Distribution of trace elements in the lipid and nonlipid matter of hair

Abstract

We studied the effect of lipid removal on the concentrations of 13 trace elements measured in human hair. We used a pooled specimen of hair from a barber shop, initially washed with de-ionized water, with ultrasonic cleaning, then analyzed for Ca, Cr, Cu, Fe, K, Mg, Mn, Na, Ni, P, Si, Sr, and Zn with use of an inductively coupled plasma emission spectrometer. The lipid was removed by Soxhlet extraction with ethanol, and the hair was re-analyzed. We found several elements present in a relatively large proportion (>20%) in the lipid fraction, mainly Na, K, Ca, Mg, Ni, and Sr. We suggest that removal of part or all of the lipids from hair by using detergents or other lipid-removing solvents for washing may account for the variability in data on elements in hair reported by different laboratories, and that those elements largely present in the lipid fraction are the result of environmental exposure, whereas those retained in the hair fiber after lipid removal can be attributed to nutritional and clinical aspects. We believe that such determination of the distribution of elements may help validate the use of hair in assessing trace elements in the body.