اﻟﺨﻼﺻــﺔ - Arabian Journal for Science and Engineering

،سﺎﺤﻨﻟاو
مﻮﻴﺸﻥاﺮﺘﺱﻻاو
LEVELS OF TRACE ELEMENTS IN DIFFERENT
VARIETIES OF WHEAT DETERMINED BY ATOMIC
ABSORPTION SPECTROSCOPY
،موﺮﻜﻟاو
،ﺖﻠﺏﻮﻜﻟاو
،صﺎﺻﺮﻟاو
A.E. Mohamed* and G.M. Taha
Chemistry Department, Faculty of Science
Aswan, Egypt
،مﻮﻴﺴﻟﺎﻜﻟاو
،ﻞﻜﻴﻨﻟاو
،ﺐهﺬﻟاو
،مﻮﻳدﻮﺼﻟاو
،ﺔﻀﻔﻟا ﺮﺻﺎﻨﻋ ﺮﻳﺪﻘـﺘﺏ
،ﺰﻴﻨﺠﻨﻤﻟاو
،مﻮﻴﺴﻨﻏﺎﻤﻟاو
ﺔــﺻﻼﺨﻟا
اﺬه ﻰﻨﻌُﻳ
July 2003 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. 163
ﺚﺤﺒﻟا
،مﻮﻴﺱﺎﺕﻮﺒﻟاو
،ﺪﻳﺪﺤﻟاو
ﺔﻔﻠﺘﺨﻡ لود ﻦﻡ
تﺬﺥأ ﻲﺘﻟا ﺢﻤﻘﻟا تﺎﻨﻴﻋ ﺾﻌﺏ ﻰﻓ يرﺬﻟا
صﺎﺼﺘﻡﻻا فﺎﻴﻄﻡ ماﺪﺨﺘﺱﺎﺏ
ﻦﻴﺻرﺎﺨﻟاو
ﻢﺕ ﺪﻗو . ﻦﻤﻴﻟاو ،ةﺪﺤﺘﻤﻟا
ﺔﻴﺑﺮﻌﻟا تارﺎﻣﻹاو
،نﺎﻤﻋو
،ﺎﻴﻟاﺮﺘﺱاو
،ﺔﻳدﻮﻌﺴﻟا ﺔﻴﺏﺮﻌﻟا ﺔﻜﻠﻤﻤﻟاو
،ﺮﺼﻡ ﻰه
تﺎﻨﻴﻌﻟا ﻰﻓ ﺮﺻﺎﻨﻌﻟا ﻩﺬه تاﺰﻴآﺮﺕ ﻰﻓ فﻼﺘﺥا
ﺞﺋﺎﺘﻨﻟا تﺮﻬﻇﺄﻓ
،ﺔﺡﻮﺘﻔﻤﻟا قاﻮﺱﻷا ﻦﻡ تﺎﻨﻴﻌﻟا ﻊﻴﻤﺠﺕ
ﺞﺋﺎﺘﻨﻟا تﺮﻬﻇأ ﺎﻤآ . لوﺪﻟا ﻩﺬه ﻰﻓ ﺎﻬﺒﻴآﺮﺕو
ﺔﺏﺮﺘﻟا ﺔﻴﻋﻮﻥ ﻰﻓ فﻼﺘﺥﻻا ﻰﻟإ اﺬه دﻮﻌﻳ ﺪﻗو . ﺔﻔﻠﺘﺨﻤﻟا
ﺾﻌﺏ تاﺰﻴآﺮﺕ ﻲﻓ برﺎﻘﺕ دﻮﺝوو ،ﺔﻀﻔﻟا
ﺮﺼﻨﻋ اﺪﻋ ﺎﻡ ﺔﻳﺮﺼﻤﻟا ﺔﻨﻴﻌﻟا ﻰﻓ ﺮﺻﺎﻨﻌﻟا ﻞآ دﻮﺝو
لوﺪﻟا ﻩﺬه ﻰﻓ ﺔﺏﺮﺘﻠﻟ ﻲﻥﺪﻌﻤﻟا ﺐﻴآﺮﺘﻟا نأ ﻰﻠﻋ لﺪﻳ اﺬهو . ﻦﻤﻴﻟاو تارﺎﻣﻹا ،نﺎﻤﻋ
تﺎﻨﻴﻋ ﻰﻓ ﺮﺻﺎﻨﻌﻟا
. ًﺎﻴﻟود ﺎﻬﺏ حﻮﻤﺴﻤﻟا دوﺪﺤﻟا ﻦﻤﺽ ﻊﻘﺕ
ﺮﺻﺎﻨﻌﻟا ﻩﺬه تاﺰﻴآﺮﺕ نأ ﺔﺱارﺪﻟا ﺖﺤﺽوأو . ﻪﺏﺎﺸﺘﻡ
*To whom correspondence should be addressed.
e-mail: gmtaha@hotmail.com

A.E. Mohamed and G.M. Taha
ABSTRACT
Trace elements, Ag, Au, Ca, Co, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, Pb, Sr, and Zn were
determined in six wheat samples purchased from the open market in different localities
(Egypt, Saudi Arabia, (KSA), Yemen, Oman, Dubai, and Australia). The dried
powdered samples were decomposed in HNO3 –HClO4 acids mixture and elements
were determined using recording atomic absorption spectrophotometer. The results
were within the safety baseline of all the assayed elements. Certified biological
standards, Bown’s Kale (BK), Orchard Leaves (OL), and Tomato Leaves (TOML)
were used to ensure the accuracy of the results. However, Co, Pb, and Sr were
absent from samples except the Egyptian samples. The obtained databases were
statistically treated. Several significant and strong positive correlation coefficients
(r = 0.506–1.00) between the groups of elements were observed. On the other hand,
strong negative correlations (r = –0.492 to –0.873) between another group of elements
were also shown.
Keywords: Wheat samples, Trace elements, Atomic absorption Spectroscopy.
164 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. July 2003

A.E. Mohamed and G.M. Taha
LEVELS OF TRACE ELEMENTS IN DIFFERENT VARIETIES OF WHEAT
DETERMINED BY ATOMIC ABSORPTION SPECTROSCOPY
1. INTRODUCTION
Trace elements play a very important role in chemical, biochemical, physiological, metabolic, geochemical,
biogeochemical, and enzymatic processes. Consequently, their importance is pronounced on the health and diseases of
plants, animals, and human being, as they are dependent on trace elements needed from food.
Trace elements present in plants to a great extent depend on the available and exchangeable trace elements present in
the soil, and in irrigation water. However, there is permissibility and selectivity in plants for the uptake of certain trace
elements (essential) from the soil, but there are other useful trace elements which accelerate, stunt, or inhibit such uptake.
The importance of trace element analysis in environmental, biological, geological, geochemical, biogeochemical,
industrial, and in many other fields is well known. There are several methods available for the determination of trace
elements in these matrixes.
Various developments in agriculture and technology can affect the trace elements content of foods. The introduction of
new varieties of plants, the use of agricultural chemicals, alterations in feeding practices used for farm animals, and other
new techniques designed to increase food production and yields affect the composition of basic food items [1].
Three major factors influence the amount of trace elements in food as consumed: (i) inherent characteristics of plants
and animals; (ii) environmental conditions affecting plants and animals; and (iii) methods for handling and processing of
the plant and animal material.
Geographical Location
Differences due to geographical location probably depend on contamination of water, air or soil with the trace
elements. Variations observed in the selenium content of foods grown in Sweden, Egypt, and the USA are a good
example of how geographical location significantly affects the trace elements contents of foods.
Foods from Sweden and Egypt have been reported [2, 3] to have rather a low selenium content as compared with the
levels found [4, 5] in the USA. Also, it was found that [6] the amounts of copper in spinach and lettuce depend on the
quantity and availability of the trace element in the soil. Atomic absorption spectrophotometry has been used [7, 8] to
determine the trace elements in plants and vegetables [9] of Lake Nasser. Inductively coupled plasma atomic emission
spectrophotometry has been utilized to determine the trace elements Be, Ca, Cr, Fe, Pb, and Zn in raw agricultural crops
(lettuce, potatoes, spinach, and wheat) [10]. Multielemental neutron activation analysis techniques have been applied
[11, 12] for the determination of Al, As, Au, La, Mo, and Zn in Egyptian crops.
The present work is aimed to introduce unprecedented monitoring of the analyzed wheat samples. In addition,
comparison between the elemental content of the different varieties of wheat samples from different locations globally
represent an important target of this work. The work is also done to establish the extent to which the elements present in
the different varieties of wheat are present at safe levels.
2. EXPERIMENTAL
Chemical and Reagents
All chemicals used were of A.R. grade (99.9 %) and purchased from BDH, Aldrich, Sigma, or E. Merck.
Certified ASS standard solutions (1 mg/ml) of Ag, Au, Ca, Cd, Co, Cu, Fe, Mg, Mn, Ni, Pb, Sr, and Zn were
purchased from BDH (UK). Working standard solutions were prepared by appropriate dilution of the stock solutions.
Biological standards [13] (Bown’s Kale “BK”, Orchard Leaves “OL”, as well as Tomato Leaves “TOML”) were used to
check the accuracy of the results.
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A.E. Mohamed and G.M. Taha
Sample Collection
Six species of wheat samples (two groups of each sample) were collected from the open markets from six locations
(Egypt, Saudi Arabia, Yemen, Oman, Dubai, and Australia).
Analytical Determination
Representative wheat samples prepared by the quartering method were powdered in an agate mortar and kept in
polyethylene bottles. Wheat samples (4g) were wet ashed in a Teflon beaker using 40 ml 1:1 v/v mixture of
HNO3–HClO4 acids, followed by the addition of three drops of HF acid. The contents were evaporated on a sand bath
near to dryness. The residue was cooled, dissolved in 5 ml conc. HCl, and made up to 100 ml using thrice distilled water.
The resulting clear solutions were then used for chemical analysis.
Equipment
A SP 1900 Pye Unicam recording flame atomic absorption spectrophotometer was used for these measurements.
3. RESULTS AND DISCUSSION
The results obtained from the analysis of the wheat samples are listed in Table 1. The statistical analysis of the
obtained data is tabulated in Table 2.
Table 1. Mean Concentration of Trace Elements in Some Varieties of Wheat Samples Determined by AAS.
Metal
Concentration
Country
Egypt KSA Australia Oman Dubai Yemen
Ag (ppb) - 2.01 - 3.19 1.90 -
Au (ppb) 12.53 7.90 1.90 4.00 3.99 1.97
Ca (ppm) 260 24.50 7.01 7.02 4.12 7.46
Co (ppb) 12.2 - - - - -
Cr (ppb) 12.8 - 7.00 - - 8.00
Cu (ppm) 0.14 0.34 0.16 0.23 0.16 0.17
Fe (ppm) 1.45 4.46 8.00 7.55 6.30 13.00
K (ppm) 126 114 87 103 108 93
Mg (ppm) 29.00 15.50 15.13 15.40 14.72 15.10
Mn (ppm) 0.86 1.00 0.80 0.77 0.57 0.81
Na (ppm) 2.02 4.98 10.7 4.0 4.5 11.9
Ni (ppb) 0.72 0.38 0.51 0.59 0.33 0.73
Pb (ppb) 11.50 - - - - -
Sr (ppb) 26.90 - - - - -
Zn (ppm) 0.46 1.60 0.91 0.94 0.61 0.93
166 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. July 2003

Silver.
A.E. Mohamed and G.M. Taha
Table 2. Statistical Factors Calculated from the Data of the Assayed Elements Present in the Wheat Samples.
Element Samples Mean Medium SD SE Min Max
Ag 6 0.0012 0.001 0.0013 0.0005 0.00 0.003
Au 6 0.0053 0.004 0.0039 0.0016 0.0018 0.012
Ca 6 53.30 7.30 106.4 4.34 4.10 270.0
Co 6 0.0022 0.00 0.0053 0.002 0.00 0.013
Cr 6 2.39 0.01 3.74 1.53 0.00 0.0126
Cu 6 0.192 0.162 0.073 0.0297 0.13 0.33
Fe 6 6.81 6.89 3.90 1.59 1.50 13.13
K 6 105.50 107.0 14.84 6.06 86.0 123.0
Mg 6 17.48 15.26 5.65 2.31 14.70 29.0
Mn 6 0.792 0.79 0.15 0.062 0.55 1.02
Na 6 6.65 4.95 4.23 1.73 2.00 12.50
Ni 6 0.53 0.54 0.17 0.068 0.33 0.71
Pb 6 0.002 0.00 0.005 0.002 0.00 0.012
Sr 6 0.0045 0.00 0.011 0.004 0.00 0.027
Zn 6 0.888 0.900 0.383 0.156 0.46 1.57
SD = standard deviation; SE = statistical error; Min = minimum value; Max = maximum value.
The mean concentration of silver present in the samples collected from Egypt, Saudi Arabia (KSA), Yemen, Oman,
Dubai, and Australia are 0.00, 0.002, 0.00, 0.0033, 0.0018, and 0.00 µg/g, respectively. It is clear that only the wheat
samples from the Asian continent contain silver. That may be related to the geographical location, which gives specific
characteristics to water, air, and soil of this area. The order of the assayed silver is Oman > KSA > Dubai > Egypt =
Yemen = Australia.
Gold.
The wheat samples collected from different localities (i.e., Egypt, KSA, Yemen, Oman, Dubai, and Australia) show
mean gold concentrations of 0.0125, 0.008, 0.002, 0.004, 0.004, and 0.0018 µg/g, respectively. The order of gold
concentrations in the samples under study is: Egypt > KSA > Oman = Dubai > Yemen > Australia. That Egyptian wheat
samples contain the highest gold concentration may be related to the geological characteristics of Egyptian soil.
Calcium.
The assayed calcium concentrations in the wheat samples of Egypt, KSA, Yemen, Oman, Dubai, and Australia are:
270, 24.25, 7.50, 7.01, 4.10, and 7.00 µg/g, respectively. It is obvious that the order of calcium concentration is
Egypt > KSA > Yemen > Oman > Australia > Dubai. The highest level of calcium in Egyptian wheat samples may be
due to the nature of Egyptian soil, irrigation water, and kind of fertilization.
Calcium is an essential constituent of the middle lamellae of the cell walls. It activates a number of enzymes including
α-amylase and plays an important role in nitrogen metabolism.
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A.E. Mohamed and G.M. Taha
Cobalt.
A part from the Egyptian wheat samples all the others are free from cobalt. This may be due to either the actual
absence of cobalt in these samples or the presence of cobalt under its detection limit. 0.0126 µg/g is the mean cobalt
concentration evaluated in the Egyptian wheat samples. The presence of cobalt in wheat samples which collected from
Egypt may be due to the characteristics of the Egyptian soil.
Cobalt is an essential nutrient activator involving vitamin B12 synthesis and nitrogen fixation [14]. Cobalt coordinates
with carboxy peptidase enzymes and catalyzes amino acids. Deficiency of cobalt results in [15] poor growth, break down
of the healthy parts of the lamina and chlorosis.
Chromium.
The mean concentrations of chromium in the wheat samples collected from Egypt, Yemen, and Australia are: 0.0126,
0.0081, and 0.0062 µg/g, respectively. On the other hand, 0.00 µg/g chromium is the level which is present in the KSA,
Oman, and Dubai wheat samples. That is may be due to either the absence of chromium in these samples or its presence
under the detection limit.
Chromium is considered [15] to be an essential micronutrient element and necessary for increasing the rate of plant
growth.
Copper.
Wheat samples collected from Egypt, KSA, Yemen, Oman, Dubai, and Australia show mean copper concentrations of
0.13, 0.33, 0.17, 0.21, 0.15, and 0.16 µg/g, respectively. It is clear that the order of the presence of copper in the samples
is: KSA > Oman > Yemen > Australia > Dubai > Egypt. The source of copper in all samples studied may be related to
the nature of soil and the surrounding environment in which the wheat samples are planted.
Copper is an important essential nutrient and forms a number of copper proteins. The presence of copper may reflect
[16] its usefulness in the plant growth and may give the greenish–olive color. It is a constituent of ascorbic acid oxidase,
lactose, and tyrosinase enzymes.
Iron.
The results of the analysis of six replicates of wheat samples show the mean iron concentrations of: Egypt: 1.50 µg/g,
KSA: 4.45 µg/g, Yemen: 13.13 µg/g, Oman: 7.53 µg/g, Dubai: 6.25 µg/g, and Australia: 7.99 µg/g. Hence, the order of
the iron magnitude is Yemen > Australia > Oman > Dubai > KSA > Egypt.
Iron is an essential nutrient activator involving vitamin B12 synthesis and nitrogen fixation. Iron forms a number of
iron proteins. Iron deficiency results in chlorosis [17].
Potassium.
The mean potassium concentrations of 123, 118, 92, 101, 113, and 86 µg/g are estimated in the wheat samples
collected from Egypt, KSA, Yemen, Oman, Dubai, and Australia, respectively.
The order of the estimated potassium is: Egypt > KSA > Dubai > Oman > Yemen > Australia. It is well known that,
the Egyptian soil is rich in potassium. As a result, the Egyptian wheat samples have the highest value of potassium
among all the wheat samples analyzed. On the other hand, the highest potassium value in the Egyptian samples may be
related to the kind of fertilization used in Egypt.
Potassium is an essential nutrient element and present in plant tissues entirely as the potassium ion. It has an important
role in amino acids and proteins synthesis from ammonium ions, and the formation of internodes is related to its role.
It activates the enzymatic reactions of carbohydrate metabolism. It regulates the osmotic pressure of extracellular fluids
and the acid–base balance. Potassium deficiency decreases the rate of amino acids synthesis and results in a low level of
protein, in weakening, chlorosis, and rolling of leaves, shortening of internodes and stunts the plant growth [18].
168 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. July 2003

Magnesium.
A.E. Mohamed and G.M. Taha
The mean magnesium concentrations of 29.00, 15.54, 15.18, 15.30, 14.70, and 15.17 µg/g are determined in the wheat
samples collected from Egypt, KSA, Yemen, Oman, Dubai, and Australia, respectively. The determined values are
ordered as: Egypt > Oman > Yemen > Australia > Dubai. The highest value of magnesium in the Egyptian wheat sample
may be attributed to the high value of magnesium in the Egyptian soil.
Magnesium is an essential nutrient element. It activates numerous enzymes and plays a significant role in the
photosynthesis, nucleic acid synthesis from nucleotide polyphosphates, dehydrogenation, carboxylase, carbohydrate
metabolism, and respiration by regulating phosphate metabolism and acts as a binding agent in the ribosomal particles.
Deficiency of magnesium results in the development of a characteristic chlorosis and in some species in the appearance
of a purple coloration in the foliage. Magnesium and calcium act as binding agents to fuse the walls of the plant cells
together [16–18].
Manganese.
The tabulated results show that mean manganese concentrations of 0.84, 1.02, 0.80, 0.76, 0.55, and 0.78 µg/g are
determined in the wheat samples collected from Egypt, KSA, Yemen, Oman, Dubai, and Australia, respectively. The
results indicate that the manganese concentration is in the order: KSA > Egypt >Yemen > Australia > Oman > Dubai.
Manganese is an essential nutrient element. It plays an important role in plant metabolism. It serves also as metal
co-factor for activating enzymes such as hydrolases, kinases, decarboxylases, and transferases, in addition to being
intimately involved with the synthesis of fatty acids, glycoprotein, DNA and RNA, and cholesterol from acetate. Taste
and color may be attributed to the existence of manganese. Deficiency in manganese causes [15, 16, 18] diseases such as
grey speck of oats and speckled yellow in beet.
Sodium.
The results of the analysis of the wheat samples collected from Egypt, KSA, Yemen, Oman, Dubai, and Australia,
exhibit a mean sodium concentration of 2.00, 5.30, 12.50, 4.20, 4.60, and 11.30 µg/g, respectively. The assayed
magnitudes of sodium ion are of the order of: Yemen > Australia > KSA > Dubai > Oman > Egypt. Certainly, the
highest value of sodium in the Yemen wheat samples is related to the nature of its soil.
Sodium is an essential element for plants. It has a catalytic effect on enzymes activity and its major function is as
osmotic pressure regulator and in acid–base balance. It has also some definite function in the growth of the roots of some
seeding plants. It is one of the major electrolytes in all extracellular fluids. Also, sodium is needed [15, 16, 18] in
vegetables and fruit for glycolsis.
Nickel.
The data shown in Table 1 indicates that the wheat samples collected from Egypt, KSA, Yemen, Oman, Dubai, and
Australia have mean concentrations of nickel ion of: 0.71, 0.35, 0.71, 0.57, 0.33, and 0.51 µg/g, respectively.
It is found that the mean concentrations are ordered as: Egypt = Yemen > Oman > Australia > KSA > Dubai.
The highest magnitude of nickel in the wheat samples of both Egypt and Yemen may be attributed to the nature of the
soil texture in both countries.
Nickel, like other metals in the first transition series of the periodic table, may play an essential physiological role.
Evidence of possible nickel essentiality is that nickel is consistently present in ribonucleic acid (RNA) from diverse
sources in concentrations many times higher than in the native material from which the RNA is isolated.
Lead.
A part from the wheat samples collected from Egypt, all the other samples analyzed are free from lead. The mean lead
concentration assayed in the Egyptian samples is 0.12 µg/g. This value of lead is under its safety baseline. Presence of
July 2003 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. 169

A.E. Mohamed and G.M. Taha
lead in the Egyptian wheat samples may be related to its high natural abundance in air, soil, and in granitic rocks, which
are abundant in Egypt. Many plants will tolerate high levels, but some show retarded growth at mg/g in solution-culture
studies.
Strontium.
Strontium was only found in the Egyptian wheat samples, at a level of 27.0 µg/g.
The absorption of strontium by plants is of importance due to [18] the presence of the long-lived radio-active isotope,
Sr 90 , in the atmospheric fallout from thermonuclear explosions.
Zinc.
Based on the results in Table 1, the mean concentrations of zinc are: 0.46, 1.57, 0.90, 0.60, and 0.90 mg/g in wheat
samples of Egypt, KSA, Yemen, Oman, Dubai, and Australia, respectively. Zinc values are ordered as KSA > Yemen =
Oman = Australia > Dubai > Egypt.
Zinc ion is an essential micronutrient element and cofactor in a number of enzyme systems. It has an important role
[17] in cell replication and for the alteration of genetic potential in cell proliferation and labialization of lysosomal
membrane in plant tissue.
Statistical Analysis
Statistical analysis of the data of wheat samples shows significant and positive correlation coefficient values
(r = 0.506–1.00) and negative correlation coefficient values (r = 0.492–0.873). From the positive correlation coefficient
values, it is evident that there are good interrelationships between the trace elements present in wheat and it is suggested
that they perhaps exist as essential elements in the interstitial spaces and as mixed metal-high molecular weight
complexes, chlorophyll, carbohydrate, humate, amino acid, vitamin, etc. in the plant cells, and they are important for
growth, pigmentation, taste, and fruiting.
On the other hand, negative correlation coefficient values may be due to disproportionation, interlocking, and
counteraction between pairs of elements.
4. CONCLUSION
Based on the results obtained from the chemical analysis of some wheat samples collected from Egypt, KSA, Yemen,
Oman, Dubai, and Australia, the following is concluded.
First of all, and based on the safety baseline of the elements [20], all the assayed elements in all the analyzed wheat
samples are either below (in most cases) or within their safety baseline.
Cobalt, lead, and strontium ions were present only in the wheat samples which were collected from Egypt. Egypt has
the highest values of gold, calcium, chromium, and magnesium ions, whereas, the lowest values of gold, calcium,
chromium, and magnesium ions were determined in the wheat samples collected from Australia, Dubai, and Yemen,
respectively. However, the lowest values of copper, sodium, iron, and zinc ions were assayed in the Egyptian wheat
samples. KSA and Yemen wheat samples have the highest values of copper sodium, iron, and zinc ions, respectively.
For potassium, the highest value is determined in the Egyptian wheat samples and the lowest value in the Australian
wheat samples. The highest values of both manganese and nickel were assayed in the Dubai wheat samples, whereas
their lowest values were determined in the wheat samples collected from KSA, Egypt, and Yemen.
Finally, for silver, the lowest values were determined in the wheat samples from Egypt, Yemen, and Australia.
Oman wheat samples have shown to have the highest value of silver ion.
170 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. July 2003

REFERENCES
A.E. Mohamed and G.M. Taha
[1] Technical Reports Series No. 197. Vienna: International Atomic Energy Agency, 1980, ch. 3, p. 29.
[2] P. Linderg, “Selenium Determination in Plant Animal Material and in Water”, Acta Vet. Scand., Suppl., 1968, p. 23.
[3] V. Maxia, S. Meloni, M.A. Roller, A. Brandone, V.N. Patwardhan, C.I. Waslien, and S. El-Shami, “Selenium and Chromium
Assay in Egyptian Foods and in Blood of Egyptian Children by Activation Analysis”, Proc. IAEA Symposium on Nuclear
Activation Techniques in the Life Sciences, Vienna, 1972, p. 527.
[4] H.A. Schroeder, D.V. Frost, and J.J. Balassa, “Essential Trace Metals in Man: Selenium”, J. Chronic Dis., 23 (1970), p. 227.
[5] V.C. Morris and O.A. Lavender, “Selenium Content of Foods”, J. Nutr., 100 (1970), p. 1383.
[6] L. Miller and H.S. Mitchell, “Correlations of Copper and Manganese Content of Plants and Mineral Additions in the Soil”,
J. Am. Diet Assoc., 7 (1931), p. 252.
[7] S. Allen, Anal. Biochem., 138 (1984), p. 346.
[8] W.J. Garcia, C.W. Blessin, and G.E. Inglett, J. Am. Chem. Soc., 51 (1974), p. 788.
[9] C.A. Rown, O.T. Zajicek, and E.J. Calabrese, Anal. Chem., 54 (1982), p. 149.
[10] W.K. Roy, A.W. Karen, and L.F. Fred, Anal. Chem., 54 (1982), p. 2146.
[11] M.K. Sherif, R.M. Awadallah, and A.H. Amrallah, J. Radioanal. Chem., 57 (1980), p. 53.
[12] M.K. Sherif, R.M. Awadallah, and A.E. Mohamed, J. Radioanal. Chem., 53 (1979), p. 145.
[13] R.R. Backer, A. Veglia, and E.R. Shmidt, Radiochem. Radioanal. Letters, 19 (1974), pp. 343–352.
[14] E.W. Russell, Soil Conditions and Plant Growth. London: The English Language Book Society, 1973.
[15] M. Gibbs, Structure and Function of Chloroplasts. New York: Springer-Verlag, 1978.
[16] E.J. Underwood, Trace Elements in Human and Animal Nutrition, 4 th edn. New York: Academic Press, 1979.
[17] D.J.F. Bowling, Uptake of Ions by Plant Roots. London: Chapman and Hall, 1976.
[18] C.P. Malik and A.K. Srivastava, Plant Physiology. New Delhi: Kalyant Publishers, 1982.
[19] G.M. Taha, “Analytical and Environmental Studies on Trace Elements in Some Plants and Soil Existing in Areas Surrounding
Some Firms Using HPLC and AAS Analysis”, Ph. D. Thesis, Fac. Sci., Aswan, South Valley University, Egypt, 1996.
[20] Stewart E. Allen, Chemical Analysis of Ecological Materials, 2 nd edn. Oxford, London: Blackwell Scientific Publications.
Paper Received 10 April 2001; Revised 10 November 2001; Accepted 12 February 2002.
July 2003 The Arabian Journal for Science and Engineering, Volume 28, Number 2A. 171