Energy Dispersive X-Ray Fluorescence Spectrometry...

Journal of Scientific & Industrial Research

Vol. 6 1. Janu ary 2002, pp 48-S2

Energy Dispersive X-Ray Fluorescence Spectrometry Analysis of Elements in Tobacco Cigarette and Ashed-Tobacco Samples

A 0 Oyewale"*, I I Funtuah and P Ekwumemgbo"

"Department of Chemistry, Ahmadu Bello Uni versity, Zari a hCentre for Energy Research and Training, Ahmadu Bello Uni versit y, Zaria

Received: 12 Jul y 200 I; accepted:28 September 200 I

EDXRF . \I)<)C I . . • spectroscopy, uS ing a ( eXCltalion source was used for the multi -element analys is of two tobacco leaves and ten brands of cigarettes Widely consumed in Nigeri a. The dried tobacco leaves. cigarettes and ashes of the samples were analysed tor 14 elements (K, Ca. As .. S r. Rh. Sr. TI. Zr. Fe. NI. Cu. Zn. Se and Pb ). An emi ssion-transmission quant ificati on method. which adequ ately proVides tor correction .of the organic da rk matri x background and scattering intensi ty cont ribution from cellul ose on the element sensit iv ities was utili zed. As. Ni. Cu. Zn. Sr. Se and Pb averages 8.7. IS.3. 3 1. 8. 22.3. 8:1 .7. 4.9 and 12.7 ppm and 13. 1. 2S.7 . 36.9. 69 .2. 3S.9. 7.6 and 19.2 ppm in tobacco and ashed sampl es res pecti vely. Stmistical correlations is found to exist between As and Pb (+0.99 ). Zr and Sr (-0.94) . Rb and Sr (-0.92). and K and Sr (-0 .96) .

Introduction

Tobacco, a plant of the genus Nico ri{/I1 (l (contains more than 60 species) is grown as an annual crop for util ization of its leaves, which are used in cigarettes for chewing and snuffing; and as a source of nicotine (wh ich in large quantity is poisonous). The tobacco leaf and cigarette smoke contains a complex mixture of several hundred chemi cal components, some of which have been identifi ed as tars, nicotine, carbon monoxide, hydrogen cyanide. and oxides of nitrogen. Man y of these components are pharmacologically active, hi ghl y tox ic, carcinogenic, mutagenic, and antigenic.

Elemental composition, parti cul arl y trace elements in tobacco have been a subject of recent studies because of the probable contribution of these elements to the hazards associated with tobacco and cigarette intake. An array of elements, ranging from the low atomic mass elements like Na. K. and Ca to heavy transition and radioactive metals, have been reported and detected at vari ous concentrati ons, in tobacco and cigarettes 1.2. The most widely used technique is Neutron Activati on An alys is (NAA ). which was employed to determine the level of trace elements in Turki shJ; Indian4

,) , and Syri an6 tobacco samples . The compos ition of tobacco smoke

* Author for correspondence

condensate7X and the pollution effects of airborne Hg, Cd , Mn and Pb from the smoke have been

d9- 11 X reporte . -ray tluorescence spe.;; troscop ic technique was used to determine the level of trace elements level in Kenyan cigarettes 12 .

Techniques like Inducti vely Coupled Plasma Mass Spectrometry (ICPMS) and Atomic Absorption Spectrometry, which in volved sample so lu bili zation . prior to analys is have also been used for trace meta l analys is in tobacc07.K, I I.I3 .14.

The present study determines the level of inorganic elements by Energy Di spersive X-ray Fluorescence (EDXRF) III tobacco leaves and cigarettes manufactured in Ni geri a and UK for comparati ve analys is. Attemts is also made to relate the concentration of these elements in the ash. produced by burning the cigarettes compareci with those detected in the source cigarettes .

Experimental Procedure Ten cigarette samples analysed in thi s study

were commercial samples, consumed widely in Nigeria, five of the samples (T1-TS) were imported cigarettes brands from the UK and the remaining five samples (T6- T 10) were cigarettes manufactured in Ni geria.Two tobacco leaves samples that were obtained from Ni gerian Tobacco Compw y as air­cured (T I I ) and tlue-cured (T 12) samples. were analysed. The ash of each of the sampl es was

O YEWA LE el a /.: ANALYS IS OF ELEMENTS IN TOBACCO C IGA RETTE & AS H-TOBACCO SAMPLES 49

obta ined by burning the tobacco in a manner akin to tobacco smoking and their ashes (ATI-ATI 2) were analyzed as for the tobacco samples.

The cigarette samples paper-wrap was removed and the sample dried at 90nC to remove moisture, until constant weight of the dried sampl es was obtained. Correcti on was made fo r the moisture content « 8 per cent) in the fin al elementa l concentrati on estimates. The samples were fine powdered and the ground samples were each homogenized with three drops of organic liquid binder (polys tyrene di ssolved in toluene) and pellets prepared from about 0.3 g of each samp le, using a 19 mm diam. die with a hydraulic press . The spectra of each sample were then measured using EDXRF system.

The EDXRF system is based on IOl)Cd-i sotope excitation and consists of a 925 MBq IOl)Cd annul ar isotopic source with a Canberra Si(Li ) detector having a resolution of 170 eV at 5.9keV. The X-ray spectra were acquired with a computer based MCA card (Trump 8k). The set up provides fo r dead- time correction and pi le-up rejecti on. Sensitivity' calibrati on of the system was perfo rmed, using thick pure metal fo il s and stable chemical compollnds.

Measurement time for spectra collecti on was 50 min and the AXIL software package was used for

I . IS 16 A b . spectra ana YS ls " . n a sorption measurement method, using a thick foil as target material for the evaluation of concentration of the elementsI7.IX. was used. Certi fied reference material , V-I 0 (hay powder)

distributed by Intern ati onal Atomic Energy Agency (IAEA) was analyzed in a similar manner to the tobacco samples for the quali ty control and for most elements there was a good agreement (Table i). Measurements were carried out th rice for each sample.

Results and Discussions

The percentage as h content ranged frolll 15.()-15.8 per cent for the foreign (T 1-T5) and 19.4- 19.5 per cent fo r Ni ge ri an (T6-TI O) manu factured cigarette tobacco sampl es ; whil e for the tobacco leaves it averaged 18.5 per cent. Statis ti cal parameters for 14 elements (K, Ca. As. Br, Rb. 51'. Ti . Zr, Fe, Ni. Cu, Zn. Se and Pb) analysed in the tobacco cigarette and ashed-tobacco samples (Table 2)

Table t- Resli its of the IAEA V - t 0 reference material compG red with Ihe cert ifi ed va llics (A ll va l lies in ppm un less

otherwise indi cated)

Element Mcasured conccntrat ion Certi fied va lue

K (per cent) 148±D.11 2.08 ± D.O()'"

Ca (per cent) 1.51 ± D. I I 2. 17 ±(l.D2:; Mn 40± II 47 ± 1.(" " Fe 152 ± 14 18 1 ± .\ . .'1 Cli 14 ± 3 9.27 ± D. I 8 Zn 20 ± 3 24.3 ± 04 Br

6±1 8.34 ± D.n Rh

7± 1 7.59±OI2 Sr

32 ± 3 40.2 ± 1.1

(i) = as provided hy the manufaclUrcr nO! certified

Tah le 2- Stat istica l data on thc clcmcnwl compos it ion of the tobacco c igarelle and ash samp les

Sample Concentrat ion range Mean (ppm) ± Rela tive standard Coe lTicient of variation size (ppm) deviation (ppm) (per cent)

Samp lc Ash Sample Ash Samplc Ash Sample Ash

As 12 7.5 -1 0.7 9 .5- 16.8 8.68 13. 1 0 .9 1.8 104 1:1 .7

Br 12 10.3-77.1 8 1-422 41. 15 23 8 26.5 136 644 :; 7. 1

K 12 1.7-3.1 # 4.8-9.7# 24" 7.6" 0 .5# 1.6# 20.8 21.1

Rb 12 12.7-59.4 34.3 - 139 3145 9 1.6 16.0 4D 50.9 4.' .7

Ca 12 1. 1-2 . 18# 34-6.6# 1.5(/ 4.8# 0 .32# 0 .9X· 20.5 2D4

Sr 12 65. 1- 102 302-4 14 83.74 359 10.4 34 .8 12.4 9 .7

T i 12 185-273 310-569 222.7 442 27.6 78.2 124 17.7

Zr 12 3.5-23.2 10-7 1.6 13 .55 39 8.3 23.5 61.3 60. 1

Fe 12 204-527 646-869 31X.6 759 g 1.5 68 25 .6 9.D

Ni 12 12.9-21.8 22 .2-3 1. 1 15 . .1 25.7 2.6 34 17.0 13.2

Cli 12 18-42 15.3-60 . .1 3 1.8 36 .9 8.2 10.2 25 .8 n.r, Zn 12 11 -48 49.3-93.9 22.3 69.2 10.5 13.5 47.1 19.5

Se 12 4-7 4.9-9.5 4 .9 7.6 0.8 1.2 16 .3 15 .X

Pb 12 11 - 16 13.8-24.6 12.7 19.2 14 2.7 J 1.0 14 . 1

# '" Per cent

50 J SCIIND RES VOL 61 JANUARY 2002

showed concentrations variation from percentage levels for light elements (K and Ca) to trace levels (ppm) for the heavy elements. The presence of potentially toxic elements like, As, Se and Pb in tobacco samples could be one of the factors for the health hazards of tobacco and cigarette ingestion , which is normally exclusively attributed to nicotine and the volatile gases like CO, HCN, NO. that are emitted from tobacco smoke.

The essential elements of plants, Ca and K, constitute about 98 per cent-ratio of the e lements determined in the samples with K levels genera ll y higher than Ca levels. For the other e lements determined their percentage ratio is almost similar in the cigarette samples, with the strongest correlation observed in the samples from the same source, i.e ., T6-TIO for Nigerian and TI-T5 for foreign samp les (Table 3). This pattern of e lemental distribution is similar to those reported for Kenya tobacco and cigarette samples and the variations with source is not surprising, as tobacco content is known to be dependent on growing conditions, particularly soil and c limate; and methods of culture and cure l2

. The

percentage coefficient of variation for e lements like Sr, Rb, Zr and Zn are high (Table 2); an ind ication that their levels in tobacco and ashed-tobacco samples vary over a wide range from the ir mean concen­trations.

The percentage ratio of the mean concentrations (Table 3) for the elements determined in the tobacco and ashed-tobacco samples showed an interesting decrease in the percentage ratio of the potentially toxic elements like As, Se, and Pb from the tobacco samples to their ashes. Thereby ind icat ing that these elements are constituents of the smoke released during tobacco burning, a large portion of which is ingested during smoking of tobacco.

Table 4 shows the correlation ana lysis between the e lements determined for the tobacco and ashed­tobacco samp les. Significantly high positive correlation is found to exist between the toxic e lements As and Pb (0.99) in both the tobacco and the ash samples. which shows that they are from the same source, presumably as lead arsenate . wide ly used as pestic ide to control insect pest llJ

• Signi ficantly high negative corre lation is found to exist between Zr and

Table 3 - Percentage ratio of clements detennined in tobacco cigarette and ash samples

K

TI 52 .0

ATI 55 .7

T2 55.1

ATI 56.9

TJ 53 .1

ATJ 45 .7

T4 51.7

AT4 54. 1

TS 43.0

ATS 59.6

T6 62.2

AT6 67 .9

T7 66.9

AT7 66.0

T8 66.9

AT8 67.7

T? 68.8

AT? 68 .8

TlO 68.8

ATlO 47.4

TIl 49.3

ATlI 56.9

Tl2 70.5

ATl2 7. 19

Ca As 8r Rh Sr Ti Zr Fe Ni CII Zn Sc I' h

46.0 0.02 0.22

42 .6 0.0 I 0.34

42 .8 0.03 0.19

41.2 0.01 0.26

44.6 0.03 0.19

52.0 0.016 0.40

46.5 0.02 0 16

44 .1 0.0 I 0.30

54 .8 0.02 0.1 X

38 .7 0.0 I 0.27

36.0 0.02 0.07

30.5 0.01 0 .0')

31.3 0.02 0.05

32 .2 0.0 I 0.13

31 .2 0.02 0.05

30.8 0.009 0.09

29.4 0.02 0.05

29.6 0.009 O.OH

29.5 0.02 0.06

50.9 0.009 0.3 I

4R3 0.02 003

4 1.7 0.008 0.05

27 .5 0.02 0.03

26.6 O.OOS 006

0.04

0.05

0.04

0.06

0.05

0.07

0.04

0.06

0.04

0.06

O.OS

0 . 10

0.0<)

0 .11

0.07

0.10

0.09

0.0<)

0 .0<)

0.04

0. 15

0 .02

0.14

0.11

0.2

0 .27

0. 17

(UO

0.22

(Ufi

0.2 1

(UO

02

o.n 0.2 1

(UO

0.2 1

0.3 1

0.2

O.2X

0.21

0.26

0.2

0.23

0.19

n.24

0.25

o.:n

0.67 0.01

028 0.00')

0 .67 0.009

0.45 0.014

0.13 om 0.3') 0 .017

O .. 'i2 0.02

0.4 1 0.0 15

0.fi2 0 .00<)

0.32 0.01

0.47 0.05

0 29 0.04

0.49 0.04

0.36 0.04

O.4X 0.03

0.26 0.05

0.52 0.05

0.39 0.04

0.55 0.05

0.36 0.0:;

O.4R OJ)4

0.37 0.02

0.46 0.06

0.34 0.04

0.58 0.04 0.1

0.62 OJ)2 0.02

0.76 0.04 0.1

0.6') 0.02 0.04

0.82 0.04 0.1

0.82 0.02 0.05

0.67 0.0:; O.OS

0.57 0.02 0.03

0.9X 0.0:; OJ)')

O.5X 0.019 0.03

0.7 0.03 0.07

0.:;8 0.02 0.04

o.n 0.03 0.0')

0.64 0.02 0.03

O.7fi 0.03 0.07

0.:;7 0.016 0.04

0.6') 0 .03 0.09

O.5H 0.02 0.03

0.6 0.03 0.0:;

0 .57 0.02 0.02

1.3 1 0.04 0.05

0.:;4 0.02 00 I

O.Sf> o.m 0.0:;

054 0.0 18 0.0 I

0 .03 0.02 O.O.j

0 .0:; 0 .07 0.02

0.03 0 .01 O.Oe!

0 .06 0.006 0.0111

0.06 0.0 1 0.04

0.06 0.007 0.02.1

O .O~ 0.0 . OJ!.'

OJ)'; O.OOX (l.OI I,

0 .0:; O.O i 0 .0.\

0.0:; 0.007 (l.() 17

0.05 0.0 1 0.0.\

OJ)7 (l .n05 00 I (,

0.(l6 0.01 0.0.\

0.07 OJ)C6 (U) I h

0.06 0.0 I (un OJ)7 0.0(;6 0.014

0.06 0 .0 1 (un 0.0:; 0 .00;' 0 .01 4

0.06 (J .OI 0 01

0.0:; O.O(J) 001 4

n. 12 0.01 (un 0.04 O. OOl) (Ull I

0.03 0.0 I o.m 0.04 0.004 (U)II

OYEWALE el al.: ANALYSIS OF ELEMENTS IN TOBACCO CIGARETTE & ASH-TOBACCO SAMPLES 51

Table 4 - Pearson's correlat ion matrix of the elements in tobacco cigarette and ash samples

As As I

Br K

Br 0.52

(0.4)

K -0.3 -0.76

Ca

Sr

Ti

Zr

Fe

Ni

Cu

Zn

Se

Pb

(-0.39) (-0.96)

(-O.O!!) (-0.64) (0.67)

0.16

(0.11 )

0.56 -0.84

(0.49) (-0.51 )

-0.42 -0.60

(-0.05) (-0.73)

-0.67 0.3 1

0.7

(06)

-0.41

0.85

(0.64)

-0.61 -0.94

(-0.34) (-0.57)

-0. 11

(0.46)

0.086

(0.13)

-0.42

(-0. 19)

0.47

(-0.44)

-0.13

(0.1 )

-0.59

(0.38)

0.28 0.49 -0.03

(0.59) (0.00 I) (0.03)

-0.21

(0.33)

0.38

(0.32)

0.99

(0.99)

-0.59

(-0.44 )

0. 17

(0.47)

0.62 -0.44

(0.16) (-0.19)

0.57 -0.34

(0.430 (-0.41 )

Rb

-0.43

(-0.8)

0.55

(0.7)

I

0.78

(0.62)

0.59

(0.06)

-0.38

(0.06)

-0.6

(0.42)

0.60

(0.56)

-0.54

(-0.4)

-0.38

(-0. I )

Ca

-0.48

(-0.6)

Sr Ti

(-0.29) (-0.27)

-0.74 0.64

(-0.2) (0.34)

(0.2)

-0.73

(0.09)

-0.28

(0.4 )

0.11

(0.7)

0.41

(0.26)

0.78

(017)

0.2 1

(-0.1 )

0. 15

(-0.3 )

0.18

(0 ... 7)

0.18

(0 I I )

0. 12

(0.32)

-0.26

(0.2 1 )

-o.m 0.64

(0.27) (-0.1 3)

0.092 -0.22

(0.35) (-0.08)

-0.62

(-D.3 )

-0.46

(-0 I )

0.46

(0. 11 )

0.77

(-D.3 1)

Zr

(-0.2)

0. 13

(0.2)

-0.57

(0.28)

-0.43

(0.28)

0.35

(0.49)

-0.59

(-0.30)

-0.65

(-0.4)

Fc

(0.34)

0.17

(0.67)

-0.3

(0.56 )

0.72

(0.39)

-0.5

(0.09)

-0. 1

(0.44)

Ni

(0. 12)

0. 15

(0.07)

-0.05

(033)

0.22

(0 . I )

0.099

(0. 11 )

Cu

-0.25

(0.72)

0.35

(0.2)

0.21)

(0.5 8)

Zn

-0.34

(0.3 )

-0.24

(0.3 )

Sc

0.4

(0.3 )

Ph

N = 12, a = 0.05, R = 0.6, Values in bracket represent thosc of the ash cigarette samples

Br (-0.94) and Rb and Br (-0.92), with Zr and Rb having a s ignificant positive correlation of 0 .77. These observations may be a pointer to the c hemi ca l similarity between Zr and Rb 111 their react ivity towards Br and hence their composition 111 the tobacco samples. A similar observation holds good for the relationship between Zr and Br (-0.94) and K and Br (-0.76), with Zr and Br having a positi ve correlation of 0 .85 . The othe r s ignificant correlations observed between the elements analysed could be attributed to che mical s imil arity or differentia l behav iours between the pairs.

The correlations observed between e lements in the tobacco samples, apparently disappears with ashing except for the strong correlation that still exists between As and Pb (0 .99) and K and Br (-0 .96) . However, some level of corre lation was a lso observed between Ca and Rb. (-0.85). Sr and Br (-0 .73). Cu and Z n and Ti (0 .72) and Ni (0 .70 ). Whether these correlations are indi cat ion of the composition or the non-volatil e components In tobacco ash needs further experiments.

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