A remote sampling sensor for determining characteristics of a sample includes measurement optics and an insertion probe. The measurement optics are configured to emit light and detect returned light. The insertion probe includes a chamber, the chamber being configured to permit the sample to enter the chamber, an insertion tip at a distal end of the insertion probe, and a retro-reflective optic adjacent the insertion tip. The retro-reflective optic is configured to return the light from the measurement optics through the chamber to the measurement optics. The insertion probe is configured to be remotely located from the measurement optics.