crap I read the chart to quick and only noticed the left side went to 13 ok I think I will call api to see what the 1109 means expiration or if it is manufacture date? the top of the bottle has a stamp that says: LOT 17A1109 Sosince I didn't read the chart that well maybe it is good after all I am not used to the multipe test solution testing yet.Plus 16 drops aint that much.20 drops just puts you at 400ppm.