It depends on the powder that you are looking for. Some things show up better using different lights.
But you can easily check using UV, which are readily available.
Remember that if you use different light sources you might have to blacken out the room.
Also, the visual detection limit might be evaluated on “coupons” and in a laboratory setting. Oce those are determined, then you can easily inspect in the field.
A google search came up with the following inexpensive UV lights. But there are many others on the market. Wavelenght and brightness might be two things to consider.