48 JOURNAL OF THE SOCIETY OF COSMETIC CHEMISTS Table II Sample for Mutagenicity Test System Sample Conventional dye Conventional dye q- Hamamelis extract Ag-zeolite dye q- Hamamelis extract PPDA q- H202 PPDA + H202 q- HE PPDA + Ag-zeo + HE Ag-zeo: Ag-zeolite containing 2.5 wt% silver. HE: Hamamelis extract. SHAMPOO STABILITY The colored tresses were stirred in a bath containing 5% of a commercial shampoo for 5 min, rinsed, and towel dried. This cycle was repeated seven times. Color measurements were taken before and after each cycle. The same area of the tress before and after treatment was measured using the special hair tress holder. The changes of color values were evaluated by the differences before and after measurement. OXIDATION REACTION OF PPDA BY SILVER IONS IN SOLUTION Carmody buffer was employed to control pH of the solvents. The preparation of the original solution containing silver ions was carried out by filtration of buffer-sus- pended Ag-zeolite after shaking. The concentration of silver ions in the buffer was determined with an Inductively Coupled Plasma Atomic Emission Spectrometer (Se- quentialplasma Spectrometer ICPS 100 II, Shimazu). The various silver concentration solutions were prepared by dilution of the original solution with buffer. The absorption spectra were measured at 25øC after mixing of the PPDA solution and silver ion solution in the spectrophotometer cell. The rate of the reaction at which PPDA was oxidized was defined as the slope that was obtained by the plot of the absorption of the solution at 450 nm vs time (min). ELUTION OF SILVER IONS FROM ZEOLITE Ag-zeolite containing 2.5 wt% silver was used. Ag-zeolite was suspended in 4 ml Carmody buffer and incubated at 25øC. The concentration of silver ions eluting into the solvent was determined with ICPS after removing the zeolite by filtration. MUTAGENICITY TEST This test was carried out using the Ames method with pre-incubation (6). We collected samples at three stages in the oxidation reaction, 0, 5, and 10 min after the start of Table III Oxidation Ability of Metal-Zeolite and Oxidation-Reduction Potential Oxidation-reduction Oxidation Metal ion potential (E ø/V) ability Ag (I) 0.799 O Fe (III) 0.771 X Cu (II) 0.153 X Zn (II) - 0.763 X

HAIR COLORING 49 Table IV Oxidation Ability of Ag-Zeolite (n = 3) Pore size Ag Content Abs. (450 nm) No. (nm) (wt%) Mean + S.D. 1 1.3 2.5 0.067 + 0.008 2 0.7 2.5 0.217 + 0.010 3 0.4 2.5 0.194 + 0.025 4 0.4 5.0 0.285 -+ 0.027 5 0.4 10.0 0.447 -+ 0.009 6 0.4 15.0 0.591 + 0.037 7 0.4 20.0 0.614 + 0.040 reaction, and tested each sample. Three systems for hair coloring shown in Table II were tested with 2-amino-anthracene (2-AA) as a positive control. RESULTS CONFIRMATION OF OXIDATIVE ABILITY OF METAL ZEOLITES Only the zeolite containing Ag(I) has been found effective in promoting fast coloring of the PPDA solution (Table III), whereas the oxidative effect was not recognized in Fe(III)-, Cu(II)-, or Zn(II)-zeolite. We investigated more closely in the case of Ag-zeolite. The progress of the oxidative reaction with Ag-zeolite was confirmed by the absorption at 450 nm after removing the zeolite (Table IV). The zeolites that have smaller pores tend to have a greater ability to oxidize PPDA. The rate of oxidation reaction is directly proportional to silver content in zeolite. HAIR COLORING USING SILVER ZEOLITE Hair tresses were colored using five kinds of Ag-zeolite that contained various amounts of silver (2.5--20 wt%). 10% Hamamelis extract solution and 0.1% PPDA solution were used for dyeing. Color values produced are shown in Table V. The hair color became reddish and dark with increasing Ag contents. The coloring effect became con- stant above 10 wt% of silver content in zeolite (Figure 2). Table V Hair Color Produced by Ag-Zeolite Ag content in zeolite (wt%) L a b 2.5 31.66 1.91 4.51 5.0 29.09 2.30 5.14 10.0 23.43 2.25 3.82 15.0 23.02 2.51 2.80 20.0 22.90 2.13 4.78