It may be possible using Atomic Absorption Spectrometer as the amount is in trace.

Is the alkaline solution KCN? You can dissolve gold in aqua regia, filter any residue and analyse the solution using ICP-OES or MS if the concentration was at ppb level. 

You can refer to this link 

However qualitative test for gold in trace level I havn't come by any method regarding it ... you can use sodium metabisulfite try to precipitate it out of aqua regia but I not sure what is the detection limit and quantification limit for the method. 

https://saif.iitm.ac.in/pdf1/icpinstr.pdf

If solution is alkaline by KCN please pay attention on acidification.

In my opinion the following is a good and quick qualitative test

You can do both with Na2S or H2S under the reaction

S-- + 2 KAu(CN)2 → Au2S + 2 KCN + 2 CN-

H2S is more Dangerous (as make dangerously acid the solution) Na2S is safe and the final product range in colour  from dark reddish-brown" that turns  to "steel-gray"

Best

.