CO2 is beginning to see use as a refrigerant (R744) and Inficon has designed a leak detector that is specifically designed to pick up this specific gas.
Similar to the D-TEK Select, the Inficon D-TEK CO2 Refrigerant Leak Detector 716-202-G1 uses an Infrared Sensing Cell to detect the presence of the CO2. This process is very precise (6g/yr or 0.2 oz/yr) and has a long life expectancy of 800hrs. There is also a sensitivity level that is selectable between high and low.