Protein A ELISA Kit

Selection Guide

Product List

Assay Principal

Figure 1. Schematic diagram of Protein A ELISA Kit, 2G

Validation Data

• Broad-range recognition of Protein A
  

  Figure 2. Various Protein A Ligand Standard curves
  L01043 is specifically designed to detect native Protein A, recombinant Protein A variants, and alkali-tolerant recombinant Protein A. It offers a highly sensitive detection range, capable of identifying Protein A concentrations as low as 50 pg/mL.

  Table 1. Typical Assay Working Ranges for Different Sources of Protein A Ligand

  Protein A ligand standard	Typical assay working ranges
  MabSelect PrismA (Cytiva)	0.0625 – 4 ng/mL
  AT Protein A (Bestchrom)	0.0625 – 4 ng/mL
  MabSelect SuRe (Cytiva)	0.1 - 6.4 ng/mL
  UniMab 50HC Protein A (NanoMicro)	0.2 - 12.8 ng/mL
  MabPurix Protein A (Srpax)	0.05 - 3.2 ng/mL
  rSPA (Repligen)	0.1 - 6.4 ng/mL

• Anti-IgG Interference
  

  Figure 3. Detection of Protein A by L01043 in Various Concentrations of IgG
  High concentrations of human IgGs have been observed to hinder the binding capacity of anti-Protein A antibodies to Protein A, potentially leading to the underestimation of actual Protein A levels. However, the L01043 kit is minimally affected by high IgG concentrations in the sample, achieving over 90% recovery in samples containing up to 10 mg/mL of IgG.

  Table 2. Recovery rate of L01043 in human IgG

  Protein A (ng/mL)	Spiked to 1 mg/mL human IgG		Spiked to 10 mg/mL human IgG
  	Measured (ng/mL)	Recovery Rate	Measured (ng/mL)	Recovery Rate
  3	2.795	93%	2.816	94%
  0.5	0.463	93%	0.453	91%
  0.1875	0.184	98%	0.174	93%

• Dilutional Linearity
  

  Figure 4. Dilutional Linearity Analysis of L01043
  The results of Protein A detection using the L01043 kit remain consistent regardless of the sample dilution factor.

  Table 3. Consistency of Results Before and After Linear Dilution

  Sample	Mean N-fold dilution (ng/mL)	Mean 2N-fold dilution (ng/mL)	Mean 4N-fold dilution (ng/mL)	CV
  Sample A	0.49	0.41	/	12.57%
  Sample B	0.94	0.83	/	8.79%
  Sample C	91.25	96.25	97.6	3.52%
  Sample D	131.92	135.63	140.73	3.25%
  Sample E	1125.72	1190.24	1166.47	2.81%
  Sample F	1400.13	1458.67	1530.93	4.48%

• Intra-day Precision
  

  Figure 5. Intra-day Precision Testing of the L01043
  The detection results of Protein A using the L01043 kit are not affected by the Days.

  Table 4. Consistency of the L01043 Kit in Detecting the Same Sample at Different Days

  Sample	Mean (ng/mL)			CV
  	Day 1	Day 2	Day 3
  Sample A	0.45	0.56	0.53	11.08%
  Sample B	0.88	0.92	0.78	8.39%
  Sample C	95.03	97.26	84.12	7.63%
  Sample D	136.09	135.53	126.42	4.09%
  Sample E	1160.81	1116.52	1064.91	4.31%
  Sample F	1463.24	1486.2	1548.44	2.94%

• Intra-assay and Inter-assay Precision
  

  Figure 6. Protein A Concentration in Various Samples Detected by Different Batches of L01043
  The intra-assay precision of the L01043 detection kit is less than 10%, and the inter-assay precision is less than 15%.

  Table 5. Results of the Same Sample Detected by Different Batches of L01043 Kits

  MabSelect PrismA (ng/mL)	Intra-assay		Inter-assay
  	Mean (ng/mL)	CV	Mean (ng/mL)	CV
  3	2.795	3.78%	2.794	4.21%
  0.5	0.457	4.08%	0.459	4.84%
  0.1875	0.173	5.75%	0.179	11.41%

• Stable Recovery
  

  Figure 7. Recovery Rate of Protein A in Various Samples Detected by L01043
  The recovery rate of Protein A in different sample matrices using the L01043 kit is stable between 80% and 120%.

  Table 6. Data of Protein A Recovery Rate in Various Samples Detected by L01043 Kits

  Samples Purified by MabSelect PrismA	Spiked with 1 ng/mL MabSelect PrismA		Spiked with 0.25 ng/mL MabSelect PrismA
  	Measured Spiked MabSelect PrismA (ng/mL)	Recovery Rate	Measured Spiked MabSelect PrismA (ng/mL)	Recovery Rate
  Sample A	1.02	102%	0.213	85%
  Sample B	0.887	89%	0.209	84%
  Sample C	0.971	97%	0.236	94%
  Sample D	1.151	115%	0.229	92%
  Sample E	1.047	105%	0.274	110%
  Sample F	1.044	104%	0.298	119%

FAQ

• 1. How to choose between the Protein A ELISA Kit and the Protein A ELISA Kit, 2G?

  For MabSelect SuRe Protein A Resin, please use the Protein A ELISA Kit (Cat. No. L00430).

  For other Protein A resins, including MabSelect PrismA Protein A Resin, Protein A ELISA Kit, 2G (Cat. No. L01043) is recommended as the first choice. This kit offers optimized sample processing, improved recovery rates, and better suitability for various Protein A structures.

• 2. What are the positive control standards provided in kits, and what are their concentrations?

  The Protein A ELISA Kit (Cat No. L00430) includes two positive control standards: a recombinant Protein A standard at a concentration of 10 μg/ml and a MabSelect SuRe Protein A standard, also at a concentration of 10 μg/ml.

  The Protein A ELISA Kit, 2G (Cat No. L01043) includes a MabSelect PrismA standard at a concentration of 1 μg/ml.

  These standards are used to establish a standard curve during the experiment, ensuring the accuracy and reproducibility of the results.

• 3. What if the Protein A used differs from the standards provided in the kit? Does GenScript offer additional standards?

  The GenScript Protein A ELISA Kit (Cat No. L00430) and Protein A ELISA Kit, 2G (Cat No. L01043) can detect various structures of natural Protein A, recombinant Protein A, and alkali-tolerant recombinant Protein A. For more accurate quantification of residual Protein A in your samples, it is recommended to use a Protein A ligand that matches the one used in your purification media as the standard. This should be done according to the methods described in the kit and regulatory requirements.
  GenScript does not provide these additional standards. We recommend obtaining them from your purification media supplier.

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