Concentration Measurement Solutions

Typical applications for the DCP007-UV include:

• Peak Detection
• Chromatographic separation
• Fractionation
• Micro- and nano-filtration systems
• Concentration of aromatic solvents

The DCP007-UV in-line process analyzer delivers superior measurement at a price point similar to older mercury arc lamp based systems. Enhanced performance allows for reduced detection thresholds and tighter cutoff points, producing greater process yields.

Traditional technology inline UV photometers use mercury vapor gas discharge lamps which continuously expose the process stream to high-intensity broad spectrum UV radiation and heat. This can result in destruction of valuable in-stream product, as well as produce unknown and [potentially hazardous] breakdown products. These traditional UV photometers suffer from systematic drift which requires constant adjustment due to optical filter erosion, and decaying lamp output resulting from age.

The Kemtrak DCP007-UV process analyzer uses state-of-the-art solid state light sources at the exact wavelength required for the analysis. Cold light reaches the process through precision fiber optics where it is delivered with energy levels very much less than that of a traditional UV photometer. The ultra-low modulated power UV light source in the Kemtrak DCP007-UV process analyzer does not systematically drift nor does it expose the product stream to high levels of UV radiation and temperature. Light sources are available at any discrete wavelengths from 250nm upwards in the UV region, ensuring that any specific requirement can be serviced.

There are many areas where the DCP007-UV analyzer outperforms other measurement devices. To detail a few:

The analyzer utilizes advanced digital electronics to allow for deep UV absorbance measurement of up to at least 4.5 AU (with a 1 cm optical path length) at up to two discrete wavelengths. A wide selection of shorter optical path-lengths allows for even deeper absorbance measurements up to 90 OD or more. DCP007-UV analyzers provide outputs that don't "cut-off" the peak.

The DCP007-UV controls the energy output of solid state light sources through a proprietary dual wavelength, four-channel measurement technique which ensures drift free measurement over long periods of time.

Photodetector quiescent state output change due to ambient temperature change is constantly corrected, while low power drive to the light sources gives extended functional life (up to 10 years). Maintenance costs for DCP007-UV systems are exceptionally low.

Zero-dead-volume hygienic measurement cells provide rapid detection of protein. Their non-diluting flow characteristics and sharp peaks provide tighter control and increase batch yields.

Non-liquid in-line verification and QA are made possible using an insertable cuvette style certified filter or liquid standard. This simple method utilizes the same traceable or prepared liquid standards used for laboratory benchtop instrumentation verification and calibration, providing a direct correlation to offline measurement techniques for added confidence in measurement.

Advances and improvements in bioprocessing methods have led to protein products being expressed and concentrated to higher and higher levels. Higher protein concentrations mean higher absorbance measurements. Therefore, UV analyzers need the ability to measure to deep absorbance. While absorbance measurement is essentially linear, many light sources generate light at wavelengths other than 280nm; this can enter the measurement path as stray light, which creates artificially low absorbance readings and non-linear responses to protein concentration, particularly at high levels.

Furthermore, these light sources are noisy, hot, and constantly drift—this makes them less than ideal, particularly for fragile protein molecule work.

Accurate, reliable, and repeatable post column UV measurements are a minimum requirement during chromatographic separation to ensure good protein fraction purity and maximum yields. With a unique Kemtrak zero volume hold-up cell installed at the column outlet, the Kemtrak DCP007 analyzer can provide single or dual wavelength UV absorbance analysis, in real time, for instant visibility and improved control of the separation process. With this, the need for offline testing and manual analysis is greatly reduced. Furthermore, the use of solid-state light sources provides the ability to measure to 4.5A at 280nm and to monitor high concentration processes up to 90 OD linearly without “peak clipping” and the undesirable effects of hot and powerful UV light sources on the process. Because of this, the Kemtrak DCP007 is the best analyzer for chromatographic separation.

In short, yes. Here's why.

The main purpose of tangential flow filtration in bioprocessing is to concentrate a product previously filtered in an earlier step in the production process. The feed solution is circulated in a closed loop, passing through the filter. This filter is selected to provide retention of the product being concentrated while allowing unwanted/excess buffer and/or background material in the circulating solution to permeate through the filter material to drain away.

The installation of UV absorbance analyzers at strategic points in the filtration system can give real-time measurements of protein concentration, which allows optimal control of feed rates for maximum filter efficiency, reduction of loss through filter failure, and accurate determination of concentration end points. All of these measurements contribute to maximizing product yield in any given batch.

Using a UV absorbance analyzer to monitor where retentate returns to a filtration system's recirculation tank, you are afforded a real time concentration signature of product retained in the circulation loop. This can be used in cascade with feed absorbance to control the amount of feed into the recirculation system, thereby keeping the loop concentration at an optimal level for filter operation. Once feed is complete, the monitor provides a measurement used to indicate retained product concentration change in the loop. When the rate of change reaches a “plateau”, the process end point has been reached.

Permeate monitoring ensures that product is not being lost through the filter membrane. Under normal operation, the monitor will provide a flat line “zero” absorbance output. If product starts to break through the filter, the measured absorbance will rise indicating a loss condition caused by either a failure of the filter media or too great a concentration in the retentate side. Once a breakthrough trend is observed, the process is usually halted.

Correct selection and installation of UV monitors is critical in every case as incorrect selection can lead to disappointing results. Unfortunately, there is no one-size-fits-all monitor that will give excellent results over many different processes. Each UV analyzer needs the right configuration in terms of optical wavelength and path length in order to provide clear and continuous monitoring that produces the resolution and repeatability needed for concise concentration determination.

UV analyzers which have poor response or truncate/clip detection peaks will not provide the information necessary to operate a filtration system at its optimum point and this can lead to loss of valuable product. As a general rule, when measuring absorbance at the same wavelength, retentate monitors will have a much shorter path length than permeate monitors while feed monitors will have a path length in between the two.

The Kemtrak DCP007-UV is an ideal UV analyzer for applications involving tangential flow filtration, as it provides:

• Drift-free measurement
• Low noise
• Exceptionally long light source life
• Zero cell hold up volume
• Single, dual, or referenced wavelength measurements