Retief, D.J

Turkstra, J

van Wyk, C.W

English

Wits Institutional Repository on DSPACE

T h e  J o u r n a l  o f  t h e  D .A .S .A ,
of trace-elements in hum an blood and 
tissues. T h e  accuracy of this analytical 
method has led to its use in the medico­
legal field. Hair, even hundreds of years 
old, can be analysed successfully for 
arsenic and other residues. It  has even 
been used to identify the geographical 
source of opium by identifying the trace- 
elements the poppy plants absorb from 
the different soils in which they grow.
H I l S U O C R A m Y
Corliss, \V. R . N eutron Activation Analysis.
United States Atom ic Energy Commission.
De Wet, W. J .  Activation analysis. Personal Com ­
m unication.
De Lance, I*. W ., arid Snyman, G. C. Gc(Li) — 
Detectors. A review of their properties and of 
their application in gam m a spectrom etry. 
Atomic Energy Hoard Publication. Pel. 135, 
Dec., 1966.
D u iv en stijn , A. J . ,  and V en v e r i.o o , L. A. J .  Prac­
tical gam m a spectrom etry. Phillips Technical 
L aboratory, Eindhoven, N etherlands, 1963.
Eouciie, K. T. Application of neu tron  activation. 
National symposium on neutron activation 
analysis and the production of isotopes in Safari 
I. A tom ic Energy Hoard, R ep. of South Africa.
K em p , D. M . Principles of neutron  activation. 
N ational symposium on neutron activation and 
the production of isotopes in Safari I. Atomic 
Energy Hoard, Rep. o f South Africa.
K och, R. S. A ctivation Analysis Handbook, 
Academ ic Press, London, I960.
L k n iiia n , J .  M . A., and  T homson, S. J. Activation 
analysis. Principles and application. Academ ic 
Press, New York, 1965.
P utman, J. L. Isotopes. Penguin Hooks Lim ited, 
M iddlesex, England.
S mai.es, A. A. N eutron-activation analysis. Chap. 
19, T race  Analysis. Edited by Yoc, J .  I I. and 
Koch, II . J .  Jo h n  W iley & S oils Inc., New 
York.
W a u l , W . IT., and K ram er , I I . II . N eutron- 
activation analysis. Scientific Am erican 216, 
No. ‘1, 68-82, April, 1967.
A QUALITATIVE AND COMPARATIVE STUDY OF 
ELEMENTS IN TEETH BY NEUTRON ACTIVATION 
AND HIGH RESOLUTION GAMMA SPECTROMETRY
1. I n t r o d u c t io n
AS the exact mineral composition ofteeth often has to be known, im­
proved methods for the detection and
quantitive analysis of the elements they
contain continually arc being sought. In
19117 Lowatcr and M u rray 1 detected
nineteen elements by spoctrographic 
methods; and later Swill2 found a large 
number quantitivcly by means of spark 
source mass spectrometry. A further ad ­
vance was tlu: use of  electron probe x-ray
microanalysis by Suga cl alJ to determine
the topographical distribution of some ol
the elements present.
A recently developed sensitive analy­
tical method —neutron activation followed 
by gam m a-ray spectrometry — may be 
used as a  qualitative and quantitative 
method for analysis of elements in teeth. 
Sorcmark and Samsahl'1'5 *-0 employed 
it for the analysis of trace-elements in 
enamel, dentin and calculus. T h e  samples 
were irradiated for 20 hours in a neutron 
(lux of approximately 2 x I0 12n.cm '2. 
sec-1. T he  activated samples were sub­
jected to a chemical group separation 
followed by gam m a spectromctric analy­
sis. A N al(T l)  scintillation crystal was 
used as a detector. Eleven elements (Ca, 
P, Na, Cl, 7.H, Sr, Br, M n, Cu, W and Au) 
were determined quantitatively, and an 
additional eight long-lived radioisotopes 
qualitatively. This work was continued 
by Sorcmark and Eim dbcrg7 *, who deter­
mined six of these long-lived radio­
isotopes (Pb, Cr, Ag, Pc, Co and Pt) 
quantitatively by employing a higher 
neutron (lux of approximately 6-5  x 
1 (J1 l *:,n.cm 2.scc'h
T he  inherent high sensitivity of neutron 
activation analysis for many elements 
makes this method suitable for the analysis 
of trace-elements. Since Gc (Li) semi­
conductor detectors1 with a superior re­
solution have superseded the Na I (Tl) 
scintillation counters for the detection and 
measurement of gamma-rays, this method 
has become even more versatile. T he  high 
resolution permits studies of complex 
gam m a spectra in m uch more detail and 
lias m ade possible the non-destructive
M a r c h , 19G9 75
D ie  T y d sk r if  v a n  d ie  T.V.S.A.
1
O l o o  200  JO O  4 0 0
CHANNEL NUMBER
Fie. 1.— G am m a spectrum  of toolli 3 after short irradiation. ‘1| o f patien t A. 'lo la l  weight 
of tooth 1 -0643 gm.
neutron  activation  analysis o f a great 
variety of sam ples0-10.
This investigation was undertaken  to 
determ ine w hether non-destructive neu­
tron activation  analysis and  high re­
solution gam m a spectrom etry is a  suitable 
m ethod for the analysis of elem ents in 
hum an teeth. A t the same tim e the results 
obtained were used to com pile “ nuclear 
fingerprints” of different teeth which 
were then com pared.
I I .  E x p e r im e n t a l  P r o c e d u r e
(a) Preparation o f  the teeth prior to irradiation
Thirty-six sound, freshly ex tracted , un ­
restored teeth  w ere used. T h ree  were ob­
tained from each of 12 individuals and  
consisted of a  p a ir of contralateral teeth, 
and  an  odd one. Obvious debris or ta rta r 
was rem oved w ith plastic instrum ents. 
T h e  teeth  w ere then thoroughly washed 
in  dc-ioniscd w ater for a few m inutes and 
dried in an  oven a t 105° C to constant 
weight, and  the weight o f each tooth was 
recorded. T h e  teeth were sealed in 
polyethylene tubes for short irrad iation , 
and  subsequently some were sealed in 
quartz  am poules for long irrad iation .
(b) Irradiation o f the samples
For the detection of short-lived radio­
isotopes, each tooth in its polyethylene 
container was irrad ia ted  for exactly one 
m inute. T h e  irrad iation  was carried out 
in the pneum atic facility o f the nuclear 
reactor Safari I* in  a  therm al neutron 
llux o f approxim ately  1 x  10I. *13n .c n r2. 
s e e 1.
T h e  long-lived radioisotopes were de­
tected after irrad ia tion  o f the teeth in  the 
poolside facility of Safari I. T hey  were 
irrad ia ted  for 50-100 hours in a therm al 
neu tron  flux of approxim ately  2 x  1013n. 
cnv^scc"1.
(c) Measuring o f the gamma activity
T h e m easurem ent of the gam m a activity 
of the samples th a t were irrad iated  for one 
m inute was com m enced exactly two 
m inutes after each irrad iation . T h e  teeth 
were placed 7-0 cm below a  Gc (Li) de­
tector; th a t used a t Pclindaba is a  5-0 
cc coaxial Ge (Li) d iodcf m ounted in  a 
cryostat and  cooled w ith liquid  nitrogen.
♦Safari I —  An O R R -type reactor of the Atomic 
Energy Board at Pclindaba.
fPrinccton G am m a Tech., Princeton, J .  J . ,  
U .S.A.
76 M a a r t  1969
T h e  J o u r n a l  o f  t h e  D .A .S .A .
co
• • O k . V
l 1l14k«v1
1 0 4 7 L .V
\
‘ ° c .
\
•V I
O l f  h « V  j
-AJL.
U *1 u v  
1
I’lC.
CHANNEL NUMBER
2.—G am m a spectrum  of the sam e tooth as in  I'ig. 1 after long irradiation.
An uncoolcd TC -130 Tennelcc p re­
amplifier, a TC-200 Tcnnelec am plifier 
and a  R  I D L bias-am plifier (only the 
cut am plifier section) were used to obtain  
low noise am plification of the diode ou t­
pu t signals. T he analysis of the gam m a- 
spectrum  was done on an  In tertcchnique 
400 channel pulse height analyser (model 
SA 40B), bypassing its built-in  amplifier. 
The resolution of the counting equipm ent 
is 4 -6  K eV  (fwhm) for the 0-662 M eV 
photopeak of 137mBa.
T h e  teeth tha t w ere irrad iated  for 50- 
100 hours were allowed to undergo rad io ­
active decay for approxim ately three 
weeks before counting was undertaken. 
T he sam e recording equipm ent was used.
T h e  results were recorded graphically 
w ith a  point p lo tter an d  prin ted  digitally.
I I I .  R esults
G raphs were d raw n from the digitally 
prin ted  results. T h e  energies of the peaks 
in the gam m a spectrum  obtained from 
each tooth were determ ined from the 
calibration curve. T h e  elements respon­
sible for these peaks were identified from 
available tables11-12. A lthough the deter­
m ination of the short-lived and  long-lived 
radioisotopes were undertaken  as a  non­
destructive analysis, it  was found th a t 
whenever the teeth were irrad iated  for
long periods they becam e b rittle  and  dis­
integrated.
(a) Qualitative analysis o f  elements in teeth 
In  36 teeth  analysed Sr, Zn, Br, M n,
Cu, N a, Cl, Ca, Fe, Co and  Sb were 
identified. Fig. 1 represents a  typical 
spectrum  obtained from one o f the teeth 
subjected to short irrad iation , and  Fig. 2 
the spectrum  obtained from the same 
tooth after long irradiation .
(b) Comparative study o f  the “nuclear finger­
prints” obtained after short irradiation 
Figs. 3, 4, 5 and 6 represent the gam m a 
spectra obtained after short term  irrad ia­
tion of a m atched pa ir and  ano ther tooth 
from one individual and  a  tooth from a 
different individual. T h e  basic “ nuclear 
fingerprin t” p a tte rn  obtained from the 
different teeth is sim ilar. C erta in  m inor 
differences occur such as the absence of 
the first chlorine peak in Fig. 4. T here  are 
also differences in the heights o f some of 
the peaks o f corresponding radioisotopes 
in  the various spectra, ind icating  a  pos­
sible difference in  the concentration  of the 
respective isotope.
IV . D iscussion
In  this prelim inary  investigation only
M a r c h , 1969 77
D ie  T y d sk r if  v a n  d ie  T .V .S .A .
4 f C .  I t C A M  M A X
Fio. 3.— G am m a spectrum of tooth 10 after short irradiation. |l  of patient B. T otal weight 
of tooth 0*9482 gm.
4
1)1 JM IN
CHANNEL NUMBER
F ig . 4.— G am m a spectrum  of tooth 11 after short irradiation . 11 of pa tien t B. T otal weight 
of tooth 0*9786 gm.
11 of the elements present in  teeth could 
be determ ined qualitatively. T h e  re­
latively sm all num ber detected can be 
a ttrib u ted  to two factors. First, the samples 
could no t be irrad ia ted  for longer than  
one m inute if  counting was to commence 
two m inutes after irradiation . Because of
the am ount o f sodium  present in  these 
teeth, the activity o f its isotope, Z4N a, is 
such th a t the recording instrum ent would 
be dam aged if  counting com m enced two 
m inutes after a  longer irrad iation . T h e  
la tte r lim itation  can be overcome by a 
chem ical separation technique w hich, by
78 M a a r t  1969
T h e  J o u r n a l  o f  t h e  D.A.S.A.
F ig . 5.— G am m a spectrum  of tooth 12 after short irradiation. 3 | of pa tien t B. T otal weight 
of tooth 0*0870 gm.
CHANNEL NUMBER
Fie. 6.— G am m a spectrum  of tooth 13 after short irradiation. |3 o f patien t C. W eight 
0-9604 gm.
means of an  ion exchange resin to remove 
the sodium  prio r to or after irradiation , 
will allow the sam ple to be irrad iated  for 
a m uch greater length o f time. A longer 
irradiation  will result in the detection of 
more short-lived radioisotopes and  a t the 
same time increase the heights of the peaks 
of the elements a lready determ ined.
Secondly, w ith the facilities available 
a t Pclindaba it was not possible to  com ­
mence counting sooner than  two m inutes 
after irrad iation  of the sam ple. T h e  de­
tection of very short-lived radioisotopes 
such as 20F, w ith a half-life of 11 seconds, 
becomes very difficult.
T he advantages o f a non-destructive
M a r c h , 19G9 79
D ie  T y d sk r if  v a n  d ie  T.V.S.A.
analysis arc obvious. A part from the fact 
th a t it excludes a  tim e-consum ing chem i­
cal separation technique, the tooth itself 
is no t destroyed, w hich is im portan t in 
the medico-legal field. This advantage of 
the non-destructive neutron activation 
analysis is, however, lim ited to the deter­
m ination  o f the short-lived radioisotopes 
in  teeth, it was found tha t w henever they 
w ere irrad iated  for long periods they be­
come brittle  and  disintegrated. T he disinte­
gration  m ay be accom panied by the 
evolution of gases resulting in an increase 
in pressure w ith in  the sealed am poule. 
This m ay have been the cause of the dis­
integration o f one o f our sealed quartz  
ampoules w hich led to the contam ination 
of the laboratory  w ith  radioactive m a­
terial. I t  therefore is recom m ended tha t 
teeth to be irrad ia ted  for long periods be 
sealed in  quartz  am poules under vacuum .
T h e  “ nuclear fingerprints” of the two 
paired teeth (Fig. 3 and  4) arc practically 
identical. T h e  “ nuclear fingerprint” p a t­
tern, besides being very sim ilar to tha t of the 
o ther tooth of the sam e person (Fig. 5), can 
also be m uch the sam e as tha t of a tooth 
from a different individual (Fig. 6). In  
this investigation the “ nuclear finger­
prin ts” obtained from the teeth after ir­
rad iation  showed no significant differ­
ences.
T h e  varia tion  in  the heights of corres­
ponding peaks w hich were apparen t need 
not necessarily be attribu ted  to the differ­
ences in  concentration  of the respective 
isotopes; it could be due to the difference 
in weight of the teeth  com pared or to the 
variation  in the relative value of the neu­
tron flux in the reactor a t the time of 
irradiation . T h e  la tte r problem  can be 
overcome by determ ining the relative 
value of the neu tron  flux for each irrad ia ­
tion.
IV . C o n clu sio n
This investigation confirms tha t neu­
tron activation followed by high resolution 
gam m a spectrom etry is a sensitive m ethod 
for the qualita tive analysis of some of the 
elements in  teeth. T h e  anticipated  advan ­
tages of the non-destructive analytical 
m ethod did not m aterialize as the teeth 
disintegrated w hen they were irradiated  
for long periods. A technique possibly
could be developed em ploying neutron 
activation  followed by high resolution 
gam m a spectrom etry in  conjunction w ith 
chem ical separation  (destructive analysis) 
for the qualitative and  quan tita tive  analy­
sis o f a g reat num ber o f elements in 
m ineralized dental tissues.
R E FE R E N C E S
1. Low ater , F .j and  M urray, M . M . Chemical 
composition of teeth. V . Spcctrographic 
analysis. ISiochcm. J . ,  31 : 837, 1937.
2. S u ga , S., Soejrm a , H .,  and  T a naka , Y. Elec­
tron  probe X -ray  m icroanalysis of developing, 
erup ted  and carious dental hard  tissues. J .  
dent. Res., 46: 1251, 1967.
3. S w ift , I’. A m ethod for the trace elem ental 
analysis of dental tissues. Brit. dent. J . ,  123 
(No. 7) : 326-327, 1967.
4. So r em a r k , R ., and  S am saiil, K . G am m a-ray 
spcclrom clric analysis o f elements in norm al 
hum an  enam el. Arch. O ra l Biol., 6 : 275-283,
1961.
5. S o rem ark , R ., and Sam saiil, K . G am m a-ray 
spcclrom clric analysis o f elements in norm al 
hum an  dentin . J .  dent. Res., 41 : 603-606,
1962.
6. So rem ark , R ., and S amsaiil , K . Analysis of 
inorganic constituents in  dental calculus by 
m eans of neu tron  activation and gam m a-ray 
spectrom etry. J .  dent. Res., 41 : 596-602, 1962.
7. So rem ark , R ., and L un d iierg , M . G am m a-ray 
spcctrom ctric analysis o f the concentration of 
C r, Ag, Fc, Co, R b  and  P i in norm al hum an 
enam el. Acta. O dont. Scand., 22 : 255-259, 
1964.
8. P russin, S. G ., H a rris, J .  A., and H o ll a n d e r , 
J .  M . A pplication of lithium -drifted ger­
m anium  gam ina-ray  detectors to neutron 
activation analysis. Ann. Chem ., 37 : 1127- 
1132, 1965.
9. Sc iir o e d e r , G. L., and E vans, R . D . D eter­
m ination of silver in  m inerals and ores by 
neutron activation analysis and high resolu­
tion gam m a spectrom etry. Ann. Chem., 38 : 
432-434, 1966.
10. D e L a n g e , P. W ., D e W e t , W . J . ,  T urkstra , 
J . ,  and V e n t e r , J .  H . Non-destructive neutron 
activation analysis o f small samples o f W it- 
watcrsraiul ore for gold. Ann. Chem., 40 : 
451-454, 1968.
11. Str o m in g er , D., H o lla n d er , J .  M ., and 
S eauorg , G. J. T ab le  of Isotopes. Rev. mod. 
Phys., 30 : 585-904, 1958.
12. H e a t ii, R. L. Scintillation spectrometry. 
G am m a-ray spectrum  catalogue. U .S. Atomic 
Energy Com., 1964.
A C K N O W L ED G M E N T S 
T he authors wish to thank the Atom ic Energy 
Board for the facilities m ade available to them ; and 
Professors A. E. Dodds and  C. J .  Dreyer for their 
help in the p reparation  of tliis paper.
80 M a a r t  1969


A qualitative and comparative study of elements in teeth by neutron activation and high resolution gamma spectrometry

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A qualitative and comparative study of elements in teeth by neutron activation and high resolution gamma spectrometry

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