Mid-infrared sensor

A sensor for monitoring a hydrate inhibitor dissolved in a liquid, the sensor comprising:

• an internal reflection window configured to contact the liquid in use;
• a mid-infrared light source configured to direct a beam of mid-infrared radiation into the internal reflection window to provide for attenuated internal reflection at an interface between the internal reflection window and the liquid;
• a first narrow bandpass filter configured to preferentially transmit mid-infrared radiation over a band of wavelengths corresponding to an absorbance peak of the dissolved hydrate inhibitor to provide for filtering internally reflected mid-infrared radiation received from the internal reflection window;
• an infrared detector configured to detect the filtered mid-infrared radiation transmitted through the first filter, wherein the first narrow bandpass filter is located in between the internal reflection window and the infrared detector;
• and
• a processor arrangement, operably coupled to the infrared detector and configured to measure intensity of the detected mid-infrared radiation transmitted through the first narrow bandpass filter and determine an amount of the hydrate inhibitor dissolved in the liquid from the measured intensity.