SoloVPE Application: Protein A280

The Most Direct Measurement for Proteins

Validate your measurements with confidence

Measurement of protein concentrations using traditional UV-Vis spectroscopy is limited to a single pathlength and a single absorbance value per measurement. To bring the sample detection into the linear (dynamic) range, the user is forced to perform dilutions on the samples with time-consuming and labor-intensive steps.


  • Samples that are viscous, do not dissolve easily, foam up, or create air bubbles, interfere with analysis. 
  • Error-prone dilution and sample handling steps are later followed by calculations and subsequent data interpretation.

Slope Spectroscopy manipulates Beer-Lambert’s law, allowing the System to accurately vary the absorbance with the change in pathlength. With near-perfect linear regression, the SoloVPE System can accurately measure a wide range of concentrations without any dilution or baseline correction and with reliable and reproducible results.

The SoloVPE Solution

  • Variable pathlength technology allows the direct measurement of proteins, including monoclonal antibodies (mAbs), which absorb light at 280 nm due to aromatic amino acids (primarily L-tyrosine and L-tryptophan). 
  • The System creates a minimum of five and up to 10 absorbance data points, generating a slope with regression R2 values of ≥0.999.
  •   System-to-system consistency and the easy and fast validation and implementation.

The SoloVPE has validated over 50 commercial drug products.


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Application Services

The passion for what we do is in the product and support services you receive

CTech is committed to our customers’ success. We design service offerings to supplement our standard support options and provide you with increased access to our highly knowledgeable and experienced professionals. We offer implementation, development, and educational guidance to maximize the benefits of your variable pathlength solutions and the Slope Spectroscopy® technique.

Application Services

  • 21 CFR Part 11 Guidance
  • Annex 11 Guidance
  • Validation Support
  • Qualification Service
  • Method Transfer Service


  • Method Design & Development
  • Comparability
  • On-Site Support
  • Custom Standards
  • Process Auditing


  • SOP Document Review
  • Advanced Slope Spectroscopy Training
  • Data Analysis
  • Maintenance & Troubleshooting

Contact a Bioanalytics Application Specialist

Your Partners in Method Development and Process Solutions.

Connect with our dedicated applications team. Our team can show you how to maximize the benefits of your variable pathlength solutions and the Slope Spectroscopy® technique. Let us help you expedite your SoloVPE Validation.

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