1-(4-Methoxyphenyl) piperazine (4-MeOPP)
5% Aqueous HAuCl4
Like the other piperazines included in this study, all tests for 4-MeOPP are very sensitive requiring less than 1 μg of the substance for a positive test. With aqueous gold chloride reagent, two forms of crystals are observed and the formation of these forms is concentration dependent. Clusters of thick irregular tablets are formed at the edge of the drop. These are colorless in bright field and bright yellow under crossed polars. The other form of crystals observed are long red rods that are arranged either individually or in loose clusters. A composite of these forms may also be observed.
Orange crosses similar to the ones observed with the acidic gold chloride reagent may also be observed at high concentrations when the reaction occurs very quickly.
5% HAuCl4 in 1:2 concentrated H2SO4: H2O
The first formation observed with the acidic gold chloride reagent are light, feathery orange crosses. The crosses form so quickly that the drop becomes orange as soon as the reagent is mixed in. The drop slowly clears up as colorless thick irregular plates form at the expense of a few orange crosses. The orange crosses appear blue to yellow under crossed polars while the stacks of plates are faint white.
Gold Bromide (HAuBr4)
Gold bromide with 4-MeOPP gives three forms of concentration dependent crystals. The immediate formation is of light orange crosses that form abundantly. As with all gold based reagents, the drop immediately becomes orange with the formation of the crosses when the substance is mixed in. The flat, distinct, orange rectangular plates are formed next alongside the crosses. Large irregular red, tablets grow fewer in number and grow slower. All three forms are bright under crossed polars.
Platinic Chloride (H2PtCl6)
4-MeOPP dissolved in aqueous or acidic solutions forms long, colorless straw like blades. These grow abundantly in the drop. They appear white or in various colors depending on their orientation in crossed polars. At high concentrations, shell like structures are formed at the edge of the drop. These are very unique to this drug-reagent combination. The shell like crystal has an outer dark edge with colorless layer that follows. At the core of the crystal are short dark needles arranged in loose clusters. Embedded in the needle clusters are small purple prisms that can be observed in high magnifications. The entire crystal form appear faint white under crossed polars with contrast between different features.
Platinic Bromide (H2PtBr6)
Large yellow, square to rectangular tablets that either grow individually or in composites are characteristic of 4-MeOPP with platinic bromide. The crystals grow very big and are bright under crossed polars.