is it a leaded brass alloy? If its just typical brass it has 0% Lead

Scarf, I have contacted my supplier and will be able to tell you more about the brass that I use.
It should be in a day or two. As for now I think it has some lead in it. The supplier will be getting me the details and I will post them here as soon as I get them.
The fishing tackle industry is getting "greener".

It is nice to be concerned about Pb poisoning in fishing lures, but surely the loons and ducks are more concerned about Pb from buckshot.

Typical brass is Cu and Zn (and as we know Zn is used to ward off colds, so it is really healthy). Pb is sometimes used (originally before Sn became available) for creating bronze alloys, but there should be very little in alloys called brass.

I believe your brass supplier should be able to provide you with a certified analysis and that should suffice; otherwise, take representative samples to an analytic lab and ask for a analysis (and expect to pay for it, as analytic chemists are a greedy lot). This is not the sort of work that an amateur should undertake, and I doubt if government agencies would accept your homegrown findings anyway.

They add lead to brasses and steels to help with machinability. Its actually quite common in brasses (0.5% to 3% weight%), because it also helps the "polish-ability" though recently there has been a shift from its use, especially in plumbing/faucet applications. The lead does not enter the alloy, rather it preciptates out as small lead inclusions which is why its easier to machine/polish, but also tends to leach out of the material.

I'm sure your manufacturer does quality control stuff, and knows the composition on any given batch. This paper work should be available to you. Especially since it may contain a substance such as Pb (lots of regulations on the manufacture of leaded alloys/compounds). Even the machine chips of leaded alloys are considered hazardous materials and need to be properly disposed of.

And to answer your original question, they typically use energy dispersive spectroscopy to determine composition. This is the most rapid way to determine composition of metals though it is not totally accurate unless a standard of known similar composition is analyzed along with your samples. Obviously, this is something you probably do not possess on hand and would require $$$$ to have the work done for you. However, most manufactures have one handy on site to analyze a wealth of different aspects of quality control. This is why I say they should have the information you need. EDS generates valus/percentages in atomic%. It can be converted to weight% fairly easily, which is one of the most common ways to quote a composition.

I was actually looking at brass sinkers the other day. I need some larger ones (1-3 Oz egg type) for bottom/surf fishing for my fishing trip this summer, I mean my honeymoon. Walmart only carried them up to 3/4 Oz. doh!

scarf,
thanks for the input. I will have my supplier contact the mfg. and get the proper details. I must be ready before the new laws are in place.
As for your fishing trip/honeymoon. I had the same kind of honeymoon a few years ago in Mexico. My wife could not believe that I brought tackle with me. Lots of Bonefish...as it were.
If you tell me just what it is you need I can (pardon the pun) hook you up with the right guys. There are re sellers of components and mfgs that specialize in lead sinkers et al. Let me know.
e me @ eric@doubleloon.com
And by the way...my stuff works well in the surf.