Use Of Gold

Applied Radiation and Isotopes 55 (2001) 595–602

Use of gold as monostandard for the determination of elemental concentrations in environmental SRMs and Ganga river sediments by the k0 method V.V.S. Ramakrishnaa, R.N. Acharyab, A.V.R. Reddyb, A.N. Gargc,* b

a Department of Chemistry, Nagpur University, Nagpur 440010, India Radiochemistry Division, Bhabha Atomic Research Centre, Mumbai 400085, India c Department of Chemistry, University of Roorkee, Roorkee 247667, India

Received 10 April 2000; received in revised form 7 February 2001; accepted 19 February 2001

Abstract Instrumental neutron activation analysis (INAA) using the k0 method by employing gold as monostandard has been used for the determination of 18 elements (As, Ba, Br, Cl, Cr, Co, Cs, Dy, Fe, Hf, Ga, In, La, Mn, Na, Rb, Sc and Th) in standard reference materials (SRMs) of environmental origin and four sediment samples collected from the Ganga river in northern parts of India. Data obtained for SRMs agree within
5–10% with the certified values for most elements. Merits and demerits of the k0 method are discussed. An attempt has been made to identify the sources of heavy metal pollutants in the sediment samples and study the mobility pattern for toxic heavy metals originating from the tanneries along with the river flow # 2001 Elsevier Science Ltd. All rights reserved. Keywords: Neutron activation analysis; k0 method; Environmental SRMs; Element concentrations; River sediments

1. Introduction Activation analysis using synthetic multielement comparators is the most prevalent method for multielement analysis. This method is based on the comparison of the specific activity of an unknown sample with that of a standard of known concentrations. However, it has a few limitations (Ehmann and Vance, 1989). Preparation of synthetic standards is tedious, time consuming and fraught with several drawbacks (IAEA, 1990). Although the use of standard reference materials (SRMs) as comparator standards has been often followed as a practice, this method yields disputed values in some cases essentially because of inaccuracies in some of their elemental characterisation. Besides, it is also not possible in certain cases to ensure identical irradiation conditions for the standard and samples *Corresponding author. Fax: +91-1332-73560. E-mail address: [email protected] (A.N. Garg).

where flux inhomogeneity occurs (Heydorn, 1995). In order to alleviate many of such difficulties Girardi et al. (1965) first suggested the use of a single comparator method for reactor activation and proposed the use of a k-factor. Later, Simonits et al. (1975, 1980) suggested several improvements by introducing a universal k0 factor. It has been suggested that elements such as Au, Co, Mn that are monoisotopic and have well defined nuclear constants can be used as monostandards. Out of these gold is the most convenient as it can be prepared in the purest form of foil, wire, alloy and solution. On irradiation with thermal neutrons, 197Au undergoes an (n, g) reaction to give 198Au (half-life=2.7 d) emitting well characterised 411.8 keV g–rays (Erdtmann, 1976). By the early 1980s, the method had developed from a mere concept to an operational tool for standardisation in reactor and epi-cadmium NAA. Erdtmann et al. (1988) analyzed high purity Al, As and Zr ceramics using the k0 method of analysis. Smodis et al. (1990) reported on the determination of 34 elements in NIST

0969-8043/01/$ - see front matter # 2001 Elsevier Science Ltd. All rights reserved. PII: S 0 9 6 9 - 8 0 4 3 ( 0 1 ) 0 0 0 7 1 - 9

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biological SRMs, with a systematic uncertainty of 48% for 12 certified elements. Freitas and Martinho (1989) and Freitas (1990) discussed the potential of the k0 method in reactor NAA by analyzing NIST SRMs and IAEA CRMs of biological and geological origin. Acharya et al. (1995) have reported k0 values for 15 elements using gold as comparator and compiled data for 111 radionuclides ranging from F to U. Comparisons of experimentally determined and calculated values have shown good agreement. Therefore, we have used the same k0 values as compiled by Acharya et al. (1995). Recently, two reports from India, dealing with the analysis of serpentine rock samples (Nair et al., 1997) and elemental analysis in environmental studies (Balaji et al., 1997) have appeared. In the recently held Ninth International Conference on Modern Trends in Activation Analysis (MTAA-9), De Corte et al. (1997) have reported the installation of k0 assisted NAA set up for use in industry and environmental sanitation. Also a k0 evaluation software has been developed for loss free counting (van Sluijs et al., 1997). Piccot et al. (1997) have developed a quasi non-dependent data format package for the k0 quantification.

2. The k0 method Girardi et al. (1965) first defined a constant k which contains nuclear constants that could be evaluated from the literature and is given by k¼

Mg * e * y * s * ; M * geys

ð1Þ

where M is the mass number of the element, g the absolute abundance of the measured g-ray, e the full energy peak efficiency of the detector for the measured g-ray, y the isotopic abundance of the target isotope, s the effective activation cross section of the neutron energy spectrum used and * corresponds to the monostandard. Once the value of k has been determined, the amount of analyte in an unknown sample, w, may be calculated by irradiating the sample together with a comparator using the following equation: w¼k

Ap S * D * w * ; Ap* SD

ð2Þ

where Ap is the specific count rate, S the saturation factor (1elt), l is decay constant and t the time of irradiation, D the decay factor. However, the k factor as defined is useful only for stable, well thermalized irradiation conditions and fixed geometry, which limits the versatility of the activation method. In order to make the k factor more verasatile,

De Corte et al. (1969) introduced the concept of conversion of the k factor determined in one irradiation channel to k values for another channel with respect to the effective cross section. If fth and fe are fluxes of thermal and epithermal neutrons then k¼

Asp M * gey s0 ðfth =fe Þ þ I0 ¼ ; * Mg * e * y * s0* ðfth =fe Þ þ I0* Asp

ð3Þ

where Asp is the specific activity of the radionuclide in the sample, Ap =ðSDwÞ, Asp* the corresponding count rate normalised to 1 mg of the comparator, s0 the thermal neutron activation cross section and I0 the infinitely diluted resonance integral. k as defined in Eq. (3) is still specific for a given reactor facility and counting set up. It had been pointed out that the tabulated nuclear data may not be reliable enough for a 3–5% accuracy level generally required for analysis. In order to overcome such practical problems, Simonits et al. (1975) proposed a new generalized factor called ‘k0 ’ that would couple the simplicity of an ‘‘almost absolute’’ method with acceptable accuracy. It is defined as k0 ¼

Asp ðf =f Þ þ ðI0 =s0 Þ * e * M * ygs : ¼ * th e * * * My g s Asp ðfth =fe Þ þ ðI0 =s0 Þe

ð4Þ

The difference between the k and k0 factors is that the new factor k0 contains only well defined invariable nuclear constants (M, y, g, M * , y * , g * ) and it does not contain any terms that relate to the experimental conditions. Therefore, k0 constants should be valid for any laboratory and are likely to be generalized. De Corte et al. (1989) and Simonits et al. (1975, 1980) have extensively worked on the accurate determination of the k0 values for different radionuclides. A compilation of k0 values and pertinent nuclear data for 198 nuclides employing gold as a comparator have been presented (Simonits et al., 1980; Moens et al., 1984; De Corte et al., 1987).

3. Experimental (i) Sampling: The SRMs in this study were procured from different agencies; Coal Fly Ash}SRM 1633a (NIST, 1985) and Urban Particulate Matter} SRM 1648a (NIST, 1982) from NIST (USA), Soil-5 (Dybcznski et al., 1979) from IAEA, Vienna (Austria) and Pond Sediment NIES No. 2 (Soma et al., 1985) from NIES (Japan) in their standard form and used as such. Sediment samples were collected from two different locations viz. Bithoor and Jajmau near the Kanpur (India) basin of the Ganga river. More than 200 tanneries are located in Kanpur where most effluent is discharged into the Ganga river which passes through the city. At both locations samples were collected from

V.V.S. Ramakrishna et al. / Applied Radiation and Isotopes 55 (2001) 595–602

the surface and subsurface i.e., at about 30 cm below the surface so as to study downward mobility of heavy metal pollutants. Of the two locations, Bithoor is in the upstream and Jajamau in the downstream direction. In our studies sediment samples from Bithoor were used as reference samples whereas others from Jajmau were used to study the accumulation of heavy metals as most tanneries are located around the Jajmau area. (ii) Sample preparation: 20–30 mg of each SRM and sediment sample were accurately weighed and packed in polypropylene tubes (for short irradiation of 10 min and 2 h) or in Al-foil (for long irradiation of 6 h). A standard solution of gold was prepared as follows: a high purity (5 N, 99.999%) metallic gold foil was dissolved in aquaregia. The solution was slowly evaporated to dryness under infrared lamp and dissolved in 0.1 M HNO3. Finally the monostandard was prepared by either of the following methods: (a) About 20 mg of the gold solution were dried on a high purity Al-foil taking care that the spot portion did not exceed 5 mm in diameter (used for long irradiation of 6 h). (b) 10–20 mg solution were transferred into a 0.25 cm diameter polypropylene tube and then sealed (used for short irradiation of 10 min and 2 h). (iii) Irradiation and counting: All irradiations were carried out at the E8 position of the APSARA reactor at the Bhabha Atomic Research Centre (BARC), Mumbai. This is the position standardised for the homogeneity of neutron flux with a sub-cadmium to epi-cadmium ratio of 52.2
2.7 using Au. Samples were irradiated at a thermal neutron flux of 1012 n cm2 s1 for 10 min, 2 h and 6 h. Short irradiation (10 min and 2 h) samples were counted using an experimental set-up consisting of a 80 cm3 coaxial HPGe detector (EG & G ORTEC) and a 4k MCA at the Radiochemistry Division of BARC, Mumbai. For long irradiation of 6 h, the samples were airlifted to our laboratory at Nagpur and counted on a 113 cm3 HPGe detector (PGT, Germany) coupled with 4k MCA (Nucleonix, India) at different intervals up to 10 days. Both detectors used for counting were calibrated for efficiency in a fixed source to detector geometry using several gamma standards such as 152Eu, 133 Ba, 137Cs and 60Co. In all cases most abundant gamma lines with least interference were used for the measurement of activity. (iv) Calculation of elemental concentrations: Elemental concentrations, r, in the samples were calculated using rðmg=gÞ ¼

Asp 1 ðf þ Q0 Þ * e * ; * k ðf þ Q Þ e Asp 0 0

where f ¼ fth =fe , Q0 ¼ I0 =s0 .

ð5Þ

597

For simplicity, a new term Kanal has been introduced and defined as Kanal ¼ k0

ðf þ Q0 Þ e : ðf þ Q0 Þ * e *

ð6Þ

Aip ; * Asp Kanal

ð7Þ

Therefore, rðmg=gÞ ¼

where Aip is the peak area of the ith element corrected for saturation, cooling and decay during counting and normalized for 1 g of the sample. The parameters k0 , the one containing f , and final Kanal values as calculated for the elements determined in this study are listed in Table 1.

4. Results and discussion Elemental concentrations as calculated using the k0 method for different environmental SRMs are given in Table 2. Also included in the table are certified/literature values for comparison. Analytical data for the sediment samples from the Ganga river are listed in Table 3. An attempt has been made to identify the sources of origin and to study the mobility for different heavy metals in sediment samples. A perusal of data in Table 2 and comparison with the certified values shows that most elemental contents in the different SRMs are within
5–10% with a few exceptions. It is further shown in Fig. 1. where the percentage deviations of the observed values from the certified values are illustrated. In the case of coal fly ash all the elemental contents are comparable within
5% except for Ba, Mn, Co, In and Fe which differ by 510%. In the case of Soil-5, the Na, K, Cr, La, Sc, Th and Dy contents are comparable within
5% but Br, Co, Ga, Mn contents differ up to
10% and the rest of the elemental contents (As, Cs, Fe and Rb) differ by more than
10%. In the case of pond sediment all the elemental contents are comparable within
5% though some elements (As, Fe, La) differ up to
10%. However, in the case of urban particulate matter Cl and Ga show wide variations up to +55% and 61%, respectively. Incidentally consensus values for these elements are not available in the certificate but these are from literature (Morselli et al., 1988). Further, we have reported elemental contents of Cs, Ga, Hf and Th in pond sediment and these may be considered as reference values by other workers. A visual inspection of Fig. 1 illustrates that in general our values for elemental contents in various standards compare well with the certified values.

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Table 1 k0 values and other nuclear data for different radionuclides Nuclide

Energy (keV)

k0

Q0 ¼ ðI0 =s0 Þ

ðf þ Q0 Þ=ðf þ Q0 Þ

Kanal

198

411 1368 1525 847 1811 487 1642 1293 511 834 554 776 559 94.7 165.7 320 312 1099 1292 889 1120 1173 1332 795 346 1077

1 4.82  102 9.86  104 4.99  101 1.37  101 6.15  102 1.87  103 2.38 3.65  102 5.37  102 2.40  102 2.83  102 5.61  102 0.35 8.63  104 2.72  102 2.39  102 7.57  102 5.78  102 1.262 1.262 1.325 1.326 0.402 7.8  103 7.4  104

15.69 0.603 0.959 1.037 1.037 1.366 7.07 16.05 1.097 6.603 19.0 19.0 13.62 0.241 0.88 0.509 11.53 1.093 1.093 0.423 0.423 1.898 1.898 12.7 2.66 11.46

1 0.778 0.783 0.784 0.784 0.789 0.873 1.005 0.785 0.866 1.05 1.05 0.97 0.772 0.782 0.776 0.939 0.785 0.785 0.775 0.775 0.797 0.797 0.956 0.808 0.937

1 0.012 2.2  104 1.94  101 2.6  102 3.98  102 4.2  104 0.801 2.3  103 2.3  103 1.8  102 1.6  102 4.0  102 1.02 1.52  103 2.6  103 2.8  102 2.47  105 1.65  105 0.49 0.39 0.414 0.370 0.21 7.2  103 2.9  104

Au Na 42 K 56 Mn 24

140

La Cl 116 In 64 Cu 72 Ga 82 Br 38

76

As Dy 139 Ba 51 Cr 233 Th(Pa) 59 Fe 165

46

Sc

60

Co

134

Cs Hf 86 Rb

181

4.1. Sediments Ganga, a mighty river, is considered as the holiest of all Indian rivers. It originates from Gangotri in the upper Himalayas and flows through a long stretch of 2525 km in northern parts of India. In recent years it has attracted much attention of environmentalists because of the highly polluted status at several points. The Ganga Action Plan has identified 27 cities and 120 factories as points of pollution from Haridwar (in Uttar Pradesh) to Hoogly (in West Bengal) of which major pollution sites are Kanpur, Allahabad, Varanasi and Patna. Kanpur is a major industrial city with over 200 tanneries and about 5 million population where treated or untreated effluents are directly discharged into the river. Therefore, several heavy metal pollutants, particularly chromium, enter into the river thus polluting the entire water stream. A perusal of data in Table 3, with statistical uncertainty of
1 to 4%, shows that Cr, Mn and Zn concentrations in both the surface and sub-surface sediments in Jajmau are higher compared to similar samples in Bithoor. This is primarily due to the fact that the metals from tannery effluents are being deposited

heavily at down streams in Jajmau. The Fe contents also follow a similar trend for subsurface sediments but for the surface sediments it is more at Bithoor than at Jajmau. Here it may be noted that the aquatic environment is contaminated with heavy metals, especially chromium, in tannery areas, as chrome liquor is extensively used in tanneries and the waste discharged into the river. In our earlier study on the analysis of different industrial wastes for heavy metal pollutants we have observed 3.34% Cr, besides higher contents of Mn (181 mg/g), Fe (6.18 mg/g) and Zn (381 mg/g) in a tannery industrial waste from Calcutta (Garg and Ramakrishna, 1997). In another study on heavy metal pollution status in some Indian cities, it has been observed that sewage sludge from Kanpur is the second highest for Cr (571 mg/ g) and Fe (21.8 mg/g) just after Calcutta (Garg et al., 1997). Based on these observations it can be emphasized that effluents from tanneries severely affect the aquatic environment by contaminating the river water chromium and other heavy metals. Besides, several other studies have also reported contamination of ground and/or river water by Cr and other pollutants due to tannery effluents (Kothandaramam et al., 1997; Rajamani et al., 1997).

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Table 2 Elemental contents obtained in some environmental/geological SRMs using the k0-method. Literature (or certified) values are given in the parenthesis. Element

Urban particulate matter, SRM 1648a

As(mg/g)

109
10 (115
10) 0.775
0.025 (0.737) 498
4 (500) 6.97 (4.5) 18.2
0.3 (18) 393
28 (403
12) 2.89
0.02 (3.0) ND

Ba(mg/g) Br(mg/g) Cl(mg/g) Co(mg/g) Cr(mg/g) Cs(mg/g) Dy(mg/g) Fe(mg/g) Ga(mg/g) Hf(mg/g) In(mg/g) K(mg/g) La(mg/g) Mn(mg/g) Na(mg/g) Rb(mg/g) Sc(mg/g) Th(mg/g)

38.7
0.8 (39.1
1.0) 15.6
0.4 (40) 29.3
0.4 () 0.81
0.06 (1.0) 9.91
0.37 (10.5
0.1) 36.5
3.8 (42) 857
65 (860) 3.93
0.02 (4.25
0.02) 56.4
1.2 (52.0) 6.78
0.36 (7) 7.6
0.7 (7.4)

Coal fly ash, SRM 1633a 133
12 (145
15) 2.07
0.03 (1.5) ND 0.292 () 49
2 (46) 190
13 (196
6) 11.1
0.2 (11) 13.8
0.3 (14) 103
6 (94
1) 59.3
0.8 (58) 10.4
0.3 (8) 0.182
0.010 (0.16) 18.8
0.7 (18.8
0.6) 95.6
1.8 (87.9) 196
15 (179
8) 1.75
0.02 (1.7
0.1) 129
12 (131
2) 40.7
1.2 (40) 24.2
2.1 (24.7
0.3)

Further, it is observed from Table 3 that Cr, Mn and Zn concentrations in subsurface sediments of Jajmau are significantly higher compared to those of Bithoor though these are lower when compared to those in the surface sediments of both sampling sites. It means that these metals are sinking down the surface after they enter into the river just before Jajmau. Surprisingly Fe, Co, Cs and Rb have not shown any definite trend as these are higher in surface at Bithoor but lower in Jajmau. Alkali metals (Na and K) are almost comparable in all the four samples.

Soil-5 105
10 (93.9
18.6) 0.550
0.16 (0.562
0.037) 4.98
1.70 (5.4
1.9) ND 13.4
0.1 (14.8
2.3) 30.2
4.2 (28.9
9.3) 49.7
1.0 (56.7
6.9) 3.89
0.20 (4.0
0.4) 48.9
0.2 (44.5
1.9) 17.2
0.5 (18.4
1.6) 6.6
0.2 (6.3
0.3) 0.787
0.023 () 18.6
1.2 (18.6
1.5) 27.5
3.0 (28.1
1.5) 909
30 (852
37) 19.6
0.4 (19.2
1.1) 120
9 (138
7) 14.9
0.2 (14.8
0.7) 11.5
1.6 (11.3
0.7)

Pond sediment, NIES No. 2 11.0
1.5 (12
2) ND 18.0
2.0 (17.0) ND 26.6
1.5 (27
3) 77.8
3.7 (75
5) 22.4
2.3 () ND 60.2
4.8 (65.3
3.5) 17.9
2.3 () 62.5
3.7 () ND 7.02
0.21 (6.8
0.6) 13.1
1.3 (17) 775
38 (770) 5.71
0.52 (5.7
0.4) 44.4
1.8 (42) 27.8
1.3 (28) 4.3
0.4 ()

In an exhaustive study on the effect of anthropogenic activity on trace element distribution in sediments, sand and silt, Bulnayev (1995) reported a high concentration of Cr (214 mg/g) in coarse grained sand from the near-surface layer of the sediment. It is also reported that some other trace elements in the near surface layer of sediments almost coincide with those from deeper layers. It seems that some elements such as Cr are preferentially absorbed by the sediments and exhibit downward movement so as to continuously pollute the flowing river waters.

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Table 3 Elemental concentrations in sediment samples using the k0 -method Element

Co(mg/g) Cr(mg/g) Cs(mg/g) Fe(mg/g) Hg(mg/g) K(mg/g) La(mg/g) Mn(mg/g) Na(mg/g) Rb(mg/g) Sc(mg/g) Th(mg/g) Zn(mg/g) Other characteristics pH Organic matter (%)

Bithoor

Jajmau

Surface

Subsurface

Surface

Subsurface

6.72 33.7 6.49 28.7 29.7 11.7 50.9 379 8.88 114 9.20 35.6 88.2

5.36 17.2 4.40 17.1 58.0 14.4 49.5 318 9.76 47.4 6.25 25.4 65.1

6.77 103 4.67 18.7 9.09 18.3 42.7 424 8.85 32.7 6.44 7.44 120

13.4 59.5 7.35 37.5 40.4 17.8 26.6 362 8.15 119 1.32 1.62 96.5

6.7 1.01

7.1 0.68

6.7 0.26

7.0 0.007

Fig. 1. Comparison of elemental contents in SRMs with their certified values.

Further, it is observed that the pH vales for all the four samples remain unchanged (6.9
0.2) but the organic matter content of both samples from Jajmau were much higher. Considering that tannery wastes contain a lot of organic matter, it is likely to settle along with the sediments thus further polluting the sediments.

5. Conclusion INAA using the k0 method is an useful method for the determination of trace element concentrations in a variety of matrices such as environmental standards and samples as more accurate and precise data are

V.V.S. Ramakrishna et al. / Applied Radiation and Isotopes 55 (2001) 595–602

obtained. Therefore, the k0 method should be exclusively used if high quality concentration data are needed or if other methods have to be validated. Higher concentrations of some of the elements viz. Cr, Mn and Zn in sediment samples collected from the Ganga river at Jajmau site compared to those from Bithoor can be attributed to the mixing up of effluents from tanneries and other industries located around the site. Cr originating from tannery waste exhibits downward movement and is preferentially absorbed by the sediments, thus polluting Ganga river.

Acknowledgements Thanks are due to the International Atomic Energy Agency (IAEA), Vienna for financial assistance under Coordinated Research Project no.7369/RB. Sincere thanks are due to Dr. A.R. Khwaja for providing us sediment samples collected from Kanpur. One of us (VVSR) thanks CSIR, New Delhi, India for the award of Senior Research Fellowship (SRF).

References Acharya, R.N., Nair, A.G.C., Burte, P.P., Reddy, A.V.R., Manohar, S.B., 1995. Reactor neutron activation analysis by single comparator method: k0 measurements. Technical Report No. BARC/1995/007, Bhabha Atomic Research Centre, Mumbai, pp. 1–49. Balaji, T., Acharya, R.N., Nair, A.G.C., Burte, P.P., Naidu, G.R.K., Reddy, A.V.R., Manohar, S.B., 1997. Elemental profiles of soil in and around Tirupati by reactor neutron activation analysis using k0 method. Proceedings of the Nuclear and Radiochemistry Symposium (NUCAR-97), Saha Institute of Nuclear Physics, Calcutta, p. 371. Bulnayev, A.I., 1995. Neutron activation analysis investigation of the composition and geochemical peculiarities of lake Baikal bottom sediments. Analyst 120, 1445. De Corte, F., Specke, A., Hoste, J., 1969. Reactor neutron activation analysis by a triple comparator method. J. Radioanal. Chem. 63, 205. De Corte, F., Simonits, A., De Wispelaere, A., Elek, A., 1989. J Radioanal. Nucl. Chem. 133, 3,43. De Corte, F., Simonits, A., De Wispelaere, A., Hoste, J., 1987. Accuracy and applicability of the k0 standardisation method. J. Radioanal. Nucl. Chem. 113, 145. De Corte, F., De Wispelaere, A., van Sluijs, R., Bossus, D., Simonits, A., Kucera, J., Frana, J., Smodis, B., Jacimovic, R., 1997. The installation of KAYZEROassisted NAA for use in industry and environmental sanitation in three central European countries: plans and achievements of a Copernicus project. J. Radioanal. Nucl. Chem. 215, 31.

601

Dybcznski, R., Tugsevul, A., Suschny, O., 1979. Soil-5, a new IAEA certified reference material for trace element determinations. Geostandard News Lett. 3, 61. Ehmann, W.D., Vance, D.E., 1989. Advances in neutron activation analysis. CRC Crit. Rev. Anal. Chem. 20, 405. Erdtmann, G., 1976. Neutron activation tables. Kernchemie in Einzeldarstellungen, Verlag Chemie, Weinheim. Erdtmann, G., Petri, H., Kaysser, B., Kulppers, G., 1988. Absolute neutron activation analysis of materials using Ghent k0 factor. J. Trace Microprobe Tech. 6, 337. Freitas, M.C., 1990. Instrumental neutron activation analysis of geological and biological reference materials using the k0 standardisation method. Biol. Trace Elem. Res. 26–27, 189. Freitas, M.C., Martinho, E., 1989. Determination of trace elements in reference materials by the k0-standardisation method. Talanta 36, 527. Garg, A.N., Ramakrishna, V.V.S., 1997. Elemental characterisation of industrial sludges and domestic wastes for heavy metal pollutants by INAA. Proceedings of the Asia Pacific Symposium on Radiochemistry (APSORC-97), Kumamoto University, Japan, p. 113, Abs. No. p. 233. Garg, A.N., Ramakrishna, V.V.S., Singh, V., Olaniya, M.S., 1997. INAA of toxic heavy metals in solid wastes from Indian cities. J. Radioanal. Nucl. Chem. 217, 31. Girardi, F., Guzzi, G., Pauly, J., 1965. Reactor neutron activation analysis by the single comparator method. Anal. Chem. 37, 1085. Heydorn K., 1995. In: Quevanviller Ph. , Maler E.A. Griepink, (Eds.), Validation of NAA Technique in Quality Assurance for Environmental analysis, techniques and instrumentation in Analytical Chemistry, Vol. 17. Elsevier, Amsterdam, p. 89. International Atomic Energy Agency (IAEA), 1990. Practical aspects of operating neutron activation laboratory. IAEATECDOC-564, IAEA, Vienna, p. 1–25. Kothandaramam, H., Latha, H., Kulasekharan, A., 1997. Ground water pollution by tanneries in chrompet}a case history. In: Anajaneyulu, Y., (Ed.), Proceedings of the International Conference on Industrial Pollution and Control Technologies. Allied Publishers, Hyderabad, p. 684. Moens, L., De Corte, F., De Wispelaere, Hoste, J., Simonits, A., Elek, E., Szabo, E., 1984. k0 measurements and related nuclear data compilation for (n, g) reactor neutron activation analysis. J. Radioanal. Nucl. Chem. 82, 385. Morselli, L., Zapolli, S., Gallorini, M., Rizzio, E., 1988. Characterisation of trace elements in dry depositions by instrumental neutron activation analysis. Analyst 113, 1575. Nair A.G.C., Acharya R.N., Burte P.P., Reddy A.V.R., Manohar S.B. and Reddy L.K., 1997. Multielemental analysis of serpentine samples by neutron activation analysis. Proceedings of the Nuclear and Radiochemistry Symposium (NUCAR-97), Saha Institute of Nuclear Physics, Calcutta, p. 362. NIST, 1982. Urban Particulate Matter (SRM-1648a). NIST, Gaithersburg, USA. NIST, 1985. Coal Fly Ash (SRM-1633a). NIST, Gaithersburg, USA. Piccot, D., Deschamps, C., Deimas, R., Revel, G., 1997. k0–LAB USE: a quasi non-dependent data format package for k0 quantification. J. Radioanal. Nucl. Chem. 215, 263.

602

V.V.S. Ramakrishna et al. / Applied Radiation and Isotopes 55 (2001) 595–602

Rajamani S., Rajan R.S., Lagerwerf J.S.A., Schyrman J.E., 1997. Waste minimisation and resource recovery in tanneries}a sustainable chromium recovery and reuse system. In: Iyer C.S.P. (Ed.), Advances in Environmental Science, Educational Publishers and Distributors, New Delhi, p. 363. Simonits, A., De Corte, F., Hoste, J., 1975. Single comparator method in reactor neutron activation analysis. J. Radioanal. Chem. 24, 31. Simonits, A., Moens, L., De Corte, F., De Wispelaere, A., Elek, A., Hoste, J., 1980. k0 measurements and related nuclear data and compilation for (n,g) reactor neutron activation analysis. J. Radioanal. Chem. 60, 461.

Smodis, B., Jocimovic, R., Jovamovic, S., Stegner, P., 1990. Determination of trace elements in standard reference materials by k0 method. Biol. Trace Elem. Res. 26–27, 43. Soma, N., Sayema, H., Okamoto, K., 1985. Characterisation of sediment reference material by X-ray photoelectron spectroscopy. Talanta 32, 177. van Sluijs, R., Bossus, D.A.W., Konings, J., De Corte, F., De Wispelaere, A., Simonits, A., 1997. Loss free counting in NAA using KAYZERO evaluation software. J. Radioanal. Nucl. Chem. 215, 283.