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CTech™ Analytical Solutions

Resource Library

Learn why Variable Pathlength Technology has been adopted by some of the largest companies around the globe and how it can help you

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Published Paper

Protein concentrations in bioprocessing are determined by multiplying the measured absorbance of UV light as it passes through a sample by the protein extinction coefficient. Conventional spectrophotometer measurements are based on a fixed pathlength depending on the cuvette used to hold the sample (typically 10 mm). Only a small portion of the UV curve is linear at that pathlength. As a result, conventional spectrophotometers have a limited linear range and are unable to measure a large range of protein concentrations reliably without dilution of a sample to within linear range.

Published Poster

Amgen: Method Development and Evaluation of the Techniques for Oligonucleotide Concentration Determination

Oligonucleotide-based therapeutics are emerging as promising modality against a variety of diseases. The determination of oligonucleotide concentration is a critical quality attribute as it directly relates to the patient’s safety and efficacy. A typical dose may require a dosing concentration of > 150 mg/mL. Traditionally, concentration determinations have been assessed through a fixed path length instrument. Due to limitations of the spectrophotometer with these high absorbance products, sample concentrations in this range must involve a timeconsuming dilution step. However, alternate technologies exist for high concentration samples which require no sample dilution, such as the NanoDrop™ and SoloVPE instruments using Slope Technology™.

A study was performed to 1) compare the range of oligonucleotide concentrations using the SoloVPE and NanoDrop™ instruments including the evaluation of multiple wavelengths and 2) evaluate the precision and accuracy of both instruments to a standard. The study encompassed an oligonucleotide concentration range up to ~200 mg/mL. Extinction coefficients of the target oligonucleotide at multiple wavelengths were determined. With the optimal wavelength determined, high concentration determinations were possible. Accuracy was assessed via a direct comparison between the instruments. Statistical analysis evaluated the equivalency of the two instruments

Published Poster

Application of In-Line Variable Pathlength CTech FlowVPX System for Use of Concentration as a Feedback Loop

Development of effective, commercially-viable process analytical technology tools requires the interconnection of processing equipment and analytical tools with robust methods and reliable controls. The objective of this study was to create a fully automated TFF process solely based on concentration and compare it to the traditional TFF process which is based on the weight of the balances. The FlowVPX System can be used in-line as a process to provide concentration data in real time to be used as a feedback loop to control the process instead of using balances.

Published Poster

Application of Inline Variable Pathlength Chromatography for High Concentration Oligonucleotide Solutions

With the increased focus on oligonucleotides within biopharmaceutical projects, real time measurements of product concentration can lead to increased efficiency within bioprocessing and manufacturing. A collaboration between Repligen and Ionis Pharmaceuticals assessed the viability of in-line measurement of oligonucleotide concentration during reversed-phase chromatography. The experiment supports the implementation of in-line variable pathlength chromatography as a viable alternative for in-line variable pathlength spectrophotometer real-time integration of high concentration oligonucleotide solutions.

General Info + Application Notes

ASTM Standard Practices for General UV-VIS Quantitative Analysis

These practices are intended to provide general information on the techniques most often used in ultraviolet and visible quantitative analysis. The purpose is to render unnecessary the repetition of these descriptions of techniques in individual methods for quantitative analysis.

Published Paper

Bacterial growth curve by OD600 and SoloVPE System

The aim of this study is to detect the bacterial growth curve of E. coli by two methods, such as standard spectrophotometer and SoloVPE method. The cell-concentration range, which can be analyzed by those methods, will be tested to show the reasonable statistical certainty and time consumption during measurements. This allows to find the most suitable method for further bacterial cells analysis during bacterial cells cultivation.

Published Poster

Biogen Inc.: Comparison of Protein Concentration Determination of a mAb Drug Substance Using Variable Pathlength Spectroscopy and UV-VIS Spectroscopy

In recent years a new technology known as “Variable Path Length Spectroscopy” (e.g. SoloVPE from C Technologies Inc.) has been developed for the determination of protein concentration in biologics such as monoclonal antibody drug substances (mAb DS). The advantage of this new technique is its increased dynamic range and resulting minimized sample handling, which leads to increased throughput and also mitigates the risk of dilution errors compared to conventional UV. In this case study for a mAb in latestage clinical development, it was desirable to change from a traditional UV method to SoloVPE for DS release, and it was shown that the protein concentration was significantly impacted by the choice of method (SoloVPE or SoloVPE LS (Corrected for Light Scattering)) compared to the historical conventional UV method. The decision to implement SoloVPE for DS release was considered using a risk-based approach.

Published Paper

Biogen Inc.: Using Slope Spectroscopy Methods Risk Assessment and Cost Savings

The biopharmaceutical industry’s need for rapid, accurate concentration measurements of protein-containing products is critical. The protein-concentration assay measures ultraviolet absorption at 280 nm (A280) and usually is performed both as an in-process test and for product-release testing. The SoloVPE system can analyze samples across a wide range of target concentrations without the need for labor-intensive and errorprone dilutions. Slope Spectroscopy methods provide companies with a universal platform for determining protein concentration for all in-process, clinical, and commercial methods

Published Poster

Boehringer Ingelheim: Implementation of Variable Pathlength Technology at Boehringer-Ingelheim Fremont

Absorption spectroscopy is used to quantify biomolecules using Beer’s Law: Absorbance (A) = Molar Absorptivity (ε) * Pathlength (L) * Concentration (c). A = ε L c

At high concentrations, samples must be diluted due to limitations of traditional spectroscopy instrumentation utilizing a fixed pathlength of 1 cm. A gravimetric correction is applied to ensure accuracy of dilution. The process of diluting, applying the gravimetric correction and washing the cuvette is time consuming and can take several hours in a controlled setting such as Quality Control (QC) or Manufacturing. The use of Variable Pathlength Extension eliminates the need to dilute samples by taking absorbance measurements at multiple pathlengths using a disposable optical fibrette and sample vessel. The software plots absorbance vs. pathlength. Using Linear regression, the software calculates a slope for the points and determines the concentration by rearranging Beer’s Law to: A/L = slope = ε c. Use of Variable Pathlength for concentration measurements results in time savings of greater than 80%.

General Info + Application Notes, Published Paper

Bristol Myers Squibb: Paving the Way for Real Time Process Monitoring in Biomanufacturing

Published Paper

Bristol Myers Squibb: Ultrafiltration Behavior of Partially Retained Proteins and Completely Retained Proteins Using Equally-Staged Single Pass Tangential Flow Filtration Membranes

Published Paper

Bristol-Myers Squibb: The Analyst’s Perspective – Assuring and Controlling Quality of Well-Characterized Biologics

Analytical methods are the foundation of all biopharmaceutical work: from product discovery, characterization, formulation, and testing to process development and optimization, raw materials analysis and equipment qualification, and quality assurance and control. Over the past 15 years, technological advancements have improved precision, robustness, reproducibility, linearity, and control over the vast array of assays and analytical instrumentation available for biochemical, microbiological, and cell biology studies. Single-use technologies have introduced organic chemistry and materials science into the mix. Authors, reader-survey respondents, and editorial advisors helped us identify and examine trends in comparability testing, multivariate analysis, automation, statistics, validation, and more.

Published Paper

Bristol-Myers Squibb: UV-Vis Based Determination of Protein Concentration

No longer are scientists bound to the time-consuming, errorprone use of dilution factors and fixed-pathlength measurements in determining the concentration of an analyte in solution. Using the slope spectroscopy technique, the Solo VPE system (from C Technologies) offers a new method of determining analyte concentration based on the Beer–Lambert law and slope derived from absorbance measurements made at multiple pathlengths.

Published Paper

Bristol-Myers Squibb: Viral Filtration Integrity Using Variable-Pathlength UV-Vis Spectroscopy for the Gold Nanoparticle Test

Viral filtration (VF) using nanofilters removes endogenous and/or adventitious viruses from biologic drug-substance manufacturing processes (1). The gold particle test (GPT) is performed as part of postuse integrity testing – to complement postuse leakage testing – for cellulose filters such as Planova 20N filters from Asahi Kasei Corporation. First, a proprietary gold-colloid solution matched to the filter type (e.g., 20N) is filtered through the test article. That filter’s pore-size distribution can be assessed using spectrophotometric absorbance readings of the integrity-test solution – e.g., 1:10 dilution of Asahi Gold Particle solution AGP-HA20 to test Planova 20N – and the correct filtrate sample (minimum volume collected for measuring absorbance) to calculate the gold-particle removal rate as a logarithmic reduction value (LRV).

General Info + Application Notes

Characterizing Gold Nanoparticle Detection Using Slope Spectroscopy

Virus-removal filters are a key component in many bio-pharmaceutical manufacturing processes. The gold particle test is a common and effective way to confirm that the filter pore size has remained unchanged throughout the process. Spectroscopic analysis of concentrated gold particle solutions pre and post filtration is the preferred method to validate filter and process integrity. To avoid the risks of passing ineffective filters and the costs of false positive results, the measurement technique used must be robust, accurate and highly sensitive. Since the post-filtration absorbance levels are in the range of 0.01 Abs on a 1 cm pathlength measurement, this verification technique can benefit from the dynamic range made possible by the variable pathlength technology in the SoloVPE System. A new Slope Spectroscopy® based method for filter verification offers time & cost savings while delivery the increased confidence associated with a slope based measurement

Video
Video

CTech SoloVPE System Maintenance

Webinar

Process monitoring and control are of the highest importance in the manufacturing of such microorganisms to allow good product quality when monitoring the growth kinetics of the cells. Learn how CTech™ SoloVPE® System’s variable pathlength technology can adapt optical density measurements as an in-line or at-line monitoring tool for cell growth in bioreactors.

General Info + Application Notes

Determination of Plasmid DNA Purity Ratio in Human Gene Therapy Products Using Slope Spectroscopy

Estimation of DNA purity in the presence of protein for gene therapy plasmid material is possible by exploiting the 260/280 UV absorbance ratio. This technique, however, has significant challenges when accurate quantification of DNA purity is required. The SoloVPE and its Slope Spectroscopy technique offer a new method to overcome these challenges, and to accurately measure DNA purity ratios in accordance with the Beer-Lambert law.

Published Paper

Determination of Polysorbate 80 Concentration of In-Process Stock Solution

Polysorbate 80 has been widely used as a stabilizer in the formulation of protein drugs including monoclonal antibodies (mAb) in biopharmaceutical industries. The CTech SoloVPE System has been developed for protein content determination and proven to be very efficient to measure absorbance from 0.01 to 450 Au for proteins without any dilution.

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Polysorbate Analysis
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SoloVPE: Protein A280

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