Production Overview

Hzymes’ recombinant factor C endotoxin detection kit offers a sustainable alternative for endotoxin testing. Its working principle relies on the specific interaction between endotoxin and recombinant factor C. Upon activation by endotoxin, recombinant factor C triggers an enzymatic cascade that cleaves specific substrates, producing measurable fluorescent or chromogenic signals for the quantitative determination of endotoxin levels. In contrast to the traditional Limulus Amoebocyte Lysate (LAL) assay, this method eliminates the need for horseshoe crab blood, thereby meeting both sustainability and ethical standards.

Key Features

• Sustainable and environmentally friendly, as it does not depend on animal-derived components.

• Demonstrates high consistency with the traditional LAL method.

• Offers a broad linear detection range (0.005-5 EU/mL) with excellent standard curve linearity (R² > 0.999).

• Exhibits high specificity, with no interference from the G factor collateral pathway, making it suitable for samples with β-glucan interference.

• Provides good reagent stability, as the reconstituted endotoxin standard can be stored at 4°C for 8 weeks.

Product Highlights

High Consistency with LAL Method

Shows strong correlation with LAL test results across a wide range of actual sample concentrations.

Excellent Adaptability and Precision:

• Linearity: R² > 0.999.

• Accuracy and Repeatability: Intra-batch CV < 10%; inter-batch CV < 15%; spike recovery between 50%-200%.

• High Specificity: Specifically detects endotoxin without cross-reactivity from β-glucan via the G factor pathway.

Good Stability

The reconstituted endotoxin standard solution maintains stability for 8 weeks at 4°C.

Applications

This kit is designed for the detection of bacterial endotoxins in a wide range of samples to ensure product safety, including:

Pharmaceutical and Biological Products:

Injections (chemical drugs, antibody drugs, traditional Chinese medicine), vaccines (inactivated, live attenuated, subunit, nucleic acid, conjugate, etc.), blood products (human albumin, immunoglobulin), and serum.

Life Science Products:

Proteins, plasmids, and other molecular biology products.

Quality Control (QC) Testing

Multi-point monitoring of intermediate products, final product release testing, and pre-/post-verification and routine monitoring of Water for Injection (WFI).

Medical Devices

Endotoxin testing for devices involved in blood transfusion, infusion, and implantation.

Performance Data

Competitive Comparison (vs. Supplier L)

The kit demonstrates superior or comparable performance in key metrics.

Note: %PPC (Positive Product Control) recovery should be 50% to 200% of the added spike value for photometric techniques and PPC must clot in gel clot methods.

High Consistency with LAL Method

Results from testing various actual samples show high agreement with LAL methods.

High Accuracy and Repeatability

Intra-batch CV < 10%; inter-batch CV < 15%.

High Specificity

No interference from the G factor collateral pathway, suitable for endotoxin detection in samples with β-glucan interference.

Stability Data

The endotoxin standard can be stored at 4°C for 8 weeks after dissolution, offering longer usability compared to some alternatives.

Custom Case

Backed by global distribution partners, this recombinant factor C (rFC) based assay is widely used by biopharma leaders, including CROs/CDMOs and developers of mRNA vaccines and cell & gene therapies. It supports critical quality control for in-process testing and lot release across proteins, plasmids, lipid nanoparticles, WFI, and raw materials.

FAQ

Q: What is the main advantage of using Recombinant Factor C over traditional LAL methods?

A: The primary advantage lies in its sustainability. This method does not rely on blood sourced from horseshoe crabs—an ancient marine species currently facing conservation challenges—making it a more ethical and environmentally responsible option that aligns with contemporary sustainability principles. It also demonstrates high specificity, exhibiting no interference from the G-factor collateral pathway, which renders it suitable for samples affected by β-glucan interference.

Q: What types of samples can this kit be used for?

A: It is suitable for testing pharmaceuticals (like injections, vaccines, blood products), life science products (like proteins and plasmids), water for injection (WFI), and medical devices that may introduce endotoxins into the human body.

Q: What could be the reasons if no signal is detected from my sample, and what troubleshooting steps can be taken to address this issue?

A: Based on the manual, possible causes and solutions include:

1. Pipetting Error: Repeat the assay.

2. If the spike recovery falls outside the 50%-200% range, this suggests the presence of interference. In such cases, try diluting the sample. If dilution alone does not resolve the issue, consider diluting the sample using the provided Unblocking Buffer 1 or 2 to mitigate the interference. (Note: If dilution with pyrogen-free water effectively resolves the problem, the use of Unblocking Buffer is not required.)

3. Inappropriate Sample pH: Test and adjust the sample pH to the neutral range (6-8).

Q: Why is the detection signal too weak, and how to improve it?

A: According to the manual, potential causes and corrective actions are:

1. Instrument Sensitivity (Gain) Too Low: Increase the sensitivity/gain setting on the fluorometer.

2. Fluorometer Parameter Error: Check and verify the parameter settings on the instrument.

3. Incorrect Incubation Temperature: Check and calibrate the incubator temperature to ensure it is 37°C ± 1°C.

4. Reagent Failure or Expiry: Check the storage conditions and expiration date. Contact technical support to obtain a new kit or reagents if needed.

Q: How to address high background fluorescence observed in the standard and negative control wells?

A: The most probable cause is contamination of assay components, including the substrate reagent, assay buffer, or rFC enzyme solution. The recommended solution is to utilize freshly opened reagents and to ensure that sterile, pyrogen-free pipette tips are used at all times.

Q: What are the possible reasons for poor linearity of the standard curve (R² < 0.980 or slope outside 0.8-1.1), and how to address it?

A: The most probable causes are the following common issues:

1. Dilution Error of the Endotoxin Standard: Accurately re-prepare the standard dilution.

2. Fluorometer Sensitivity Issue Causing Saturation: If the fluorescence reading at the highest standard concentration (e.g., 5 EU/mL) exceeds the instrument's detection range, it can distort the curve. Try using a fluorometer with higher detection sensitivity or adjusting the gain to a lower setting to avoid signal saturation.