Materials and Methods
Samples of commonly used personal care products were
purchased from some local stores in western part of
Nigeria. The samples include medicated soaps and cream,
non-medicated soaps and cream and hair cream. The items
were transferred to the laboratory for analysis.
All reagents used were of analytical grade of BDH
chemicals. 1,000 ppm of each of the metals analysed were
prepared by dissolving their salt in appropriate volume of
water and made up to 1 dm3 in a volumetric flasks, using
dilution factor. The appropriate volume of the stock solution
was diluted with distilled water to give concentration
of the working ranges (Bruce and Whiteshide 1984).
Solid samples were dried in an oven at 105C to constant
weight and then stored in a desiccator. Creamy
samples liable to charring were dried at 70–80C. About
0.2 g of each of the dried samples was weighed into a
porcelain crucible and dry-ashed in a muffle furnace by
stepwise increase of the temperature up to 550C over a
few hours (Crosby 1977). A few drops of concentrated
nitric acid were added to the solid as an ashing aid before
ashing was commenced. The ash was dissolved with IM
HNO3. Sample such as cream and lotions, which could not
be conveniently processed by dry-ashing, were wet digested
with a 4:1 mixture of nitric acid and perchloric acid.
The digest was evaporated to almost dryness and then
made up with distilled water to 100 mL. The sample
solutions were subsequently analysed for Cd, Cr, Cu and
Zn, using a flame atomic absorption spectrophotometer
available at the Centre for Energy Research and Development,
Obafemi Awolowo University, Ile-Ife, Nigeria. The
instrument working condition and parameters for the
determinations are shown in Table 1. Each sample was
analysed in triplicate, and reagent blank determination was
performed to ascertain that no impurity was introduced
during the extraction procedure.