FaktorCAssay

FaktorCAssay, also known as Factor C assay, is a laboratory method used to detect and quantify endotoxins in pharmaceuticals, medical devices, and biological samples by measuring the activity of Factor C, a protease from the horseshoe crab immune system that initiates the endotoxin-triggered cascade.

In the presence of endotoxin, Factor C becomes active and activates downstream enzymes, producing a detectable signal. Readouts include chromogenic and turbidimetric assays that measure color development or turbidity, respectively; an alternative gel-clot format offers a qualitative result. There are two main variants: traditional Limulus amebocyte lysate (LAL) assays using native Limulus extracts, and recombinant Factor C (rFC) assays that use purified Factor C.

Typical workflow involves sample preparation, reaction setup with standardized endotoxin controls, incubation under defined conditions, and signal measurement against a standard endotoxin curve. Results are reported in endotoxin units per milliliter (EU/mL) and compared to specification limits set by pharmacopeias.

FaktorCAssay has become a standard tool for sterility and pyrogen testing in drug manufacturing. It offers high sensitivity and a broad dynamic range but may be affected by interference from beta-glucans or sample matrix. Regulatory agencies recognize LAL-based and rFC methods under established guidelines.

See also: Limulus amebocyte lysate assay, endotoxin, pyrogen test, recombinant Factor C.