You can make your own
I include this video for educational purposes only. There are PPM (particle detectors) for sale which will ensure your solution does not exceed safety requirements. Check out the next video for a smurfy example that you will remember (NOTE: I do not necessarily believe in the legitimacy of the Smurf Man's actual affliction but it's note worthy and used by critics of Colloidal Silver use to dismiss it's beneficial usage in health treatment)
The Dangers of Colloidal Silver
Okay, this is serious.