The analytical results obtained by the batch wise separating funnel method was relatively high compared with that of the microchip method. This may be caused from the isobars of Al, because 8-HQ also extracts Al at pH 5.5. In the Al alloy, Si, Mg and Ti are included which seem to interfere with the determination of Cu. The interference from Si and Mg, however, could be neglected because these elements were hardly extracted with 8-HQ in o-xylene. On the other hand, the content of Ti in JSAC 0121-C is half that of Cu, whereas the certified value of Ti in the 7074 Al alloy is not shown. The concentration of Ti was determined by ICP-OES: it was a quarter of that of Cu. The extraction efficiency of Ti was about 40% at pH 5.5 by the microchip method, and the back-extraction efficiency of Ti was about 10%. The interference isobars which affect the determination of Cu are 47Ti and 49Ti and these contents were calculated to be 7.3% and 5.5% of the initial Ti concentration, respectively. As a result, the effect of Ti could also be neglected. The blank value of this microchip method was 0.1 ng g−1 which did not affect the measurement of the JSAC 0121-C and the 7074 Al alloy.