Table 1.
Sample preparation by demineralization agents: EDTA (ethylene-diamine tetraacetic acid), formic acid (CH2O2), hydrogen chloride (HCl), and HCl/EDTA mixture.
| Agents | Concentration | Treatment time | Procedures |
|---|---|---|---|
| Untreated | N/A | N/A | Cut samples to 2 mm × 2 mm × 4 mm; polish; demineralization treatments on an agitation rocker until the samples were translucent (except for EDTA mixture—endpoint was based on the weighing method; remove chemicals by a sonicator; rinse samples by deionized water; dehydration by ethanol; critical point drying |
| EDTA | 1 M | 7 days | |
| CH2O2 | 0.5 M | 2 days | |
| HCl | 0.5 M | 7 h | |
| HCl/EDTA mixture | 3.3 M HCl, 2.4 mM EDTA, 0.72 mM C4H4O6Na2, 28 mM KNaC4H4O6·4H2O | 3 h |