Claude Veillon U S . Department of Agriculture Vitamin and Mineral Nutrition Laboratory Beltsville, Md. 20705
T i c e ElementAnalysis BiologicalF-mples In the late 1960s and 1970s, atomic absorption spectrometry (AAS) underwent explosive commercial development and acceptance. It seemed as if everyone, in every field, was discovering this technique and getting in on the action. One of its originators, Sir Alan Walsh of the CSIRO in Australia, once showed a plot of the exponential rise in the number of instruments vs. years. Extrapolating this curve, and assuming that each instrument occupied an area of 1m2, it was obvious that in a few more years atomic absorption spectrometers would cover the entire land mass of the earth! Most of the interest during this period revolved around instruments using chemical flames for sample atomization, and determinations were mostly in the parts-per-million (ppm, or g / g ) range. For most elements and samples, these systems are generally quite specific and free of interferences, and in this concentration range prevention of sample contamination is manageable. Users in the biological sciences and medical and clinical areas really took to the technique, and interest in the biological role of trace elements soared. For many samples, the matrix was a hit messy, what with proteins, salts, viscosity, etc., to contend with, but once these problems were identified solutions usually followed. Much interest was in the “essential” trace elements, such as iron, zinc, and copper, present at parts-per-million levels in many biological samples, and in “toxic” elements, such as lead and cadmium. It soon became evident that some elements, such as zinc, are uhiquitous, and present in things like glass, rubber stoppers, acids and anticoagulants. So a good deal of had data crept into the literature, as well as some erroneous conclusions, but the situation is better today and improving. Then along came the graphite furnace atomizer, and opportunities to make mistakes really increased, ri0003-2700/88/0358-851A$01.50/0 @ 1986 American Chemical Society
Problems and Precautions valed only by the advent of computers. Very early in the development of AAS, L‘vov in Russia demonstrated the use of a resistively heated graphite tube as an atomizer for atomic absorption, It was an extremely successful device from a performance standpoint, with analytical sensitivities for many elements about 3 orders of magnitude better than chemical flame atomizers and few interferences. The design was not very attractive to instrument manufacturers, mostly because of size and convenience considerations. A furnace design similar to L’vov’s was championed for many years by Woodruff at Montana State University and was even offered commercially. But despite its impressive performance and advantages, it was never adopted by atomic absorption instrument manufacturers, and there weren’t enough homemade instrument builders to ensure its success. Numerous electrothermal atomizers came and went commercially during these years of explosive growth, such as graphite tubes, rods and cups, tantalum devices, etc., all offering compact size and convenience. The devices generally retained the extraordinary sen-
sitivity increase over chemical flames of the L‘vov furnace, but posed extraordinary problems with interferences, particularly in the case of biological samples, which usually have a substantial matrix compared with the analyte. Newer designs with improved features and materials have helped a great deal, but the overall performance level of the original L‘vov and Woodruff devices has still not been reached. In the biological, clinical, and nutrition areas, these graphite furnace systems were widely accepted, primarily because of the increased sensitivity they offered. Many of the trace elements of current biological interest are present in samples at levels well below those measurable by flame atomic absorption. The elements vanadium, chromium, molybdenum, manganese, cobalt, nickel, and aluminum are frequently present at concentration levels in the parts-per-billion (ppb, or ng/g) range and below. For example, in the biological fluids serum, plasma, and urine, normal levels of chromium are now accepted to be in the 0.1 nglg region. That’s one part in 10 billion. T o put this in perspective, it is equivalent to a single second in 317 years! Yet, with modern instrumentation, contamination control bordering on fanatical, and sufficient attention to detail, it is possible to measure chromium directly in some samples at the 0.1-ppb level. At these very low levels, there are perhaps only three analytical methods with sufficient sensitivity for the determination: neutron activation analysis, mass spectrometry, and graphite furnace AAS. The first two are not widely available, and the third technique is the one most susceptible to matrix interference effects. So a situation evolved where extremely sensitive instrumentation became readily available in laboratories not equipped to adequately control contamination or to verify the accura-
ANALYTICAL CHEMISTRY. VOL. 58, NO. 8. JULY 1986
-
851 A
hu and apparent lir concenuarion - r o 1. Correlation between background Adapted with permission horn ReferenCB 1
cy of the determinations. I t was not universally appreciated that a sudden gain of 100 or loo0 in analytical sensitivity also multiplied contamination and other problems by the same amount if one were to utilize the increased sensitivity. This REPORT discusses some of the problems encountered and precautions to be taken in determining trace elements in the parts-per-billion concentration range and below. Much of our experience is in determining chromium in biological samples by graphite furnace atomic absorption, and this article will concentrate on that determination as an example. It is perhaps one of the most difficult determinations and has an interesting history. Much of the discussion applies to other elements, matrices, and techniques as well.
Thechromiurnstory Chromium is an essential trace element in the human diet. It is poorly absorbed, and concentrations in various tissues and fluids within the body are very low. Little is known with certainty about ita biochemical role, except that i t is involved in glucose metabolism andlor the mechanism of action of the pancreatic hormone insulin. A biochemical role for chromium was first pointed out by Mertz and Schwarz more than 25 years ago. Since then, a great deal of activity, analyses, and data have appeared regarding this element. Naturally, many of the analyses were performed by AAS, espe-
cially after graphite furnaces became commercially available. Chromium excretion via urine had been proposed as a means of assessing the chromium nutritional status of individuals. However, reported values for urinary chromium varied by well over an order of magnitude. Between 1964 and 1970, reported values for 24-h urine collections ranged from 18 rglday to as much as 1500 rglday. Those reported between 1970 and 1978 ranged from approximately 3 to 10 eg/day. A roughly parallel situation exists for reported concentrations in human blood plasma or serum, ranging from about 1-40 ng1mL prior to 1978. The urinary chromium values presented a dilemma from a nutritional standpoint. One might suspect that urinary chromium output could have dropped from 18 eglday in 1964 to 3 pg/day by 1977, reflecting a sixfold decrease in dietary chromium intake in just 13 years. However, values for dietary chromium reported in 1962 were similar to those reported more than 15 years later. Further, chromium absorption (i.e., fraction appearing in the urine) had been shown rather conclusively to be about 0.5% by radiotracer experiments. So if we have 3 pg/day being excreted, and 0.5% absorption, ingestion would have to be about 600 pg/day, or 10-fold higher than the actual average intake. Commercially available, state-ofthe-art atomic absorption instruments in 1978 used deuterium arc lamps as
852A * ANALYTICAL CHEMISTRY, V M . 58. NO. 8. JULY 1986
continuum light sources for correction of the nonatomic background absorption, particularly with graphite furnace atomizers. Using one of these instruments, Guthrie and eo-workers (1) demonstrated conclusively that urinary chromium could not be measured, because the corrector lamp intensity was too low a t the 357.9-nm chromium wavelength. A direct correlation between background absorption and apparent chromium concentration was found (Figure 1).The implications of Figure 1are quite serious. This means that measurements of urinary chromium, with the best instruments available (at the time) were merely a measure of the background produced in the furnace by the urine matrix. This cast serious doubt on the validity of all previously reported urinary chromium values obtained by this technique. The realization that all previous data of this kind were probably wrong was a unique experience, a t least for me. Fortunately, we had access to a novel continuum source, echelle monochromator, wavelength-modulated atomic absorption spectrometer developed by O’Haver’s group a t the University of Maryland. This instrument had far greater background correction capabilities, and, lo and behold, observed urinary chromium concentrations measured with it were about a factor of 10 lower than any reported before. These also made sense in terms of the intakes and fractional ahsorbances mentioned earlier. However, you can’t use values much lower than those ever before seen and obtained with a unique instrument to make much of a case for everyone else being wrong. So, confirmation of the value by an independent method was needed, and this was accomplished by stable isotope dilution, isotope ratio mass spectrometry. Further evidence came independently from other laboratories. At about the same time, Kayne and co-workers in Philadelphia modified an instrument similar to the one used by Guthrie, enhancing its background correction capabilities considerably. They too observed urinary chromium concentrations below 1ng1mL. By carefully controlling furnace conditions and by adding hydrogen to the furnace gas, Routh a t Varian in Australia was able to reduce background absorption from the urine matrix and also observed values below 1 ng/mL. Although this sudden 10-fold lowering of urinary chromium levels appeared to resolve the intake-absorptionexcretion discrepancies of the earlier literature, it suddenly increased blank and contamination requirements by the same amount. Since 1978, considerable experience
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has been gained in measuring chromium levels in urine, serum, foods, and tissues, largely as a result of improved commercial instrumentation. Improved background correction systems using Kayne’s modification and other techniques such as the Zeeman effect have helped overcome these problems. Analysts must also now be aware that caution is advised and verification is imaerative.
Causes of analytical error The primary causes of analytical error in trace element analysis of biological samples are improper sampling, especially contamination during sample collection; contamination from, or adsorption loss to, the container; contamination, analyte loss, and uncontrolled blanks during sample preparation; and errors introduced by the analysis procedure itself. Note that three of the four involve contamination. Although element dependent to some extent, contamination is strongly concentration dependent, i.e., about 1000 times worse at nanograms-pergram levels than at micrograms-pergram levels. Sampling. Collecting a meaningful, representative sample without contaminating it is the first step in a successful analysis. Failure at this step renders all subsequent steps a t best meaningless, and at worst harmful, say, in the case of medical diagnosis prior to treatment. The 195’7statement by Thiers is still valid: “Unless the complete history of any sample is known with certainty, the analyst is well advised not to spend his time analysing it.” Collecting blood samples, for example, is widely accomplished with disposable stainless steel needles. Because the normal levels of elements like chromium, manganese, and nickel (major components of stainless steel) are in the nanograms-per-milliliter range and below, this practice invites serious contamination problems. For this purpose, plastic catheters or cannula are recommended, and the initial portion of the sample should be discarded or used for other measurements. We have had success using metal needles that have been siliconized, which renders the surface hydrophobic and prevents sample contamination with adventitious trace elements. Blood samples are often collected using evacuated glass containers with rubber stoppers or syringes with rubber plungers, sometimes containing an anticoagulant. These can all lead to sample contamination. I once received a call from a colleague trying to measure chromium in blood plasma. The conversation went something like this: He: “We’re getting ash buildup in the furnace tubes, even with a fivefold 854A
sample dilution.” I: “A fivefold dilution would put them below your detection limit.” He: “Oh, no. We get very consistent values, all about 2 ppb.” I: “Next you’re going to tell me you collected the samples in-(a particular evacuated tube type).” He: “How did you know?” I: “That’s what we get when we use those too.” It was due primarily to the anticoagulant used in the devices, at least in that batch. The established level of chromium in plasma is about an order of magnitude lower than that. Moral: Check everything. In the words of Wayne Wolf here at the U S . Department of Agriculture, to analyze samples in the parts-per-billion and subparts-per-billion range, one has to become “usefully paranoid’’ about contamination. Storage. The container used to store the sample, be it the collection vessel itself or another one, is a potential source of contamination, and in some cases even analyte loss by adsorption. Generally, plastic materials such as polyethylene or polypropylene serve best. Once again, the analyst is cautioned to check everything carefully. For samples stored frozen in plastic containers for long periods, another possible source of error exists. Plastic materials are not completely impermeable to water vapor, and even frozen water has a finite vapor pressure. This can lead to a gradual moisture loss by lyophilization with time. This process can be slowed by packaging the frozen sample containers in sealed plastic bags containing a few cubes of ice, so they are in an approximately 100%relative humidity environment within the freezer. Alternatively, the samples could be freeze-dried before storage. This might be beneficial if subsequent sample preparation procedures can benefit from a dry sample. Keep in mind that biological fluids often segregate during freezing so the dry material may not be homogeneous. This is not a serious problem if the entire contents of a container are one sample or if the sample is to be reconstituted with water prior to analysis. Each of these possibilities should be carefully checked before procedures are adopted. Sample preparation. Anything done to the sample prior to analysis obviously can lead to contamination. Besides containers, other possible sources of contamination (or analyte loss) include reagents, airborne particulates, and even the analyst. In the best of worlds and with analytical techniques that are sufficiently sensitive and free of matrix interferences, one could perhaps place an aliquot of an uncontaminated sample
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
collection directly into the instrument with little or no contamination. Blanks would be minimal or even unnecessary. Although there are such situations, rest assured that they are the exception rather than the rule. Urinary chromium, for example, can be determined directly by graphite furnace atomic absorption using the method of additions. Given adequately controlled sample collection, storage, containers, pipet tips, etc., the main source of contamination might be airborne. If sample manipulation is carried out in a clean room or Class100 laminar flow hood this is minimized, and routine determinations at the 0.1-0.2 ng/mL level are possible. For serum chromium determinations, the situation is far more difficult. Sample collection is not as easy, and the organic matrix needs to be destroyed by dry ashing in quartz tubes in a controlled environment, after freeze-drying, after adding a matrix modifier (e.g., Mg(NO&), after dissolution of the ash in acid, and so on. Just to make things more fun, the levels of serum chromium are slightly lower than those of urine. The good news (?) is that the uniform inorganic matrix of serum makes it unnecessary to do every sample by the method of additions. Remember, think “usefully paranoid.” Another source of contamination is the analyst. Handling things with bare hands has obvious disadvantages, and skin, hair, and clothes generate particles. So you don nice vinyl gloves to prevent some of this, but not the ones powdered with talc to make them easy to put on. Then you find out that handling plastic containers with plastic gloves creates a thing called static electricity, helping to clear the air in the laboratory of airborne particles. Seriously, the analyst must take measures to protect the samples from himself or herself. In some cases, these measures are also to protect the analyst from the sample. W h e n dealing with samples of h u m a n origin, t h e analyst m u s t keep in mind t h e possibilit y of disease transmission. Contamination, by definition, leads to analysis results that are too high. Occasionally, results that are too low are obtained. Aside from analyte adsorption onto surfaces, several other causes of erroneously low results are possible. Some extraction, dissolution, or solubilization process in the procedure might be incomplete. A component of the matrix might cause a suppression of the analyte signal to a greater degree than the “standards.” This is why, for example, recovery experiments and the method of additions do not verify (by themselves) the accuracy of a trace element determination in a biological matrix. These
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are necessary-but-not-sufficient tests. Another cause of low results is loss of analyte by volatilization. This can occur during sample drying, dry ashing, wet digestion, treatment with reagents, or because of the existence of reducing (or oxidizing in some cases) conditions during sample preparation. It is more of a problem with the elements considered “volatile,” such as As, Se, and Hg. The elements Zn and Cd could be lost during dry ashing a t 856A
too high a temperature, or in the presence of chloride, which could form volatile compounds of the analyte. In biological samples, the analyte might be present in a volatile organic form lost at unsuspected temperatures or a form that is somewhat refractory to complete breakdown with expected chemical treatments, leading to incomplete recoveries. Again using chromium as an example, persistent reports over the years
ANALYTICAL CHEMISTRY, VOL. 58. NO. 8. JULY 1986
have appeared suggesting that some biological forms of the element exist that could be lost during sample drying or dry ashing. Versieck and Cornelis ( 2 )reviewed this literature and concluded that this argument cannot be sustained. We have conducted numerous experiments with animal fluids and tissues endogenously radiolabeled with W r in checking out various sample preparation and analysis procedures. No significant chromium losses have ever been observed, including dry ashing temperatures up to 450 “C and furnace charring temperatures of 1200 “C. All other causes of analytical error in the determination of chromium would produce high results. This is consistent with the pattern evident in the literature on this determination. Analysis. A number of analytical techniques are suitable for determining elements in biological samples. For the major elements, i.e., elements normally present in substantial quantities, such as Na, K, Ca, and Mg, most techniques allow or require a substantial dilution of the sample. This also dilutes the sample matrix as well, although these elements usually are the matrix for the trace elements present at much lower concentrations. Techniques most popular for these elements include flame atomic emission spectrometry, flame AAS, ion-specific electrodes, and colorimetry. For the trace elements present in the partaper-million concentration range, e.g., Fe, Cu, and Zn, a wide variety of the techniques are used, including atomic emission, absorption, and fluorescence; voltammetry; and neutron activation. Probably the most widely used technique is flame AAS. For the ultratrace elements, those with concentrations in the parts-per-billion region and below, the number of suitable techniques drops rapidly, because of the analytical sensitivity required. Some determinations, generally those somewhat above the 1-ng/g level, have been reported using inductively coupled plasmas (ICPs), both by atomic emission and by atomic fluorescence, and by voltammetry. As stated earlier. for elemental concentrations a t these levels, and especially for those in the sub-parts-per-billion range, neutron activation, mass spectrometry, and furnace atomic absorption techniques are needed, the last being by far the most accessible. Accuracy verification. Because of the ready availability of atomic absorption spectrometry, and because many users of the technique do not fully understand or appreciate the limitations of the methodology, a great deal of questionable data has a p peared in the literature. I t is questionable in the sense that the accuracy of
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the results has not been adequately established. This problem was addressed recently by Versieck in a paper titled “Trace element analysis-A plea for accuracy” ( 3 ) .In the abstract he states that: Mounting evidence suggests that much previous work on trace elements in human body fluids and tissues must have severely suffered from methodologic deficiencies. In these days of confusion about the reliability and validity of trace element measurements, upon which far reaching decisions are made concerning health affairs, accuracy is urgently needed and indeed required if rational conclusions are to he reached.
I agree entirely with this and feel very strongly that all analytical data published by journals should be verified for accuracy. Accuracy of an analytical determination can be established in one of two ways. The first way would be to analyze the same samples (or representative samples if the matrix is uniform) by two or more i n d e p e n d e n t methods. Because many laboratories do not have (or have access to) two independent methods for the same determination, the second way would be to analyze reference materials. These are materials whose analyte content(s1 has been established by two or more independent methods, and whose m a trix is as nearly identical t o t h a t o f t h e samples as possible. In the past, the number of suitable
biological reference materials was small, and the analyte concentrations not always in the most useful range. This situation, however, has changed a great deal in the past few years. A number of organizations and laboratories have produced and established the analyte concentrations in a variety of biological reference materials. The most complete and recent compilation of these is that of Muramatsu and Parr ( 4 ) of the International Atomic Energy Agency in Vienna, Austria. The box on p. 856 A is a list of suppliers of these biological materials, and the appendix following this article lists the elements for which information is available. A complete copy of the survey can be obtained from R.M. Parr, IAEA, P.O. Box 100, A-1400 Vienna, Austria. The use of these reference materials in verifying the accuracy of methods used to generate data on trace element content of biological samples is perhaps, in the words of Versieck ( 3 ) , “the only way out of the morass of confusion.” There are still some gaps in available materials, particularly in materials where the analyte content is very low, but several groups are working to fill these gaps in the very near future. I urge all editors and reviewers, particularly in nonanalytical journals that publish analytical data, and especially those in the biological areas, to insist that analytical data be verified and/or the accuracy of the method for t h a t
determination in t h a t sample t y p e be established. I know that this is not always possible, due to lack of an appropriate reference material or access to an independent method. But if this is the case, do we really need these data?
References ( 1 ) Guthrie, B.E.;Wolf, W. R.; Veillon, C.
Anal. Chem. 1978,50,1900. (2) Versieck, J.; Cornelis, R.; Anal. Chim. Acta 1980,116,217. (3) Versieck, J. Trace Elem. Med. 1984,1, 2. (4) Muramatsu, Y.;Parr, R. M. IAEA/RL/ 128,December 1985.
Claude Veillon is a research chemist i n t h e V i t a m i n and Mineral N u t r i tion Laboratory, one o f f i v e laboratories comprising t h e Beltsville H u m a n N u t r i t i o n Research Center of t h e U.S. Department of Agriculture. H e received his undergraduate training i n chemistry a t t h e University of Southwestern Louisiana and graduate training i n analytical chemistry (Ph.D. 1965) f r o m t h e University of Florida, specializing in atomic spectroscopy. I n t h e early 1970s, his research interests turned toward t h e role of trace metals in biological systems. His current interests are in developing valid methods f o r essential trace elements in biological samples, application of enriched stable isotopes in metabolic tracer studies in h u m a n s , and preparation of biological reference materials.
Appendix. Overview of biological and environmental reference materials and elements quoteda Supplier
BCR
Name or code No (Supplier)
Code NO. (this report)
Unit weight or volume
Cost
Quoted elements
Blologlcal materials Aquatic plant
CRM-060
BCR-CRM-060
25 9
$25
Aquatic plant
CRM-06 1
BCR-CRM-061
25 9
$25
Olive leaves
CRM-062
BCR-CRM-062
25 9
$25
Skim milk powder
CRM-063
BCR-CRM-063
30 9
$45
Skim milk powder (lower level spiked) Skim milk powder (higher level spiked) Blood Blood Blood Single-cell protein
CRM-150
BCR-CRM-150
30 9
$30
AI Ca CdCl CuFe HgK Mg MnNNaP Pb S Si Ti Zn AI Ca CdCl Cu Fe HgK Mg MnN Na P Pb S Si Ti Zn AI Ca CdCl Cu Fe HgK Mg MnN Na P Pb S Si Ti Zn Ca Cd CI Co Cu Fe Hg K Mg Mn N Na Ni PfbSeTIZn CdCo Cu Fe Hg IMn Ni Pb Se TI Zn
CRM-151
BCR-CRM-15 1
30 9
$30
CdCoCuFeHgIMnNiPbSeTIZn
CRM-194 CRM- 195 CRM- 196 CRM-273
BCR-CRM-194 BCR-CRM- 195 BCR-CRM-196 BCR-CRM-273
?
?
? ? ?
? ?
BCR-CRM-038
69
$20
Material
Envlronrnental materials (nonblologlcal) Fly ash CRM-038
Coal Soil (calcareous loam)
CRM-040 CRM- 141
BCR-CRM-040 BCR-CRM-141
?
Cd f b Cd Pb Cd Pb Ca Fe K Mg N P As Cd Co Cr Cu Fe Hg Mn Na Ni Pb Th V Zn As Cd Co Cr F Hg Mn Ni Pb TI Zn AI Ca Cd Co Cr Cu Fe Hg K Mg Mn Na Ni P Pb Se Si Ti Zn
continued a
If the element symbol is italicized, a certified or recommended value is available: if not italicized, only an information value is available.
858A
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
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Appendix, continued Supplier
BCR
Material
Name or code No. (Suppller)
Code No. (this report)
Envlronmental materlais (nonblologlcal) cont. Soil (light sandy) CRM- 142 BCR-CRM-142 Soil (amended sewage sludge) Sewage sludge (domestic origin) Sewage sludge Sewage sludge (industrial origin) City waste Incineration ash Gas coal Coking coal Steam coal
Unit weight or volume
Cost
40 9
$25
CRM-143
BCR-CRM- 143
40 9
$25
CRM- 144
BCR-CRM-144
40 g
$25
CRM- 145
BCR-CRM-145
40 g
$25
CRM- 146
BCR-CRM-146
40 g
$25
CRM-176
BCR-CRM-176
30 g
$25
CRM- 180 CRM- 181 CRM-182
BCR-CRM-180 BCR-CRM-18 1 BCR-CRM-182
? ? ?
? ? ?
Quoted elements
AI Ca Cd Co Cr Cu Fe Hg K Mg Mn Na NiPPbSeSiTiZn AI Ca Cd Co Cr Cu Fe Hg K Mg Mn Na NiPPbSeSiTiZn AI As Ca Cd Co Cr Cu Fe Hg K Mg Mn Na Nip Pb Se Si Ti Zn AI Ca Cd Co Cr Cu Fe Hg K Mg Mn Na NiPPbSeSiTiZn AI Ca Cd Co Cr CuFe HgK Mg Mn Na NiPPbSeSiTiZn AI AsCa W C o C r C u F e H g K M g M n Na NIP Pb S Sb Se Si Ti TIZn As C Cd CI H Hg Mn N Pb Se VZn As C CdCl H Hg Mn N Pb Se VZn As C Cd CI H Ha Mn N Pb Se V Z n ~~~
BI
Biological materials Blood
Blood
Urine
Urine
Urine
Control blood for metals 1 (OSSD) Control blood for metals 2 (OSSE) Lanonorm metals 1 (OSSA) Lanonorm metals 2 (OSSB) Lanonorm metals 3 IOSSC)
BI-CBM-1
4X5mL
$22
CdCrHgPb
BI-CBM-2
4X5mL
$22
CdHgPb
BI-CUM-1
12 X 50 mL $74
As Cd Co Cr Cu F Hg Ni Pb
81-CUM-2
12 x 50 mL $74
As Cd Co Cr Cu F Hg Ni Pb TI
BI-CUM9
12 x 50 mL $74
As CdCo Cr C u F Hg NiPb TI ~~
BOWEN Biological materials Kale
Kale
~~~
BOWEN's Kale
100 g
$15
~~~~
Ag AI As Au B Ba Br C Ca CdCe CI Co Cr Cs CuEu F F e Ga H Hf Hg I In K L a Li Lu Mg Mn Mo N Na N i O PPb Rb Ru S Sb Sc Se SiSm Sn Sr Th U VW
zn IAEA
Blological materlals Milk powder
A-1 1
IAEA-A-11
$40
Animal blood
A-13
IAEA-A-13
$80
Animal muscle
H-4
IAEA-H-4
$80
Animal bone Horse kidney
H-5 H-8
IAEA-H-5 IAEA-H-8
$40 $40
Copepod
MA-A-1(TM)
IAEA-MA-A-1
$40
Fish flesh
MA-A-P(TM)
I AEA-MA-A-2
$40
Mussel tissue
MA-M-P(TM)
I AEA-MA-M-2
$40
Rye flour
V-8
IAEA-V-8
$40
Cotton cellulose
v-9
IAEA-V-9
$80
Hay powder
v-10
IAEA-V-10
$80
AI As Au B Ba Br Ca Cd CI Co Cr Cs Cu F F e H g l K L i MgMnMo NaNiPPb Rb Sb Se Si Sn Sr V Zn Br Ca Cu Fe KMg Na NI P Pb Rb S Se Zn AI As Br CaCe CICo Cr Cs Cu Fe Hg K MgMnMoNaRbSSeVWZn Ba Br Ca CI Fe K Mg Na P Pb Sr Zn BrCaCdCICoCsCuFeHgKMgMn M o N a P R b S SeSrZn A g As Cd Co Cr Cu Fe Hg Mn Ni Pb Sb Se Zn Ag As Cd Co Cr Cu Fe Hg Mn Ni Pb Sb Se Zn Ag As Au Br Ca CdCl Co Cr Cu Fe Hg Mg Mn Na Pb Rb Sb Sc Se Sr Zn AI A u B a B r C a C d C I C o C s C u F e K M g Mn Mo Na P Rb S Sb Zn AI Ba Br Ca Cd CI Cr Cu Fe Ga Hf Hg Li Mg Mn Mo Na NiPbS Sc Se Sm Sn SrTh U V AI Ba Br Ca Cd Co Cr Cs CuEu Fe Hg K La Mg Mn Mo Na Ni P Pb Rb Sb Sc Se Sr Zn
continued8 6 0 A * ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
IBM INSTRUMENTS ANNOUNCES AN IMPORTANT MERGER.
FT-IR will never be the same. Introducing the IR/44 from IBM Instruments. It’s more than a combination of advanced IR optics, innovative software, versatile accessories and the IBM Personal Computer AT. It’s a merger of the technical expertise of IBM Instruments with the computer expertise of 1BM.Theresult is an IR spectrometer that offers dependable operation for repetitive analyses, as well as the performance and versatility for applied spectroscopy. For repetitive analyses, the proven optics deliver precise, reproducible results. Our innovative software is easy to learn and use in interactive or automated mode. So, now you have the power to do more with your data than ever before. For applied spectroscopy, high energy optics and 0.5 cm-’resolution give you the performance you need for demanding experiments.
chemometrics allows you to perform complex spectral arithmetic automatically, so you can get the best answers. S tem software incorporates quantitative analysis and spectral search routines, so you can increase productivity through instant access and methods automation. Multicolor overlays make your spectral data easier to analyze. And data analysis and reporting capabilities can easily be expanded to include spreadsheets and scientific word processing. So whether your goal is quantitative analysis or structural characterization, you’ll tale your hat off to the new IR/44. For more information, call us today at 800-243-7054 (in Connecticut, 800-952-1073), or write to: IBM Instruments, Inc., Dept. 78Y, P.O.Box 3332, Danburi, C T 06810.
Ts
CIRCLE 107 ON READER SERVICE CARD ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
861 A
Appendix, continued Supplier
IAEA
RANT
KL
Name or code No.
Code No.
(SUPPller)
(this report)
Material
Environmental materials (nonbiological) Air filter Air-3/1
IAEA-Air-3/ 1
Marine sediment
SD-N-l/P(TM)
IAEA-SD-N-1/2
Lake sediment
SL- 1
IAEA-SL-1
soii
SOIL-7
IAEA-SOIL-7
Fresh water
w-4
IAEA-W-4
Fresh water
w-5
IAEA-W-5
Unit welght w volume
cost
Qwted elements
$80
AsAuBa CdCoCrCu FeHg MnMo Ni Pb Se U VZn
$80
A g AI As Au Ba Be Br Ca Cd Ce CI Co Cr Cs Cu Dy Eu Fe Hf Hg I K La Li Lu Mg Mn Mo Na Nd Nl P Pb Rb Sb Sc SeSiSmSrTaTbThTiUVWYYb Zn Zr
25 g
$80
25 g
$80
AsBaBrCaCdCeCoCrCsCuDyEu FeGa Ge HfHg K LaLi Lu Mg MnMo Na Nd Ni Pb Rb S Sb Sc Se Sm Sr Ta Tb T h T i U V W Y YbZnZr AI As Ba Br Ca Cd Ce Co Cr Cs Cu Dy EuF Fe Ga Hf Hg HoK LaLi Lu Mg MnMoNaNb NdNiPPbRbSbSc SeSiSmSrTaTbThTiUVYYbZn Zr AI As B Ba Be Ca CdCo Cr Cu Fe Hg K Mg Mn Mo Na Ni Pb Se Sr U VZn
Six filters (+ six blanks) 25 g
Concentrates $80 in quartz ampule Concentrates $40 in plastic bottle
(Same as W-4)
Environmental materials (nonbioioglcal) Coal fly ash ECH
IRANT-ECH
50 9
$80
Coal fly ash
EN0
RANT-EN0
50 9
$80
Coal fly ash
EOP
RANT-EOP
50 g
$80
Contox No. 0100 (High) Contox No. 0100 (Low) Contox No. 0100 (Medium) Contox No. 01 10 (High) Contox (No. 0110 (Low) Contox No. 01 10 (Medium) Contox No. 0140 (I) Contox No. 0140 (Ii) Contox No. 0141 (I) Contox No. 0141 (ii) Contox No. 0146 (I) Contox No. 0146 (11)
KL-100-H
4X5mL
$40
Pb
KL- 100-L
4X5mL
$30
Pb
KL- 100-M
4X5mL
$30
Pb
KL- 110-H
4X5mL
$40
Pb
KL- 110-L
4X5mL
$30
Pb
KL- 110-M
4X5mL
$40
Pb
KL-140-1
4X5mL
$50
As Cd Hg
KL-140-11
4X5mL
$50
As Cd Hg
KL-141-1
4X5mL
$50
As Cd Hg
KL-141-11
4X5mL
$50
As Cd Hg
KL-146-1
4X5ml
$50
Cu Fe Zn
KL-146-11
4X5mL
$50
Cu Fe Zn
Biological materials Blood (lead control) Blood (lead control) Blood (lead control) Urine (lead control) Urine (lead control) Urine (lead control) Urine (heavy-metal control) Urine (heavy-metal control) Blood (heavy-metal control) Blood (heavy-metal control) Serum (trace metal control) Serum (trace metal control)
AI As Ba Be Ca CdCe Co Cr Cs Cu Eu Fe Ga Hf K L a Lu Mg Mn Na Ni Pb Rb Sb Sc Si Sm Sr Ta Tb Th Ti U V Yb Zn Zr AlAsBaCaCeCoCrCsCuEuFeGa Hf K La Lu Mg Mn Na Ni Pb Rb Sb Sc Si Sm Sr Ta Th Ti U V Yb Zn Zr A I As Ba Be Ca Cd Ce Co Cr Cs Cu Eu Fe Ga Hf KLa Lu Mg Mn Na Ni Pb Rb Sb Sc Si Sm Sr Ta Tb Th Ti U V Yb Zn Zr
continued 862A
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
-
NAPCO GLASSWARE WASHERS AND DRYERS. FlTT..NG CEAUUNESS. NAPCO washers and dryers not only clean glassware, they also fit into any lab. How? With models ranghg from economical single-basket . ..to roomier two-basket. . . to fourbasket, ..to high-volume si-basket. Or, if your space is really tight, with compact undercounter units. Remdess of caoacitv "~ requirements. we have the washer to fit. But, there's more. NAPCO glassware washers also fit tough lab demands for durabdity, convenience and thorough cleaning. Panels and parts (Randy, above. foms them) are made from high-grade corrosia and contamination-resistant stainle steel. Di&l controls provide conv nient. push-button selection of was cycles and water temperature. A patented moving jet spray system reaches into glassware of all sizes and shapes, even the smallest ~
~~
~
I
~
.
I
pipette. And, NAPCOs exclusive triple-plumbing system provides contamination-free cleaning. And if you need a dryer for that clean glassware, NAPCO can still help. We make four and six-basket configurations. AU stainless steel lke our washers. And all with oroerammable control. f l y autoAtiF operation and mechanically convected heat. NAPCO glassware washers and dryers. Fitting cleanliness. Because we want a place in your lab. For more information, call us tollfree, 800-547-2555. Or, write NAPCO, 20210 S. W. Teton, PO. Box 1o00, Tualatin, Oregon 97062.
P E ~ B U I VwIEIIyIDlAElWToRY L ~ EWMlEM CIRCLE 150 ON READER SERVICE CARD
I
Appendix, continued Name or code No. (Supplier)
Code No. (this report)
RM-50 RM-84 19
NBS-RM-50 NBS-RM-8419
2 X 35g 3 X 4mL
$81 $52
Milk powder (nonfat)
SRM-1549
NBS-SRM1549
100 g
$138
Oyster tissue
SRM-1566
NBS-SRM1566
30 9
$89
Wheat flour
SRM-1567
Rice flour
SRM-1568
Brewers yeast
SRM-1569
Citrus leaves
SRM-1572
NBS-SRM1567 NBS-SRM1568 NBS-SRM1569 NBS-SRM1572
Tomato leaves
SRM-1573
Pine needles
SRM-1575
Bovine liver
SRM-1577a
Supplier
NBS
Material
Biological materials Albacore tuna Bovine serum
Urine (normal) SMR-2670 (Freeze-dried) Urine (spiked) SRM-2670 (Freeze-dried) Environmental materials (nonblologlcal) Crude oil RM-8505 Coal fly ash SRM- 1633a
NlES
NBS-SRM1573 NBS-SRM1575 NBS-SRM1577a NBS-SRM2670 NBS-SRM2670
Unit weight or volume
Cost
70 9
$102
70 g
$102
50 9
$1 16
AI As Ba Br Ca Cd Ce CI Co Cr Cs Cu Eu Fe Hg I K L a Mg Mn MoN Na Ni P Pb Rb S Sb Sc Se Sm Sn SrTe TI U z n AI A s 6 Br CaCd Ce Co Cr CuEu f e H g KLa Mg Mn N PPb Rb Sc Sr Th TI U Zn A i As Br Ca Ce Co Cr Cr Cu Eu Fe Hg K LaMnNNiPPbRbSbScSrThTIU AgAl AsBr Ca WCICoCufemgKMg Mn Mo N Na P pb Rb S Sb Se Sr TI UZn AI As Be Ca Cd CI Cr Cu Hg K Mg Mn NaNiPbPtSSe AI A s B e C a C d C l C r C u H g K M g M n Na Ni Pb Pt S Se
2 X 20mL
$184
NBS-RM-8505 NBS-SRM1633a
275 mL 75 9
$52 $125
NBS-SRM1634a NBS-SRM1635 NBS-SRM1636a NBS-SRM1641b NBS-SRM1642b NBS-SRM1643b NBS-SRM1645 NBS-SRM1646
100mL
$153
75 9
$108
Set(l2)
$111
6X20mL
$126
950mL
$154
Hg
950mL
$163
70 9
$135
75 9
$116
2g
$127
A g As B Ba Be Bi Cd Co Cr Cu f e Mn MoNiPbSeSrT/VZn A i As Ca Cd Co Cr Cu F Fe Hg KLa Mg Mn Na Ni Pb S Sb Sc Se Th TI U VZn A I As Be Ca Cd Ce Co Cr Cs Cu Eu f e GeHgKLiMgMnMoNaNiPPbRb S Sb Sc Se Si Te Th Ti TI VZn Ag A I As Ba Br Cd Ce CI Co Cr Cs Cu Eu Fe Hf I In K La Mg Mn Na Ni Pb Rb S Sb Sc Se Sm Th Ti U V W Zn
SRM- 1634a
Coal (Sub-bituminous) Fuel
SRM-1635
Water
SRM-1641b
Water
SRM-1642b
Water
SRM-1643b
River sediment
SRM-1645
Estuarine sediment
SRM- 1646
Urban particulate
SRM- 1648
NBS-SRM1648
Blologlcal materlals Pepperbush
CRM-1
NIES-CRM-1
14 9
Free
Chlorella Human hair
CRM-3 CRM-5
NIES-CRM-3 NIES-CRM-5
36 9 29
Free Free
Mussel
CRM-6
NIES-CRM-6
10 9
Free
NIES-CRM-2
20 g
Free
Environmental materials (nonblologlcal) Pond sediment CRM-2
As HgK Mn Na Pb Se Zn A i Ca Co Cr Cu Fe K Mg Mn Mo Na Ni Se V Zn Ag AI AI As Br Ca Cd CI Co Cr Cu F f e HgIKMgMnMoNaPPbRbSSbSe Si Sn Zn Ag As Br Ca CdCl Co Cr Cu F f e Hg I K Mg Mn Mo Na Ni P Pb Rb S Se Sr Th TI U VZn AsBr C a C d C u f e H g K M n M o N a N i Rb SeTe Zn As Br Ca Cd Co Cu Fe Hg K Mn Mo Na Ni Pb Rb Se Te
cr
Fuel oil
SRM-1636a
Quoted elements
v AI As Ba Be Ca Cd Ce Co Cr Cs Cu Eu FeGaHfHgKMgMnMoNaNiPbRb Sb Sc Se Si Sr ThTi TI U V Zn As Be Br Ca Cd CI Co Cr Fe Hg Mn Mo Na NiPb S Se VZn AI As Cd Ce Co Cr Cu Eu Fe Ga Hf Mn Na NiPb S Sb Sc Se ThTi U VZn Pb
As 6a Ca Cd Co Cr Cs Cu Fe Hg K Mg Mn Na N i p Pb Rb SrTl Zn Ca Cd Co Cu Fe K Mg Mn P Pb Sc Sr Zn AI Ba Br Ca Cd CI Co Cr Cu Fe Hg K Mg Mn Na N i p Pb Rb Sb Sc Se SrTi Zn Ag AI As Ca Cd Co Cr Cu Fe Hg K Mg MnNaNiPPbSeSrZn A i As Br Ca Cd Co Cr Cu Fe Hg K La Mn Na Nip PbRb Sb Sc Si Sr Ti V Zn
~
continued 864A
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
+
Sm-MOGRAM t , GCl.-IR (with times the of light pipe IST ' IMPOSSIBU. I T S CiULED bbCRYOLECT. 100
sensitivity
analysis)
SEND FORA TECHNIGU INFORMATION KIT ON THE CRYOLECT Matrix isolation-enhanced infrared spectra yield chemical information that goes far beyond conventional IR technology. GC/MUFT-IR is known to exhibit GCMS sensitivity, but its unique specificity makes it a new problem-solving tool for analytical chemistry.
mecqoien~~im-i~ system
The Cryolect is frequently used in the foflowine axeas: ~
0 0
Petrochemicals Flavors and Fragrances Pharmaceuticals Specialty Chemicals &ricultural Chemicals Environmental Monitoring
and Control
P
A NEW TECHNI
UE FOR
CWTURINC IN ORMATION ?he Cryolect GCMVFT-IR System the separationcap&liw of a gas with the Epectral specificip, of a ~~~~i~~ T ~ form Infrared Spectrometer. Now high resolution infrared absorption spectra can be recorded for less than
nanomam.~eve~ quantities ofsample.
The Cryolect uses matrix isolation (MI)at cryogenic temperatures to immobilize moleculesin an inert "cage" of argon. The entire processsample deposition, infrared collection and data processing-is completely automated.
SUPERIOR RESOLUTIONAND SAMPLERETEVTION Up to five hours of effluent peaks can be~collectedand held at one time, with five-second peak resolution (or less, after spectral manipulation). Reduced sample area is the single most impor. tant factor in the Cryolect's improved ~sensitivity, ~ ~giving , infrared absorbances 16 to 144 times stronger than "on-the. fly" GC sampling. The Cryolect can distinguish between nearly identical chemical SMCNWS, such as isomers, with no destruction of the sample.
C l R W 141 ON READER SERVICE CARD
Send for our free folder "ProblemSolving with the Cryolect System." It explains in detail how the Cryolect works and the kinds of problems it is being used to solve. Please write J.E. Carroll at Mattson Instruments and describe the specific application area that concerns y
Appendix, continued Supplier
NRCC
NYE
SABS
Name or code No. (Supplier)
Code NO. (this report)
Unit weight or volume
Cost
NRCC-TORT- 1
30 9
$62
As Ca Cd CI Co Cr Cu Fe Hg K Mg Mn Mo Na Ni P Pb S S e Sr VZn
Envlronmental rnaterlals (nonblologlcal) Marine sediment BCSS- 1
NRCC-BCSS-1
80 9
$87
AI As
Seawater Marine sediment
CASS-1 MESS-1
NRCC-CASS-1 NRCC-MESS- 1
2L
80 g
$109 $87
Seawater
NASS- 1
NRCC-NASS-1
2L
$109
Biologlcal materials Serum Urine Serum
SERONORM(105) SERONORM(108) SERONORM( 164)
NYE-105 NYE-108 NYE-164
6X3mL 6 X 10 mL 10 x 5 mL
? ? ?
Se Se Ca CI Cu Fe K Mg N Na P Zn
SABS-SARM18
120 g
?
A I B Ba BeBr Ca Ce Co CrCs CuEu Fe Ga Ge H f Hg K L a Li Mg Mn Mo Na Nb Ni PPb Rb S Sb Sc Si Sm Sn SrTa Tb Th T i U VW Y Zn Zr AI As B Ba Be Br Ca Ce CI Co Cr Cs Cu Eu Fe Ga Ge HfHg K La Li Mg Mn Mo Na Nb Ni P Pb Rb S Sb Sc Se Si Sm Sn SrTa Tb Th Ti U V W Y Yb Zn Zr AI As B Ba Be Br Ca Ce Co Cr Cs Cu Eu Fe Ga Hf Hg K La Li Mg Mn Na Nb Ni P Pb Rb S Sb Sc S e Si Sm Sn Sr Ta Tb Th Ti U V W Y Yb ZnZr
Material
Biological materials Lobster hepatopancreas
TORT- 1
Environmental materials (nonbiologlcal) Coal (Witbank) SARM- 18
Coal (0.F.S)
SARM- 19
SABS-SARM19
120 g
?
Coal (Sasolburg)
SARM-20
SABS-SARM20
120 g
?
Quoted elements
Be C Ca Cd CI Co Cr Cu Fe Hg K Mg Mn Na Ni P Pb S Sb Si Ti V Z n As Cd Co Cr Cu Fe Mn Ni Pb Zn AI As Be C Ca Cd CI Co Cr Cu Fe Hg K Mg Mn Na Ni P Pb S Sb Si Ti V Z n As Cd Co Cr Cu Fe Mn Mo Ni Pb Zn
Rapid Scan Spectrophotometer .Minimum dead time - 500 psec 0 16 spectra measured every 1 msec sequentially *Simple and robust mixing system without syringe 0 Fluorescence, T-jump and flash accessories. CIRCLE 2 ON READER SERVICE CARD
866A
ANALYTICAL CHEMISTRY, VOL. 58, NO. 8, JULY 1986
Please write to:
ATAGO BUSSAN C0.9 LTD. 7-23,5-chome Shimbashi, Mtnato-ku, Tokyo 105 Telex: 28421 Phone: (03)432-8741
