heavy metals in tea

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DETERMINATION OF HEAVY METALS (CADMIUM, CHROMIUM,

COPPER, LEAD AND NICKEL) IN SLIMMING TEAS BY USING

ATOMIC ABSORPTION SPECTROSCOPY

ERINA ASMAWANI BT ABU BAKAR

BACHELOR OF SCIENCE (Hons.) CHEMISTRY

FACULTY OF APPLIED SCIENCES

UNIVERSITI TEKNOLOGI MARA

NOVEMBER 2008

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ERINA ASMAWANI BT ABU BAKAR

Final Year Project Report Submitted in

Partial Fulfillment of the Requirements for the

Degree of Bachelor of Science (Hons.) Chemistry

in the Faculty of Applied Sciences

Universiti Teknologi MARA

NOVEMBER 2008

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ACKNOWLEDGEMENTS

Upon completion of this project, I would like to express my gratitude to manyparties. My heartfelt thanks goes to my supervisor, Prof. Madya Zuraidah

Abdullah Munir. Her guide, patience and word of wisdom has made it possible

for me to complete this thesis. Her careful reviews, helpful suggestion andthoughtful critism also have been so important for the improvement and

completion of this work. I also express my fond thanks to my parents and

friends, whose words of encouragement and constant support that kept megoing through difficult periods and tight deadlines. Beside that, I would like to

thank Encik Adnan Bin Ismail, Encik Khairul, Encik Rosmi and Encik Mohd

Kadim Bin Sarmean for their help in assisting me in doing the laboratory work.I would also express my thanks to the efforts of the previous researchers, book

authors and the website authors for their endless effort in giving their bestdefinition of understanding analytical chemistry. They have certainly eased the

completion of this thesis. To all that are not mentioned here, I am deeply sorryand would do my very best to thank you.

Erina Asmawani Bt Abu Bakar

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TABLE OF CONTENTS

Page

ACKNOWLEDGEMENTS iii

TABLE OF CONTENTS iv

LIST OF TABLES vi

LIST OF FIGURES vii

LIST OF ABBREVIATIONS viii

ABSTRACT x

ABSTRAK xi

CHAPTER 1 INTRODUCTION1.1 Background 11.2 Significance of study 31.3 Objectives of study 4

CHAPTER 2 LITERATURE REVIEW

2.1 Herbal tea 52.2 Previous study 62.3 The beneficial of minerals in tea 72.4 The negative effects of heavy metals in tea 82.5 The sources of heavy metals in tea 9

CHAPTER 3 METHODOLOGY

3.1 Chemicals 12

3.2 Collection of sample 133.3 Treatment of sample 14

3.4 Preparation of standard solutions 16

3.5 Analysis of sample 17

CHAPTER 4 RESULTS AND DISCUSSION 19

CHAPTER 5 CONCLUSION AND RECOMMENDATIONS 28

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CITED REFERENCES 31APPENDICES 33CURRICULUM VITAE 41

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LIST OF TABLES

Table Caption Page

3.1 Series of standard solutions that have been prepared foreach element 16

4.1 The wavelength for maximum absorption of metal 19

4.2 Mean concentration (mg/L) of heavy metals in slimming teasamples 20

4.3

Mean concentration (mg/kg) of heavy metals of the dry weightof slimming tea samples 20

4.4 Fourteenth Schedule (Regulation 38) Maximum PermittedProportion of Metal Contaminants in Specified Food

Malaysia, 1985 23

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LIST OF FIGURES

Figure Caption Page

1.1 Common herbs in slimming tea preparations. 12.1 CTC machine processing tea 103.1 The general process flow of the sample treatment 15

3.2 Flame atomic absorption spectroscopy (FAAS) 17

3.1

Schematic diagram of FAAS 18

3.2 Operation principle of FAAS 184.1 Comparison of heavy metal content in slimming tea samples 214.2 Heavy metals content in each sample from different countries 25

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LIST OF ABBREVIATIONS

Al : Aluminum

Ag : Silver

As : Arsenic

Ba : Barium

Ca : Calcium

Cd : Cadmium

Cr : Chromium

CTC : Crush Tear Curl

Cu : Copper

Co : Cobalt

FAAS : Flame Atomic Absorption Spectroscopy

Fe : Iron

g : Gram

g/cm3

: Gram per centimeter cube

O Hydrogen PeroxideH2 2 :

Hg : Mercury

HNO Nitric Acid3 :

K : Potassium

M : Molar

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Mg : Magnesium

mL : Milliliter

Mn : Manganese

mg/kg : Milligram per kilogram

mg/L : Milligram per liter

Pb : Lead

ppm : Part per million

PPO : Polyphenol oxidase

Sb : Antimony

Sn : Tin

Zn : Zinc

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ABSTRACT




Slimming tea is one of the many popular Asia herbal products. The presence of

heavy metals in the slimming tea has received special attention because they are

directly related to health. Six slimming teas from different brands and countrieswhich were two slimming tea products from local, two from Indonesia and

another two from China were used in this project. All samples were treatedusing acid digestion method and concentration of Cd, Cr, Cu, Pb and Ni weredetermined by using Atomic Absorption Spectroscopy. The result of analysis

showed that the content of Cr in all slimming tea samples ranged between 4.900

and 31.350 mg/kg which the lowest content found in sample (X), a productfrom Malaysia and highest content of Cr was found in sample (3) which was

product from China respectively. The levels of Cd in the slimming tea samples

were between 2.500 and 3.850 mg/kg which the lowest level of Cd was found

in sample (X) which product from Malaysia and highest from sample (Z) whichis China product. The Cd value in all samples was higher than maximum

permitted proportion of metal contaminants in specified food Malaysia, 1985

(regulation 38) which is 1.0 mg/kg. Analysis of Cu content in slimming teasamples indicated that the mean value of copper ranged between 2.150 and

18.600 mg/kg. The lowest value of Cu was found in sample (2) and the highestin sample (Y) and both of samples were from Indonesia. Ni in the slimming tea

sample was in the range of 1.100 to 11.850 mg/kg. The lowest Ni content was

found in sample (2) which product from Indonesia and highest in sample (Z)which is China product. For the Pb analysis, the absorbance measurements for

all samples were too low which means that the Pb concentrations were non

detectable

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ABSTRAK

PENENTUAN TAHAP KEPEKATAN LOGAM BERAT ( KADMIUM,

KROMIUM, KUPRUM, PLUMBUM DAN NIKEL) DI DALAM TEH

MERAMPINGKAN BADAN DENGAN MENGGUNAKAN

SPEKTROSKOPI PENYERAPAN ATOM

Teh merampingkan badan adalah satu daripada pelbagai produk herba Asia.Kehadiran logam berat di dalam teh pengurusan badan telah menerima

perhatian khas kerana ia berkait terus dengan kesihatan. Enam tehmerampingkan badan dari jenama dan negara yang berbeza iaitu dua produkmerampingkan badan dari tempatan, dua produk merampingkan badan dari

Indonesia dan dua produk merampingkan badan dari China telah digunakan

dalam projek ini. Kesemua sampel telah dirawat menggunakan kaedahpencernaan asid dan kepekatan Cd, Cr, Cu, Pb dan Ni telah ditentukan

menggunakan spektroskopi penyerapan atom. Keputusan analisa menunjukkan

kandungan Cr di dalam kesemua sampel teh dalam julat 4.900 dan 31.350

mg/kg yang mana kandungan paling rendah dijumpai di dalam sampel (X),produk dari Malaysia dan kandungan paling tinggi dijumpai di dalam sampel

(3) iaitu produk dari China. Tahap nilai Cd di dalam kesemua sampel teh adalah

di dalam julat antara 2.500 and 3.850 mg/kg yang mana tahap paling rendahdijumpai dalam sampel (X) iaitu produk dari Malaysia dan paling tinggi dari

sampel (Z) iaitu produk dari China. Nilai Cd di dalam kesemua sampel adalahtinggi daripada tahap maksima yang dibenarkan oleh Peraturan- Peraturan

Makanan Malaysia (1985) iaitu 1.0 mg/kg. Analisis kandungan Cu di dalam

kesemua sampel teh menunjukkan nilai purata Cu di antara julat 2.150 and18.600 mg/kg. Nilai Cu yang terendah dijumpai di dalam sampel (2) dan yang

paling tinggi dijumpai di dalam sample (Y) dan kedua-dua sampel adalah dari

Indonesia. Nilai Ni di dalam kesemua sampel teh di dalam julat antara 1.100dan 11.850 mg/kg. Kandungan Ni paling rendah telah dijumpai di dalam

sampel (2) iaitu produk dari Indonesia dan paling tinggi di dalam sample (Z)

iaitu produk China. Untuk analisis Pb, sukatan penyerapan untuk kesemuasampel adalah terlalu rendah di mana purata kepekatan Pb tidak dapat dikesan.

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CHAPTER 1

INTRODUCTION

1.1 Background

Slimming tea is one of the many popular Asian herbal products. Slimming teas

are herbal teas, marketed for their slimming properties; contain laxatives or

diuretics or a combination of both. A laxative is defined as any medicines that

either stimulates bowel movements or soften the stools for emptying while

diuretic is used to rid the body of excess water through an increased rate of

urination. Besides tea, common herbs used in these local and imported

preparations are the laxatives senna, cascara, buckhton or rhubarb root and the

diuretics uva ursi, mallow or licorice root. Many cases reported nowadays are

about toxic heavy metals in Asian herbal products (Ernst, 2005).

(a) Senna leaves (b) Cascara (c) Uva Ursi

Figure 1.1 Common herbs in slimming tea preparations.

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Heavy metals are metallic elements that have density greater than 5 g/cm

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and

can be hazardous at elevated concentration. Heavy metals are dangerous

because they tend to bioaccumulate. Bioaccumulation means an increase in the

concentration of a chemical in a biological organism over time, compared to the

chemical's concentration in the environment. Compounds are accumulated in

living things any time they are taken up and stored faster than they are

metabolized or excreted. Heavy metals can not be degraded or destroyed. They

can enter our bodies to a small extent via food, drinking water and air. As trace

metals, some heavy metals give undesirable effect and some heavy metals give

a negative effect. Death can occur from metal poisoning but is dependent upon

the dose. Usually people inhale or ingest small amounts of metals which build

up in the body slowly interfering with function and slowly causing illness

which may ultimately end in death.

In this study, heavy metals in slimming tea were detected by using flame

atomic absorption spectroscopy. Flame atomic absorption is a very common

technique for detecting metals and metalloids in environmental samples. It is

very reliable and simple to use.

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1.2

Significance of study

Nowadays people are obsessed to slimming down their body. They want fast

result and easiest method. They take slimming tea. Slimming tea has been

reported ensure rapid weight loss. But many cases have been reported about

toxic heavy metals in herbal products especially products from Asia. The intake

of food contaminated by heavy metal is harmful to human health and several

countries have imposed food laws to restrict the presence of heavy metal in

food and beverages. From this study, heavy metal contents in six slimming tea

products were determined. Knowledge of the heavy metal contents enable us to

compare to the allowable limits. Besides that, by comparing the heavy metal

contents in the samples, it can help consumers to choose which products are

safe to use and which product must be avoided.

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1.3 Objectives of studyIn this study, five heavy metals were detected and the concentrations of these

heavy metals were determined.

The objectives of the project include to:

1. Determine cadmium (Cd), chromium (Cr), copper (Cu), nickel (Ni) andlead (Pb) in slimming tea samples which were two products from

Malaysia, two products from Indonesia and another two products from

China by using flame atomic absorption spectroscopy.

2. Compare heavy metal contents in slimming tea samples from localproducts with those from other countries.

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CHAPTER 2

LITERATURE REVIEW

2.1 Herbal tea

A variety by themselves, herbal tea is completely different from the other

varieties of tea. Not being tea in the true sense, herbal tea is simply fresh herb

containing medicinal properties. By infusing a teaspoon of these fresh herbs

like mint, tutlsi, ginger, jasmine and many others into hot water, their medicinal

properties seep into the water giving the drinkers the desired effect, which

could be laxative, curative, refreshing, sedative or antacid in nature.

Herbal tea is referred to in various ways. Among its nicknames are as

sleeping tea, slimming tea, dieters' tea, cholesterol lowering tea , depending

upon their specific medicinal effect. Most herbal tea contain tea (Camellia

sinensis) which was mixed with the herbs. Camellia sinensis is the tea plant, the

plant species whose leaves and leaf buds are used to produce tea. It is of the

genus Camellia , a genus of flowering plants in the family Theaceae. White tea,

green tea, oolong and black tea are all harvested from this species, but are

processed differently to attain different levels ofoxidation.

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http://en.wikipedia.org/wiki/Planthttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Teahttp://en.wikipedia.org/wiki/Camelliahttp://en.wikipedia.org/wiki/Theaceaehttp://en.wikipedia.org/wiki/White_teahttp://en.wikipedia.org/wiki/Green_teahttp://en.wikipedia.org/wiki/Oolonghttp://en.wikipedia.org/wiki/Black_teahttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Oxidationhttp://en.wikipedia.org/wiki/Black_teahttp://en.wikipedia.org/wiki/Oolonghttp://en.wikipedia.org/wiki/Green_teahttp://en.wikipedia.org/wiki/White_teahttp://en.wikipedia.org/wiki/Theaceaehttp://en.wikipedia.org/wiki/Camelliahttp://en.wikipedia.org/wiki/Teahttp://en.wikipedia.org/wiki/Specieshttp://en.wikipedia.org/wiki/Plant


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2.2 Previous study

Bagelet al

(2005) reported the daily mineral intake by consuming herbal teas

for a 70 kg person per day are 500 mg Ca, 300 mg Mg, 15 mg Fe, 5 mg Al, 2.8

mg Mn, 15 mg Zn, 2.5 mg Cu, 1.6 mg Sr, 1.1 mg Ba, 0.025 mg Ni, 0.05-0.2mg

Cr, 0.04 mg Co, 0.415 mg Pb and 0.057 mg Cd. This shows that the amounts of

heavy metals are presence in herbal tea.

Most of slimming tea products consists of tea (Camellia sinensis

) which is

either green tea or black tea. Ansari et al (2007) stated that tea (Camellia

sinensis) is the most popular beverage in the world and contains several

essential nutrients, which are beneficial for human health. The contamination of

tea leaves by heavy metals may pose a serious threat to human, because they

are not biodegradable and remain in environment and pass to food chain. The

concentration of heavy metals of Cd, Pb, Ni, and Al and macro elements of Fe,

Zn, Cu and Mn were determined by atomic absorption spectrometry on 30

samples of black tea cultivated in Iran and compared with the results for 30

samples of imported black tea in 2006. The results of analysis showed that the

mean level of Al was 699.2172.7 mg/kg for Iranian and 388.398.3 mg/kg for

imported black tea. However, the values for Cd, Pb, and Ni were non-

detectable. The most abundant nutritive metal was manganese with 155.2-214.2

mg/kg and 96.7-332.9 mg/kg in Iranian and imported black tea, respectively.

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Seenivasan et al (2007) have done a research about heavy metal content of

black teas from South India. A total of one hundred black tea samples, collected

from the tea growing regions of Valparai and Nilgiris in Tamil Nadu,

Vandiperiyar, Wayanad and Munnar in Kerala and Karnataka state were

analyzed for heavy metals. Cu, Cr, Ni, Cd and Pb in tea samples were analyzed

using atomic absorption spectrophotometer equipped with flame and graphite

furnace. Air-acetylene flame was used for determination of metal content. The

mean values for the results of analysis of tea samples in mg /kg, were 24.07 for

Cu, 4.76 for Cr, 2.53 for Ni, 0.14 for Cd and 0.81 for Pb in tea. There were

wide variations in the heavy metal contents of black teas collected from

different regions of South India. The results indicated that the contents of Cu,

Cr, Ni, Cd and Pb in tea were different for the different agro climatic regions.

Xie et al(1998) reported that the average Pb level in Chinese black tea samples

is higher than Pb level in South India black tea samples.

2.3 The beneficial of minerals in tea

Herbal teas contain beneficial minerals such as Ca, Na and K. Ca is the main

component of bone and teeth and its function in cell membranes, in muscles, by

regulation of endo and exoenzymes and has great importance in regulation of

blood pressure (Kili & Kse, 2001).

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Na and K are of great importance for many regulation systems in the body. Na

is excreted in sweat by the body. Besides tea, fruits, vegetables and coffee are

good sources of K and Na. The minimum daily intake of Na and K are 2.4 g

and 3.5 g (Baysal, 2002).

Stagg et al(1975) emphasized the therapeutic action of tea. Tea is an important

source of manganese (Mn) and potassium (K) which could be beneficial for

hypertensive patients.

2.4 The negative effects of heavy metals in tea

Besides minerals, herbal teas also containing several heavy metals such as Al,

Mn, Zn, Cu, Cr, Co, Cd and Pb. Heavy metals such as copper (Cu) is essential

to maintain metabolism of the human body but at higher concentration they can

lead to poisoning. It can cause kidney and liver damage. Nickel (Ni) is also

needed in small amount to produce red blood cells but at higher concentration it

becomes mildly toxic. It can cause heart and liver damage. Cadmium (Cd) is

associated with renal dysfunction and it may also produce bone defects such as

osteoporosis.

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Beside copper (Cu), chromium (Cr) can be can accumulated in kidney and liver

and can cause severe damage to those systems. In addition, this metal can also

damage the circulatory and nerve tissue. High levels of lead (Pb) may result in

toxic biochemical effects in humans which in turn cause problems in the

synthesis of haemoglobin, effects on the kidneys, gastrointestinal tract, joints

and reproductive system and acute or chronic damage to the nervous system

and also can cause mental retardation.

2.5 The sources of heavy metals in tea

The main sources of heavy metals in plants are their growth media, nutrients,

agro inputs and soil. Other sources may include pesticides and fertilizers.

Elevated heavy metal levels cause damage to plants such as delayed flowering,

lower chlorophyll content and reduction in the number and quality of shoots

(Setia et al, 1989).

Seenivasan et al(2007) stated that Cu is one of the native metals found in tea,

central to polyphenol oxidase enzyme. Polyphenol oxidase (PPO) enzymes

catalyse the o-hydroxylation of monophenols (phenol molecules in which the

benzene ring contains a single hydroxyl substituent) to o-diphenols (phenol

molecules containing two hydroxyl substituents). They can also further catalyse

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http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6S-4P9F3CH-1&_user=2512477&_coverDate=07%2F29%2F2007&_alid=680205701&_rdoc=1&_fmt=full&_orig=search&_cdi=5038&_sort=d&_docanchor=&view=c&_ct=3&_acct=C000027478&_version=1&_urlVersion=0&_userid=2512477&md5=2da8bc5fb80af165d01790f3dd742816#bib14http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6S-4P9F3CH-1&_user=2512477&_coverDate=07%2F29%2F2007&_alid=680205701&_rdoc=1&_fmt=full&_orig=search&_cdi=5038&_sort=d&_docanchor=&view=c&_ct=3&_acct=C000027478&_version=1&_urlVersion=0&_userid=2512477&md5=2da8bc5fb80af165d01790f3dd742816#bib14http://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6S-4P9F3CH-1&_user=2512477&_coverDate=07%2F29%2F2007&_alid=680205701&_rdoc=1&_fmt=full&_orig=search&_cdi=5038&_sort=d&_docanchor=&view=c&_ct=3&_acct=C000027478&_version=1&_urlVersion=0&_userid=2512477&md5=2da8bc5fb80af165d01790f3dd742816#bib14http://en.wikipedia.org/wiki/Phenolhttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Phenolhttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Phenolhttp://en.wikipedia.org/wiki/Hydroxylhttp://en.wikipedia.org/wiki/Phenolhttp://www.sciencedirect.com/science?_ob=ArticleURL&_udi=B6T6S-4P9F3CH-1&_user=2512477&_coverDate=07%2F29%2F2007&_alid=680205701&_rdoc=1&_fmt=full&_orig=search&_cdi=5038&_sort=d&_docanchor=&view=c&_ct=3&_acct=C000027478&_version=1&_urlVersion=0&_userid=2512477&md5=2da8bc5fb80af165d01790f3dd742816#bib14


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the oxidation of o-diphenols to produce o-quinones. It is the rapid

polymerisation ofo-quinones to produce black, brown or red pigments

(polyphenols) that is the cause offruit browning. The used of copper fungicides

cause the presence of undesirable levels of Cu content and also increase the

accumulation of Pb and Cd in black tea.

Cr is considered as a local contaminant and comes mainly through the crush

tearcurl (CTC) rollers during the manufacturing of black tea. CTC machine is

shown in Figure 2.1.

Figure 2.1 CTC machine processing tea.

Franklin et al(2005) reported that potassic fertilizers contained 2.7 to 16 mg/kg

Ni as impurity while commercial phosphatic fertilizers contained 19 to

24 mg/kg Ni. It is clearly evident that Ni mainly comes through the foliar and

soil application of low quality fertilizers and micro nutrients. They also

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http://en.wikipedia.org/wiki/Quinonehttp://en.wikipedia.org/wiki/Quinonehttp://en.wikipedia.org/wiki/Polymerisationhttp://en.wikipedia.org/wiki/Polyphenolshttp://en.wikipedia.org/wiki/Browning_%28chemical_process%29http://en.wikipedia.org/wiki/Browning_%28chemical_process%29http://en.wikipedia.org/wiki/Polyphenolshttp://en.wikipedia.org/wiki/Polymerisationhttp://en.wikipedia.org/wiki/Quinone


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reported 4.9 to 5.5 mg/kg of Cd in phosphatic fertilizers and 11.8 to 50.9 mg/kg

in zinc sources. It appears that contaminated phosphatic and zinc fertilizers

were the sources of Cd in tea.

Michie et al(1977) Tsushida et al, (1977and ) reported that tea soils are acidic

and this condition favours solubility of heavy metals. Tea bushes adjacent to

heavy traffic gets exposure to Pb and Cd through fallout from automobile

exhaust and dust.

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CHAPTER 3

METHODOLOGY

3.1 Chemicals

The list of chemicals used were:

Standard stock solutions (1000 ppm) of Cd, Cu, Cr, Pb and Ni

6.0 M HNO3

30% Hydrogen Peroxide(H O )2 2

3.2 Collection of sampleSix slimming tea products of different brands were used in this project. Two of

the tea products were from local, two from Indonesia and another two from

China. Four slimming tea products which were two from Malaysia and two

from Indonesia were purchased from the local retail outlets. Another two

slimming tea products which are from China were purchased from local

Chinese medicine shop.

heavy metals in tea

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