Review on 🧪 Macherey Nagel 90736 Analytical Strips for Efficient Determination by Reginald Ward

A much cheaper alternative to very complex electronic gauges that require regular recalibration. Seems to work well: I inserted a wand into the SoClean machine that generates ozone to sanitize CPAP machines and got a deep staining very quickly. However, the lowest measured value is 90 µg/m3 (about 45 ppb). Our sticks don't hit that low in our bedroom, although we can smell the ozone from the air purifier. We understand that ozone can be detected through the nose at about 5 parts per billion, so we know we have at least that amount. It would be great if these test sticks could be upgraded to measure levels below 45ppb.