Citrate detector for blood processing system

A blood processing system for use in combination with a replacement fluid flow conduit of a disposable set and comprising:

• a citrate detector including
• a light source configured to emit an infrared light having a wavelength of approximately 6,353.24 nm, which is absorbed by citrate, but at least partially transmitted by the replacement fluid flow conduit of the disposable set,
• a light detector configured to receive at least a portion of the light from the light source and generate a signal indicative of the presence or absence of citrate in the replacement fluid flow conduit based, at least in part, on the amount of light received from the light source;
• and
• a controller configured to receive the signal from the light detector and determine whether citrate is present in the replacement fluid flow conduit based, at least in part, on the signal.

A method of monitoring fluid within a blood processing system having a replacement fluid flow conduit, the method comprising:

• directing infrared light into the replacement fluid flow conduit, the light having a wavelength of approximately 6,353.24 nm, which is absorbed by citrate, but at least partially transmitted by the replacement fluid flow conduit;
• detecting light exiting or reflected by the replacement fluid flow conduit;
• and
• determining whether citrate is present in the replacement fluid flow conduit based, at least in part, on the light exiting the replacement fluid flow conduit.