ZInc in Hair
Transcript of 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:
Mass of zinc in hair = 0.772 mg/L x 100/1000 L= 0.0772 mg
Zinc concentration in hair = 0.0772 mg/0.3463 g
= 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
Zinc concentration in hair = 0.1054 mg/0.3514 g
= 0.2999 g/g
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Sample 5:
Mass of zinc in hair = 1.174 mg/L x 100/1000 L= 0.1174 mg
Zinc concentration in hair = 0.1174 mg/0.3526 g
= 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
Sample 6:Mass of zinc in hair = 1.280 mg/L x 100/1000 L
= 0.1280 mg
Zinc concentration in hair = 0.1280 mg/0.3617 g
= 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
Sample 8:Mass of zinc in hair = 1.347 mg/L x 100/1000 L
= 0.1347 mgZinc concentration in hair = 0.1347 mg/0.3363 g
= 0.4005 g/g
Sample 9:Mass of zinc in hair = 1.552 mg/L x 100/1000 L
= 0.1552 mg
Zinc concentration in hair = 0.1552 mg/0.3588 g
= 0.4326 g/g
Sample 10:
Mass of zinc in hair = 1.054 mg/L x 100/1000 L= 0.1054 mg
Zinc concentration in hair = 0.1054 mg/0.3552 g
= 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.