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What if there was a way to enrich liquids with gases of interest, in a controlled manner?

Biotech Fluidics offers high-efficiency in line degassing equipment to obtain >90% removal of dissolved gasses from liquids, employing vacuum-based degassing. Some applications, however, require the opposite, i.e. enrichment of certain gasses in given liquids. Utilizing the reversed principle of vacuum-based degassing, we here present new insight on the vacuum-chamber, which can evidently be used to enrich fluids with gases of interest. By applying an over-pressure of a given gas on the chamber, through which your fluid of interest is pumped, the amount of dissolved gas can be substantially increased, allowing you to regulate the gas content in a highly controlled manner.

The principle was demonstrated by pumping tap water through a 9000-1523 degassing chamber with and without over-pressure of air (0.15 MPa). As expected, the enrichment of oxygen is highly temperature dependent, while the flowrate displays a negligible impact. With the current setup, the amount of dissolved oxygen could easily be increased by 100%, corresponding to an absolute enrichment of approximately 6.7 mg/ml at 10 °C and 7 ml/min. Due to lower solubility of gasses at high temperatures, the enrichment was 2.6 mg/ml at 50 °C and 7 ml/min, yet corresponding to 67% increase.

This shows the dual functionality of the vacuum chamber, which appears to be not only great for degassing purposes, but is also a terrific device for dissolved gas enrichment.  Using such a chamber you can now easily add an in-line mechanism to your setup to boost the solutions with gasses of interest.

Learn more about the Biotech Fluidics vacuum chambers at the product webpages linked below, or contact Biotech Fluidics to discuss the most appropriate chamber for your application.

Experimental details: 0.15 MPa overpressure of air was applied on a 9000-1523 degassing chamber, through which regular tap water at various temperatures was pumped at 7 ml/min and 14 ml/min respectively. The amount of dissolved oxygen was monitored continuously before and after the pressurized chamber.

Intuitive click fitting for low pressure applications

Are you dreaming about trouble-free and consistent low-pressure tubing connections? Would a fitting providing this facilitate your laboratory life? Especially in locations where you frequently exchange fluid path components, such as flash columns, in-line filters or eluent bottles?

The new Intuitive™ fitting system with its patented self-adjusting torque-limiting nut for low pressure applications, provides a haptic feedback click when it has been sufficiently tightened. You never again have to worry about leaking connections, nor about overtightening and squeezing tubes or damaging ports. The click feedback is built to work for at least 80 repeated assemblies and is thus ideal in positions where components are changed frequently. Being designed for ¼”-28 ports compatible with Flanged, Flangeless, and Super Flangeless ferrule designs, and available in versions for both 1/16” and 1/8” OD tubing, we are confident this is the most easy-to-use, flexible and intuitive low-pressure fitting system available. Hence the name.

Biotech Fluidics can deliver the Intuitive™ connection system as pre-mounted components in ready-made kits, allowing you to save time and effort at your assembly station. Contact us to learn more or check out the product page linked below.

Experiments with plug flow in a KOT tubular coil reactor

The knitted open tubular (KOT) coil reactors from Biotech Fluidics are designed to maintain plug flow in a variety of liquid flow systems. They accomplish this through a winding flow path design that enhance radial mixing, while minimizing axial dispersion. This makes KOT reactors ideal flow elements to allow time for reactions, or for automatic decision making during a continuous flow. These features make KOT reactors popular for example, in plug flow chemistry reaction development or in liquid chromatography reaction detection.

To showcase the potential of KOT reactors, we had an experiment performed to compare the effect on chromatographic peaks when transported through a KOT reactor, versus when being conveyed through a straight tube of identical material and dimensions. The setup was suppressed ion chromatography, but the outcomes would apply to any flowing liquid of similar linear flow rate and viscosity. The results clearly show that the KOT reactor prevented most of undesired axial mixing and preserved the peak integrity, only causing a peak broadening of 3-11%. In contrast, the peaks passing through a straight tube of identical dimension and volume, were affected up to ten times more and increased in width by 32-70%. This distinctly displays that the straight tube exposed the peaks to significantly more zone dilution by the transport liquid compared to the KOT reactor.

The applied linear flow rate in this experiment was 10 cm/s (1.2 mL/min), which corresponds to the lowest recommended flow rate to establish stable radial mixing in a KOT reactor with the present internal diameter (0.5 mm). At higher flow rates it would thus be expected that the dispersion in the straight tube would be even more problematic relative to the KOT reactor. All data in this example were generated by an independent laboratory (Diduco AB) according to established scientific principles.

Learn more about the Biotech Fluidics KOT reactors at the product webpages linked below, or contact Biotech Fluidics to discuss the most appropriate KOT reactor for your application.

Experimental details: An ion chromatography setup separating chloride and sulphate (10 µM in water) using a Shodex SI-90 4E column (250×4 mm) operated with an eluent of 3.9 mM NaHCO₃ and 3.1 M Na₂CO₃ delivered at 1.2 mL/min. The delay flow element (KOT or straight tube 0.5 mm ID, 4 m length, 785 µL volume) was inserted between the suppressor (XAMS membrane suppressor automatically regenerated by ASUREX-A200), and the conductivity detector cell. Injection of 50 µL standard solution created original peak volumes (at triangulated base) of 210 µL and 440 µL, respectively. Data was plotted compensated for delay volume to facilitate visual comparison. Experiments performed by Diduco AB (www.diduco.com).

Plug flow preserved in KOT tubular coil reactors

The KOT tubular coil reactors from Biotech Fluidics are the ideal delay elements to preserve plug flow while allowing time for reactions or other events in a stream of flowing liquid. Whether employed in the context of flow chemistry synthesis, or in more traditional liquid chromatography setups, the KOT reactors provide an unmatched capability of preventing zones from mixing with the surrounding upstream and downstream liquid in a flowing stream. This feature can be used to maintain high concentrations of reagents during plug flow chemistry reaction development, with minimum dilution by the transport liquid. Originally, KOT reactors were designed to preserve the integrity of chromatographic peaks during post-column reaction detection in HPLC. They were later applied to allow time for data collection and automatic decision making during online monitoring of semi-preparative liquid chromatography fractionation. Both these are still important application areas. The picture below shows some typical set-ups incorporating KOT reactors in these different systems handling plug flow in fluid streams.

The capability of the knitted open tubular (KOT) coil reactor is a result of a principle that is both simple and clever. By an intricate winding design with frequently alternating direction in three dimensions, the flowing liquid is exposed to centrifugal forces. This pushes the liquid to mix radially, thereby minimizing axial dispersion and dilution. Constructed from inert poly(tetrafluoroethene) [PTFE] material, the Biotech Fluidics KOT reactors are translucent and can thus easily be used in photochemistry, as well as temperature-controlled environments. Applicable flow rates range from about 0.3 mL/min up to several tenths of millilitres per minute. The total residence times can be varied from a few seconds up to several minutes, depending on dimensions, flow rates, and the number of KOT reactors combined in series.

Consult the Biotech Fluidics KOT product webpages and brochure for more information about available dimensions and recommended operational conditions. Biotech Fluidics will also be at your service to discuss the most appropriate KOT reactor for your application.

 Eluent inlet filters prevents dust and other foreign particulate matters from entering the flow path of your liquid chromatography instrument. Such particles would otherwise eventually reach the column inlet, increase the system backpressure and might then also introduce radial flow heterogeneity which could affect peak shape.

Biotech Fluidics offers a range of competently designed inlet filters in different materials and porosities for a variety of solvents and requirements. All of these have a defined homogenous pore size to effectively block particles above a certain size, while letting the mobile phase through without significant pressure increase. The Bottom-of-the-Bottle™ design of these inlet filters make it possible to use mobile phases very efficiently down to the last few millimetres from the bottom of your eluent bottle. Replacement of inlet filters should be performed a couple of times per year and during the regular instrument service routines.

The patented stainless-steel Bottom-of-the-Bottle™ inlet filter features a replaceable filter cup in either 2 or 10 µm pore size that allows solvents to be drawn down to 3.2 mm (1/8 inch) from the bottle bottom. They allow flow rates up to 40 ml/min (10 µm filter) or 10 ml/min (2 µm filter) making it a trusted choice for many situations.

The all-PEEK Bottom-of-the-Bottle™ biocompatible inlet filters are equipped with a bottom withdrawal filter (2 or 10 µm pore size) allowing solvents to be used down to 2 mm (0.08 inch) from the bottom. These inert biocompatible are connected without any fittings and are available for a variety of tubing diameters, while allowing flow rates up to 30 ml/min. In addition, these inlet filter enables the connection of an optional auxiliary helium sparging line.

The inert and biocompatible UHMWPE Bottom-of-the-Bottle™ filter assembly comes with a replaceable filter cup and is an economic alternative enabling solvent withdrawal down to 2.5 mm (0.1 inch) from the bottom of your eluent bottle. These filters allow flow rates up to 5 ml/min although the hydrophobic filter material might require some surface wetting with organic solvents such as methanol or acetonitrile for optimum performance.

Biotech Fluidics also offers additional filters for liquid chromatography, HPLC and other equipment handling delicate fluids. Browse the online catalogue of IDEX Health & Science LLC for more information or contact Biotech Fluidics for guidance and to discuss your application needs.

New Refractive Index Detector

More robust, more sensitive, and more communicative. The new REFRACTi™ MASTER refractive index detector that will be launched by Biotech Fluidics at Analytica in Munich June 21-24 takes RI detection into the modern era of HPLC. The design is meeting all demands of classical liquid chromatography RI applications such as analysis of simple sugars and more complex carbohydrates. The detector can also be applied to HPLC quantification other molecules with poor UV absorbance including alcohols, fatty acids, and polymers.

The REFRACTi™ MASTER RI detector enables an unsurpassed cell temperature control range, from room temperature up to 80 °C, thus greatly facilitating use with highly viscous solvents such as isopropanol, dimethyl formamide (DMF), dimethyl acetate (DMAc) and dimethyl sulfoxide (DMSO).

Stay tuned for more information!

What is the most efficient batch degassing?

The understanding how dissolved gases in HPLC and liquid chromatography can result in problems during detection and pumping is by no means new knowledge. Already 40 years ago, investigations were conducted about this issue while comparing means of solving it using the batch degassing methods available at the time.
It was manifested that bubbling eluents with a gas such as helium, having lower solubility in the mobile phase mixtures compared to the oxygen and nitrogen gases present, was a reasonably efficient way of removing dissolved gases. Almost as powerful was exposing the eluent to an external vacuum, although none of these methods could compare to the most efficient, but highly impractical arrangement of continuously refluxing the solvents. In contrast, especially considering todays rather widespread practice of ultrasonication, was that this approach was remarkably poor at removing dissolved gases from solvents.

“Ultrasonic degassing was
particularly disappointing”

The authors in one scientific paper even explicitly stated that “Ultrasonic degassing was particularly disappointing” after observing that this method only managed to remove one third of the dissolved gases. The citation above and the data on dissolved oxygen gas in methanol plotted in the figure below, were extracted from the scientific paper “Solvent degassing and other factors affecting liquid chromatographic detector stability” by Janet N. Brown et al., published in Journal of Chromatography 204 (1981) 115-122.
Contact Biotech Fluidics to learn how today’s efficient and convenient inline degassers can replace the outdated and ineffective practise of ultrasonication, thus eliminating the source of bubble formation in buffers and mobile phases utilised in HPLC and liquid chromatography.