TSip™ for UHPLC

Tip Sealing Intellectual Property (TSip™) is a patented method to reduce both dispersion and variance of dispersion for improved HPLC, & UHPLC

TSip™ significance to UHPLC, and UHPLC in the US Economy

TSip™ significance to UHPLC, and UHPLC in the US Economy

The pharmaceutical sector of the US economy is highly dependant on a chemical separations technique called 'HPLC', or High Performace Liquid Chromatography. This technique is the primary method used to isolate unknown chemicals of interest for new drug discovery, and, is used in drug purification. The HPLC analysis uses a singificant amount of solvents, which require proper disposal. The technique can take from 10 to 20 minutes per analysis. Many many thousands of analysis are required to test even a single new drug. The solvents and samples under analysis pass through several separate instruments, through small diameter tubing. These tubes are secured to the instruments with numerous 'fittings'. These fittings has been one source of sample dilution (or, dispersion) which had been one of the limiting technologies barring further advancement. A chicken-and-egg situation existed which did not allow fittings and high performance HPLC column technologies to evolve independantly. An example is found in
this study. 'UHPLC' is an evolution of HPLC, and stands for Ultra High Performance Liquid Chromatography. UHPLC has been steadily improving over about the last decade. UHPLC is important to the general public, and to those companies which use it for the following reasons: An essential requirement for UHPLC is reduction of the amount of a parasitic artifact called 'dispersion'. To acheive lowered dispersion, and in turn the economic gains offered by UHPLC, the Tip Sealing approach (as described in this 2007 patent publication) provides two key advances in the state of the art in sealing the ubiquitous 'HPLC port'.

Animation Pre-UHPLC
Dispersion of PRE - 'First Generation' UHPLC fittings

This figure shows two effects which are inherent to the port. First, a sample (blue) in injected in the solvent stream. Both dilution and tailing are shown by how the (cyan) sample behaves. For good measure, slipping is shown. Finally the animation repeats.

The effect of tubing slipage on column resolution is shown

As instruments become more capable of UHPLC resolutions (whether or not operating at high pressures) it is of significant economic interest that uncertainties of 'connection' issues be minimized, since dispersion variance can lead to significant amounts of lost time in diagnosing system problems. Further, it seems intuitive that method validation protocols must take variability of extra-column dispersion into account, therefore, to reduce this cost, fittings which allow for greater possibility of extra-column dispersion variance should be minimized.

Animation Pre TSIP
'First Generation' UHPLC fittings

The so-called 'First Generation' UHPLC fittings have a common element, that is they use a cone-shaped ferrule to acheive a pressure seal. There are variations in the design of this ferrule, but with each design, the primary method to reduce dispersion is to attempt to 'bottom' the tubing in the port, thus minimizing swept dead volume. However; this first generation is subject to the uncertainty of 'indeterminate sweeping' of the cylindrical dead volume surrounding the tubing (at the port bottom).

It is speculated this thin cylindrical volume may not neccesarily be universally swept or unswept. Since no provision is made to attempt to seal the microscopically rough bottom of the port, pressure fluctuations in the flow path could conceivably communicate sample into this volume. This 'thin cylindrical volume' can easily be in the 400-600 nL range using measurements of typical ports. Some manufacturers appear to be aware of this possibility and minimize the diameter of the port such that it more closely matches that of the tubing. This 'tight fit' is desireable, but special care must be taken in design of TSip™ style fittings to avoid 'sticking' of the tip, as has been observed in early TSip™ prototypes.

Animation TSip
Tip Sealing TSip™ method

Additional arguments for TSip™ styles are based on the number of potential re-uses of TSip™ fittings. The actual cost of fittings per instrument on a per-use basis now favors the TSip™ technology. This applies to all high resolution methods, those at high and low pressures. Lastly, the actual time and 'fussiness' required to make a consistent connection with 'First Generation' UHPLC fittings necessitates significant operator awareness and training on the use of the fittings themselves. The TSip™ style fittings finally return to the old and simple rule of merely "tighten a fitting just until leaking stops". This rule applied nicely 20 years ago, and applies again today. But through the era of 'First Generation' UHPLC fittings (cone ferrule types), the persistance of the rule (tighten till the leak just stops) may have been responsible for significant 'finger pointing' as UHPLC resolutions were improved. This 'finger pointing' refers to falsely blaming wither the column or instrument for inconsistency of performance which may have ben attributable to 'complex' fittings.

TSip™ basic implementation components

TSip™ basic implementation components

Required components
Figure: Minimum components for simplest implementation.
The components are...
  • 1. The seal. Designed to seat at the bottom of the port.
  • 2. Linking tube. Crimps around seal and tubing.
  • 3. Fitting body. Can take a variety of forms, but uses linking tube to press seal 'down and around' the tubing.
  • 4. Small diameter tubing. Can be PEEK, Fused Silica, Stainless steel, or other.
  • 5. Jacket. Loose fitting PEEK. Not called out in patent for TSip™, but very practical to protect fused silica tubing.
Optimized geometries of components 1 and 2 are necessary to acheive...
  • maximum operating pressure
  • minimum dispersion
  • stick free design
  • long life, and
  • ease of assembly
Optimized geometries of component 3, the body, is necessary to acheive...
  • Avoidance aganst overtightening (for long seal life)
  • Adequate tightening force, and
  • general ease of use
Some of the many possible configurations of the
body which satisfy these requirements are shown.

TSip™ embodimemts Body and Tip

TSip™ embodimemts Body and Tip

Group of first generation UHPLC fittings
Figure: Four embodiments of the TSip™ method
This series shows 4 variants of body styles, and the two major methods of Tip Sealing as claimed in
US patent 9217522. They are not positioned chronologically, but the enumeration is chronological in terms of prototype fabrication and testing.

Grey Seal Prototype Manufacturing

Grey Seal Prototype Manufacturing

Crimpers amd components
Figure: Components manufactured by lathe to allow experimentation with optimized geometries of components.

The array of TSip™ body parts, Tip Seals, Linking tubes, and bodies, were CNC machined using a Citizen B12 Swiss Lathe (Japanese), or EMCO Super 11 (Austrian). Many design teams might elect to proceed directly to injection molding of the seal component, but by taking the intermediate prototyping step, a variety of slight variants, particularly of the seal, were possible. This allowed very low cost correction of design oversights such as those surrounding the precise shape and dimentions at the critical sealing area. Oversights in this area can not only lead to poor performance, but to very annoying problems such as a seal becoming stuck in a port.

Also shown are:

General Chronology of TSip™ filings

General Chronology of TSip™ filings

  • In the 2007 US patent 8006367 is the first use of the term 'Tip Sealing' to describe and teach the new method of creating a seal at the bottom of the HPLC port, also referred to as a 'CPI' port. This is the first disclosure of the invention of the tip sealing method for the standard 10-32 HPLC (CPI) port. CPI is an acronym for 'Chemical Process Industry', and the port is reported to have been invented by Parker-Hannefin in the 1960's.
  • It is believed that until 2007, the method of sealing the CPI port had been exclusively by use of cone shaped ferules as intended by Parker-Hannefin. Upchurch Scientific, Valco Instruments and others used the CPI port in variations of this fashion, using cone shaped ferrules as originally prescribed.
  • In October 2007, US patent 8887371 aditionally describes Tip Sealing as a new method to seal the CPI port, and again shows a construction embodiment of a 'malleable seal' manipulated against the sholder of the CPI port.
  • The inventor coined and claims the trademark "TSip™" an acronym for Tip Sealing Intellectual Property
  • In 2015, a method patent 9217522 was granted by the US patent office. The priority date of the patent is February, 2008. This patent claims two methods for using the CPI port by sealing at the shoulder of the port, described as the extreme bottom flat portion of the port. This method (called TSip™) was determined by the USPTO to be a new method to seal the CPI port, in relation to the previous method of using the tapered area of the port and a longitudinally hollow cone shaped ferrule to seal.
  • In 2016, the inventor seeks an interested party capable of attaing high levels of production at costs which allow the general LC community to exploit the IP, and to license the IP to those parties which have shown a committtment to fair-play, consistent manufacturing, and on-going development and validation.

Additional notes to any entity seeking right to sell or manufacture any embodiment of a fitting which would facilitate an end user to employ the TSip™ methods:

  • Commercial entities may not manufacture fittings which employ TSip™ described in the patents referenced herein without first securing licensure agreement with the named Inventor.
  • The named Inventor is seeking an entity capable of assessing the total market inpact of ownership of TSip™, and which can navigate arriving at contractural arrangements to receive assignment of the IP for sub-licensure with third parties, or exclusive right to provide and/or regulate the use of the methods described in 9217522.
  • Patents 8887371 & 8006367 are bundled with 9217522 in order to fully secure rights to TSip™.

General form changes of TSip™ through early development:

Prototype TSip fitting
Figure 1. Prototype body style.
2006-2008 was an intense period of experimentation with variations of TSip™, and the fixed linking tube design won out as being the simplest to secure, and least prone to accidental damage of the seal. Another embodiment used a sliding linking tube, which was comeletely independent of the narrow diameter (typically 1/32") tubing it captured. A few bad results with dropping the seals, or denting them showed that this route seemed to have an intrinsic 'operator hassle' similar to the non-TSip™ 'cone-ferrule fittings' which were already on the market. As a result, this second 'sliding tube' implementation of TSip™ was not pursued.

The fitting shown has a generic body style which can be finger tightened, and optionally wrench tightened. It is approximately 3/8" in diameter, which was found to be far greater in diameter than was necessary or desireable. Though many of this variety were used in early testing, it was thought to reduce the diameter significantly such that typical finger tightening force would not over-tighten.

It is also noted that although the knurl-hex body style, pioneered by Best Instrument, Inc. is quite handy for use with pre-UHPLC 'coned ferrule' style fittings, that the hex portion does allow a wrench to be used, and the use of a wrench is not necessary, desireable or recommended with any embodiment of the TSip™ fitting yet developed. That said, it was carried over to a preferred version of the TSip™ body shown as Example 4 here.

Static pressure testing

Static pressure testing

15KPSI Pressure Test
Figure 2. Static pressure test.
Some number of these early TSip™ prototypes are shown in the previous Figure. This style allowed the underlying 'non-slideable linking tube' design to be tested. The initial estimations for internal geometries of the gray tip seal and linking tube were relatively good, as the very first units were able to easily withstand 15,000 - 16,000 PSI pressure tests.

The test apparatus is a military surplus hand-lever operated pump, which allows gradual application of pressure. Limited temperature cycling is attained by applying forced hot air monitored by thermocouple.

The technique of testing 2 fittings simultaneously is shown, so the lesser of the two devices under test will tend toward a worst case failure limit. Subsequent testing with slightly modfied crimping parameters yielded results in the 20,000+ PSI range. The consistently acheivable upper pressure limit is presently unknown.

Kotoni / Sapienza study

TSip™ Samples used for silica qualification

Study fittings
Figure 3. TSip™ embodiment manufactured for the Kotoni/Sapienza study.
Kotoni / Sapienza Evaluation of Supelco's new Titan monodisperse silica would have been unsuccessful without optimizing the instrument using TSip™ fittings shown.

Several optimized body styles were available at the time of the study, but the body design which was selected was the original 3/8" knurl-hex body design, with the addition of an identification band. The overall deficiencies of this body design were ignored in supplying the samples for the study, as they were being sent to a well established laboratory which could easily handle the risks of the larger body diameter. And, it was conceivable that over-tightening studies might be done, though there is no evidence in the study that this was performed. Typical result of over-tightening with the optimized tip designs of figure 3 and 4 are a disk shaped deformation of the seal which does not cause catastrophic failure, but is believed to shorten life. This supposition remains untested.