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

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Library of Congress Cataloging-in-Publication Data

Elemental analysis of fuels and lubricants: recent advances and future prospects/R.A.

Kishore Nadkarni, editor.

p. cm.~STP; 1468)

Includes bibliographical references and index.

ISBN 0-8031-3494-0 (alk. paper)

1. Fuel--Analysis. 2. Lubrication and lubricants--Analysis. I. Nadkami, R.A. II.

Series: ASTM special technical publication; 1468.

TP321.E46 2005

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2005022779

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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

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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

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Printed in Baltimore, MD

September 2005

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

Zen and the Art (or is it Science) of a Perfect Analysis--R. A. K. NADKARNI

vii

ATOMIC 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

Elemental Analysis of Lubricating Grease by Inductively Coupled Plasma

Atomic Emission Spectrometry (ICP-AES)--B. s. FOX

The Use of Microwave Digestion and ICP to Determine Elements in Petroleum

Samples--J. D. HWANG, M. HORTON, AND D. LEONG

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

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

Fuel Analysis by Filter Furnace Electrothermal Atomic Absorption

Spectrometry--P. TII~rARELLL M. PRIOLA. S. RICCHIUTO, D. A. KATSKOV, AND

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

SULFUR DETERMINATION AND X-RAY 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

Determination of Sulfur Content in Crude Oil Using On-Line X-Ray

Transmission Technology--s. FESS

Low-Level Sulfur in Fuel Determination Using Monochromatic WDXRFASTM D 7039-04--z. w. CHEN, F. WEI, I. RADLEY, AND B. BEUMER

Latest Improvements on Using Polarized X-Ray Excitation EDXRF for the

Analysis of Low Sulfur Content in Automotive Fuel--D. WISSMANN

Rapid Determination of Sulfur in Liquid Hydrocarbons for At-Line Process

Applications Using Combustion/Oxidation and UV-Fluorescence

Detection--s. TARKANIC AND J. CRNKO

Pyro-Electrochemicai On-Line Ultra Low Sulfur Analyzer--J. R. RHODES

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

108

116

128

137

152

164

MERCURY DETERMINATION

Sampling and Analysis of Mercury in Crude Oil--s. M. WILHELM.

D. A. KIRCHGESSNER. L. LIANG, AND P. H. KARiHER

Determination of Total Mercury in Crude Oil by Combustion Cold Vapor

Atomic Absorption Spectrometry (CVAAS)--B. s. Fox. K. J. MASON. AND

F. C. MCELROY

Mercury Measurements in Fossil Fuels, Particularly Petrochemicals--

P. B. STOCKWELL, W. T. CORNS, AND D. W. BRYCE

181

196

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

Improvements in the Determination of Fluorine in Fuel and Lubricants by

Oxidative Combustion and Ion-Selective Electrode Detection--L J. NASH

Phosphorus Additive Chemistry and its Effects on the Phosphorus Volatility of

Engine Oils--T. w. SELBY, R. J. BOSCH. AND D. C. FEE

Analysis of the Volatiles Generated During the Selby-Noack Test by 31p NMR

Spectroscopy--R. J. BOSCH, D. C. FEE, AND T. W. SELBY

Index

221

232

239

255

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 3 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 6 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 4 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 ELEMENTAL ANALYSIS 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 (< 1 min 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 ELEMENTAL ANALYSIS 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 2 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.

2. 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.

3. 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.

4. 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.

OVERVIEW xi

5. Finally, Mason et al. (ExxonMobil Research and Engineering) describe the approaches

used for assay of fresh and spent reformer catalysts to determine the precious metals

(platinum and rhenium) in them. Methods such as WDXRF, ICPAES, and classical wet

chemistry methods are used for such analysis. Precise and accurate methods are critical

for these analyses, since small errors in analysis can have a large impact in commercial

transactions of these catalysts between the catalyst vendors and the oil companies.

Hopefully, the papers included here will provide the readers with the current state-of-theart and future research trends in the field of elemental analysis in the oil industry. Most

modern techniques used in the field are represented here.

Acknowledgment

I want to thank various ASTM staff members (particularly David Bradley, Dorothy Fitzpatrick, Crystal Kemp, Hannah Sparks, and Roberta Storer) for their prompt response and

cooperation that made the symposium and subsequent efficient publication in JAI and of this

volume possible. My thanks are also due to the reviewers who did a very good job of

providing technical reviews of all original paper submissions. Their invaluable assistance in

reviewing the papers made the final publication a much better quality product.

R. A. Kishore Nadkarni

Chairman, D02.SC 3 and

Symposium Chairman

R. A. Kishore Nadkarni 1

Journal of ASTM International, March 2005, Vol. 2, No. 3

Paper ID JAI12964

Available online at www.astm.org

Zen and the Art (or is it Science) of a Perfect Analysis

ABSTRACT: An analytical laboratory in any industry plays a crucial role in product quality

management and ultimate customer satisfaction. Some factors need to be considered for an aspiring

laboratory to become a perfect performer. These range from sampling, calibration, contamination control,

and use of valid test methods to statistical quality assurance. Some approaches may be utilized to achieve

a perfect analysis including: staff training, participation in proficiency testing, use of standard reference

materials in the analytical sequence, internal and external audits, agency accreditation, continuous

improvement program, benchmarking, etc. Laboratories managed in this way show demonstrated

superiority in data precision and accuracy over the labs which do not practice such quality management.

Well-managed industrial laboratories can have insignificant laboratory sigma compared with

manufacturing variability in the plant production. For a flawless perfect analysis, determination to excel,

mental discipline to stay the course, willingness to overcome inertia and resistance, and focus on

producing a perfect analysis at all levels of laboratory staff are essential.

KEYWORDS: analysis, quality management, perfect analysis

As Robert Pirsig wrote in his landmark iconic autobiographical novel "Zen and the Art of

Motorcycle Maintenance," the art of motorcycle maintenance is primarily a mental phenomenon

[1]. One may have the tools, but unless there is mental preparation to achieve high goals, the

tools alone will not help. A similar mindset is needed to achieve excellence in a laboratory to

make it into a perfect laboratory that produces flawless performance. Tools may be available, but

if there is no organizational passion and will to excel, the laboratory will not become a perfect

laboratory.

The culture of excellence must be pervasive throughout the laboratory organization from the

laboratory manager to the laboratory technician. Higher management especially needs to show

through visible actions that only the best will do. Perfection cannot be achieved through shortterm stop-gap measures. A long-term improvement plan must be in place and followed upon to

be effective.

What is a perfect laboratory? It is a laboratory which delivers the product (i.e., accurate and

precise data) on time; if necessary, continuously improves on itself; makes the analysis "Right

the First Time," thus eliminating repeat analysis and giving erroneous information to the

customers; communicates with its customers and sometimes educates them when necessary. This

laboratory cares about the success of its customers' business.

Customer Services

A laboratory is a microcosm of its parent organization. The product delivered from a

laboratory is quality data. Hence, the primary objective of a laboratory should be to be the best in

quality. A laboratory needs to deliver a consistent product on time which meets or exceeds

customers' expectations, and which increases customers' confidence in the laboratory's

Manuscript received 7 September 2004; accepted for publication 19 October 2004; published March 2005.

i Millennium Analytics, Inc., East Brunswick, NJ 08816.

2 ELEMENTAL ANALYSIS OF FUELS AND LUBRICANTS

reliability and dedication to quality. A customer needs to know that the laboratory cares. "Total

Care" is the sum of impressions formed during contact with the customers. A perception by the

customer that the laboratory is a caring organization can convert a customer from being forced to

be a customer to becoming a customer by choice. Substantial or continuing violations of a

customer's justified expectations will cause the customer to feel that the laboratory, organization

simply does not care.

Pillars to Build a Perfect Laboratory

There are at least twelve components which help to produce flawless laboratory performance.

In the approximate order in which an analysis is performed, these include but may not be

conEmed to the following (See Fig. 1 on page 3):

1. Training

2. Representative Sampling and Contamination Control

3. Calibrations

4. Technical Details of Test Methods

5. Statistical Quality Assurance

6. Use of Certified Reference Materials

7. Documentation

8. Internal and External Audits

9. Proficiency Testing

10. External Agency Accreditation

11. Benchmarking

12. Ethics

Training

As Mark Twain reportedly said, "Training is everything. Cauliflower is nothing but a

cabbage with a college education." The point is that without adequate training, staff cannot

produce the best results. Training courses should include periodic refresher and new technology

courses to improve the technical ability of staff members. These courses will benefit the staff

members by helping them to think through the analysis rather than mechanically doing the test,

to identify ways to improve the methodology, to obtain better precision and accuracy, and to

improve the turnaround time.

Some of the areas in which a laboratory staff member must be fully trained include safety,

data security, laboratory instrumentation, test methods used, calibration protocols, statistical

quality assurance, use of certified reference materials, long term analytical needs and goals, and

ethical behavior. In today's culture, it is still up to the supervisors and management to filter the

Zen attitude down to the working level people. The very fundamental first step toward obtaining

a perfect analysis is through staff training. Dr. Derek Bok, former president of Harvard

University once commented, "If you think education is expensive, try ignorance."

Sampling

Obviously the first critical step in any analytical sequence is the integrity and validity of a

sample being analyzed. More often than not this sampling step does not involve actual laboratory

NADKARNI ON PERFECT ANALYSIS 3

4 ELEMENTAL ANALYSIS OF FUELS AND LUBRICANTS

staff; usually the chain of custody for a sample starts with the receipt of the sample in the

laboratory. Once the laboratory acquires the sample, however, it is the laboratory's responsibility

to have a system for unique identification of each sample, sample handling, storage and retention

procedures, as well as safe disposal procedures. Identification of the population from which the

sample is to be obtained, selection and withdrawal of valid gross samples of this population, and

reduction of each gross sample to a laboratory sample suitable for the analytical technique to be

used are some of the key steps to be considered in obtaining a representative sample for analysis

[2]. Equally important is documented chain of custody procedures to authenticate and maintain

the sample integrity. Several ASTM standards deal with sampling aspects for the analysis of

petroleum products and lubricants:

* D 4057: Manual Sampling of Petroleum and Petroleum Products

9 D 4177: Automatic Sampling of Petroleum and Petroleum Products

9 D 4840: Sampling Chain of Custody Procedures

o D 5842: Sampling and Handling of Fuels for Volatility Measurements

9 D 5854: Mixing and Handling of Liquid Samples of Petroleum and Petroleum Products

Additionally, some ASTM standards give instructions for specific sampling requirements for

specific analytical tests. Attention must be paid to these caveats to obtain reliable test results.

Contamination Control

Gross contamination of the sample in any analysis and in particular for trace analysis is a

serious problem which, if unchecked, will completely negate the validity of the analytical results.

The problem can become particularly insidious as one is working in the range of ppm and subppm levels of analytes. Contamination from particulates in the air, impurities in reagents, trace

elements from the sample containers as well as glass- or plastic-ware used during analyses are all

potential sources of contamination [3]. An accompanying "blank" sample used throughout the

analysis sequence may or may not accurately measure the extent of contamination, since such

contamination from air or glassware, etc. may not be uniformly present when in contact with the

blank and a real sample. The point is that both a blank determination and a rigorous protocol for

contamination control in the laboratory are essential for obtaining perfect results, particularly in

the area of trace analysis. An excellent source book for discussion on contamination control is

given in [4].

Calibration or Verification

Virtually all analytical test methods require some form of calibration or verification before

actual samples are analyzed. Different test methods require different calibration intervals. Thus,

a decision about appropriate calibration frequency must be made on a ease by case basis. There

is a tendency among many laboratories to do the bare minimum calibrations similar to their

approach toward quality control requirements. This is not the way to achieve superior

performance. Moreover, if an instrument is out-of-calibration, under no circumstances can data

from that instrument be reported to the customers.

Appropriate calibration standards must be utilized during analysis. A wide variety of such

standards are available from commercial sources, NIST, etc. Many laboratories have capabilities

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