A PROJECT REPORT ON

DETERMINATION OF SOME HEAVY METAL LEVELS IN TEA SAMPLES USING FLAME ATOMIC

ABSORPTION SPECTROPHOTOMETER (FAAS)

SUBMITTED TO DEPARTMENT OF CHEMISTRY, ST. JOHN’S COLLEGE, AGRA

FOR THE DEGREE OF MASTER OF SCIENCE (M Sc) IN PHYSICAL CHEMISTRY (2013-2014)

UNDER THE SUPERVISION OF:

Dr. SUSAN VERGHESE .P Associate Professor

Department of Chemistry St. John’s College, Agra

SUBMITTED BY: SHOWKAT ALI BHAT M Sc Final Physical Chemistry 2013-14

CERTIFICATE

This is to certify that this project entitled “DETERMINATION OF SOME HEAVY METAL LEVELS IN TEA SAMPLES USING FLAME ATOMIC ABSORPTION SPECTROPHOTOMETER (FAAS)” submitted to St. John’s College, Agra, for the fulfillment of the requirement for the Master degree is a bona fide project work carried out by SHOWKAT ALI BHAT student of M Sc Final (PHYSICAL CHEMISTRY) under my supervision and guidance during the session 2013-2014. The assistance and help rendered during the course of investigation and sources of literature have been acknowledged.

Dr. Susan Verghese .P Associate Professor Department of Chemistry St. John’s College, Agra

(Supervisor)

Dr. Hemant Kulshreshtha HEAD

Department of Chemistry St. John’s College, Agra

ACKNOWLEDGEMENT

It is my proud privilege to express my profound sense of gratitude and sincere indebtedness to honorable Dr Alexander Lal, Principal of St. John’s College, Agra, for providing infrastructure for the completion of this project. I am thankful to Dr Hemant Kulshreshtha, Head of the Chemistry Department; he was always affectionate, pain taking and source of inspiration to me. I am highly obliged to him for their guidance, constructive criticism and valuable advice which they provided to me throughout the tenure of my project. The project work could not have been possible without his worthy suggestions and constant co-operation. I am also thankful to my supervisor Dr Susan Verghese to guide me on the various sides of this project and her help and guidance she provided to me for the initiation of this project. My heart is filled with deep sense of thankfulness and obeisance to my teachers Dr. R P Singh, Dr. H B Singh, Dr. P E Joseph, Dr. Raju V John, Dr. Shalini Nelson, Dr. Mohd. Anis, Dr. Anita Anand, Dr. Padma Hazra, and Dr. David Massey for their valuable suggestions and lively moral boosting during the progress of this investigation. I am also thankful to Ms. Nisha Siddhardhan (Instrumentation in-charge) for their kind support during the project work. I also place my sincere thanks to non-teaching staff for their support and co-operation. I am highly grateful to my parents for their affectionate and moral support. They have always been source of inspiration for me. Above all, I thank The Almighty for giving me strength to complete this project. Last but not the least I extend my sincere thanks to all those who have helped me in one or the other way during my project work.

SHOWKAT ALI BHAT M Sc Final (Physical Chemistry)

ABBREVIATIONS

RDA = Recommended Dietary Allowance

AI = Adequate Intake

UL = Upper Limit

DDI = Daily Dietary Intake

DRI = Dietary Reference Intakes

MAL = Maximum Acceptable Limit

SAM = Standard Addition Method

AA = Atomic Absorption

FAAS = Flame Atomic Absorption Spectroscopy

HCL = Hollow Cathode Lamp

MIBK = Methyl isobutyl ketone

APDC = Ammonium pyrrolidine dithiocarbamate

ND = Non Detectable

PMT = Photomultiplier tubes

LPG = Liquefied petroleum gas

ppm = Parts per million

Cu = Copper

Cr = Chromium

Pb = Lead

Ni = Nickel

Na = Sodium

Fe = Iron

Ca = Calcium

Cd = Cadmium

UL = The maximum level of daily nutrient intake that is likely to pose

no risk of adverse effects. Unless otherwise specified, the UL

represents total intake from food, water, and supplements.

ND = Non detectable due to lack of data of adverse effects in this age

group and concern with regard to lack of ability to handle excess

amounts. Source of intake should be from food only to prevent high

levels of intake.

Introduction

Tea is an aromatic beverage commonly prepared by pouring hot or boiling

water over cured leaves of the tea plant, Camellia sinensis. After water, tea is

the most widely consumed beverage in the world. It has a cooling, slightly

bitter, and astringent flavour that many people enjoy

Tea originated in China as a medicinal drink. It was first introduced to

Portuguese priests and merchants in China during the 16th century. Drinking tea

became popular in Britain during the 17th century. The British introduced it to

India, in order to compete with the Chinese monopoly on the product

Tea has long been promoted for having a variety of positive health benefits.

Recent studies suggest that green tea may help reduce the risk of cardiovascular

disease and some forms of cancer, promote oral health, reduce blood pressure,

help with weight control, improve antibacterial and antivirasic activity, provide

protection from solar ultraviolet light, and increase bone mineral density. Green

tea is also said to have "anti-fibrotic properties, and neuroprotective power."

Additional research is needed to "fully understand its contributions to human

health, and advise its regular consumption in Western diets."

Tea catechins have known anti-inflammatory and neuroprotective properties,

help regulate food intake, and have an affinity for cannabinoid receptors, which

may suppress pain and nausea and provide calming effects.

Consumption of green tea is associated with a lower risk of diseases that cause

functional disability, such as “stroke, cognitive impairment, and osteoporosis”

in the elderly.

Tea contains L-theanine, an amino acid whose consumption is mildly associated

with a calm but alert and focused, relatively productive (alpha wave-dominant)

mental state in humans. This mental state is also common to meditative practice.

The phrase herbal tea usually refers to infusions of fruit or herbs made without the tea plant, such as rosehip tea, chamomile tea, or rooibos tea. Alternative phrases for this are tisane or herbal infusion, both bearing an implied contrast with "tea" as it is construed here.

Health effects of Tea

Tea contains a large number of possibly bioactive chemicals, including

flavonoids, amino acids, vitamins, caffeine and several polysaccharides,

and a variety of health effects have been proposed and investigated. It has

been suggested that green and black tea may protect against cancer, though

the catechins found in green tea are thought to be more effective in

preventing certain obesity-related cancers such as liver and colorectal

cancer, while both green and black teas may protect against cardiovascular

disease

Negative effects of tea drinking are centered around the consumption of

sugar used to sweeten the tea. Those who consume very large quantities of

brick tea may experience fluorosis.

Numerous recent epidemiological studies have been conducted to

investigate the effects of green tea consumption on the incidence of human

cancers. These studies suggest significant protective effects of green tea

against oral, pharyngeal, oesophageal, prostate, digestive, urinary tract,

pancreatic, bladder, skin, lung, colon, breast, and liver cancers, and lower

risk for cancer metastasis and recurrence.

Review of Literature

Başgel et 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 699.2±172.7

mg/kg for Iranian and 388.3±98.3 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.

RANK OF TEA PRODUCTION IN DIFFERENT

COUNTRIES

Rank Country 2008 2009 2010 2011

1 China 1,274,984 1,375,780

1,467,467

1,640,310

2 India 987,000 972,700 991,180 1,063,500

3 Kenya 345,800 314,100 399,000 377,912

4

Sri

Lanka

318,700 290,000 282,300 327,500

5 Turkey 198,046 198,601 235,000 221,600

6 Vietnam 173,500 185,700 198,466 206,600

7 Iran 165,717 165,717 165,717 162,517

8 Indonesia

150,851 146,440 150,000 142,400

9 Argentina

80,142 71,715 88,574 96,572

10 Japan 96,500 86,000 85,000 82,100

Total

World 4,211,397 4,242,280 4,518,060 4,321,011

Health effects of nickel

Nickel is a compound that occurs in the environment only at very low

levels. Humans use nickel for many different applications. The most

common application of nickel is the use as an ingredient of steal and

other metal products. It can be found in common metal products such

as jewelry.

Food stuffs naturally contain small amounts of nickel. Chocolate and

fats are known to contain severely high quantities. Nickel uptake will

boost when people eat large quantities of vegetables from polluted

soils. Plants are known to accumulate nickel and as a result the nickel

uptake from vegetables will be eminent. Smokers have a higher nickel

uptake through their lungs. Finally, nickel can be found in detergents.

Humans may be exposed to nickel by breathing air, drinking water,

eating food,Beverages or smoking cigarettes. Skin contact with

nickel-contaminated soil or water may also result in nickel exposure.

In small quantities nickel is essential, but when the uptake is too high

it can be a danger to human health.

An uptake of too large quantities of nickel has the following

consequences:

- Higher chances of development of lung cancer, nose cancer, larynx

cancer and prostate cancer

- Sickness and dizziness after exposure to nickel gas

- Lung embolism

- Respiratory failure

- Birth defects

- Asthma and chronic bronchitis

- Allergic reactions such as skin rashes, mainly from jewelry

- Heart disorders

Nickel fumes are respiratory irritants and may cause pneumonitis.

Exposure to nickel and its compounds may result in the development

of a dermatitis known as “nickel itch” in sensitized individuals. The

first symptom is usually itching, which occurs up to 7 days before

skin eruption occurs. The primary skin eruption is erythematous, or

follicular, which may be followed by skin ulceration. Nickel

sensitivity, once acquired, appears to persist indefinitely.

Carcinogenicity- Nickel and certain nickel compounds have been

listed by the National Toxicology Program (NTP) as being reasonably

anticipated to be carcinogens. The International Agency for Research

on Cancer (IARC) has listed nickel compounds within group 1 (there

is sufficient evidence for carcinogenicity in humans) and nickel

within group 2B (agents which are possibly carcinogenic to humans).

OSHA does not regulate nickel as a carcinogen. Nickel is on the

ACGIH Notice of Intended Changes as a Category A1, confirmed

human carcinogen.

Health effects of chromium

People can be exposed to chromium through breathing, eating or

drinking and through skin contact with chromium or chromium

compounds. The level of chromium in air and water is generally low.

In drinking water the level of chromium is usually low as well, but

contaminated well water may contain the dangerous chromium(IV);

hexavalent chromium. For most people eating food that contains

chromium(III) is the main route of chromium uptake, as

chromium(III) occurs naturally in many vegetables, fruits, meats,

yeasts and grains. Various ways of food preparation and storage may

alter the chromium contents of food. When food in stores in steel

tanks or cans chromium concentrations may rise.

Chromium(III) is an essential nutrient for humans and shortages may

cause heart conditions, disruptions of metabolisms and diabetes. But

the uptake of too much chromium(III) can cause health effects as

well, for instance skin rashes.

Chromium(VI) is a danger to human health, mainly for people who

work in the steel and textile industry. People who smoke tobacco also

have a higher chance of exposure to chromium.

Chromium(VI) is known to cause various health effects. When it is a

compound in leather products, it can cause allergic reactions, such as

skin rash. After breathing it in chromium(VI) can cause nose

irritations and nosebleeds.

Other health problems that are caused by chromium(VI) are:

- Skin rashes

- Upset stomachs and ulcers

- Respiratory problems

- Weakened immune systems

- Kidney and liver damage

- Alteration of genetic material

- Lung cancer

- Death

The health hazards associated with exposure to chromium are

dependent on its oxidation state. The metal form (chromium as it

exists in this product) is of low toxicity. The hexavalent form is toxic.

Adverse effects of the hexavalent form on the skin may include

ulcerations, dermatitis, and allergic skin reactions. Inhalation of

hexavalent chromium compounds can result in ulceration and

perforation of the mucous membranes of the nasal septum, irritation

of the pharynx and larynx, asthmatic bronchitis, bronchospasms and

edema. Respiratory symptoms may include coughing and wheezing,

shortness of breath, and nasal itch.

Carcinogenicity- Chromium and most trivalent chromium compounds

have been listed by the National Toxicology Program (NTP) and

International Agency for Research on Cancer (IARC) as having

inadequate evidence for carcinogenicity in experimental animals.

According to NTP, there is sufficient evidence for carcinogenicity in

experimental animals for the following hexavalent chromium

compounds; calcium chromate, chromium trioxide, lead chromate,

strontium chromate,and zinc chromate.

Health effects of copper

Copper can be found in many kinds of food, in drinking water and in

air. Because of that we absorb eminent quantities of copper each day

by eating, drinking and breathing. The absorption of copper is

necessary, because copper is a trace element that is essential for

human health. Although humans can handle proportionally large

concentrations of copper, too much copper can still cause eminent

health problems.

Copper concentrations in air are usually quite low, so that exposure to

copper through breathing is negligible. But people that live near

smelters that process copper ore into metal, do experience this kind of

exposure.

People that live in houses that still have copper plumbing are exposed

to higher levels of copper than most people, because copper is

released into their drinking water through corrosion of pipes.

Occupational exposure to copper often occurs. In the working

environment, copper contagion can lead to a flu-like condition known

as metal fever. This condition will pass after two days and is caused

by over sensitivity.

Long-term exposure to copper can cause irritation of the nose, mouth

and eyes and it causes headaches, stomachaches, dizziness, vomiting

and diarrhea. Intentionally high uptakes of copper may cause liver and

kidney damage and even death. Whether copper is carcinogenic has

not been determined yet.

There are scientific articles that indicate a link between long-term

exposure to high concentrations of copper and a decline in

intelligence with young adolescents. Whether this should be of

concern is a topic for further investigation.

Industrial exposure to copper fumes, dusts, or mists may result in

metal fume fever with atrophic changes in nasal mucous membranes.

Chronic copper poisoning results in Wilson’s Disease, characterized

by a hepatic cirrhosis, brain damage, demyelization, renal disease, and

copper deposition in the cornea.

Health effects of lead

Lead is a soft metal that has known many applications over the years.

It has been used widely since 5000 BC for application in metal

products, cables and pipelines, but also in paints and pesticides. Lead

is one out of four metals that have the most damaging effects on

human health. It can enter the human body through uptake of food

(65%), water (20%) and air (15%).

Foods such as fruit, vegetables, meats, grains, seafood, soft drinks and

wine may contain significant amounts of lead. Cigarette smoke also

contains small amounts of lead.

Lead can enter (drinking) water through corrosion of pipes. This is

more likely to happen when the water is slightly acidic. That is why

public water treatment systems are now required to carry out pH-

adjustments in water that will serve drinking purposes.

For as far as we know, lead fulfils no essential function in the human

body, it can merely do harm after uptake from food, air or water.

Lead can cause several unwanted effects, such as:

- Disruption of the biosynthesis of haemoglobin and anaemia

- A rise in blood pressure

- Kidney damage

- Miscarriages and subtle abortions

- Disruption of nervous systems

- Brain damage

- Declined fertility of men through sperm damage

- Diminished learning abilities of children

- Behavioural disruptions of children, such as aggression, impulsive

behavior and hyperactivity

Lead can enter a foetus through the placenta of the mother. Because

of this it can cause serious damage to the nervous system and the

brains of unborn children

Health effects of cadmium

Human uptake of cadmium takes place mainly through food.

Foodstuffs that are rich in cadmium can greatly increase the cadmium

concentration in human bodies. Examples are liver, mushrooms,

shellfish, mussels, cocoa powder and dried seaweed.

An exposure to significantly higher cadmium levels occurs when

people smoke. Tobacco smoke transports cadmium into the lungs.

Blood will transport it through the rest of the body where it can

increase effects by potentiating cadmium that is already present from

cadmium-rich food.

Other high exposures can occur with people who live near hazardous

waste sites or factories that release cadmium into the air and people

that work in the metal refinery industry. When people breathe in

cadmium it can severely damage the lungs. This may even cause

death.

Cadmium is first transported to the liver through the blood. There, it

is bond to proteins to form complexes that are transported to the

kidneys. Cadmium accumulates in kidneys, where it damages filtering

mechanisms. This causes the excretion of essential proteins and

sugars from the body and further kidney damage. It takes a very long

time before cadmium that has accumulated in kidneys is excreted

from a human body.

Other health effects that can be caused by cadmium are:

- Diarrhoea, stomach pains and severe vomiting

- Bone fracture

- Reproductive failure and possibly even infertility

- Damage to the central nervous system

- Damage to the immune system

- Psychological disorders

- Possibly DNA damage or cancer development

Health effects of calcium Calcium is the most abundand metal in the human body: is the main

constituent of bones and theets and it has keys metabolic functions.

Calcium is sometimes referred to as lime. It is most commonly found

in milk and milk products, but also in vegetables, nuts and beans. It is

an essential component for the preservation of the human skeleton

and teeth. It also assists the functions of nerves and muscles. The use

of more than 2,5 grams of calcium per day without a medical

necessity can lead to the development of kidney stones and sclerosis

of kidneys and blood vessels.

A lack of calcium is one of the main causes of osteoporosis.

Osteoporosis is a disease in which the bones become extremely

porous, are subject to fracture, and heal slowly, occurring especially

in women following menopause and often leading to curvature of the

spine from vertebral collapse.

Unlike most of the people think, there is an intense biological activity

inside our bones. They are being renewed constantly by new tissue

replacing the old one. During childhood and adolescence, there’s

more production of new tissue than destruction of the old one, but at

some point, somewhere around the 30 or 35 years of age, the process

is inverted and we start to loose more tissue than what we can replace.

In women the process is accelerated after the menopause (he period

marked by the natural and permanent cessation of menstruation,

occurring usually between the ages of 45 and 55); this is because their

bodies stop producing the hormone known as estrogen, one of which

functions is to preserve the osseous mass.

Evidence suggests that we need a daily intake of 1,000 milligrams of

calcium in order to preserve the osseous mass in normal conditions.

This is both for man and pre-menopausic women. The recommended

daily intake rises to 1,500 for menopausic woman.

The main calcium sources are the dairy products, but also nuts, some

green vegetables like spinach, and cauliflower, beans, lentils…

Calcium works together with magnesium to create new osseous mass.

Calcium should be taken together with magnesium in a 2:1 rate, that

is to say, if you ingest 1000 mg of calcium, you should also ingest

500 mg of magnesium. Some magnesium sources in the diet are

seafood, whole-grains, nuts, beans, wheat oats, seeds and green

vegetables.

Other important measures to prevent osteoporosis are:

• Doing regular exercise (at least three times a week)

• Taking adequate amounts of manganese, folic acid, vitamin B6,

vitamin B12, omega 3 (it aids calcium absorption and stimulates new

osseous mass production) and vitamin D (it aids calcium absorption in

the small intestine).

• Not abusing of sugar, saturated grease and animal proteins

• Not abusing of alcohol, caffeine, nor gaseous drinks

• Not smoking

Other triggers for osteoporosis are the hereditary factor and the stress.

EXPERIMENTAL

MATERIALS AND METHODS

Sample Collection

Tea samples were collected from Rajamandi, the main market of

Agra. Sampling was done at random from different retailers and

vendors of this market. A total of six (6) varieties broke bond taza,

dhadkan, patakha, razana, red lebel and tata tea were collected.

Sampling was done during four days in December 2013. The tea

samples were then analyzed for Cd, Cr, Cu, Ni, Pb, and Ca.

Sample Preparation

Took 1 gm of tea sample and digested in aqua-ragia. Then made upto

the mark in 100 ml measuring flask.

Sample treatment and analysis

All metal salts dissolved in tea are adsorbed on some materials

present as impurities in tea. Therefore, the sample should be digested

rigidly under controlled condition. Maintain constant sample volume,

acid strength and contact time. Use the least rigorous digestion

method to provide acceptable and consistent recovery compatible to

analytical method and metal being analyzed.

HNO3 DIGESTION

Transfer a 1gm of sample to a flask or a beaker and add 5ml conc.

HNO3. If the beaker used, partially cover it with a watch glass to

minimize contaminations. Take the container under a fume hood and

heat solely on a hot plate or burner to boiling and evaporate to

dryness. The solution at this state should be clear having a light

colour. If not continue heating and adding conc. HNO3 till the

digestion is complete i.e., a clear or light coloured solution is

obtained.

Remove the flask or beaker and cool for 10 min. wash down its and

watch glass cover with water and if necessary. Transfer filtrate to a

100 ml volumetric flask with 5ml portion of water adding this rinsings

to the vol. flask, dilute to mark and mix thoroughly .take portions of

the solution for required metal determinations.

HNO3-HCl

If the above solution has any ppt. or residue at 10ml of dilute HCl in

20ml of water per 100ml anticipated final volume. Heated for an

additional 20 minutes to dissolve the ppt or residue . Cool wash down

beaker wall and watch glass with water , filtered to remove insoluble

material and transfer filterate to a 100ml of volume flask with rinsing.

Alternatively, centrifuge . adjusted to volume and mixed thoroughly.

Apparatus

A Perkin-Elmer AAnalyst100 double beam atomic absorption

spectrophotometer (Perkin-Elmer corp., CT) was used at a slit width

of 0.7 nm, with hollow cathode lamps for mineral measurements by

FAAS. Samples were atomized for Cr, Cu, Cd, Ni, and Pb. All

analyses were performed in peak height mode to calculate absorbance

values.

SYSTRONICS Flame photometer 130 was used for the estimation of

Ca.

All solutions were prepared from analytical reagent grade reagents,

for e.g., Commercially available 1,000 μg/mL Cu [prepared from

Cu(NO3)2.3H2O in 0.5 M HNO3] were used. The water employed

for preparing the standards for calibration and dilutions was ultra pure

water with a specific resistivity of 18 m_ cm-1 obtained by filtering

double-distilled water immediately before use.

Calcium can be easily analysed by Flame Photometer. Standards can

be prepared as follows-

Calcium – 1000 ppm

Dissolved 2.497 g CaCO3 in approx 300 ml glass distilled water and

added 10 ml conc. HCl diluted to 1 litre. For calibration 20, 40, 60, 80

and 100 ppm solutions were prepared from the stock solution.

INSTRUMENTATION

Introduction Atomic absorption spectroscopy

Atomic absorption is a very common technique for detecting metals

and metalloids in environmental samples. It is very reliable and

simple to use. Figure 1 shows which elements are commonly detected

through atomic absorption. The technique is based on the fact that

ground state metals absorb light at specific wavelenths. Metal ions in

a solution are converted to atomic state by means of a flame. Light of

the appropriate wavelength is supplied and the amount of light

absorbed can be measured against a standard curve.

In analytical chemistry the technique is used for determining the

concentration of a particular element (the analyte) in a sample to be

analyzed. AAS can be used to determine over 70 different elements in

solution or directly in solid samples used in pharmacology, biophysics

and toxicology research.

Atomic absorption spectroscopy was first used as an analytical

technique, and the underlying principles were established in the

second half of the 19th century by Robert Wilhelm Bunsen and

Gustav Robert Kirchhoff, both professors at the University of

Heidelberg, Germany.

The modern form of AAS was largely developed during the 1950s by

a team of Australian chemists. They were led by Sir Alan Walsh at

the Commonwealth Scientific and Industrial Research Organisation

(CSIRO), Division of Chemical Physics, in Melbourne, Australia.

Atomic absorption spectrometry has many uses in different areas of

chemistry such as:

• Clinical analysis: Analyzing metals in biological fluids and

tissues such as whole blood, plasma, urine, saliva, brain tissue, liver,

muscle tissue, semen

• Pharmaceuticals: In some pharmaceutical manufacturing

processes, minute quantities of a catalyst that remain in the final drug

product

• Water analysis: Analyzing water for its metal content.

Basic Principle

The technique of atomic absorption spectroscopy (AAS) requires a

liquid sample to be aspirated, aerosolized, and mixed with

combustible gases, such as acetylene and air or acetylene and nitrous

oxide. The mixture is ignited in a flame whose temperature ranges

from 2100 to 2800 oC.

During combustion, atoms of the element of interest in the sample are

reduced to free, unexcited ground state atoms, which absorb light at

characteristic wavelengths, as shown in figure 3.

Figure 3. Operation principle of an atomic absorption spectrometer.

The characteristic wavelengths are element specific and accurate to

0.01-0.1nm. To provide element specific wavelengths, a light beam

from a lamp whose cathode is made of the element being determined

is passed through the flame. A device such as photonmultiplier can

detect the amount of reduction of the light intensity due to absorption

by the analyte, and this can be directly related to the amount of the

element in the sample.

The technique makes use of absorption spectrometry to assess the

concentration of an analyte in a sample. It requires standards with

known analyte content to establish the relation between the measured

absorbance and the analyte concentration and relies therefore on the

Beer-Lambert Law.

Instrumentation Hardware

Figure; Flame absorbrion spectrometer with attached graphite

furnace.

Figure shows an atomic absorption spectrometer. This instrument in

particular is designed to operate either with a flame or with a graphite.

The graphite furnace is additionally equipped with an auto sampler.

In order to analyze a sample for its atomic constituents, it has to be

atomized. The atomizers most commonly used nowadays are flames

and electrothermal (graphite tube) atomizers. The atoms should then

be irradiated by optical radiation, and the radiation source could be an

element-specific line radiation source or a continuum radiation

source. The radiation then passes through a monochromator in order

to separate the element-specific radiation from any other radiation

emitted by the radiation source, which is finally measured by a

detector.

Flame atomic absorption hardware is divided into six fundamental

groups that have two major functions: generating atomic signals and

signal processing. Signal processing is a growing additional feature to

be integrated or externally fitted to the instrument. The instrument

parts are shown in figure

Figure . schematic of basic instrumental parts of atomic absorption

spectrometer

.

A cathode lamp (1), is a stable light source, which is necessary to emit

the sharp characteristic spectrum of the element to be determined. A

different cathode lamp is needed for each element, although there are

some lamps that can be used to determine three or four different

elements if the cathode contains all of them. Each time a lamp is

changed, proper alignment is needed in order to get as much light as

possible through the flame, where the analyte is being atomized, and

into the monochromator.

The atom cell (2), shown in figure , is the part with two major

functions: nebulization of sample solution into a fine aerosol solution,

and dissociation of the analyte elements into free gaseous ground state

form. Not all the analyte goes through the flame, part of it is disposed

as shown in the figure.

Figure . Atom cell.

As the sample passes through the flame, the beam of light passes

through it into the monochromator (3). The monochromator isolates

the specific spectrum line emitted by the light source through spectral

dispersion, and focuses it upon a photomultiplier detector (4), whose

function is to convert the light signal into an electrical signal.

The processing of electrical signal is fulfilled by a signal amplifier

(5). The signal could be displayed for readout (6), or further fed into a

data station (7) for printout by the requested format.

TABLE-I

Metal concentration in mg/L studied in Tea samples during

this project

Samples

Elements

Broke

bond

Taza

Dhadkan Patakha Razana Red

lebel

Tata

tea

UL

Copper 0.923 0.481 0.8083 0.7429 0.2392 0.735 < 1

Nickel 1.012 1.125 0.893 0.792 0.962 0.786 0.5- 1

Lead 1.151 0.755 0.958 0.835 0.899 0.650 < 2

Cadmium 0.080 0.029 0.122 0.046 0.051 0.084 0.1

Chromium 4.683 6.914 3.717 4.741 3.708 2.961 3

Calcium 70 70 68 66 60 66 100

Result and discussion

Table 1 presents the concentrations of metals found in the teas

considered. These contents agree with literature data reported by other

researchers. The maximum copper concentration was found in the

broke bond taza sample and the lowest copper concentration was in

red lebel. However, these values were found to be in accordance with

UL approved by WHO.

There was not much variation in the concentration of nickel in all

samples. The concentration was safe according to WHO.

Although, the highest lead concentration was found in Broke Bond

Taza but it was not too high to consider.

But ofcourse, chromium level was found to be extremely high in

Dhadkan sample.

The calcium level was low as recommended by WHO.

The DDI of the studied metals are tabulated here.

TABLE-I

Nutrient Life Stage Group

RDA/AI (μg/d)

UL (μg/d)

Copper

Males 14-18 y 19-50 y Females 14-18 y 19-50 y Pregnancy 19-30 y 31-50 y Lactation 19-30 y 31-50 y

890 900 890 900 1000 1000 1300 1300

8,000 10,000 8,000 10,000 10,000 10,000 10,000 10,000

TABLE-II

Nutrient Life Stage Group

RDA/AI (μg/d)

UL (μg/d)

Chromium

Males 14-18 y 19-50 y Females 14-18 y 19-50 y Pregnancy 19-30 y 31-50 y Lactation 19-30 y 31-50 y

35 35 24 25 30 30 45 45

ND ND ND ND ND ND ND ND

TABLE-III

Nutrient Life Stage Group

RDA/AI (mg/d)

UL (mg/d)

Calcium

Males 14-18 y 19-50 y Females 14-18 y 19-50 y Pregnancy 19-30 y 31-50 y Lactation 19-30 y 31-50 y

1,300 1,000 1,300 1,000 1,000 1,000 1,000 1,000

2,500 2,500 2,500 2,500 2,500 2,500 2,500 2,500

TABLE-IV

Nutrient Life Stage Group

RDA/AI (mg/d)

UL (mg/d)

Nickel

Males 14-18 y 19-50 y Females 14-18 y 19-50 y Pregnancy 19-30 y 31-50 y Lactation 19-30 y 31-50 y

ND ND ND ND ND ND ND ND

1.0 1.0 1.0 1.0 1.0 1.0 1.0 1.0

TABLE-IV

LEAD

For Whom Amount Known To Cause Health Problems (μg/d)

FDA’s Recommended Safe Daily Diet Lead Intakes (μg/d)

For children under age 6 60 6

For children 7 and up 150 15

For Adults 750 75

Conclusions

Tea is the most common beverage used in everyday life by everyone.

It must follow the UL recommended by WHO for heavy metals. In

present study six tea samples (Broke Bond Taza, Dhadkan, Patakha,

Razana, Red lebel and Tata tea) were analysed for Cu, Ni, Pb, Cd, Cr

and Ca. on the basis of tea analysis report for the elements studied, we

have concluded that the most of the tea samples were under DL and

PL. therefore the samples were found to be fit to consume. However

some samples were found to be polluted and are therefore completely

unfit to consume.

Tea should not consume in high quantity because chromium was

found to be crossing the UL proposed by WHO.

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