Agilent Determination of Metals in Oils by ICP-OES Application Note Manual
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1. e o e e Author Deen Johnson Determination of Metals in Oils by ICP OES Application Note Inductively Coupled Plasma Optical Emission Spectrometers Introduction The determination of metals in oils and petroleum products is important in many petroleum laboratories and manufacturing operations The samples can be crude oils lubricating oils gas oils and fuel oils to name a few Fast accurate and precise analytical results are required in this industry The metals analyzed in the sample varys with the product or its source or use which is discussed by Johnson 1 McKenzie 2 Van Loon 3 Hofstader Milner and Runnels 4 and Pradham 5 The analysis of oils and petroleum products has been performed by flame atomic absorption spectrometry graphite furnace atomic absorption spectrometry arc spark atomic emission spectrometry and ICP OES The ICP has many benefits for the analysis of oils The samples are typically diluted in kerosene or other suitable solvent and aspirated directly into the ICP The ICP analysis is very fast and gives accurate precise results The analysis of organic materials using the ICP can present difficult problems for the spectroscopist The power requirements may be higher for many organic sol vents and matrices used in the analysis of oils 6 7 Additionally it is necessary to reduce the sample uptake rate to minimize solvent loading of the plasma with some organics which could caus2. The dynamic mode of background correction was used to compensate for background and viewing height was opti mized using intensity The search and scan windows were optimized to eliminate any interference peaks and assist the instrument in the peak location for the lower concentration levels of the metals in the oil matrices There were no spec tral interferences encountered and therefore no corrections made A glass concentric K type nebulizer was used for sample aspi ration The peristaltic pump was fitted with organic resistant tubing The sample delivery tube was white white and the drain tube was white gray Because the fuel oil samples contained a high amount of par ticulate materials the nebulizer spray chamber system needed more frequent rinsing with the kerosene The fuel oil did exhibit some carry over but rinsing for 3 minutes with kerosene minimized the problem Results The common parameters used for the analysis of all three matrices are found in Table 1 The analyses were performed with manual sample introduction Table 1 Liberty 200 Instrument Parameters Nebulizer pressure kPa 150 Stabilization time s 15 Sample delay s 30 Rinse time s 10 Snout purge OFF Integration s 3 Replicates 3 PMT V 650 Power kW 1 50 Plasma L min 13 5 Auxiliary L min 2 25 Pump speed rpm 10 Nebulizer pressure kPa 150 Background mode Dynamic Standard 1 10 Standard 2 50 Standard 3 100 Units mg L Max cu
3. Table 2 Measurement Parameters for the Liberty 200 View Search Scan Wavelength height window window Element nm mm nm nm Filter Order Ni 231 604 5 0 030 0 060 6 2 Ba 233 527 8 0 040 0 060 6 2 Si 251 611 8 0 040 0 060 6 2 Fe 259 940 8 0 040 0 060 6 2 Cr 267 716 8 0 040 0 060 6 2 Mg 279 553 4 0 040 0 060 6 2 V 292 402 8 0 040 0 060 6 2 Na 589 592 8 0 080 0 120 7 1 Al 308 215 8 0 040 0 060 6 2 Ca 317 933 5 0 040 0 060 6 2 Zn 213 856 8 0 027 0 040 1 3 Pb 220 353 8 0 027 0 040 1 3 Table 3 Mean Results Used Lube Oil Gas Oil Fuel Oil Mean S D Mean S D Mean S D Element mg L mg L RSD mg L mg L RSD mg L mg L RSD Ni 24 14 0 1 0 4 15 68 0 4 2 5 911 8 42 7 46 Ba 12 21 0 39 3 2 0 90 1 03 114 3 0 50 0 52 105 3 Si 33 22 2 89 9 6 3 01 1 58 52 7 156 9 3 91 2 5 Fe 10 51 0 27 2 5 3 72 0 09 2 3 34 88 0 93 2 7 Cr 0 23 0 13 57 0 0 41 0 2 49 7 1 39 0 3 21 6 Mg 2 48 0 1 4 2 0 43 0 02 4 6 3 01 0 13 4 3 V 0 55 N A N A 22 08 0 39 1 8 1143 0 25 6 2 2 Na 12 86 8 51 66 2 3 78 N A N A 27 36 1 62 5 9 Al 29 93 2 0 6 7 37 58 1 06 2 8 102 9 1 92 1 9 Ca 217 7 3 08 1 4 lt 0 01 0 0 0 0 4 93 0 5 10 1 Zn 73 11 0 68 0 9 2 28 0 15 6 8 5 12 0 59 11 5 Pb lt 0 25 N A N A 4 98 3 83 76 9 14 02 2 09 14 9 Table 4 Recovery for 50 ppm QC Standard Metal Concentration mg L Recovery Ni 51 44 102 9 Ba 52 42 104 8 Si 50 93 101 9 Fe 52 88 105 8 Cr 53 74 107 5 Mg 52 46 104 9 V 52 86 105 7 Na 51 60 103 2 Al 52 43 104 9 Ca 54 22 108 4 Zn 53 49 107
4. 0 Pb 53 38 106 8 Result No 5 Program LUBE OIL 600 0 lt A7T wM2m427 200 0 231 575 Result No 7 Program LUBE OIL 20000 lt 4A ozmaz 0 000 231 575 VIEW SCAN Aceite Usado Ni 231 604 WAVELENGTH nm Scale AUTOLINEAR VIEW SCAN Fuel Oil Ni 231 604 WAVELENGTH nm Scale AUTOLINEAR ANAL ANAL 231 633 231 633 Figure 1 Nickel scans for used lube oil and fuel oil VIEW SCAN Result No 6 ega Program LUBE OIL i ANAL 800 0 l N T E N 5 l T Y 500 0 WAVELENGTH nm 251 581 Scale AUTOLINEAR alate VIEW SCAN Result No 7 Fuel Oil Program LUBE OIL Si 251 611 ANAL 6000 I N T E N S T Y 0 000 251 591 WAVELENGTH nm Scale AUTOLINEAR eee Figure 2 Silicon scans for gas oil and fuel oil Result No 6 Program LUBE OIL 600 0 292 372 Result No 7 Program LUBE OIL 30000 Figure 3 lt q 0 zmz Vanadium scans for gas oil and fuel oil VIEW SCAN Gasoleo V 292 402 xq o zm4z T WAVELENGTH nm Scale AUTOLINEAR VIEW SCAN Fuel Oil V 292 402 WAVELENGTH nm Scale AUTOLINEAR The QC data indicates the analysis and instrument are per forming well The data was accumulated over a two day period The QC check after the analysis of the fuel oil samples was generally higher and in the range approximately 120 recovery These results after the fuel oil analysis were used in overall recovery calculations The overall recoveries are
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6. e the plasma to be extinguished The purpose of this study was to analyze 12 elements in a used lubricating oil a gas oil used as the feed stock for gasoline production and a fuel oil 6 using the Liberty 200 The work determined the concentration of nickel barium silicon iron chromium magnesium vanadium sodium aluminium calcium zinc and lead in all three sample matrices The primary elements of interest in the used lube oil are Fe Si Al Cu Cr and Pb The elements of interest in the gas oil are Na Fe Ni Cr Cu and Al Finally the prime elements for the fuel oil are Ca Fe Ni V and Na The Ba Si Mg and Zn are also of interest ee Agilent Technologies Experimental Instrumentation The Agilent Liberty 200 ICP OES was used in this study The system was controlled with a Compaq 386 20e computer Analytical Procedures The samples were analyzed after simple dilution using the weight volume preparation The samples were prepared by weighing 5 grams of oil and diluting with 5 mL analytical grade deodorized kerosene as the solvent The dilution ratio was 1 10 The standards were prepared with a 1 10 weight volume dilution of kerosene with 10 50 and 100 ppm Conostan 8 S 21 standards A blank was prepared by diluting base oil 75 1 10 weight volume dilution with the kerosene During the analysis the 50 ppm standard was used as a OC Standard to check the accuracy and stability of the instrument and the analysis
7. excellent ranging from 101 9 108 Conclusion The Liberty ICP OES instruments offer a fast accurate and precise method for the determination of metal constituents in oil matrices The simple dilution method provides an easy sample preparation scheme for the analysis with accurate results for trend analysis The Liberty s 40 68 MHz RF generator easily handles the hydrocarbon matrices resulting in stable precise results Dynamic background correction and the instrument s high res olution compensate for background problems and minimize spectral interferences The Liberty could analyze the 12 metals with 3 replicates in the samples in approximately 6 minutes 30 seconds Coupled with the ability to analyze OC samples periodically it gives the analyst assurance of fast accurate results Acknowledgments Agilent Technologies Inc would like to thank the Corporven Refinery of Venezuela for providing the samples used in this study References 1 D Johnson The Determination of Vanadium in Heavy Industrial Fuel Oils Using the GTA 95 AA At Work AA 36 November 1983 Varian Instrument Group Sugar Land Texas 774478 U S A 2 T N McKenzie Atomic Absorption Spectrophotometry for the Analysis of Oil Samples AA At Work AA 10 January 1981 Varian Techtron Pty Limited Springvale Victoria Australia 3 J C VanLoon Analysis of Petroleum and Petroleum Products Chapter 7 p 264 In Analytical Atomic Abo
8. rption Spectroscopy Selected Methods Academic Press Inc New York 1980 4 R A Hofstader 0 1 Milner and J M Runnels Analysis of Petroleum for Trace Metals Advances in Chemistry Series No 156 American Chemical Society Washington D C U S A 1976 5 N K Pradham Coal and Petroleum Analysis by Atomic Absorption Spectroscopy Varian Techtron Pty Limited Springvale Victoria Australia 1976 6 T T Nham R M Bombelka Determination of Metals in Lubricating Oils by Inductively Coupled Plasma Atomic Emission Spectroscopy Varian Australia Pty Limited Mulgrave Victoria 3170 Australia and Varian GmbH Darmstadt German Federal Republic ICP At Work ICP 2 June 1991 7 Determination of Trace Elements in Methanol by ICP ES ICP At Work ICP 4 September 1991 Varian GmbH Germany 8 Conostan Metallo organic Standards Conostan Division Continental Oil Company Ponca City Oklahoma U S A For More Information For more information on our products and services visit our Web site at www agilent com chem www agilent com chem Agilent shall not be liable for errors contained herein or for incidental or consequential damages in connection with the furnishing performance or use of this material Information descriptions and specifications in this publication are subject to change without notice Agilent Technologies Inc 1993 Printed in the USA November 1 2010 ICPE
9. rve order 4 C C limit 0 9950 Table 2 shows the wavelength viewing height search window scan window filter and order which were optimized for each line in the program The results for the used lube oil the gas oil and the fuel oil are given in Table 3 Each sample was analyzed in triplicate The used lube oil and gas oil required a rinse time of only 10 seconds between sam ples but required a rinse time of 2 minutes between the sam ples and the OC standard Because of the higher solids and particulate content of the fuel oil and problems with the par ticulates sticking to the pump tubes nebulizer and spray chamber a 3 minute rinse was used The rinsing was per formed with kerosene Figures 1 2 and 3 are representative scans for nickel in the used oil and fuel oil silicon in the gas oil and fuel oil and vanadium in the gas oil and fuel oil The nickel and silicon exhibit some band structure which is characteristic when analyzing hydrocarbon samples The nickel peak is the middle peak None of the high level scans show any band structures From the literature and experience in the analysis of these types of hydrocarbon samples one would expect the gas oil to have the lowest concentration of metals followed by the used lube oil with the fuel oil containing the highest concen tration of metals Indeed the results follow the expected trend Recovery data for the quality control standard of 50 ppm is presented in Table 4
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Agilent Determination of Metals in Oils by ICP OES Application Note Manual