs) (Reported as relative mole %.) 104pprn 97ppm ZDDPA Sample V, t=10 V, t=20 V, t=30 V, t=50 R, t=10 R, t=20 R, t=30 R, t=50 5 84pprn 69ppm 30ppm 2ppm 28 30 27 28 5 5 1 55 69 67 69 54 57 64 70 38 26 28 25 trace T A B L E 14 -Integrals of the 3Jp NMR results for ZDDP B (2-Ethylhexanol + High Phos P2S5) (Reported as relative mole %.) zDDPB Sample V, t=10 V, t=20 V, t=30 V, t=50 R, t=10 R, t=20 R, t=30 R, t=50 104ppm 97ppm 53 62 67 67 32 24 23 19 84ppm 69ppm 26 28 25 27 4 65ppm 2 30pprn 5 2ppm 59 69 71 73 Discussion General From the foregoing studies engine oils decompose during species, some portion o f which ZDDPs also break down under in an engine it is evident that the ZDDPs in all the engine oils and simulated the Selby-Noack test and are converted to different phosphate are volatile Similarly, it has been shown in other studies [2] that analogous conditions o f temperature, time, and oxygen exposure BOSCH ET AL ON PNMR SPECTROSCOPY 267 First Study The NMR analyses shown in Figs 1-5 and Tables 1-5 indicated that the various samples of volatiles from these Selby-Noack volatilization tests contain multiple phosphorus species and that most of these species are different from those present in the original motor oil Perhaps more interesting, the first study gave clear evidence that different formulations of engine oils with different values of PEI gave considerably different phosphorus breakdown products The residue oil left in the heated cup after completion of the Selby-Noack volatility test also contains totally different phosphorus species than those in the original motor oil More specifically, all of the residue samples were observed to consist of a broad peak centered at 0-4 ppm, which is indicative of inorganic and/or simpler organophosphate compounds than ZDDP In these typical GF-3 oils, a PEI of corresponds to approximately % of the phosphorus volatilizing from the engine oil sample In three of the five motor oils tested, the ZDDPs completely decomposed under test conditions In samples 7450 and 7538, small amounts of ZDDP remained in the residual oil at the end of the test Second Study In the experiments on RO-780 (typical GF-3 oil) in which the effect of extending the time of the heat up ramp from to 60 was examined, it was found that although the PEI increased when the time to operating temperature was considerably extended, the NMR spectra did not change significantly That is, the same species were volatilized from the oil This is illustrated Fig and summarized in Table Third Study The experiments performed on samples EO-7450 and RO-780 (see Figs 7-gand Tables and 8) were, as noted, run to determine what and when different volatile phosphorus species were generated The tests were run in 10-, 20-, 30-, 50-, and 60-rain (from the first and second studies) exposure times to the Selby-Noack operating condition From these samples the NMR analyses of the residue and volatile samples collected from the samples at 10 and 50 were compared Unexpectedly, in the RO-780, the decomposition of the motor oil was essentially complete after 10 In addition, it was noted that the PEI of the 50-min sample was lower than that of the 10-min sample Although this might be associated with repeatability of the PEI at low values, it may also indicate that some of the phosphorus-containing species in the collected volatiles could be lost because of even further volatilization from the collection vessel during the SelbyNoaek test This requires further investigation The NMR spectra of the volatiles obtained in these two runs were compared with Figs 5, 6, and Qualitatively, the respective spectra were found to be very similar, which illustrates the repeatability of the volatilization and collection technique as an analytical method As observed before, in sample 7450, the decomposition of the phosphorus containing species is not complete after 50 rain It is very interesting to note that both the 10-rain and 50-rain residue spectra are significantly different from that of the original oil sample It appears that this oil first decomposes to an intermediate state, which then undergoes further reaction to generate additional phosphorus volatile species It is also noted that the NMR spectra obtained on the 10and 50-mi volatile samples qualitatively consisted of the same peaks However, the proportionate size of the peaks varied between the two samples 268 ELEMENTALANALYSIS OF FUELS AND LUBRICANTS Fourth Study -ZDDP Composition Effects Evolution of volatile components was found to depend strongly on the alcohol used in ZDDP manufacture, as illustrated in Figs 10-14 and Tables 9-12 ZDDPs C and D made from the secondary alcohols, 4-methyl-2-pentanol, appear to break down readily under the conditions of the Selby-Noack test Within the first 10 min, whatever volatile species were formed were given off, and the only phosphorus-containing species in the residual oil were fully oxidized phosphates Interestingly, the PEI values were comparatively low and constant In contrast, ZDDPs A and B made from the primary alcohols, 2-ethylhexanol, have a longer life Volatile phosphorus-containing species were given off for up to 60 Concomitantly, the residual oil contained some of the original ZDDPs, but consisted primarily of other phosphoruscontaining components in addition to fully oxidized phosphates However, in contrast to aforementioned results with the primary alcohol, the PEI values increased with time and became comparatively high These differences in rate and degree of breakdown between ZDDPs made with primary and secondary alcohols reflect other findings in the literature [2] Fourth Study Stoichiometric Effects Results with ZDDPs A, B, C, and D -In the limited testing described in this paper, the phosphorus/sulfur molar ratio of the PzS5 does not appear to have a very significant effect on the composition of the volatile species generated from the ZDDP made from 2-ethylhexanol Similar results were obtained from ZDDP made from both High and Low Phos P2S5 However the PEI values obtained on the ZDDPs manufactured form High and Low Phos PzS5 and 4-methyl-2pentanol differed significantly Close examination indicates that some of the unique impurities in ZDDP D are most likely volatilizing and thereby increasing the PEI value of this oil These impurities are observed in both the original oil and the volatiles at 3-8 and from 65-70 ppm Unpublished studies at Astaris have found that typical yields of dithioacids (the ZDDP precursor prepared from the reaction of P2S5 and alcohol) are generally between 85 and 95 % These reactions are typically run with an excess of alcohol to drive the reaction to completion The phosphoms/sulfiar molar ratio in the P2S5 has been found to affect the trace components generated during the reaction of PzS5 and alcohols Use of P2S5 o f a slightly lower-thanstoichiometric phosphorus level generates some impurities that are rich in sulfur, while some of the impurities generated in reactions performed with PzSs at a slightly higher-than-stoichiometric level of phosphorus consist of p+3 compounds but not include sulfur-rich impurities Similarly, the P+3 impurities of higher than stoichiometric reactions are not generally found in the products generated from P2S5 with a lower than stoichiometric level of phosphorus This was one of the primary points of interest in performing the stoichiometric experiments with P2S5, i.e., to see if these different impurity mixtures lead to ZDDPs with different PEIs, which, in fact, appears to be the case To generate more detailed information regarding the composition of the volatile products from the PEI studies, the relative ratios of the various peaks found in Tables 13 and 14, which were taken over the time interval of 10-50 rain of the Selby-Noack test, were multiplied by the PEI values of these samples to calculate the PEIs of the individual peaks That is, the total PEI value for the sample was separated into the individual PEI components in the same relative ratio as the 31p NMR peaks The results o f this comparison are presented in Figs 15 and 16 and show interesting trends BOSCH ET AL ON PNMR SPECTROSCOPY 269 FIG 15 ZDDP A, PEI values by NMR peak FIG 16 ZDDP B, PEI values by NMR peak Some peaks grow while some stay the same or slightly shrink during the duration of the test Two peaks, those at 104 and 84 ppm, remain the same or shrink The peaks at 97 and 69 ppm clearly grow, and the peak at 30 ppm appears to grow somewhat, but not dramatically Before the test, Oil A has peaks at 104, 98.1, 69.5, and 65 ppm, and Oil B has peaks at 104.1, 103.5, 98.5, 69.7, and 65 ppm Therefore, it is possible that the peak at 104 ppm is an impurity that volatilizes and the small peak at 69 ppm in the before-test oils is generated during the thermal decomposition of the oils during the PEI test and subsequently is volatilized The large peak at approximately 98 ppm in the before-test oil is perhaps represented as the dithioacid in the volatilized oil samples Further study is required General Observations Volatile components from ZDDPs may arise from the manufacturing process Zinc dithiophosphates are typically a mixture of phosphorus containing species In addition to the desired ZDDP, [(RO)2P(S)S]2Zn and basic ZDP salt, there are a number of other trace components containing phosphorus, as shown in Table 15 Some of the trace components in the unused oil were also observed in the volatiles Expedment lab oven 180*C, in air I I lab; 200=to 260~ in air *~ lab; 150" to 200~ in air * [,o3] i I m] i r~toss] I I 40~ 17o] I I [691 I (RO)zP(S)OR [60 to 72] [96to100) I I J'40TO 45] (RohP(s)o" I (RO)zP(S)O- I ~ all ZDDP gone in hr at 200" and 260~ Feto8o] I I t I(RO)zP(O)SR [20to26] [0.5 to 12] I I I I I I I '~"~"~ I I ~~ I (RO}~P(O) [13t0-13] I I (RO)sP(O) I t I (RO)2P(O)SR [24 to 30] [13 to-13] I The volatile components from ZDDPs may also arise from thermal degradation and/or oxidation The mechanisms proposed for ZDDP anti-wear and anti-oxidation performance in motor oil have included both the effects of ZDDP degradation and oxidation [2] In addition, 3~p NMR studies at other Laboratories have identified ZDDP breakdown fragments in the used motor oil [12], as shown in Table 15 Moreover, ZDDP breakdown fragments have been observed using 3~p NMR in lab tests elsewhere [13-16] These lab tests were also done in the presence of air So the relative contribution of thermal degradation versus oxidation is not clear The direct oxidation era ZDDP with hydroperoxide [17], as observed by 3~p NMR, also gives fragments that may be volatile *ZDDP gone in hr at 200~ or 24 hr at 150~ ~101to103] I t -,, (RO)2P(S)O" [(RO)zP(O)S]~ [49l [22] [37 to 551 'shift, ppm] ((RO)=P(S)S)eZn40((RO)2P(S),S)~Zn~(RO)zP(S)SR (RO)2P(S)SH[ (RO)2P(S)OR 1817- ODPsyrlthesis ,] ZDOP+ cumene 17 ~ hydropemxide ((RO)2P(S)S)eZn,OI ((RO)2P(S)S~Zn] (RO)zP(S)SR 16 15 I ""14,'1 lab4-ballin air rigs 13 15000km ((RO)2P(S)S)eZn~O((RO)2P(S)S)2Zr (RO)2P(S)SR 12 ertgine field test Ref ((RO)2P(S)S)sZr~C ((RO)2P(S)S)~.r RO)2P(S)SnR(RO)2P(S)SH (RO)zP(S)OR (RO)zP(S)O- [(RO)2P(O)S]2 (ROhP(O)SR (RO)3P(O) (OR)P(S)(SR)2 (S)P-(SRh sulfide n = basic ZDDP neutral ZDDP I r2r3 thio acid thiophosphate :hiophosphodcsai' thiophosphate phosphate Species Observed., Table 15 - Literature Survey of 31p NMR Analyses of ZDDPs Z i1> z FC C m r" o-rl ffJ Z t' - m z m rm ",.4 BOSCH ET AL ON PNMR SPECTROSCOPY 271 The evolution of volatile components has been found to depend strongly on the alcohol used in ZDDP manufacture ZDDPs made from the secondary alcohol 4-methyl-2-pentanol appear to break down readily under the conditions of the Selby-Noack test, but only a small percentage of the phosphorus break-down products were volatile Within the first 10 min, all the volatile species were given off, and the only phosphorus-containing species in the residual oil were fully oxidized phosphates In contrast, ZDDPs made from the primary alcohol 2-ethylhexanol appear to have a longer life but produce more volatile phosphorus over their breakdown life Volatile phosphorus-containing species were generated for at least 60 In concert, the residual oil contained ZDDPs and other phosphorus-containing components in addition to fully oxidized phosphates The rapid breakdown of ZDDPs has also been observed elsewhere: Lab tests in air using 31p NMR show that all the ZDDP is gone in h at 200~ [15], 24 h at 150~ [15], h at 200~ [16], or h at 260~ [16] In the latter two tests, the only phosphorus containing species was a fully oxidized phosphate A recently published study by scientists at MIT [20] has indicated how to quantify the amount of oil lost by three possible mechanisms These include thermal decomposition of the oil in the engine, aerosol generation, and oil volatilization The information gathered in the present paper using the Selby-Noack and the related NMR spectroscopy testing methods can be used to quantify phosphorus volatility in the same manner Measurement of zinc in the volatiles can be used to determine the amount of phosphorus generated via aerosol generation In addition, it appears that careful 31p NM-R analyses of the volatiles could be used to measure the phosphorus generated by volatilization of the components of the motor oil versus the phosphorus homologs generated by thermal decomposition Earlier studies by Savant showed that there were trace levels of zinc in the phosphorus volatiles obtained from the Selby-Noack test The combination of varying the length of the Selby-Noack test, followed by 3lp NMR analysis of the volatiles and residues, has the potential to be a very useful tool to further understand the mechanism of phosphorus volatility of motor oil Conclusions The 31p ~ data are reproducible using the Selby-Noack procedure For the same conditions of time and temperature, the information, though limited, shows that the composition data are consistent when the experiments are repeated Different oils formulated with different ZDDPs and other additives have different volatile components Moreover, the composition of the volatile phosphorus containing components depends on the specific ZDDP In most cases, the phosphorus forms found in the volatiles appeared to contain some of the ZDDP additive But the 31P NMR spectrum also indicated the presence of more species in the volatiles than in the untested oil That is, the volatile components appear to be generated primarily by the decomposition of ZDDP However, volatile phosphorus containing trace components arising from the ZDDP manufacturing process may be significant in some cases It appears possible to meet engine oil performance standards using additives having low phosphorus volatility Although all the oils in the IOM Database for North America are presumed to have met minimal standards for engine wear and oil oxidation, there is a large difference in Phosphorus Emission Index (PEI) among these oils By using PEI as an additional criterion for additive selection, it would seem reasonable to provide protection for both the 272 ELEMENTALANALYSIS OF FUELS AND LUBRICANTS engine and the emissions control system Certainly, approaching the control of phosphorus volatility by actual measurement is highly preferable to attempting to control phosphorus volatility by limiting the phosphorus content of fresh engine oil Acknowledgments The authors would like to thank Dr Andre' d'Avignon at Washington University for performing the 31p NMR studies, Mr Skip Ramsey for synthesizing the ZDDP samples, and Chevron Oronite Company, LLC for providing typical GF-3 oil samples with and without ZDDP References [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] Selby, T W., Bosch, R J., and Fee, D C., "Phosphorus Additive Chemistry and Its Effects on the Phosphorus Volatility of Engine Oils," submitted to ASTM International Spikes, H., "The History and Mechanisms of ZDDP," Tribology Letters, Vol 17, No 3, 2004, pp 469-489 Selby, T.W., et al., "A New Approach to the Noack Test for Volatility Measurement," SAE International Fuels & Lubricants Meeting and Exposition, Philadelphia, PA, USA, 1993 K Noack, Angewandt Chemie, Vol 49, 1936, p 385 ASTM Standard D 5800, "Evaporation Loss of Lubricating Oils by the Noack Method," Annual Book of ASTM Standards, Vol 5.03, ASTM International, West Conshohocken, PA, 2004, pp 352-366 Determination of Evaporation Loss of Lubricating Oils, (Noack Method), DIN 51-581, 1981 Selby, T W and Reichenbach, E A., "Engine Oil Volatility Studies - Generation of Phosphorus," Proceedings of the International Tribology Conference, Yokohama, Japan, 1995, pp 813-816 Institute of Materials Engine Oil Database, Published by the Institute of Materials, Midland, Michigan, issued yearly from 1984 Selby, T W., Development and Significance of the Phosphorus Emission Index of Engine Oils, Proceedings of 13th International Colloquium - Lubricants, Materials, and Lubrication Engineering, Esslingen, Germany, 2002, pp 93-102 Johnson, M D., McCabe, R W., Hubbard, C P., Riley, M E., Kirby, C W., Ball, D.J., et al., "Effects of Engine Oil Formulation Variables on Exhaust Emissions in Taxi Fleet Service," SAE Paper #2002-01-2680, SAE Powertrain Meeting, 2002 Selby, T W., "Phosphorus Volatility of Lubricants - Use of the Phosphorus Emission Index of Engine Oils," 9th F&L Asia Conference, Singapore, January 21-24, 2003 Peng, P., Hong, S Z., and Lu, W Z., "The Degradation of Zinc Dialkyldithiophosphate Additives in Fully Formulated Engine Oil as Studied by P-31 NMR Spectroscopy," Lubrication Engineering, Vol 50, No 3, 1994, pp 230-5 Coy, R C and Jones, R B., "The Thermal Degradation and EP Performance of Zinc Dialkyldithiophosphate Additives in White Oil," Internationales Jahrbuch tier Tribologie, Vol 1, 1982, pp 345-50 Coy, R C and Jones, R B., "The Degradation of Zinc Dialkyldithiophosphate Additives in Rigs and Engines," 1Mech E Conference Publications, Vol 1, 1982, pp 17-22 BOSCH ET AL ON PNMR SPECTROSCOPY 273 [15] Fuller, M L S., Kasrai, M., Bancroft, G M., F3ffe, K., and Tan, K H., "Solution Decomposition of Zinc Dialkyl Dithiophosphate and Its Effect on Antiwear and Thermal Film Formation Studied by X-Ray Absorption Spectroscopy," Tribology International, Volume Date 1998, Vol 31, No 10, 1999, pp 627-644 [16] Harrison, P G and Brown, P., "External Reflection FTIR, Phosphorus-31 MAS NMR and SEM Study of the Thermal Decomposition of Zinc(II) Bis(O,O'-dialkyldithiophosphates) on 316 Stainless Steel," Wear, Vol 148, No 1, 1991, pp 123-34 [17] Yagishita, K and Igarashi, J., "31P NMR and Mass Spectrometric Studies of the Reaction of Zinc Dialkyldithiophosphates with Cumene Hydroperoxide (Part 1) Kinetics and Mechanisms of the Initial Homolytic Reaction," Sela'yu Gakkaishi, Vol 38, No 6, 1995, pp 374-83 [18] Zimmermann, V., Jaeger, G., and Meyer, H., "Characterization of Reaction Mixtures in Zinc Bis(O,O'-dialkyl dithiophosphate) Synthesis by Phosphorus-31 NMR Spectroscopy," Chemische Technik (Leipzig, Germany), Vol 38, No 4, 1986, pp 169-72 [19] Oehler, R., Zimmermann, V., and Jager, G., "Preparation of Zinc Dialkyl Dithiophosphates Reaction and Reaction Products," Erdoel & Kohle, Erdgas, Petrochemie, Vol 40, No 2, 1987, p 87 [20] Yilmaz, E., Tian, T Wong, V W., and Heywood, J B., "The Contribution of Different Oil Consumption Sources to Total Oil Consumption in a Spark Ignition Engine," SAE Paper, 2004-01-2909 STP1468-EB/Sep 2005 Author Index A Mason, Kelly John, 42, 196 McEIroy, Frank C., 42, 196 Mennito, Anthony S., 42 Mustacich, Robert V., 164 Anderson, Daniel E, 71 B N Beumer, Berry, 116 Bosch, R J., 239, 255 Brouwer, P., 98 Bryce, Derek W., 207 Nash, Lisa J., 232 Ngobeni, Prince, 59 C O Chen, Z W., 116 Corns, Warren T., 207 Cruko, John, i 37 Onyeso, Chris C., 17 P D Paszek, Joseph, 42 P6cheyran, C., 51 Prinzhofer, A., 51 Priola, Marco, 59 Diehl, John W., 221 Di Sanzo, Frank P., 221 Donard, O E X., 51 Dreyfus, S., 51 R F Radley, Ian, I 16 Rhodes, John R., 152 Ricchiuto, Silvia, 59 Fee, D C., 239, 255 Fess, Scott, 108 Fox, Brian S., 24, 196 G Selby, T W., 239, 255 Shearer, Randy L., 164 Stockwell, Peter B., 207 Gras, Rhonda L., 164 I-I Horton, Meaghan, 33 Hwang, J David, 33 T Tarkanic, Steve, 137 Tittarelli, Paolo, 59 K Kariher, Peter H., 181 Katskov, Dmitri A., 59 Kirchgessner, David A., 18 I Kishore Nadkarni, R A., I, 85 V Vrebos, B., 98 L W Leong, David, 33 Liang, Lian, 181 Lienemann, C P., 51 Lukas, Malte, 71 Luong, Jim C., 164 Wei, Fuzhong, 116 Wilhelm, S Mark, 181 Wissmann, Dirk, 128 Wolska, J., 98 u M Magnier, C., 51 Yurko, Robert J., 71 275 Copyright9 2005by ASTMInternational www.astm.org STP1468-EB/Sep 2005 Subject Index A Additives, 17, 24, 221,239 Analysis, perfect, Analytical laboratory, I Asphaltenes, 51 ASTM D 5453, 137 ASTM D 5623, 164 ASTM D 6920, 152 ASTM D 7039, 116 Atomic emission detection, 221 Atomic fluorescence spectrometry, 207 Fluorine, 232 Fossil fuels, 207 Fuels, 108, 221 analysis, 98, 232 G Gas chromatography, 221 Gasoline, 17, 59, 85, 137, 223 low sulfur content, 128 ultra-low sulfur, 152 Gasolines, 221 l-I C Combustion cold vapor atomic absorption spectrometry, 196 Combustion/oxidation UV-fluorescence detection, 137 Comprehensive two-dimensional gas chromatography, 22 I Contaminant particles, analysis, 71 Crude oil, 51, 108, 181, 196 D Diesel fuel, 17, 59, 85, 116, 137 ultra-low sulfur, 116, 137, 152 Doubly curved crystal optics, 116 Dual plasma sulfur chemiluminescence detector, 164 Hetero-atom speciation, 221 Hydrocarbons, sulfur determination, 164 Inductively coupled plasma atomic emission spectrometry, 17, 24, 33, 71 Inductively coupled plasma-mass spectrometry, 33, 42, 51 Interlaboratory crosscheck programs, 85 Ion chromatography, 42 Ion-selective electrode, 232 Jet fuel, 59, 221 E EDXRF, 128 Electrochemical sensors, 152 Electrothermal atomic absorption, 59 Elemental analysis, 98, 232 Energy dispersive x-ray spectrometer, 98 Engine oils, 239 Exhaust catalyst, 239, 255 Exhaust emissions, 239, 255 F Fast on-line/at process sulfur determination, 137 Filter furnace electrothermal atomic absorption spectrometry, 59 Fluoride, 232 L Liquid chromatography, 42 Lower limits of detection, 98 Low thermal mass gas chromatography, 164 Lubricants, 232 Lubricating grease, 24, 98 M Maltenes, 51 Mercury, 181, 196, 207 volatile, 181 Microflow nebulizer, 51 Microwave digestion, 33 Monochromatic wavelength dispersive x-ray fluorescence, 116 276 INDEX 277 N Neutron activation analysis, 181 NIST 1084a, 51 NIST 1085b, 51 NIST 1634c, 51 Nitrogen converters, 152 Nuclear magnetic resonance spectroscopy, 255 O On-line process analyzers, 152 Organic solvents, 51 Oxidative combustion, 232 Sample preparation, 33 Selby-Noack volatility test, 255 Selenate, 42 Selenite, 42 Selenium, 42 Selenocyanate, 42 Speciation, 181 Spray chamber, 17, 51 Sulfur, 108, 116, 128, 164, 221 analysis, 85 ultralow, in diesels, 85 Sulfur chemiluminescence detection, 164 Sulfur/nitrogen chemiluminescence, 232 T 3zp Nuclear magnetic resonance spectroscopy, 255 Petroleum and petrochemical products, 33, 183, 207 Phosphorus emission index, 239, 255 Phosphorus volatility, 239, 255 Pipeline, 108 Pneumatic nebulizer, 17, 51 Polarization, ! 28 Polarized energy dispersive x-ray spectrometry, 128 Pooled limit of quantification, I 16 Pyro-electrochemical on-line ultra low sulfur analyzer, 152 Q Thermal oxidation, 152 Trace metals, 51, 59 Transverse heated filter atomizer, 59 U Ultrasonication, 181 Ultra-trace metals, 42, 51 U S EPA 7473, 181 Used oil analysis, 71 W Wavelength dispersive x-ray spectrometer, 98 Wear metals, 17 Wear particles, analysis, 71 Quality management, X R Rapid sulfur analysis, 137 Refinery, 108 Refining, 181 Rotating disc electrode spectrometer, 71 Rotrode filter spectroscopy, 71 Round robin test, 128 X-ray fluorescence spectrometry, 98 X-ray spectrometry, 98 X-ray transmission, 108 Zinc dithiophosphates, 239, 255