How much turbidity can the Lachat Flow Injection Analysis (FIA) methods handle?
Turbidity concerns with Lachat FIA
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.