zinc in hair

7/28/2019 ZInc in Hair

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Abstract

Following mini project is based on determination of zinc level in human hair. Total number of 10

samples collected and their zinc level analyzed and compared with respect to two parameters:

1. Gender2. Dyed and non-Dyed hairs

Each sample was analyzed using Flame Atomic Absorption Spectrometry to determine its zinc

concentration.

Calculation of zinc level for each sample was carried out based on the calibration line corresponding to

the standard zinc solutions, which were prepared according to the procedure.


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Introduction

Zinc is an essential trace mineral required by living organisms as wide ranging as microorganisms,

plants and animals. It is a component in many enzymes, numbering from 100 to 300 specific enzymes

and is the only metal, which appears in all enzyme classes. Furthermore it is the second most abundant

transition metal in organisms after iron.

Among some notable functions of zinc are RNA and DNA metabolism, signal transduction and gene

expression; affects synaptic plasticity in brains; regulates apoptosis; and the functioning of the male

prostate gland. The interconversion of blood carbon dioxide and bicarbonate in respiration is carried

out by the zinc-containing enzymes carbonic anhydrase and carboxypeptidase.

Salivary glands, the prostate, the immune system and intestine cells use zinc signaling as cellular

communication. The distribution of zinc is found to be highest in the choroid of the eye and optic

nerve, followed by the prostate, bone, liver and kidneys, muscles, heart, spleen, testes, brain, and

adrenal glands. The skin also has a high concentration of zinc and can often be a sensitive indicator of

zinc levels.

The role of zinc in physiology are numerous, hence biomedical studies attempt to establish a link

between zinc levels and health, or major disorders such as depression, immune deficiency or genetic

diseases. A relation between low concentrations of zinc and mental health problems, especially in at

risk populations has been demonstrated in a study by Whittle, N. (2009). Another study by Pfeiffer

(1975) showed how severe zinc deficiency is seen in acrodermatitis enteropathica, a genetic disorder

occuring in children and how zinc supplements improved their conditions. Hence, there is a wide range

of research in zinc levels that could potentially give important insights in human physiology and

disease treatment.


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A survey of studies conducted on zinc levels will indicate that the samples in studies used are typically

plasma, serum, blood, and hair, nails and saliva. Hair is the most non-invasive biological marker and

carries the least risk of contamination. According to Hashem and Abed (2007), hair is a complex matrix

of inorganic and organic materials formed over a period of time. It can provide a more permanent

record of trace element associated with normal and abnormal metabolism as well as those assimilated

from the environment. Plasma and serum zinc levels regarded as being less reliable information since

they are regulated by the bodies homeostasis system and will be reduced during acute illnesses.

Hair zinc levels poses some difficulty in interpretations since the underlying mechanisms of zinc

transfer and deposition to and from hair is not clearly known. For example, high hair zinc can indicate

low body levels, but low hair zinc also correlates well with low red blood cell and total body zinc.

Significantly higher hair zinc is usually interpreted as a sign of zinc wasting and low body zinc levels.

In this study, the hair zinc levels in males and females in the age group 20-30 as well as in females in

the same age group with dyed or non-dyed hair were determined by atomic absorption spectrometry

(AAS)


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Procedure

Apparatus Chemicals

Beaker Detergent

Pipettes Water

Volumetric Flask Methanol

Spatula Concentrated Nitric Acid

Oven Perchloric Acid

Flame AAS Standard Zinc Solutions

Hair samples were collected from male and female volunteers in the age range of 20-30 years old and

sorted into dyed and undyed categories.

Each hair sample was rinsed a few times with distilled water, followed by three rinses of methanol.

Fig 1. Washing and soaking the hair samples in methanol.


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The hair samples were oven dried at 100 C for 45 minutes to remove solvent traces. After cooling, 0.3

g of each sample was weighed into a conical flask. 10 ml of concentrated nitric acid was added to each

sample and the mixture was boiled gently in the fumehood until its volume halves. The samples were

cooled to room temperature before 2 ml of perchloric acid was added to each. The samples were boiled

further until around 1-2 ml remained. (Fig.2).

Fig. 2. Boiling samples to 1-2 ml.

The samples were cooled and made up to 100 ml in volumetric flasks. (Fig.3). A calibration curve was

constructed through measuring the absorption of zinc standards of concentrations 0.25, 0.5, 0.75, 1.00,

1.50 and 2.00 ppm by AAS. The measurement from each sample was plotted on the curve and the

concentration of zinc in each was determined, (Fig.4).


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Fig 3. Hair Samples.

Fig 4. FAAS machine.


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Results and Discussion:

Table 1: Males hair samples:

No Age Dyed Mass of

sample (g)

1 24 no 0.3608

2 26 no 0.3463

3 25 no 0.3433

4 24 no 0.3514

5 25 no 0.3526

Table 2: Females hair samples:

No Age Dyed Mass of

sample (g)

6 23 yes 0.3617

7 22 no 0.3584

8 22 no 0.33639 22 yes 0.3588

10 23 yes 0.3552

Table 3: Atomic absorbances of standard solutions

No Standard

solutions

Entered

concentrati

on (m g/L)

Calculated

concentration

(m g/L)

Mean of

absorbance

Standard

deviation

Relative

standard

deviation

1 Blank 0.00 0.000 0.000 0.0000 0.00

2 Standard 1 0.25 0.323 0.162 0.0009 0.54

3 Standard 2 0.50 0.646 0.324 0.0007 0.21

4 Standard 3 0.75 0.904 0.454 0.0013 0.295 Standard 4 1.00 1.126 0.566 0.0021 0.37

6 Standard 5 1.50 1.495 0.751 0.0023 0.31

7 Standard 6 2.00 1.780 0.895 0.0025 0.28


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Fig 5: Calibration curve with absorbance versus concentration of standard solutions

Table 4: Atomic absorbances of male sample solutions

No Mean of

concentration

(m g/L)

Standard

deviation

(m g/L)

Relative

standard

deviation

(m g/L)

Mean of

absorbance

Standard

deviation

Relative

standard

deviation

1 1.257 0.004 0.284 0.782 0.0022 0.28

2 0.772 0.002 0.208 0.480 0.0010 0.21

3 1.088 0.004 0.339 0.676 0.0023 0.34

4 1.054 0.008 0.794 0.655 0.0052 0.79

5 1.174 0.004 0.366 0.730 0.0027 0.37

Table 5: Atomic absorbances of female sample solutions

No Mean of

concentration

(m g/L)

Standard

deviation

(m g/L)

Relative

standard

deviation

(m g/L)

Mean of

absorbance

Standard

deviation

Relative

standard

deviation

6 1.280 0.006 0.488 0.796 0.0039 0.49

7 0.998 0.004 0.419 0.621 0.0026 0.42

8 1.347 0.005 0.400 0.837 0.0033 0.40

9 1.552 0.008 0.506 0.965 0.0049 0.51

10 1.054 0.007 0.632 0.655 0.0041 0.63


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Calculation of actual hair samples zinc concentration:Since 100 ml of sample solution was prepared, therefore the mass of zinc in hair:

Sample 1:

Mass of zinc in hair = 1.257 mg/L x 100/1000 L= 0.1257 mg

Zinc concentration in hair = 0.1257 mg/0.3608 g

= 0.3484 g/g

Sample2:



= 0.2229 g/g

Sample 3:Mass of zinc in hair = 1.088 mg/L x 100/1000 L

= 0.1088 mg

Zinc concentration in hair = 0.1088 mg/0.3433 g= 0.3169 g/g

Sample 4:Mass of zinc in hair = 1.054mg/L x 100/1000 L

= 0.1054mg


= 0.2999 g/g


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Sample 5:



= 0.3330 g/g

Table 6: Male

Age Absorbance conc/ppm con/ g/g

24 0.782 1.257 0.3484

26 0.480 0.772 0.2229

25 0.676 1.088 0.3169

24 0.655 1.054 0.2999

25 0.730 1.174 0.3330


= 0.1280 mg


= 0.3539 g/g

Sample 7:

Mass of zinc in hair = 0.998mg/L x 100/1000 L

= 0.0998 mgZinc concentration in hair = 0.0998 mg/0.3584 g

= 0.2785 g/g


= 0.1347 mgZinc concentration in hair = 0.1347 mg/0.3363 g

= 0.4005 g/g


= 0.1552 mg


= 0.4326 g/g

Sample 10:



= 0.2967 g/g


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Table 7: Female

Age Absorbance conc/ppm con/ g/g

23 0.796 1.280 0.3539

22 0.621 0.998 0.2785

22 0.837 1.347 0.4005

22 0.965 1.552 0.432623 0.655 1.054 0.2967


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Discussion

In this experiment, concentration of zinc in 10 hair samples comprising of male and female of age

group 20-30 was analyzed, the results of which are given in Table 6 and Table 7. Two parameters were

chosen for comparison; sex (Male vs Female) and dyed versus non-dyed females. Absorbance for these

samples were measured using an AAS machine and the concentration was found using the absorbance

graph for a series of standard solutions of zinc (Fig.5). Six standard solutions, excluding the blank were

used to plot this graph, to give a standard deviation of 1.0, which shows the accuracy of calibration

curve.

The First comparison was done to find the difference (if any) in the zinc content between male and

female of same age group. As shown in Fig. 6, and Tables-6 and 7, the concentration of zinc present in

the female samples was found to be 7.7% greater than that in the male samples. These results could be

explained by several reasons. This maybe caused due to variation in food habits due to diets that

includes zinc. The major sources of zinc are red meat, poultry, fish and seafood, whole cereals and

dairy products. Thus taking food rich in zinc would ensure higher concentration of zinc in the body.

According to Reinhold, Kfoury, Ghalambor and Jean (1966) the dietary levels of some essential

microelements have been reported to correspond to hair concentration of the elements. Moreover,

Contiero and Folin (1994) have said the analysis of Zn in hair represents an addition to conventional

materials in the assessment of the nutritional status of groups of individuals.

Another reason for higher zinc concentration in female than in male is the possibility of exposure to

various chemical substances causing variation in zinc concentration level. This is in reference to care

and maintenance of hair; the type of shampoo used, cosmetic treatments and how often hair is washed,

all these factors will contribute in to this. For an example, it is proven that using anti-dandruff shampoo

can increase the concentration of zinc in hair while chelating agent present in permanent waving lotion


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can decrease the zinc level in hair as they easily remove the zinc during treatment process. There are

also other hair treatments, which reduce the zinc concentration in hair.

In reviews of environmental contamination and toxicity (175) there are several factors influencing the

levels of elements in body, which is hair in this case. These factors can be categorized in to four groups:

biological, personal, environmental and analytical/methodological factors. Dying the hair can be

considered as an environmental factor. In this experiment, dyed and non-dyed female hair was also

compared to see the zinc content. It was found out that the dyed hair has 4% more zinc concentration

than non-dyed. (Fig.7). This is because of the presence of high levels of zinc (together with other

elements) in the dye products. For an example, the brand Garnier has zinc added in to its products.

Last, but not the least factor to be considered is the method by which the zinc concentration was

analyzed. In this project Flame Atomic Absorption Spectroscopy was used to determine the zinc level

in each sample solution. The technique of flame atomic absorption spectroscopy (FAAS) 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 2800oC.

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. One of the disadvantages of this

method is that the flame should be set manually and may be altered during the experiment, which may

cause error in results. Also the flame may blow away some of the atoms before they could be analyzed

by the beam, therefore affecting the absorbance value given. This problem could be overcome by using

a Graphite Furnace instead of the flame, which uses graphite-coated furnace to vaporize the sample.

Thus minimizing the above-mentioned problems associated with FAAS.


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Conclusion

A total 10 hair samples of male and females were analyzed to find out concentration of zinc. It was

found out that the concentration of zinc present in the female samples were 7.7% greater than that in

the male samples while the comparison between dyed and non-dyed female hair samples showed that

the dyed hair has 4% more zinc concentration than non-dyed.

To conclude, concentration of zinc in human hair sample is not a good method of measuring zinc in

body as the zinc level in hair can be altered by several factors. The alternative, more accurate way of

measuring zinc level in body could be achieved by using nail samples.


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References:

1. http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional/2. http://medfac.mans.edu.eg/english/forensic/january2009/S. %206_. pdf3. Cutler, A.H Hair Test Interpretation: Finding Hidden Toxicities4. http://www.traceelements.com/Docs/The%20Nutritional%20Relationships%20of%20Zinc.pdf5. http://calosol.com/zinc.php6. AR Hashem and KF Abed, Aluminum, Cadmium and Microorganisms in Female Hair and Nails

from Riyadh, Saudi Arabia Journal of Medical Sciences Volume 7, Number 2, 263-266, 2007

7. Pfeiffer CC: Mental and Elemental Nutrients. Keats Pub. New Canaan, Conn. 1975.8. Whittle, N.; Lubec, G. and Singewald, N. (2009) : "Zinc deficiency induces enhanced

depression-like behaviour and altered limbic activation reversed by antidepressant treatment in

mice". Amino Acids; 36 (1):147-158.

9. Reinhold, J. G.; Kfoury, G.A.; Ghlambor, M. A.; Jean, C.: Zinc and Copper concentrations inhair of Iranian Villagers. AM J Clin Nut 1966; 18.

10. Contiero E, Folin M., Trace elements nutritional status. Use of hair as a diagnostic tool,Biological Trace Element Res. 1994 Feb; 40(2): 151-60.

11.Sukumar A. Factors influencing levels of trace elements in human hair ReviewsEnvironmentContamination Toxicology, 175(2002): 47-78.

zinc in hair

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