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J Sci Food Agric 1998, 77, 456�8
Mineral Element Composition of Spinach
Santanu Bhattacharjee,* Pranab Dasgupta, Adhir R Paul, Sunanda Ghosal,
Karuna K Padhi and Lallan P Pandey
Analytical Chemistry Division, National Metallurgical Laboratory, Jamshedpur 831007, India
(Received 27 August 1996 ; revised version received 24 October 1997 ; accepted 20 November 1997)
Abstract : An extensive study has been made on the mineral element compositions of spinach leaves and stems. Twenty two locally grown di?erent spinach
samples have been analysed for 16 elements using ICP and atomic absorption
spectrophotometric techniques. Both spinach leaves and stems were analysed
separately. A detailed elucidation of the inorganic matrix in spinach leaves and
stems has been provided. ( 1998 SCI.
J Sci Food Agric 77, 456�8 (1998)
Key words : spinach ; leaf ; stem ; mineral elements ; ICP ; AAS
INTRODUCTION
In the second category, an established method was used
for the determination of one or more elements in
spinach for the purpose of monitoring.
Presently, a project is being carried out at National
Metallurgical Laboratory, Jamshedpur on the
?Appraisal of Metal Concentrations in Indian Vegetable
Crops�. The study of mineral elements in spinach constitutes a part of this study. In this communication, an
extensive report on the mineral element compositions of
spinach leaves and stems has been provided. Twenty
two local spinach samples collected at di?erent times
and from di?erent places were analysed for 16 elements
using 補me atomic absorption spectrometry (AAS) and
inductively coupled plasma optical emission spectrometry (ICP-OES). The objective of the present communication is to provide a comprehensive account of the
mineral element values in spinach and 衝d out their
pattern of occurrence in spinach leaves and stems. To
the best of the authors� knowledge no such study on
spinach has been reported before.
Spinacia Linn, family : Chenopodiaceae, a small genus of
annual herbs may be found from the eastern Mediterranean to central Asia and Afghanistan. One species, S
oleracea, native to south-west Asia is extensively cultivated in India and is well known for its nutritious
leaves. This species is also known as garden spinach.
Spinach is a mineral-rich vegetable. An earlier study
on the edible portion (87%) of spinach records (%) :
moisture, 92�; protein, 2�; fat, 0�; 衎re, 0�; mineral
matter, 1�; carbohydrate, 2�; and oxalic acid, 658 (mg
per 100 g). Mineral composition includes (mg per
100 g) : calcium, 73 ; magnesium, 84 ; potassium, 206 ;
iron, 10�; phosphorus, 21 ; sodium, 58�; copper, 0� ;
sulphur, 30 ; nickel, 0� ; manganese, 9� ; molybdenum, 0� ; zinc, 13� ; and strontium, 0�7. Spinach
is a good source of the vitamin B complex, ascorbic
acid, vitamin A and carotin. It is also a natural source
of vitamin K (CSIR 1976).
Mineral elements in spinach have been studied by
several workers employing a large number of techniques
(Lin and Julshamn 1984 ; Stephen et al 1985 ; Salinas et
al 1987 ; Alegria et al 1988 ; Yan and Schwedt 1990 ;
Mittal et al 1993). The available literature may be
broadly classi衑d into two categories. In the 衦st category, a newly developed reagent or a technique was
tested for a particular element with reference to spinach.
EXPERIMENTAL
Preparation of spinach leaf and stem samples
Spinach samples were procured from within an area of
64 km2 around Jamshedpur. Each sample was cleanly
separated into its leaf and stem sections. Each section
was thoroughly washed and cut into very small pieces
* To whom correspondence should be addressed.
456
( 1998 SCI.
J Sci Food Agric 0022�42/98/$17.50.
Printed in Great Britain
Mineral element composition of spinach
457
and dried in an oven at 110 for 4 h. Dried samples
were powdered and again dried for 1 h at 110. A
total of 22 spinach samples were processed which gave
22 leaf sections and 22 stem sections.
Dissolution of spinach samples
Standard wet digestion procedure was used in the
present work for dissolving the spinach leaf and stem
samples. Approximately 1 g of the dried sample was
weighed accurately and digested with 10 ml of concentrated HCl and 5 ml of concentrated HNO for about
3
2 h. HClO (5 ml) was added to the solution and heated
4
till dense white fumes came out and the solution
became clear. Distilled water (20 ml) was added to it
and digested for D 30 min. The resulting solution was
cooled and the volume was made upto 50 ml. For every
batch of samples a representative blank was prepared.
Reagents
HCl, HNO , HClO and other reagents used were of
3
4
AR grade. 18 M) ASTM Grade 1 water was used for
preparing the solutions.
Instrumental
Mg, Ti, Cr, Mn, Al, Fe, Cu, Co, Ni and Zn were
analysed by a Shimadzu GVM1014P Simultaneous
ICP-OES. Na, K, Ba and Sr were analysed by a Shi-
madzu ICPS-1000III Sequential ICP-OES. Ca was
analysed by GBC 908-AA 補me atomic absorption
spectrometer. For the determination of Ca the sample
solution was diluted 10 times followed by addition of
1000 ppm of K and La to suppress the interference due
to ionisation and presence of P, respectively. The blank
was also diluted accordingly. Results obtained from
ICP-OES were occasionally cross checked by 補me
AAS. Barnstead nanopure system water was used for
making 18 M) water.
RESULTS AND DISCUSSION
Table 1 gives the average concentrations of 16 elements
on a dry basis in spinach leaves and stems obtained
from 22 di?erent spinach samples. Also, given in Table
1 are the standard deviations and range of occurrence
for these elements.
Some general inferences may be derived from Table 1.
Except for Na, K and Co, the remaining elements have
a higher trend of occurrence in spinach leaves. The inorganic matrix in both leaves and stems are primarily
comprised of Na, K, Mg and Ca. Mg is generally appreciable in all green vegetables because of its association
with chlorophyll but the abundance of Na, K and Ca
show the mineral-rich nature of spinach. P comes next
in terms of signi衏ance. It may be noted that both
leaves and stems contain appreciable amount of Al.
Spinach leaves and stems also contain signi衏ant
amount of Fe. However, it is interesting to note that the
occurrence of Fe is usually associated with trace
TABLE 1
Compositions (dry wt%) of 16 elements in spinach leaves and stems obtained from 22
di?erent spinach samples (n \ 22)
Elements
Na
K
Sr ] 10~3
Ba ] 10~3
Mg
Al
P
Ca
Cr ] 10~3
Ti ] 10~3
Mn ] 10~3
Fe ] 10~3
Cu ] 10~3
Co ] 10~3
Ni ] 10~3
Zn ] 10~3
a n \ 20.
L eaf
Stem
Range
Average
SD
Range
Average
SD
1�1
1�8
21�1�1�1
0�3
0�8
0�2
0�0�37�2267
1�0�0�37�
2�
3�
4�
4�
1�
0�
0�
0�
1�
15
16�52�1�
0�
0�7�
1�
1�
1�
1�
0�
0�
0�
0�
0�
1�
19�
49�
0�
0�
0�
3�
1�1
2���
2�0
1�0�8
0�8
0�1
0�6
0�0�21�700
0�0��
26�
4�
5�
3�
3�
1�
0�
0�
0�
0�
1�
6�
41�
1�
0�
�
6�
2�
1�
1�
1�
0�
0�
0�
0�
0�
0�
6�
40�
0�
0�
�
3�
S Bhattacharjee et al
458
occurrence of Mn and Zn. Other remaining elements
occur only at ultratrace level.
To derive more information about the inorganic
matrix in di?erent spinach samples, all the elements in
each sample were sorted in the descending order of their
concentration. For both leaves and stems, the inorganic
matrix may be classi衑d into four categories : major,
submajor, trace and ultratrace. Na, K and Mg constitute the major matrix for both leaves and stems. Their
relative positions, however, change from sample to
sample. Only on one stem sample, P replaced Mg as the
third element. P, Ca and Al constitute the submajor
matrix in both leaves and stems. Once again their relative positions change from sample to sample. In the
trace category, Fe, Zn and Mn are the mostly occurring
elements with Sr and Ba occasionally changing places
with Mn and/or Zn. In at least one sample, Fe was
obtained in appreciable amount. Sr, Ba, Ti, Cr, Cu, Co
and Ni are generally present in ultratrace amounts in
both leaves and stems with no apparent order of
occurrence.
It may be seen in Table 1 that for most of the elements the width of the concentration range is considerably large. This may be due to several factors that
include soil condition, fertiliser, humidity, irrigation
water quality etc. The distributions have also been
found to be severely skewed. All these together result
into high SD values. However, this may be noted with
caution that a probable outlier does not necessarily
mean an erroneous measurement. Especially, in biological samples, it may also indicate a phenomenon,
probably caused by some extreme environmental
parameters.
CONCLUSION
The present study concludes the following. Na, K and
Mg constitute the major inorganic matrix of spinach
leaves and stems followed by Ca, Al and P which are
present in appreciable quantity. Both spinach leaves
and stems contain signi衏ant amount of Fe which normally cooccurs with Mn and Zn. Other remaining elements usually occur at ultratrace level with occasional
crossover by Sr and Ba from ultratrace to trace. Of the
16 elements studied, except for Na, K and Co, the
remaining elements have a higher trend of occurrence in
spinach leaves.
ACKNOWLEDGEMENT
The authors wish to thank the Director, NML for his
permission to publish this work.
REFERENCES
Alegria A, Barbera R, Farre R 1988 Atomic absorption
spectrophotometric determination of Ni in foods. J Micronutr Anal 4 229�9.
CSIR 1976 T he W ealth of India. A Dictionary of Indian Raw
Materials & Industrial Products. Raw Materials (Vol X :
Sp-W). Publications & Information Directorate, CSIR, New
Delhi, India, pp 12�.
Lin S W, Julshamn K 1984 Comparative study of the determination of phosphorus by electrothermal AAS and solution
spectrophotometry. Anal Chim Acta 158 199�6.
Mittal R, Allawadhi K L, Sood B S, Singh N, Kumar A,
Kumar P 1993 Determination of potassium and calcium in
vegetables by X-ray 製orescence spectrometry. X-Ray
Spectrometr 22 413�7.
Salinas F, Munoz de la Pena A, Murrilo J A, Jimenez Sanchez
J C 1987 Spectro製orimetric determination of boron in
plants with quinalizarin and sulphuric acid. Analyst 112
913�5.
Stephen S C, Littlejohn D, Ottaway J M 1985 Evaluation of a
slurry technique for the determination of lead in spinach by
electrothermal atomic absorption spectrometry. Analyst 110
1147�51.
Yan D, Schwedt G 1990 Simultaneous ion chromatography of
inorganic anions together with some organic anions and
alkaline earth metal cations using chelating agents as
eluents. J Chromatogr 516 383�3.
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