like pHotoFlex® STD, additionally: Integrated pH measurement Automatic temperature compensation NH3 and CO2 The portable photometer pHotoFlex® pH demonstrates its capability with complex tasks in environmental and process monitoring at a variety of sites. The integrated pH function allows measurements of pH 0 ... 16 with automatic buffer recognition (TEC/NIST). Temperature compensation is automatic within the permitted range of – 5 ... 100 °C (23 … 212 °F). WTW‘s MultiCal®-routine allows the automatic calibration with up to 3 calibration points. WTW offers a large selection of pH sensors as optional accessories: For field use, the maintenance-free SenTix® 41 is recommended, whereas for precision measurements in the laboratory, the SenTix® 81 glass electrode could be used. The electrodes are described in detail in the pH measuring chapter.