Escherichia coli (protein-expressing bacteria) is the core prokaryotic expression host for biological therapeutic products such as recombinant cytokines, enzymes and peptide drugs. Host cell protein (HCP) residues generated during the production and purification process are key process-related impurities. These trace contaminants may pose an immunogenic risk and compromise the purity and safety of the finished product. HCP residue detection is a core project for process characterization, process control and product release. The key raw materials such as antigens and antibodies in this kit are all independently produced by Zhuhai Baorui Biotechnology Co., LTD. The kit has undergone comprehensive methodological performance verification in accordance with regulations such as the United States Pharmacopeia, the Chinese Pharmacopoeia, and the European Pharmacopoeia, meeting the technical requirements for HCP detection set by domestic and international biopharmaceutical regulatory authorities. The detection limit (LOD) of this kit is approximately 0.577 ng/mL, and the lower limit of quantification (LLOQ) is approximately 1.55 ng/mL.
Express the exclusive detection requirements of the system.
Calibration curve (detection range)
Overview: Test the standard substances provided by the kit and one blank sample. Each concentration was repeatedly detected three times, and a total of three independent experiments were conducted. The calibration curve was fitted using a four-parameter logistic regression model.
Figure 1 Test results of the detection range
Conclusion: In the three repeated experiments, the calibration curve R² fitted by the 4PL model was ≥ 0.99, and the RE and CV at all concentration points were ≤ 15% (the highest and lowest concentration points were ≤ 20%). The detection range of this kit is 2-100 ng/mL.
2. Accuracy
Overview: Prepare calibration curves within the verified range. Set five quality control (QC) levels - ULOQ, high (H), medium (M), low (L), and LLOQ, and repeat the testing of each level three times.
Figure 2 Accuracy test results
Conclusion: The CV and RE at each concentration point are both ≤20%, which meets the requirements.
3. Repeatability
Overview: Prepare the calibration curve by referring to the verified linear range. In addition, prepare quality control points H, M, and L, and perform 8 parallel repetitions for each quality control point. The CV of the sample detection concentration is ≤20%
Table 1 Repeatability Test Results
Conclusion: The CV of the measured concentration is ≤20%.
4. Precision among people, during the day, and between instruments
Overview: Simultaneously prepare calibration curves and HQC, MQC, and LQC samples to test the precision among different analysts, different dates, and different instruments.
Figure 3 Precision test results
Conclusion: Among the five QC concentration levels used for accuracy assessment, all RE values are within 20%. The CV values among different analysts, different dates and different instruments were all below 20%, meeting the acceptance criteria.
5. Specificity
Overview: Prepare calibration curves within the verified range while preparing potential interferers. Select the low (L) QC level as the final spiked concentration.
Table 2 Results of Specificity Tests
Conclusion: This kit has no cross-reaction with Pichia pastoris, Sf9, MDCK, and CHO host cell proteins at a concentration of 1 µg/mL, and the spiked recovery rate is within an acceptable range.
