Elemental Analysis of Hair Using Portable X-Ray Fluorescence Spectroscopy Yekini Abu; Sam Gong; Ling Huang, Ph.D. Chemistry Department, Hofstra University, Hempstead, NY 11549-0151
INTRODUCTION
RESULTS
Hair is a material that naturally catalogues the various substances that the host encounters. Metals can accumulate in hair over time. Hair elemental composition could
Possible Elemental Sources:
The following elements displayed significant results:
Zinc - hair care & diet (fish) Copper - dyes (red, blue, or green) Chromium - diet (meats) Calcium - diet (dairy) Potassium - diet Sulfur - found naturally in keratin
potentially provide information about a person’s diet, the hair treatment products they use, and possibly their geographical location. The elemental composition of hair could be used to analyze forensic evidence to help build the identity of a victim or a suspect, linking an individual to a crime scene. The elemental profiles could also be used to study health consequences of diet, pollution, and other environmental factors. Portable X-
Zinc, Copper, Chromium, Calcium, Potassium, and Sulfur
The levels of each metal in the field blank were subtracted from the reported levels in the hair samples to provide the actual amount of each element in the hair. From the elemental profiles, it is possible to determine factors of a person’s life:
Each element was first individually compared to each other between hair samples before being compiled into the below elemental profiles.
ray fluorescence, or pXRF spectroscopy was used to determine the elemental composition of hair samples. A
Tungsten X-ray beam is directed at the sample and ejects inner shell electrons. The outer shell electrons fill the voids
ANALYSIS
Diet, hair care products, and geographic location are only small pieces of information that can be obtained
a
CONCLUSIONS
created and emit fluorescence photons. Each element has a set of unique emitted photons of specific energy levels A
spectrum of these energies is plotted and their relative signal strengths can be used to determine the amount of each element present in a sample.
Figure 2. A diagram detailing the mechanism of the portable XRF instrument.
Some samples contained less metals that were otherwise expected to be present in higher concentrations.
MATERIALS & METHODS Hair Collection Process ●
Hair samples were all collected anonymously from individuals who had filled out a survey prior to sample collection ○
●
(i.e. Sample A.M has lower concentrations of Zinc than expected despite high usage of hair care products.)
b
Continued study could be done with more reliable techniques such as TXRF, SEM-EDS, etc. Future steps:
The survey contained general questions regarding their hair care, diet, living environments, etc., as well as their consent to participating in this study
● Formulation of a new initial survey that is more specific and expands upon current questions for more detailed correlations.
Samples of hair, omitting the root, were collected from the heads of the individual volunteer and labeled with the volunteer’s initials
● Preserve samples for observation using other detection methods
Sample Preparation ● ●
Samples were placed in jewelry-sized, zip-lock bags Individual hairs were packed together using tweezers
○ Cut a portion of the samples for SEM-EDS mounting ○ Digest a portion of the samples for TXRF spotting
c
REFERENCES
pXRF Analysis ● Using the soil method of the Niton XL3t GOLDD+
1. Iwegbue, C. M. A.; Emakunu, O. S.; Obi, G.; Nwajei, G. E.; Martincigh, B. S. Evaluation of
Field Portable XRF Analyzer, the following parameters were set: ○
●
Human Exposure to Metals from Some Commonly Used Hair Care Products in Nigeria. Toxicology Reports 2016, 3, 796–803. https://doi.org/10.1016/j.toxrep.2016.10.001.
300 second scans - 5 cycles ■ ■ ■
2. Liang, G.; Pan, L.; Liu, X. Assessment of Typical Heavy Metals in Human Hair of Different
30 seconds without a filter 15 seconds w a high-pass filter 15 seconds w a low-pass filter
An empty bag served as a field blank for the comparison of metals present in bag to those present in the hair samples
The observation of our data yielded promising results. Data that was collected from the pXRF had correlation with the results compiled from the survey.
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3. Schroeder, H. A.; Nason, A. P. Trace Metals in Human Hair**from the Department of
Figure 3. The elemental profiles for each individual. The error bars represent 95% confidence intervals, n=3. Panels b & c zoom in to show the lower elemental concentrations more clearly.
Figure 1. Hair sample N.K packaged closely together and marked where the sample window would observe.
Figure 4. Sample pXRF spectrum for hair sample A.M. The red and blue signals represent the high pass and low pass filters, respectively.
Physiology, Dartmouth Medical School, Hanover, New Hampshire and the Brattleboro Memorial Hospital, Brattle-Boro, Vermont. Journal of Investigative Dermatology 1969, 53 (1), 71–78. https://doi.org/10.1038/jid.1969.110.
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