In Search of an Accurate, Easy to Use, Handheld Ozone PPM Sensor

Roving Blue is an early commercial stage company in the business of manufacturing electrolytic ozone generators to dissolve 03 into water.  In the past we have used colormetric kits to determine ozone levels.

While these have served us well for general purposes, we have had complaints from OEM companies testing our components about false positive results, etc. 

Does anyone here have a suggestion about any devices (ideally, handheld), which would give accurate ozone ppm levels? ).

We would certainly welcome your suggestions.  Thank you!