Here and there I use 5ml sample for chlorine testing. It comes in handy for anticipated high level where high accuracy is not required.
Since it's less accurate than 10ml, I decided to at least get accurate amount of water to test. I figured I could use my scales for this since 5ml of pool water will be pretty close to 5g. To my surprise it wasn't so. It look like there was at least 10% disagreement.
I decided to try to 10ml which is what usually used for this kind of testing. I'm using a test tube that came with a speed stir, but standard taylor k-2006 seemed to match it.
When I pour 10ml into the tube (as accurate as I can judge, measuring at the bottom of a concave meniscus level), the weight showed 9.1g:
When I poured exactly 10g, here is what level looked like:
I'm a little surprised with discrepancy. I thought my scales might be off, but tests with a penny and a quarter were accurate to 0.05g.