Youtube Channle: DFRobot
DFRobot Analog pH Sensor is compatible with both Arduino and Raspberry Pi. Our friend DavyBot gives you a general overview of linear functions and interpolation in this video. Plus he will show you how to write custom code to use this sensor on an unsupported platform (Espruino).
DFRobot Analog pH Sensor: https://www.dfrobot.com/product-1782.html?tracking=5b603d54411d5
Arduino Library: https://github.com/DFRobot/DFRobot_PH
DFRobot ADC Converter: https://www.dfrobot.com/product-1730.html?tracking=5b603d54411d5