How much turbidity can the Lachat Flow Injection Analysis (FIA) methods handle?

Document ID

Document ID TE6623

Published Date

Published Date 27/05/2017
Question
How much turbidity can the Lachat Flow Injection Analysis (FIA) methods handle?
Summary
Turbidity concerns with Lachat FIA
 
Answer
Lachat does not have a "set limit" for turbidity recommended before filtering samples
  • Turbid samples can clog the injection valve and filaments can get stuck in the flow cell. 
  • Turbid samples should typically be filtered. Care needs to be taken with ammonia samples as filtering can introduce contamination.
  • If the valve does get clogged or something gets stuck in the flow cell, the user may try pumping 1 molar hydrochloric acid or 1 molar sodium hydroxide through the manifold. 
  • If turbidity does not cause clogs but does reach the detector it can cause a positive response as the turbidity scatters light. Turbid samples may be analyzed without the color reagent to determine if there is a significant response.  If there is, the results can be subtracted from the results with the color reagent. 
  • In some cases, it may be possible to analyze by dialysis. This removes the analyte from the sample itself.  This is typically only a solution for volatile analytes such as ammonia and cyanide.