Fisher Award Address
Evaluation of Lunar Elemental Analyses GEORGE H. MORRISON Department of Chemistry Cornell University Ithaca, N.Y. 14850
Jet Propulsion Laboratory
Examination of chemical analyses data of a Moon soil sample demonstrates some of the difficulties in the analysis program. Far-reaching geochemical interpretations of lunar history can be generated from the existing data, but substantiation awaits correction of some of the deficiencies in the analytical data
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ANALYTICAL CHEMISTRY, VOL. 4 3 , NO. 7, JUNE 1971
REPORT FOR ANALYTICAL CHEMISTS
QTXJDY OF THE Apollo lunar samples ^ represents a unique scientific ad venture and an intellectual chal lenge of t h e first magnitude. As one might expect, chemical analysis, and particularly trace analysis, plays a very important role in t h e L u n a r Analysis P r o g r a m of the N a tional Aeronautics and Space Ad ministration. B y comparing t h e elemental abundance patterns of lunar material with those of solar, meteoritic, and terrestrial materials, some insight into t h e cosmological history of t h e Moon is being ob tained. Thus, the chemical compo sition of t h e lunar surface reflects at least three major processes: chemical fractionations during a c cretion of the Moon from the solar nebula, magnetic differentiation, and infall of meteorites and cosmic dust. Although much has been pub lished on the results of the study of lunar samples returned b y t h e Apollo 11 and 12 missions and their geochemical significance (1-4), lit tle has been said about the analyti cal techniques employed and t h e quality of the analytical data. As an analytical chemist and one of the Principal Investigators in this ex citing program, I would like on the occasion of this award symposium to acquaint the community of ana lytical chemists with some interest ing facts and figures on the analyses performed on these precious sam ples. At this point it would be helpful to indicate t h e different types of lunar material returned. The Apollo 11 mission returned 22 kg of soil and rocks collected on the sur face of M a r e Tranquillitatis, Apollo 12 returned 33.6 k g of similar ma
terial from Oceanus Procellarum, and most recently, Apollo 14 r e turned approximately 49 kg of high land material from F r a M a u r o . T h e Soviet Union with its u n manned Luna 16 mission h a s also returned some 100 g of material from the surface of M a r e Fecunditatis. The different types of m a t e rials returned from the maria re gions b y the Apollo 11 and 12 mis sions include fine-grained (type A) and medium-grained (type B ) b a saltic igneous rocks, microbreccia (type C) which are compacted co herent rocks consisting of a m e chanical mixture of soil, igneous rock fragments and glass, and soil material (type D ) of an average particle diameter of 100 μ. Also found in the soil and in some rocks were glassy beads a n d fragments. After preliminary examination of the material a t the M a n n e d Space craft Center in Houston, selected samples were distributed to some 170 Principal Investigators around the world for use in detailed studies {5). The L u n a r Sample Analysis P r o gram of NASA consists of four ma jor areas of study: (1) mineralogy and petrology, (2) chemical a n d isotopic analysis, (3) physical stud ies, and (4) organic and biochemical analysis. I n this article we limit our discussion t o chemical analysis. I n the category of chemical and iso topic analysis, various principal in vestigators a r e concerned with o b taining information on elemental composition including major, minor, and trace elements. Other studies include t h e determination of iso topic, composition, ages, surface composition, t h e nature of t h e oxi dation states of certain elements,
and the distribution of elements in the various mineral phases. To accomplish these different tasks, a variety of analytical tech niques is being employed. Apollo 12 is used as an example, and these techniques are listed in Table I along with t h e number of labora tories who used each in their studies. I t should be noted t h a t an impor t a n t aspect of the analysis program is to provide a reasonable duplica tion of effort to ensure meaningful results. Also, many of the investi gators have had considerable pre vious experience in t h e analysis of meteorites a n d terrestrial geologi cal samples using these techniques. Examination of this list reveals the inclusion of all major techniques for the determination of elemental and isotopic concentrations. T o determine elemental composi tion, t h e techniques of activation analysis, atomic absorption, emis sion spectroscopy, flame photome try, inert gas fusion, mass spec trometry, spectrophotometry, wet chemistry, and X - r a y fluorescence were employed. Because of t h e large number of elements t o b e de termined and t h e large concentra tion range encompassed b y these elements, use of all of these tech niques was essential. For isotopic information, mass spectrometry and gamma spec trometry of radioactive isotopes were required. Surface studies in volved t h e use of Auger spectros copy, and oxidation states were studied using Môssbauer spectroscopy, nuclear magnetic resonance, and electron spin resonance. Perhaps t h e most useful tool t o t h e mineralogist is t h e electron microprobe t o provide information on in-
ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971
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Table 1. Analytical Techniques Used to Study Lunar Materials No. of labo ratories
Technique Activation analysis Instrumental neutron activation Neutron activation and radiochemistry 14-Mev neutron activation Photon activation Atomic absorption spectrometry
No. of labo ratories
Technique Mass spectrometry (contd.) Isotope dilution Laser Rare gas Spark source Microprobe Electron
5
13
2 2
8 1 6 4
22 1
Ion
3
Mossbauer spectroscopy
2
Auger spectroscopy
1
Emission spectroscopy Flame photometry
Nuclear magnetic resonance and electron spin resonance
3
2
6
Scanning electron microscopy
3
Spectrophotometry
3
Wet chemistry
6
1
Wet chemistry—gas chromatography
1
S
X-ray fluorescence spectroscopy
4
Gamma spectrometry for radioactive isotopes
3
Inert gas fusion and combustion chromatographic analysis Mass spectrometry Chemical isolation
dividual mineral phases. From both ion microprobe analysis and scanning electron microscopy, much valuable information was obtained on the distribution of elements in the lunar samples. Examination of the table reveals that the most pop
ular techniques in geochemical analysis are activation analysis, mass spectrometry, and electron mi croprobe analysis. Elemental Composition
Since elemental abundances are so important in understanding the
geochemistry of the lunar materials, it is informative to summarize their general behavior. The various ele ments were classified geochemically by V. M. Goldschmidt in 1923 to include siderophile, chalcophile, lithophile, and atmophile groups ac cording to their affinity for metallic iron, for sulfides, for silicates and other oxidic minerals, and for the atmosphere, respectively. Figure 1 gives the geochemical classification of the elements based on their dis tribution in the common chondritic meteorites. A few elements such as Fe, Mo, Bi, and Ga appear in more than one group. Thus, every ele ment is of potential geochemical interest. From the analytical point of view, this presents a formidable challenge since in the lunar samples the concentrations of the many dif ferent constituents range from per centages to fractional parts per bil lion. Obviously no one technique is capable of obtaining this informa tion. By using a combination of techniques and the efforts of a num ber of different investigators, from
Γ Hi L..-J
Li
Β !C
Be
Ca Sc Ti V
Rb Sr Y
0
Al Si P [ i l Cl ιΑ
Να Mg Κ
Ni
Cr MnÎFeÎCo Ni Cujlzn ;Ga| Ge AsIîSejlBrIjKri
Zr Nb'iMoJiTc : Ru Rh Pd\\Ag Cd lni:Sn Sb:|Te!| I ||Xe! :
Cs Bo Lo Hf Ta|iW
:'
Re Os Ir
•
: — j .
Pt AuljHg TI PbJBij; Po At Rn
Fa Ra Ac
Ce Pr Nd Pm|Sm Eu Gd Tb Dy Ho Er Tm Yb Lu | ThiPal U
Np Pu Am Cm Bk Cf Es Fm Md No Lw
Figure 1. Geochemical classification of elements Lithophile
Siderophile
Chalcophile
Atmophile
ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971 · 25 A
Report for Analytical Chemists
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a few samples we obtained informa tion on 79 elements including the rare gases, with a lesser number of elements determined on a broader range of samples. In the subse quent treatment, the rare gases will be omitted since they represent a special class of gaseous elements of
interest in solar wind studies re quiring specialized techniques for their measurement. Two general approaches to the determination of the elemental com position of lunar samples have been single element determination and multielement survey analysis. In
Table II. Results of Analyses Element
Mean
AI
6.71
Rel. No. of std. dev., % v a l u e s
Range
Techniques' 1
Major Elements, Wt % 11
6.50-6.9
NAA,XRF,Chem,ES
2
41.4,42.6
NAA
2.6
8
20.3-22.2
NAA,XRF,Chem,ES
4.1
12
11.5-13.2
5.0
10
6.5-7.6
NAA,XRF,Chem,ES, NAA,XRF,Chem, ES, ID
0.170
6.3
11
0.134
6.6
Na
0.330
7.2
Ti
1.70
Κ
0.196
Mg
6.35
10
9
Cr
0.267
10
13"
1.8
0
42.0
2
Si
21.4
Fe
12.5
Ca
7.3
Mn Ρ
0.155-0.190
NAA,XRF,Chem,ES
0.120-0.140,(0.064)
SS,XRF,CHEM
12
0.290-0.370
8.6
11
1.5-2.1
NAA,XRF,Chem,ES, ID,AA NAA,XRF,Chem, ES, ID
9.1
14*
0.150-0.220,(0.12)
NAA,XRF,Chem,ES, ID, 7
5.7-7.9
NAA,XRF,Chem,ES
0.208-0.303,(0.70)
NAA,XRF,Chem,ES, AA.GC
5»
Trace Elements, PPM F Se
61.5 0.25
3.4
2»
60,63,(241)
NAA.SS
3.6
2»
0.246,0.259,(1.1)
NAA,SS
12* φ
35-43,(63) 10.6-12.6,(6.3,26)
NAA,SS,XRF,ES
39.4-52,(17) 3-3.86,(8)
NAA,SS,XRF,ES SS,MS,ID
164-220 14.7-19,(8.05)
NAA,SS,ID
Se
39
6.7
Pr
12
7.2
Co
44
7.8 7.9
14*
Pb
3.2
46
Ni
195
8
11
Sm
17
9
Ub
Er
14
NAA,SS
NAA,SS,XRF,ES
9.2
8"
12.9-16,(8.4,29)
NAA.SS.ID
Be
3.6
9.4
5
3.21-4.0
U
1.68
9.9
10*
1.4-1.96,(1)
SS,ES,GC NAA,SS,XRF,ID,
270-423,(672)
NAA,SS,XRF,ES,ID
MS,T
Ba
357
11
15*
Y
129
11 12
8»
110-145,(180)
NAA,SS,XRF,ES
10»
20.2-29,(13.7)
NAA,SS,ID
11*
1.3-1.9,(4.2) 5.52-6.9,(2.0)
NAA,SS,ID NAA,SS,XRF,ID,T
120-190 8.3-14,(6.7,20) 62-115,(50.7)
NAA,SS,XRF,ES,ID NAA,SS,ES,ID NAA.SS NAA,SS,XRF,ES,ID NAA,SS NAA,SS,XRF,ES,ID
Dy Lu Th
23 1.7 6.1
12 12 13
12* 14
Ce Ho
12 88 5.2
13 14
15* 14*
14
9*
La Hf
33 13
16*
Rb Zr
6.7 470
15 15 16
4.3-6.7,(2.65,15.7) 22-42.5,(82)
10 17 10*
11.2-17.2 5.6-9.5 370-600,(872)
Sr Yb
143
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26 A • ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971
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NAA,SS,XRF,ID
NAA,SS,XRF,ES
Report for Analytical Chemists
the former approach, more precise information has been obtained by activation analysis with radiochem ical separation, fast neutron and photon activation analysis, atomic absorption, flame photometry, inert gas fusion, various types of mass spectrometry, spectrophotometry,
and wet chemistry. Here optimiza tion of the method for a given ele ment is involved. The more com prehensive multielement approach was used to a greater extent, how ever, in view of the large number of samples to be analyzed, the large number of elements to be deter
of Lunar Soil Sample 12070 Element
Mean
Rel. std. dev. %
W
0.65
17
4
V
No. of values Range Trace Elements, PPM
Techniques'1
0.5-0.74
NAA.SS
111
18
10»
72-142.5,(49)
NAA,SS,XRF,ES,ID
Gd
19
19
9
12.8-25
NAA,SS,ID
Li
17
20
&>
12-22,(28)
NAA,SS,ES,ID
Eu
1.6
20
Uh
0.88-1.9,(3.6)
NAA,SS,ID
Ta
1.6
21
3"
1.41-2.05,(3.3)
NAA
Nd
55
21
11
32-74
NAA,SS,ID
Nb
34
22
7
25-45
SS.XRF.ES
22
9»
1.99-4.1,(7.3)
NAA.SS
b
Tb
3.3
Cs
0.28
22
8
0.2-0.39,(1.7)
NAA,SS,ID
Ga
3.9
24
9"
2.5-4.9,(15)
NAA,SS,XRF,ES
Cu
8.1
30
10
5-12.5
NAA,SS,XRF,ES
Tm
1.7
30
S>
1.07-2.4,(10.8)
NAA.SS
31
S>
24-48,(106)
NAA,SS,XRF
7.4-15.5
NAA.SS.XRF.ES
CI
32
Zn
9.5
31
11
Ir
0.0068
32
3
0.0043-0.0085
NAA
35
4
520-1200
SS.XRF
S
900
In
0.45
37
4"
0.218-0.62,(2)
NAA.SS
Br
0.226
46
4
0.123-0.330
NAA.SS
Au
0.0030
55
3
0.0018-0.0050
NAA
Β
7.4
61
3
2.3-11
NAA.SS
Ge
0.56
86
3
0.21-1.1
NAA.SS SS
Mo
0.3
92
3
0.03-0.6
Ag As
0.09
105
3
0.026-0.2
NAA
0.21
117
4
0.022-0.575
NAA.SS
Cd
0.8
121
3
0.045-1.9
NAA.SS
Sb
0.44
164
3
0.009-1.27
Ν
40
NAA SS
Ru
1.1
SS
Rh
0.4
SS
Sn
0.3
SS
1
0.046
NAA
Pd
0.0065
NAA
Hg Tl
0.002
NAA
0.002
NAA
Bi
0.002
NAA
"Techniques include neutron activation analysis (NAA), spark source mass spec trometry (SS), X-ray fluorescence (XRF), wet chemical (Chem), isotope dilution-mass spectrometry (ID), emission spectroscopy (ES), gamma spectrometry of radioactive iso topes (y), atomic absorption (AA), chemical isolation-gas chromatography (GC), chem ical isolation-mass spectrometry (MS). * Number of values used in computing the mean excluding rejected values given in parentheses in the range.
mined, and the limited size of sam ples available. Incidentally, con siderable pressure is exerted on the investigators to reduce the size of the samples they request. Thus, the multielement survey techniques are of particular value in the study of small samples of such items as rock chips and mineral separates. These techniques include activation analy sis using high-resolution solid-state detectors, emission spectroscopy, spark source mass spectrometry, and X-ray fluorescence spectros copy. Evaluation of Results
To date, analytical information has been published on 35 rocks and 2 soil samples from Apollo 11, and 26 rocks and 13 soil samples from Apollo 12. While it is much more glamorous to discuss the geochemical significance of the results and their implications regarding the his tory of the Moon, the important question of the quality of the ana lytical results must also be consid ered. Inaccurate and incomplete data can lead to faulty geochemical conclusions and speculations. Since it is impossible in the space available to evaluate the large body of elemental analysis data obtained so far, I have chosen to examine in detail just one sample, soil sample 12070 from Apollo 12. Soil samples are those materials which pass a 1-mm sieve, so that from the ana lytical viewpoint they are consider ably more homogeneous than the rock chip samples. Of all of the samples studied, 12070 has been analyzed by the largest number of investigators so that a detailed evaluation of this sample is most appropriate. With the exception of 12070 and soil sample 10084 from Apollo 11, only one to three values per element have been reported on all other samples. In general, the Apollo 12 data are better, presum ably due to the experience gained in analyzing the Apollo 11 samples. Incidentally, 12070 is the con tingency sample collected by Astro naut Pete Conrad. Table II, which is a composite of all the available information on sample 12070, as reported at the Apollo 12 Lunar Science Conference in Houston, Jan. 11-14, 1971, lists the element, the mean of the re-
ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971
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Table III. Values for Chromium in Sample 12070, Wt % Technique
Reported values
SSMS
0.28, (0.7)
NAA
0.227, 0.243, 0.248, 0.26, 0.28, 0.28, 0.30
XRF
0.208, 0.29
Chem-GC
0.270
ES
0.28, 0.303
ported values, the percent relative standard deviation of these values, the number of values included, the range, and the techniques employed. I n a number of cases, one outlier or a t most two obvious outliers were rejected in computing the mean, and these values are in parentheses. The elements a r e conveniently di vided into majors and traces and are arranged in increasing order of relative standard deviation. How can we objectively evaluate these d a t a ? Since only 50 elements have four or more reported values with a maximum number of 17, but on the average only 9 to 12, a rig orous statistical treatment is im possible. I n addition to t h e need for larger numbers of values, it would require calculating weighted averages for each component, m a k ing due allowance for the respective variances of all the methods used. Instead, we are forced to examine the spread of values for a n y given element, bearing in mind the vari ous factors contributing to t h e spread. I n some instances, com parison of the means with values obtained by "better methods" gives some insight into the quality of the results. Major Elements. Evaluation of all 12 major elements shows t h a t the relative standard deviations ranged from a low of 1.8% for Al to a high of 1 0 % for M g and C r with an average of 6 % . With the exception of O, five or more values were avail able for each element so t h a t mean ingful evaluation is possible. I n the cases of Ρ , Κ, and Cr, one of the values reported for each was obvi ously an outlier and therefore re jected. Incidentally, the rejected values were all from the same lab oratory. When we consider the a n alytical techniques employed, a spread of values up to 1 0 % is not
surprising. I n the case of Apollo 11 soil sample 10084, where more wet chemical analyses were r e ported, the average relative stan dard deviation for t h e majors was only 4 % , indicating their superior ity for determining high concentra tions. With the Apollo 12 soil sam ple, there was less spread with ele ments of higher concentrations with the exception of Mg. As a typical example, Table I I I shows detailed data for C r by the various techniques employed. Variation within a given technique and between different techniques is observed. One mass spectrometric value was rejected as a n outlier. The one technique t h a t comes clos est to the mean of 0.267% C r is chemical isolation-gas chromatog r a p h y which is the only example of a single-element technique opti mized for the element. All of the others are multielement in nature so t h a t a spread of 10% is under standable. Trace Elements. With the wealth of information reported on 59 trace elements, only general ob servations and a few specific ex amples can be presented here. T h e relative standard deviations range from 3.4% all the w a y to 164%. There are a variety of reasons for the spread of a given element, in cluding an insufficient number of values reported, the low concentra tion of the element present, hetero geneity a n d contamination for cer tain elements, differences in capa bilities of analytical techniques em ployed, and most important, the ability of the investigator. Each will be discussed with examples. I N S U F F I C I E N T N U M B E R OF V A L
UES. I n a n y evaluation it is dan gerous to draw conclusions from only a limited amount of data. Thus, in Table I I there are 20 ele ments which cannot be properly a s sessed because there are fewer t h a n four values for each. Elements with only one reported value are N , Ru, R h , P d , Sn, I , Hg, T l , and Bi. Those with two reported values a r e F and Se, and those with three are T a , I r , Au, Β , Ge, Mo, Ag, Cd, and Sb. Although one m a y not be able to attribute much confidence to their reliability, their concentra tions are sufficiently revealing in understanding their geochemical be
28 A • ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971
havior. Thus, the strong depletion of siderophile and volatile elements in the lunar material is immediately apparent. E L E M E N T S OF Low CONCENTRA TION. One of the m a i n reasons for
the limited data on the above ele ments is their presence a t extremely low concentrations and the analyti cal difficulties associated with their determination. With the exception of F , B , and N , all of these elements are present below 1 ppm and a num ber are a t the low ppb level. Five other elements with four or more values reported and which are present a t concentrations below 1 ppm a r e W , Cs, B r , I n , and As. Their relative standard deviations are 17, 22, 46, 37, and 117%, re spectively, which is understandable in the determination of ultratrace elements. I n the concentration range of 1— 10 ppm, there are 15 elements with relative standard deviations rang ing from 7.9% to 6 1 % with an aver age of 2 1 % . I n the concentration range of 10-50 ppm, t h e relative standard deviations for 13 elements range from 6.7% to 3 1 % with an average of 14%. F o r 10 elements above 50 ppm, the relative standard deviations range from 3.4% to 3 5 % with an average of 1 5 % . I t a p pears, therefore, t h a t in the lowppm range, the spread in values is somewhat greater t h a n at higher concentrations. HETEROGENEITY AND CONTAMINA
TION. Although the soil samples a r e more homogeneous t h a n the rock samples, there is a possibility of nonhomogeneity of certain elements in the soils, especially a t the low trace level. I n particular, those elements attributed to meteoritic infall—i.e., Cu, Zn, M o , Ge, and As show rather large relative standard deviations. Cobalt and N i , which are also possible meteoritic con taminants, a r e present a t relatively high concentrations so t h a t their relative standard deviations are small. Perhaps the most obvious source of contamination is the Ag i n vacuum gaskets used on the sam ple return containers. Relative standard deviations for Ag and I n are 105% and 3 7 % , respectively. D I F F E R E N C E S D U E TO ANALYTICAL T E C H N I Q U E S . A S mentioned earlier,
most of the information on the trace
Report for Analytical Chemists
elements has been obtained using multielement techniques of widely different capabilities for different elements. T h u s , it is unreasonable to give equal weight to each tech nique. Also, laboratories using t h e same technique employed widely different procedures which are diffi cult to equate. A specific example of the results for La, present a t the 33-ppm level, is shown in T a b l e IV. This element was selected because it h a d the largest number of reported values and included a number of different techniques. Variation within a given technique and between differ ent techniques can be observed. T h e relative s t a n d a r d deviation ex cluding one outlying mass spectrometric value is 1 5 % , which one must consider high for t h e determi nation of a trace element at this concentration level. If one is willing a r b i t r a r i l y t o ac cept a relative s t a n d a r d deviation for trace elements of 10% or less as satisfactory, then there are 32 ele ments with four or more reported values t h a t lie outside this accept able limit. Nine additional ele ments with relative s t a n d a r d devia tions greater t h a n 1 0 % have only three or two reported values and, therefore, are difficult t o evaluate. PERFORMANCE
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Table IV. Values for Lanthanum in Sample 12070, PPM
ID-MS XRF ES
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H a v i n g considered most of the problems involved in t h e analysis of lunar samples using soil sample 12070 as a good example, we are now r e a d y t o evaluate the per formances of the individual labora tories. T w o ground rules are in voked. Only those elements with four or more values used in com puting the mean are used to com p a r e the performance of each lab oratory. M e a n s arrived at using fewer t h a n four values are less likely to approximate the actual concentrations. T h e second cri-
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ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971
EK-305
terion is that only elements with deviations from the mean of 10% or less may be considered satisfactory. Table V summarizes the perform ance of the various laboratories involved in compositional analysis. The first entry represents the results of our group at Cornell. The re maining laboratories are identified by number to preserve their ano nymity. Included in the table is the total number of elements deter mined and the number of elements for which meaningful comparisons can be made—i.e., four or more values used in computing the means. Also included are the average per cent deviation from the means for those elements which can be com pared, the number of elements with percent deviations of 10% or less, and the techniques employed. The only element with four or more values whose mean was deemed unacceptable for compari son was As since the relative stan dard deviation for the four values was 117%, indicating considerable uncertainty as to the correct mean value. The first six laboratories report 30 or more elements each, in which are included anywhere from 26 to 46 trace elements. Since maximum information on trace elements is important in studying the geochemical behavior of lunar materials, multielement analyses such as these are indispensable. Although the determination of many of the trace elements is more difficult, the results of all but Laboratory 2 are reason able. It should be noted that a bad value for just a few trace elements can dramatically affect the average for a given laboratory. Laboratories 7 through 13 report substantially fewer trace elements (average of 17), with less possibil ity of large deviations. With the exception of Laboratories 8 and 12, their average de\dations are greater than 10%, with Laboratory 13 be ing particularly bad. Laboratories 14 through 28 report from 1 to 16 elements. With the exception of Laboratories 16 and 18, they all use single-element tech niques so that better results would be expected. Laboratory 16's re sults are particularly poor. On the other hand, Laboratory 17's results are better than indicated, since their
Report for Analytical Chemists
total of 28 laboratories, 16 pro duced results with an average devi ation of 10% or better. Labora tories employing multielement tech niques, while achieving an accept able degree of accuracy, are at the same time providing useful infor mation on a much larger number of elements as compared with the lab oratories employing single-element techniques. In summary, the quality of the results is commensurate with the magnitude of the analysis program and the limited time available for performing the analyses and report ing the results. While in many cases the results are satisfactory, there is a glaring number of weak points in the elemental data for the soil sample. With considerably fewer data available for the rock
six elements compared are trace elements in the low-ppm and -ppb range, with greater inherent error in their determination. Similarly, two of the four elements determined by Laboratory 19 are difficult trace elements. Finally, it should be noted that those laboratories using isotope dilution-mass spectrometry obtained some of the best results on the limited number of elements they determined. There is considerable variability in the performance of different lab oratories. Although single-element techniques, in general, produce bet ter results, the use Of comprehensive multielement techniques by superior laboratories is capable of providing good results. This becomes all the more important in analyzing lunar samples of limited size. Of the
Table V. Performance of Individual Laboratories in Analysis of Sample 12070 Labo ratory
1
Total N o . of elements determined
No. of elements compared with mean
Av. dew. from mean, %
No. of ele ments with deviations < 10% of mean
56
48
8.1
37
SS.NAA SS.ES
Techniques
2
56
47
76
10
3
46
38
11
20
NAA
4
39
32
9.4
21
NAA
5
35
34
8.0
24
NAA.PAA
6
32
30
11
18
SS.ES
7
28
28
14
21
XRF.ES.AA
8
28
28
10
18
XRF.ES.Chem
9
28
28
11
15
XRF.ES.Chem
10
28
28
11
17
XRF.ID
11
27
26
13
14
NAA.ES.ID.PAA
12
22
21
15
NAA
13
18
17
4
NAÀ
14
16
16
5.3
15
15
14
14
4.1
14
16
14
14
39
0
NAA
17
13
6
25
2
NAA
18
12
12
11
NAA
19
7
4
20
5
4
21
5
2
22
4
4
23
3
24
8.0 56
6.1 24 3.3
ID
Co. (ΆΝΑ£. CHEM. 42, No. 12, 59 A,
1970), was cited for his outstanding research achievements and leader ship in the field of trace analysis and materiah characterization, and for his service to other scientists by providing them with the methodol ogy necessary to pursue their ob jectives. He was one of the select group of Principal Investigators in the NASA program to analyze the first lunar material returned to earth. Dr. Morrison is professor of chemistry and Director of the Ma terials Science Center Analytical Facility at Cornell University.
samples, the situation is much worse. While a considerable amount of geochemical interpretation of farreaching significance to lunar his tory has been generated from the existing data, a substantiation of the concepts evolved can only be done after the deficiencies in the analytical data have been corrected.
ID
1
NAA.PAA
4
NAA
1
NAA
6.4
4
ID
3
2.6
3
y
3
3
4.2
3
y
25
3
3
2.0
3
MS
26
3
3
3.2
3
MS.a
27
2
2
6
2
Chem-GC
28
1
1
4.5
1
MS
11
George H. Morrison, winner of the 1971 American Chemical Society Award in Analytical Chemistry, sponsored by the Fisher Scientific
References (1) "Summary of Apollo 11 Lunar Sci ence Conference," Science, 167, 449784 (1970). (2) "Proceedings of the Apollo 11 Lunar Science Conference," Geochim. et Cosmochim. Acta, Supplement 1, Vol. 34, Pergamon Press, New York, Ν. Υ., 1970. (3) "Proceedings of the Apollo 12 Lunar Science Conference," M I T Press, Cam bridge, Mass., in press. (4) B . Mason and W. G. Melson, "The Lunar Rocks," Wiley & Sons, New York, Ν . Υ., 1970. (5) Κ. Μ. Reese, "Chemical Analysis of Moon Samples," ANAL. CHEM., 42 (6),
26 A (1970). Fisher Award Address presented a t the 161st ACS National Meeting, Los Ange les, Calif., 1971
ANALYTICAL CHEMISTRY, VOL. 43, NO. 7, JUNE 1971 • 31 A
