- Email: [email protected]
Elemental Analysis of Brown Rice by Inductively Coupled Plasma Atomic Emission Spectrometry and Instrumental Neutron Activation Analysis
Available online at www.sciencedirect.com
ScienceDirect Energy Procedia 56 (2014) 85 – 91
11th Eco-Energy and Materials Science and Engineering (11th EMSES)
Elemental Analysis of Brown Rice by Inductively Coupled Plasma Atomic Emission Spectrometry and Instrumental Neutron Activation Analysis Wannee Srinuttrakula,* , Arporn Busamongkola
0F
a
Research and Development Division, Thailand Institute of Nuclear Technology (Public Organization), 9/9 Mu 7, Sai Mun, Ongkharak, Nakhon Nayok 26120, Thailand
Abstract Thai jasmine rice samples were collected from the paddy field in the north and northeast of Thailand. After dehulling, the brown rice samples were determined for the elemental concentrations by inductively coupled plasma atomic emission spectrometry (ICP-AES) and instrumental neutron activation analysis (INAA). The concentrations of Ca, K, Mg, and P were determined by ICP-AES and the concentrations of Fe, Mn, and Zn were analyzed by INAA. The ICP-AES and INAA methods were validated by certified reference materials. The results showed that the methods are reliable to analyze the elemental concentrations in rice samples. The order of the mean concentration of elements was P > K > Mg > Ca >Mn > Zn > Fe. The concentrations of elements ranged from 3,024-3,830 mg kg-1 P, 1,404-1,927 mg kg-1 K, 980-1,284 mg kg-1 Mg, 72-128 mg kg-1 Ca, 21.9-43.8 mg kg-1 Mn, 22.5-32.7 mg kg-1 Zn, and 5.10-9.75 mg kg-1 Fe. © Ltd. This is an open article under the CC BY-NC-ND license © 2014 2014Elsevier The Authors. Published byaccess Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi Peer-review (RMUTT). under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT) Keywords: Brown rice; Elemental analysis; ICP-AES; INAA.
1. Introduction Rice is a diet staple in Thailand. From varieties of rice were planted in Thailand, Thai jasmine rice or Hom Mali rice (Oryza sativa L.) is well known for Thai rice and worldwide. However, there are not much data about the
* Corresponding author. Tel.: +66-2-401-9889 ext. 5103; fax: +66-2-562-0121. E-mail address: [email protected].
1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT) doi:10.1016/j.egypro.2014.07.135
86
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
concentrations of elements in Thai jasmine rice. Generally, white rice is the diet of various peoples including Thai, Japanese and Korean. Nowadays, the consumption of brown rice is increasing in Thailand because of its benefit to human health such as anti-cancer, anti-diabetes and anti-cholesterol activities [1]. Brown rice contains more nutrient components such as protein, amino acids, vitamins, dietary fibers and minerals than the ordinary white rice [2]-[5]. The concentration of elements in the brown rice is valuable information for the database of Thai rice and for human dietary intake. The concentrations of elements in rice samples were investigated by various techniques such as graphite furnace atomic absorption spectrometry (GFAAS) [1], [6]-[7], instrumental neutron activation analysis (INAA) [1], inductively coupled plasma atomic emission spectrometry (ICP-AES) [6], [8] and inductively coupled plasma mass spectrometry (ICP-MS) [9]-[10]. ICP-AES is a useful technique with the advantage of simultaneous determination of multi-element, wide linear range and rapid analysis. INAA is a suitable method for determination of various elements with the advantage of a non-destructive method. In the present research, the elemental concentrations in Thai jasmine rice samples were studied to obtain the nutrient database for food ingestion in Thailand. The rice samples were collected from the paddy fields in the north and northeast of Thailand. ICP-AES was used to determine the concentrations of Ca, K, Mg, and P. The contents of Fe, Mn, and Zn were analyzed by INAA. 2. Material and method 2.1 Reagents and standards All the chemical reagents used were analytical grade. Water (>18 M:) was used throughout this work. The standard solutions were purchased from AccuStandard, Inc. The certified reference materials used to check the method were rice Àour (NIST 1568a; National Institute of Standards and Technology, USA) and marine sediment (NMIJ7302-a; National Metrology Institute of Japan). 2.2 Sample collection and preparation Jasmine rice samples were collected from three provinces in the north (Chiang Rai, Phayao and Lampang) and three provinces in the northeast (Surin, Ubon Ratchathani, and Roi Et) of Thailand. Five samples were collected in each province. All samples were dried in an electric oven at 60 ± 2 qC for 4 hours. After that, samples were ground into fine particles using a high speed blender (1093 Cyclotec Sample Mill, Sweden). The grinding step was repeated until fine particles passed completely through a sieve No.60 mesh. The rice powders were dried again in an oven at 50-60qC until constant weight, kept in polyethylene containers and stored in a desiccator until elemental analysis. 2.3 Elemental analysis 2.3.1 Inductively coupled plasma atomic emission spectrometry (ICP-AES) All dry samples (0.5 g) were digested with 65% HNO3 and 48% HF using sealed Teflon vessels on a hot plate. After digestion, the samples were evaporated to dryness and the residues were dissolved in 65% HNO3 and 40% H2O2. After dryness, the residues were dissolved and diluted to 10 mL with 4% HNO3. Finally, the proper concentrations of dissolution samples were determined by ICP-AES (Optima 5300DV, Perkin Elmer, USA). Sample digestions were done in triplicate. The ICP-AES operating parameters for all elements are shown in Table 1.
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91 Table 1. ICP-AES operating parameters. Parameter
Condition
RF power
1,300 watts
Nebulizer flow rate
0.8 L min-1
Auxiliary gas flow rate
0.2 L min-1
Plasma gas flow rate
15 L min-1
Sample uptake rate
1.5 mL min-1
2.3.2 Instrumental neutron activation analysis (INAA) Packing sample for analysis, three replicates with sample weights 50-70 mg were sealed in clean polyethylene bags for irradiation. These containers were re-packed into polyethylene container for medium irradiation and in aluminum cans for long irradiation. Samples were irradiated in an open pool type Thai Research Reactor (TRR-1/M1) at the Thailand Institute of Nuclear Technology (TINT), Bangkok. The concentration of each element was obtained by comparison with the certi¿ed reference materials (Rice Àour, NIST 1568a) and marine sediment (NMIJ7302-a). The experimental conditions for elemental analysis are as follows: x Medium irradiation for medium half-life radionuclide (Mn): Each sample was irradiated for 12 h at epithermal neutron Àux of 1.8 x 109 n cm-2 s-1 and decay time for 12 h. x Long irradiation for medium half-life radionuclide (Fe and Zn): Each sample was irradiated for 36 h at a thermal neutron Àux of 3.4 x 1011 to 5.6 x 1011 n cm-2 s-1 and decay time for 2 weeks. After appropriate decay time, the elemental concentrations were analyzed by gamma spectrometry (EG&ORTEC, USA) using a high purity germanium (HPGe) detector with relative efficiency of 60% and resolution of 1.95 keV at1.33 MeV of 60Co energy peak. The gamma-ray spectra were processed using the Gamma Vision-32 computer program. The gamma-ray activity of samples was counted using the counting time of 1,800 s for Mn and 3,600 s for Fe and Zn measurement. 3. Results and discussion 3.1 Validation of analytical method In order to assess the accuracy of the methods, certified reference materials of rice flour ((NIST 1568a) and marine sediment (NMIJ7302-a) were analyzed, the obtained results compared with the certified value and the relative error was calculated. Good agreements between the certified and measured values were observed for certified reference materials (see Table 2). Precisions calculated using four independent runs of rice flour and marine sediment (NMIJ7302-a) were better than 5% relative standard deviation (RSD) for all elements determined by ICP-AES and INAA.
87
88
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91 Table 2. Analytical results of reference materials obtained by ICP-AES and INAA in comparison with the certified values. Certified Value %Error Observed Value a Elements (mg kg-1)
(mg kg-1)
Ca
111
118b
6
K
1,211
1,280b
11
Mg
497
560b
5
P
1,445
1,530b
6
Fe
5.44
5.40c
1
Mn
19.7
20b
2
Zn
19.7
19.4b
2
ICP-AES
INAA
a
Mean values of four independent runs.
b
Certified value of rice flour (NIST 1568a).
c
Certified value of marine sediment (NMIJ7302-a).
3.2 Concentration of elements in brown jasmine rice by ICP-AES Analytical results of elements in thirty brown jasmine rice samples collected from the north and northeast of Thailand are shown in Fig. 1 and Table 3. The high concentrations of P, K, Mg and Ca were observed as the macronutrients for all studied samples. The concentration of Ca was remarkably lower compared with that of other macronutrients in brown rice samples. The order of the mean concentration of element was P > K > Mg > Ca. The concentrations of elements varied from 3,024-3,830 mg kg-1 P, 1,404-1,927 mg kg-1 K, 980-1,284 mg kg-1 Mg, and 72-128 mg kg-1 Ca. The relative standard deviation in the concentration of these elements in brown rice was 7 16%. The highest value of relative standard deviation was observed for Ca. In comparison with the elemental concentrations (Ca, K, Mg, and P) in brown rice collected from the north and northeast of Thailand, the result showed that no significant difference (t-test; p < 0.05) for all elements was observed. The concentrations of these elements were not affected by the regional area. Table 3. Mean and median concentration of elements in brown jasmine rice samples by ICP-AES (mg kg-1). Elements Mean Median Minimum Maximum Ca
100
101
72
128
K
1,611
1,566
1,404
1,927
Mg
1,152
1,145
980
1,284
P
3,462
3,478
3,024
3,830
89
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
Ca
K
Mg
P
R3-1
R3-2
R3-3
R3-4
R3-5
R6-1
R6-2
R6-3
R6-4
R6-5
R2-5
R2-4
R2-3
R2-2
R2-1
R1-5
R1-4
R1-3
R1-2
R1-1
Concentration (mg kg-1)
(a) 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Sample
Ca
K
Mg
P
R5-5
R5-4
R5-3
R5-2
R5-1
R4-5
R4-4
R4-3
R4-2
R4-1
Concentration (mg kg-1)
(b) 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Sample
Fig.1. Concentration of elements in brown jasmine rice samples collected from (a) the north, and (b) the northeast of Thailand by ICP-AES.
3.3 Concentration of elements in brown jasmine rice by INAA The elemental concentrations in thirty brown jasmine rice samples measured by INAA are presented in Fig. 2. The statistic values are summarized in Table 4. The concentrations of Mn, Zn, and Fe were observed as the micronutrients for all studied samples. The order of the mean concentration of element was Mn > Zn > Fe. The concentration ranges are 21.9-43.8 mg kg-1 Mn, 22.5-32.7 mg kg-1 Zn, and 5.10-9.75 mg kg-1 Fe. The relative standard deviation in the concentration of Fe, Mn, and Zn was 15%, 21% and 10%, respectively. In comparison with the concentrations of Fe, Mn, and Zn in brown rice collected from the north and northeast of Thailand, significant difference (t-test; p < 0.05) of mean concentration for all elements was found. The
90
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
(a)
Concentration (mg kg-1)
30
Fe
Mn
R2-3
35
R2-2
concentrations of Fe, Mn, and Zn from the northeast were higher than those from the north of Thailand. The difference in the concentration of elements within the different regions is attributed to many factors such as the mineral composition of the soil, soil type, fertilizer and agricultural chemicals [11].
Zn
25 20 15 10 5
R3-4
R3-5
R6-4
R6-5
R3-2
R6-2
R3-3
R3-1
R6-1
R6-3
R2-5
R5-5
R2-4
R2-1
R1-5
R1-4
R1-3
R1-2
R1-1
0
(b)
45
Fe
Mn
R5-3
50
R5-2
Sample
Zn
Concentration (mg kg-1)
40 35 30 25 20 15 10 5
R5-4
R5-1
R4-5
R4-4
R4-3
R4-2
R4-1
0
Sample
Fig.2. Concentration of elements in brown jasmine rice samples collected from (a) the north, and (b) the northeast of Thailand by INAA.
Table 4. Mean and median concentration of elements in brown jasmine rice samples by INAA (mg kg-1). Elements Mean Median Minimum Maximum Fe
7.98
8.12
5.10
9.75
Mn
29.6
28.8
21.9
43.8
Zn
27.0
26.9
22.5
32.7
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
4. Conclusions The concentrations of elements in brown jasmine rice samples collected from the paddy fields in the north and northeast of Thailand were investigated using ICP-AES and INAA. The high concentrations of P, K, Mg, and Ca and the minor contents of Mn, Zn, and Fe were observed for all brown rice samples. Both methods are reliable to analyze the elements in brown jasmine rice sample. Analyses for elements have provided much information on the nutrient database of Thai jasmine rice. Further studies on other regions of Thailand with other varieties of rice are earnestly desired.
Acknowledgements The authors would like to thank the International Atomic Energy Agency (IAEA) for partially financial support. References [1] Parengam M, Judprasong K, Srianujata S, Jittinandana S, Laoharojanaphand S, Busamongkol A. Study of nutrients and toxic minerals in rice and legumes by instrumental neutron activation analysis and graphite furnace atomic absorption spectrophotometry, J Food Comp Anal 2010;23:340–5. [2] Chen H, Siebenmorgen TJ, and Griffin K. Quality characteristics of long-grain rice milled in two commercials systems. Cereal Chem 1998;75:560-65. [3] Itani T, Tamaki M, Arai E, Horino T. Distribution of amylase, nitrogen, and minerals in rice kernels with various characters. J Agr Food Chem 2002;50:5326-32. [4] Lamberts L, Delcour JA. Carotenoids in raw and parboiled brown and milled rice. J Agr Food Chem 2008;56:11914-19. [5] Ning HF, Qiao JF, Liu ZH, Lin ZM, Li GH, Wang QS, Wang SH, Ding YF. Distribution of proteins and amino acids in milled and brown rice as affected by nitrogen fertilization and genotype. J Cereal Sci 2010;52: 90-5. [6] Antoine JMR, Fung LAH, Grant CN, Dennis HT, Lalor GC. Dietary intake of minerals and trace elements in rice on the Jamaican market, J Food Comp Anal 2012;26:111–21. [7] Qian Y, Chen C, Zhang Q, Li Y, Chen Z, Li M. Concentrations of cadmium, lead, mercury and arsenic in Chinese market milled rice and associated population health risk. Food Control 2010;21:1757-63. [8] Ogiyama S, Tagami K, Uchida S. The concentration and distribution of essential elements in brown rice associated with the polishing rate: Use of ICP-AES and Micro-PIXE. Nucl Instr and Meth in Phys Res B 2008;266:3625–32. [9] Wang KM, Wu JG, Li G, Zhang DP, Yang ZW, Shi CH. Distribution of phytic acid and mineral elements in three indica rice (Oryza sativa L.) cultivars, J Cereal Sci 2011;54:116-21. [10] Mihucz VG, Silversmit G, Szalóki I et al. Removal of some elements from washed and cooked rice studied by inductively coupled plasma mass spectrometry and synchrotron based confocal micro-X-ray fluorescence. Food Chem 2010;121:290-97. [11] D’Ilio S, Alessandrelli M, Cresti R, Forte G, Caroli S. Arsenic content of various types of rice as determined by plasma-based techniques. Microchem J 2002;73:195-201.
91
ScienceDirect Energy Procedia 56 (2014) 85 – 91
11th Eco-Energy and Materials Science and Engineering (11th EMSES)
Elemental Analysis of Brown Rice by Inductively Coupled Plasma Atomic Emission Spectrometry and Instrumental Neutron Activation Analysis Wannee Srinuttrakula,* , Arporn Busamongkola
0F
a
Research and Development Division, Thailand Institute of Nuclear Technology (Public Organization), 9/9 Mu 7, Sai Mun, Ongkharak, Nakhon Nayok 26120, Thailand
Abstract Thai jasmine rice samples were collected from the paddy field in the north and northeast of Thailand. After dehulling, the brown rice samples were determined for the elemental concentrations by inductively coupled plasma atomic emission spectrometry (ICP-AES) and instrumental neutron activation analysis (INAA). The concentrations of Ca, K, Mg, and P were determined by ICP-AES and the concentrations of Fe, Mn, and Zn were analyzed by INAA. The ICP-AES and INAA methods were validated by certified reference materials. The results showed that the methods are reliable to analyze the elemental concentrations in rice samples. The order of the mean concentration of elements was P > K > Mg > Ca >Mn > Zn > Fe. The concentrations of elements ranged from 3,024-3,830 mg kg-1 P, 1,404-1,927 mg kg-1 K, 980-1,284 mg kg-1 Mg, 72-128 mg kg-1 Ca, 21.9-43.8 mg kg-1 Mn, 22.5-32.7 mg kg-1 Zn, and 5.10-9.75 mg kg-1 Fe. © Ltd. This is an open article under the CC BY-NC-ND license © 2014 2014Elsevier The Authors. Published byaccess Elsevier Ltd. (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi Peer-review (RMUTT). under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT) Keywords: Brown rice; Elemental analysis; ICP-AES; INAA.
1. Introduction Rice is a diet staple in Thailand. From varieties of rice were planted in Thailand, Thai jasmine rice or Hom Mali rice (Oryza sativa L.) is well known for Thai rice and worldwide. However, there are not much data about the
* Corresponding author. Tel.: +66-2-401-9889 ext. 5103; fax: +66-2-562-0121. E-mail address: [email protected].
1876-6102 © 2014 Published by Elsevier Ltd. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/3.0/). Peer-review under responsibility of COE of Sustainalble Energy System, Rajamangala University of Technology Thanyaburi (RMUTT) doi:10.1016/j.egypro.2014.07.135
86
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
concentrations of elements in Thai jasmine rice. Generally, white rice is the diet of various peoples including Thai, Japanese and Korean. Nowadays, the consumption of brown rice is increasing in Thailand because of its benefit to human health such as anti-cancer, anti-diabetes and anti-cholesterol activities [1]. Brown rice contains more nutrient components such as protein, amino acids, vitamins, dietary fibers and minerals than the ordinary white rice [2]-[5]. The concentration of elements in the brown rice is valuable information for the database of Thai rice and for human dietary intake. The concentrations of elements in rice samples were investigated by various techniques such as graphite furnace atomic absorption spectrometry (GFAAS) [1], [6]-[7], instrumental neutron activation analysis (INAA) [1], inductively coupled plasma atomic emission spectrometry (ICP-AES) [6], [8] and inductively coupled plasma mass spectrometry (ICP-MS) [9]-[10]. ICP-AES is a useful technique with the advantage of simultaneous determination of multi-element, wide linear range and rapid analysis. INAA is a suitable method for determination of various elements with the advantage of a non-destructive method. In the present research, the elemental concentrations in Thai jasmine rice samples were studied to obtain the nutrient database for food ingestion in Thailand. The rice samples were collected from the paddy fields in the north and northeast of Thailand. ICP-AES was used to determine the concentrations of Ca, K, Mg, and P. The contents of Fe, Mn, and Zn were analyzed by INAA. 2. Material and method 2.1 Reagents and standards All the chemical reagents used were analytical grade. Water (>18 M:) was used throughout this work. The standard solutions were purchased from AccuStandard, Inc. The certified reference materials used to check the method were rice Àour (NIST 1568a; National Institute of Standards and Technology, USA) and marine sediment (NMIJ7302-a; National Metrology Institute of Japan). 2.2 Sample collection and preparation Jasmine rice samples were collected from three provinces in the north (Chiang Rai, Phayao and Lampang) and three provinces in the northeast (Surin, Ubon Ratchathani, and Roi Et) of Thailand. Five samples were collected in each province. All samples were dried in an electric oven at 60 ± 2 qC for 4 hours. After that, samples were ground into fine particles using a high speed blender (1093 Cyclotec Sample Mill, Sweden). The grinding step was repeated until fine particles passed completely through a sieve No.60 mesh. The rice powders were dried again in an oven at 50-60qC until constant weight, kept in polyethylene containers and stored in a desiccator until elemental analysis. 2.3 Elemental analysis 2.3.1 Inductively coupled plasma atomic emission spectrometry (ICP-AES) All dry samples (0.5 g) were digested with 65% HNO3 and 48% HF using sealed Teflon vessels on a hot plate. After digestion, the samples were evaporated to dryness and the residues were dissolved in 65% HNO3 and 40% H2O2. After dryness, the residues were dissolved and diluted to 10 mL with 4% HNO3. Finally, the proper concentrations of dissolution samples were determined by ICP-AES (Optima 5300DV, Perkin Elmer, USA). Sample digestions were done in triplicate. The ICP-AES operating parameters for all elements are shown in Table 1.
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91 Table 1. ICP-AES operating parameters. Parameter
Condition
RF power
1,300 watts
Nebulizer flow rate
0.8 L min-1
Auxiliary gas flow rate
0.2 L min-1
Plasma gas flow rate
15 L min-1
Sample uptake rate
1.5 mL min-1
2.3.2 Instrumental neutron activation analysis (INAA) Packing sample for analysis, three replicates with sample weights 50-70 mg were sealed in clean polyethylene bags for irradiation. These containers were re-packed into polyethylene container for medium irradiation and in aluminum cans for long irradiation. Samples were irradiated in an open pool type Thai Research Reactor (TRR-1/M1) at the Thailand Institute of Nuclear Technology (TINT), Bangkok. The concentration of each element was obtained by comparison with the certi¿ed reference materials (Rice Àour, NIST 1568a) and marine sediment (NMIJ7302-a). The experimental conditions for elemental analysis are as follows: x Medium irradiation for medium half-life radionuclide (Mn): Each sample was irradiated for 12 h at epithermal neutron Àux of 1.8 x 109 n cm-2 s-1 and decay time for 12 h. x Long irradiation for medium half-life radionuclide (Fe and Zn): Each sample was irradiated for 36 h at a thermal neutron Àux of 3.4 x 1011 to 5.6 x 1011 n cm-2 s-1 and decay time for 2 weeks. After appropriate decay time, the elemental concentrations were analyzed by gamma spectrometry (EG&ORTEC, USA) using a high purity germanium (HPGe) detector with relative efficiency of 60% and resolution of 1.95 keV at1.33 MeV of 60Co energy peak. The gamma-ray spectra were processed using the Gamma Vision-32 computer program. The gamma-ray activity of samples was counted using the counting time of 1,800 s for Mn and 3,600 s for Fe and Zn measurement. 3. Results and discussion 3.1 Validation of analytical method In order to assess the accuracy of the methods, certified reference materials of rice flour ((NIST 1568a) and marine sediment (NMIJ7302-a) were analyzed, the obtained results compared with the certified value and the relative error was calculated. Good agreements between the certified and measured values were observed for certified reference materials (see Table 2). Precisions calculated using four independent runs of rice flour and marine sediment (NMIJ7302-a) were better than 5% relative standard deviation (RSD) for all elements determined by ICP-AES and INAA.
87
88
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91 Table 2. Analytical results of reference materials obtained by ICP-AES and INAA in comparison with the certified values. Certified Value %Error Observed Value a Elements (mg kg-1)
(mg kg-1)
Ca
111
118b
6
K
1,211
1,280b
11
Mg
497
560b
5
P
1,445
1,530b
6
Fe
5.44
5.40c
1
Mn
19.7
20b
2
Zn
19.7
19.4b
2
ICP-AES
INAA
a
Mean values of four independent runs.
b
Certified value of rice flour (NIST 1568a).
c
Certified value of marine sediment (NMIJ7302-a).
3.2 Concentration of elements in brown jasmine rice by ICP-AES Analytical results of elements in thirty brown jasmine rice samples collected from the north and northeast of Thailand are shown in Fig. 1 and Table 3. The high concentrations of P, K, Mg and Ca were observed as the macronutrients for all studied samples. The concentration of Ca was remarkably lower compared with that of other macronutrients in brown rice samples. The order of the mean concentration of element was P > K > Mg > Ca. The concentrations of elements varied from 3,024-3,830 mg kg-1 P, 1,404-1,927 mg kg-1 K, 980-1,284 mg kg-1 Mg, and 72-128 mg kg-1 Ca. The relative standard deviation in the concentration of these elements in brown rice was 7 16%. The highest value of relative standard deviation was observed for Ca. In comparison with the elemental concentrations (Ca, K, Mg, and P) in brown rice collected from the north and northeast of Thailand, the result showed that no significant difference (t-test; p < 0.05) for all elements was observed. The concentrations of these elements were not affected by the regional area. Table 3. Mean and median concentration of elements in brown jasmine rice samples by ICP-AES (mg kg-1). Elements Mean Median Minimum Maximum Ca
100
101
72
128
K
1,611
1,566
1,404
1,927
Mg
1,152
1,145
980
1,284
P
3,462
3,478
3,024
3,830
89
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
Ca
K
Mg
P
R3-1
R3-2
R3-3
R3-4
R3-5
R6-1
R6-2
R6-3
R6-4
R6-5
R2-5
R2-4
R2-3
R2-2
R2-1
R1-5
R1-4
R1-3
R1-2
R1-1
Concentration (mg kg-1)
(a) 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Sample
Ca
K
Mg
P
R5-5
R5-4
R5-3
R5-2
R5-1
R4-5
R4-4
R4-3
R4-2
R4-1
Concentration (mg kg-1)
(b) 4500 4000 3500 3000 2500 2000 1500 1000 500 0
Sample
Fig.1. Concentration of elements in brown jasmine rice samples collected from (a) the north, and (b) the northeast of Thailand by ICP-AES.
3.3 Concentration of elements in brown jasmine rice by INAA The elemental concentrations in thirty brown jasmine rice samples measured by INAA are presented in Fig. 2. The statistic values are summarized in Table 4. The concentrations of Mn, Zn, and Fe were observed as the micronutrients for all studied samples. The order of the mean concentration of element was Mn > Zn > Fe. The concentration ranges are 21.9-43.8 mg kg-1 Mn, 22.5-32.7 mg kg-1 Zn, and 5.10-9.75 mg kg-1 Fe. The relative standard deviation in the concentration of Fe, Mn, and Zn was 15%, 21% and 10%, respectively. In comparison with the concentrations of Fe, Mn, and Zn in brown rice collected from the north and northeast of Thailand, significant difference (t-test; p < 0.05) of mean concentration for all elements was found. The
90
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
(a)
Concentration (mg kg-1)
30
Fe
Mn
R2-3
35
R2-2
concentrations of Fe, Mn, and Zn from the northeast were higher than those from the north of Thailand. The difference in the concentration of elements within the different regions is attributed to many factors such as the mineral composition of the soil, soil type, fertilizer and agricultural chemicals [11].
Zn
25 20 15 10 5
R3-4
R3-5
R6-4
R6-5
R3-2
R6-2
R3-3
R3-1
R6-1
R6-3
R2-5
R5-5
R2-4
R2-1
R1-5
R1-4
R1-3
R1-2
R1-1
0
(b)
45
Fe
Mn
R5-3
50
R5-2
Sample
Zn
Concentration (mg kg-1)
40 35 30 25 20 15 10 5
R5-4
R5-1
R4-5
R4-4
R4-3
R4-2
R4-1
0
Sample
Fig.2. Concentration of elements in brown jasmine rice samples collected from (a) the north, and (b) the northeast of Thailand by INAA.
Table 4. Mean and median concentration of elements in brown jasmine rice samples by INAA (mg kg-1). Elements Mean Median Minimum Maximum Fe
7.98
8.12
5.10
9.75
Mn
29.6
28.8
21.9
43.8
Zn
27.0
26.9
22.5
32.7
Wannee Srinuttrakul and Arporn Busamongkol / Energy Procedia 56 (2014) 85 – 91
4. Conclusions The concentrations of elements in brown jasmine rice samples collected from the paddy fields in the north and northeast of Thailand were investigated using ICP-AES and INAA. The high concentrations of P, K, Mg, and Ca and the minor contents of Mn, Zn, and Fe were observed for all brown rice samples. Both methods are reliable to analyze the elements in brown jasmine rice sample. Analyses for elements have provided much information on the nutrient database of Thai jasmine rice. Further studies on other regions of Thailand with other varieties of rice are earnestly desired.
Acknowledgements The authors would like to thank the International Atomic Energy Agency (IAEA) for partially financial support. References [1] Parengam M, Judprasong K, Srianujata S, Jittinandana S, Laoharojanaphand S, Busamongkol A. Study of nutrients and toxic minerals in rice and legumes by instrumental neutron activation analysis and graphite furnace atomic absorption spectrophotometry, J Food Comp Anal 2010;23:340–5. [2] Chen H, Siebenmorgen TJ, and Griffin K. Quality characteristics of long-grain rice milled in two commercials systems. Cereal Chem 1998;75:560-65. [3] Itani T, Tamaki M, Arai E, Horino T. Distribution of amylase, nitrogen, and minerals in rice kernels with various characters. J Agr Food Chem 2002;50:5326-32. [4] Lamberts L, Delcour JA. Carotenoids in raw and parboiled brown and milled rice. J Agr Food Chem 2008;56:11914-19. [5] Ning HF, Qiao JF, Liu ZH, Lin ZM, Li GH, Wang QS, Wang SH, Ding YF. Distribution of proteins and amino acids in milled and brown rice as affected by nitrogen fertilization and genotype. J Cereal Sci 2010;52: 90-5. [6] Antoine JMR, Fung LAH, Grant CN, Dennis HT, Lalor GC. Dietary intake of minerals and trace elements in rice on the Jamaican market, J Food Comp Anal 2012;26:111–21. [7] Qian Y, Chen C, Zhang Q, Li Y, Chen Z, Li M. Concentrations of cadmium, lead, mercury and arsenic in Chinese market milled rice and associated population health risk. Food Control 2010;21:1757-63. [8] Ogiyama S, Tagami K, Uchida S. The concentration and distribution of essential elements in brown rice associated with the polishing rate: Use of ICP-AES and Micro-PIXE. Nucl Instr and Meth in Phys Res B 2008;266:3625–32. [9] Wang KM, Wu JG, Li G, Zhang DP, Yang ZW, Shi CH. Distribution of phytic acid and mineral elements in three indica rice (Oryza sativa L.) cultivars, J Cereal Sci 2011;54:116-21. [10] Mihucz VG, Silversmit G, Szalóki I et al. Removal of some elements from washed and cooked rice studied by inductively coupled plasma mass spectrometry and synchrotron based confocal micro-X-ray fluorescence. Food Chem 2010;121:290-97. [11] D’Ilio S, Alessandrelli M, Cresti R, Forte G, Caroli S. Arsenic content of various types of rice as determined by plasma-based techniques. Microchem J 2002;73:195-201.
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