IRIS digester-evaporator interface

Abstract

A digester-evaporator interface for partially digesting a sample mixed in a solvent with an acid and for evaporating the solvent and the acid after partial digestion, said digester-evaporator including a digester portion and an evaporator portion. The digester includes at least one reaction coil having an input and an output, said at least one reaction coil adapted for receiving at its input a flow of a sample in a solvent and an acid suitable for partial digestion of the sample so as to partially mix and begin partial digestion in the reaction coil; a heating element arranged along a portion of the reaction coil; at least a portion of the reaction coil proximate to its output being preheated by the heating element to a degree sufficient to convert a partially digested sample into vapor; a collector spoon with carrier water for collecting sample vapor; and an evaporator portion including an evaporation chamber including a cover with a first opening having the substantially vertically-oriented tube extending from the cover, and the evaporation chamber includes an axial opening longitudinally arranged therein, and the evaporation chamber adapted to contain fluid at a bottom portion. The collector spoon is arranged in the top of the substantially vertically-oriented tube after a vapor sample has been collected from the digester portion, and a gas supply tube for supplying a preheated gas provided in a top of the substantially vertically-oriented tube and in the axial opening of the evaporation chamber so as to create a cyclonic gas flow into the chamber and carry the sample to a container area in a bottom portion of the chamber. The interface is especially useful in the separation and quantification of selenium containing proteins.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

For purposes of illustration and not intended to limit the scope of the invention in any way, the aforementioned and other characteristics of the invention will be clear from the following description of a preferred form of the embodiments, given as non-restrictive examples, with reference to the attached drawings wherein:

FIG. 1 is a photo showing the carbon build-up that occurs with the prior art processes of quantification;

FIG. 2 is a schematic of an IRIS Digester-Evaporator (IRIS-DE) interface device according to the present invention;

FIG. 3 is a schematic of the IRIS Evaporator of FIG. 2 without the digester portion;

FIG. 4 is a photograph of the IRIS-DE interface under test conditions;

FIGS. 5A and 5B are photographs of an actual collector spoon that can be used with and IRIS-DE according to the present invention;

FIGS. 6A and 6B are photos showing the alignment between the quartz coil, collector spoon, the nitrogen gas flow line, and the top entrance of the evaporator;

FIG. 7 is a graph of the intensity of the selenium versus the evaporator temperature.

DETAILED DESCRIPTION OF THE INVENTION

It is understood by a person of ordinary skill in the art that the drawings are presented for purposes of illustration and not for limitation. The embodiments shown and described herein do not encompass all possible variations of the arrangement of structure or the type of substances that can be quantified thereby. Therefore, an artisan appreciates that many modifications can be made within the spirit of the invention and the scope of the appended claims than the illustrative examples shown and described.

FIG. 2 is a front view of an IRIS-DE interface device. The IRIS-DE 100 has a chamber 101, which is typically constructed of a glass (IS THERE ANY particular type of glass that is preferred/required and/or can a different material be used?) housing. There is both a digester portion and an evaporator portion. Within the device 100, there exists a temperature gradient, with a higher temperature in the digester portion than in the evaporator. A top cover 103 has an opening so that a tube 105 extends from the center of the cover 103.

With continued reference to FIG. 2, the digester part of the chamber 101 includes a PEEK (polyetherketone) high temperature tee 107, a PEEK reaction coil 109, a second reaction call quartz made generally from quartz (hereinafter “quartz reaction coil” 111) and a heating pad/element 113. The Peek high temperature tee 107 has a first opening 107a that receives a flow from an HLPC system, and a second opening 107b that typically receives concentrated nitric acid (HNO₃,) so as to begin to mix with the flow of HPLC. Fluids entering the tee at 107a, 107b exit the tee at 107c and enter into the PEEK reaction coil 109.

However, it should be noted that while it is preferred that the sample-in-solvent and acid first begin to premix when exiting a common output of the tee 107, it is well within the spirit of the invention and the scope of the appended claims that either the sample-in-solvent or the acid could pass into the coil 109 consecutively.

Also, a person of ordinary skill in the art understands that it is within the spirit of the invention and the scope of the appended claims that there can be substitutes for the tee shown and described, for example, a collector vessel/pre-mixing device that could provide as an output a combination of the sample-in-solvent and acid. While nitric acid is preferred, there could be a different acid other than nitric used in operation depending upon the material to be digested. The function is to perform the partial digestion, and there may be instances where different degrees of digestion are desired by either varying the type or possibly the concentration of acid used.

The PEEK reaction coil 109 is connected to the output of the tee 107c so that the fluids exiting the tee 107 will begin to mix and start the acid digestion process. Additionally, as shown in FIG. 2, the PEEK reaction coil 109 is arranged outside of the chamber housing 101 and the fluids passing therein are exposed to room temperature during the beginning of the acid digestion process.

The Peek reaction coil 109 is connected to the quartz reaction coil 111. The reaction coil is preheated, typically on order of 250-300° C. There is a heating pad 113 arranged at the bottom of the chamber housing 101, which aids to assist in keeping the fluids passing through the quartz reaction coil 111 at the preheated temperature.

The sample is partially digested at this point and transferred to a vapor phase.

FIG. 3 shows only the Evaporator portion, with the digester portion removed for clarity purposes. As there can be temperatures ranging as high as 300° C. during operation of the IRIS-DE interface device, the entire housing should be able to withstand such a high degree of heat. As discussed previously, the cover 103 has an opening in the vicinity of its center, and the opening is sized so as to receive an open tube 105 which allows the flow to coat the surface and increases the evaporative contact area with gas, said typically comprising a flow of preheated nitrogen gas.

For purposes of illustration and not for limitation, the nitric acid may typically have 1 ppb Se in 100% HNO₃, 0.28 mL/min using a peristaltic pump (not shown) 0.015ID, 18 rpm tygon tube).

A collector spoon 115 is arranged within the open tube 105 (as shown by the arrows), via the throat of the open tube 105, and down into a lower portion close to the digester. The arrangement of the collector spoon 115 in the open tube 105 assists in the receipt/collection of sample vapor. Typically, some carrier water is placed on the collector spoon to enhance the vapor collection process. In addition, a glass tube 117 is used to supply pre-heated Nitrogen gas before it enters the evaporator chamber through an axial opening 119. Is there anything else about the collector spoon that is needed to be discussed, other than its placement in the open tube 105 with carrier water thereon? Is there something about the spoon that is critical?

FIG. 4 is an actual photo of the IRIS-DE interface in use. There is a large venting duct above the apparatus.

FIGS. 5A and 5B are photographs of an actual collector spoon 115 used to collect a vapor sample according to the present invention.

FIG. 6 shows photographs of the alignment between the quartz coil, collector spoon 115, the nitrogen gas flow line 119, and the top entrance of the evaporator.

In operation, with reference to FIGS. 2-4, it should be noted that the IRIS-DE is coupled to the HPLC using reversed-phased (RP) chromatography processes HPLC effluent by digesting protein analytes with nitric acid, evaporates the undesirable high concentration excess of nitric acid and organic solvent on-line, and sends the sample to the ICP-MS, also coupled to the IRIS-DE at am output, in a highly aqueous stream. Through this process, a continuous flow received from reversed phase liquid chromatography systems with gradient elution can be easily handled by existing ICP-MS instruments.

More particularly, a flow of preheated nitrogen (N₂) in the line 119 and the preheated quartz chamber is used to evaporate the remaining nitric acid and most of the organic solvent from the sample mix. The sample travels through the open tube 105 (that goes into the chamber at the top).

The design of the IRIS-DE is such that the flow coats the surface and increases the evaporative contact area with the gas, so that molecules with lower boiling points evaporate first and are removed from the flow by the nitrogen gas; the organic solvent evaporates faster than the water. The nitrogen flows create a cyclonic gas flow into the chamber that, together with the glass cover, helps to maintain the chamber temperature. Also, the nitrogen gas acts as a carrier that sweeps vapor molecules from the flow, and sends them out the chamber through the top and axial openings.

When the flow reaches the chamber bottom, the digested sample is dissolved mainly in water. Then a peristaltic pump (not shown) is used to continuously pull flow from the evaporator chamber and send it into the ICP-MS.

The IRIS Evaporator shown in FIG. 3 can also be used to concentrate a low amount of analyte, by introducing a sample flow with a peristaltic pump that would replace the HPLC flow.

FIG. 7 shows a graph of the Iris Evaporator temperature versus the Se intensity. The IRIS evaporator capability was tested at temperatures less than 100° C. for a 100% acetonitrile HPLC effluent. The HPLC instrument without a column was coupled to the ICP-DRC-ICP_MS instrument using the Iris evaporator shown in FIG. 4.2. The acetonitrile effluent flow rate was 0.25 ml min⁻¹. Four independent injections of 10 uL of a standard solution of selenium at 1 mg kg⁻¹ (prepared from NIST SRM 3149) were made at four different temperatures of the evaporator chamber, and the ⁸⁰Se response was measured. Can a brief comment be provided on what conclusion may be drawn from the graph? inventor comments are welcome.

The IRIS-DE interface can be commercially implemented as an HPLC-ICP-MS interface system by construction in an enclosure fitted with a vacuum exhaust flow, and accurate control of variables. The variables for this device can include: the temperature of the digester and the evaporator, the nitrogen gas flow, the carrier water flow, the position of the collector spoon, the peristaltic pump removal and the physical dimensions.

Another advantage of the present invention is that the next run is unaffected by the previous run, resulting in a measurement system that is more robust than known heretofore. The reason is because virtually all of the organic solvent is eliminated online in a run of the IRIS-DE, so conditions such as nitrogen flow, temperature, and carrier water, can be optimized for each application. The dimensions can be modified to suit different flow rates. In addition, the system is able partially to digest the analyte before the solvent evaporation process.

While the invention has been described with reference to a specific example, a person of skill will certainly be able to achieve many other equivalent forms, all of which will come within the field and scope of the invention. For example, the invention is not limited to HPLC-ICP-MS applications, as it can be used as a faster on-line sample preparation device for ICP systems and also for flame atomic absorption spectro-photometry (FAAS).

Claims

1. A digester-evaporator interface for partially digesting a sample mixed in a solvent with an acid and for evaporating the solvent and the acid after partial digestion, said digester-evaporator includes: a digester portion comprising:at least one reaction coil having an input and an output, said at least one reaction coil adapted for receiving at its input a flow of a sample in a solvent and an acid suitable for partial digestion of the sample so as to begin mixing and partial digestion in the reaction coil;a heating element arranged along a portion of the reaction coil;at least a portion of the reaction coil proximate to its output being preheated by the heating element to a degree sufficient to convert a partially digested sample into vapor;a collector spoon with carrier water for collecting sample vapor; andan evaporator portion comprising:an evaporation chamber including a cover with a first opening having the substantially vertically-oriented tube extending from the cover, said evaporation chamber includes an axial opening longitudinally arranged therein, and said evaporation chamber adapted to contain fluid at a bottom portion;said collector spoon arranged in the top of the substantially vertically-oriented tube after a vapor sample has been collected from the digester portion;a gas supply tube for supplying a preheated gas provided in a top of the substantially vertically-oriented tube and in the axial opening of the evaporation chamber so as to create a cyclonic gas flow into the chamber and carry the sample to a container area in a bottom portion of the chamber;wherein an output of said evaporation chamber is in fluid communication with an output device.

2. The digester-evaporator interface according to claim 1, wherein said digester portion is coupled to a flow from a High Performance Liquid Chromatography (HPLC) device.

3. The digester-evaporator interface according to claim 2, wherein the HPLC device is reverse-phased.

4. The digester-evaporator interface according to claim 2, wherein the output device in fluid communication with the output of the evaporation chamber comprises an inductively coupled plasma-mass spectrometry (ICP-MS) device, the acid suitable for digestion of the sample comprises nitric acid, the solvent comprises an organic solvent, and the fluid contained in the container area of the chamber comprises water.

5. The digester-evaporator interface according to claim 1, wherein said digester portion includes: a tee connector being in fluid communication with the input of said digester, said tee having one or more inputs and two outputs, said tee being adapted to receive at a first input a sample in a solvent and output from a high performance liquid chromatography (HPLC) system, and for receiving at a second input of said tee an acid used in a digestion process of said sample in the solvent, wherein the sample in the solvent and the acid both exit the tee connector at its output.

6. The digester-evaporator interface according to claim 4, wherein said digester portion includes: a tee connector being in fluid communication with the input of said digester, said tee having one or more inputs and two outputs, said tee being adapted to receive at a first input a sample in a solvent and output from a high performance liquid chromatography (HPLC) system, and for receiving at a second input of said tee an acid used in a digestion process of said sample in the solvent, wherein the sample in the solvent and the acid both exit the tee connector at its output.

7. The digester-evaporator interface according to claim 6, wherein the at least one reaction coil comprises two reaction coils, a first coil comprising a (polyetherketone) PEEK reaction coil connected to the output of the tee connector, and the second reaction coil comprising a quartz reaction coil that includes a heater.

8. The digester-evaporator interface according to claim 7, wherein the gas supply tube carries nitrogen gas that has been preheated by the heater associated with the quartz reaction coil.

9. The digester-evaporator interface according to claim 7, further comprising a first peristaltic pump in communication with the bottom portion of the evaporation chamber.

10. The digester-evaporator interface according to claim 9, further comprising a second peristaltic pump for pumping acid into the tee connector.

11. The digester-evaporator interface according to claim 9, wherein the sample in a solvent comprises at least selenium-containing proteins.

12. A method of providing a digester-evaporator interface for partially digesting a sample mixed in a solvent with an acid and for evaporating the solvent and the acid after partial digestion providing a comprising the steps of: providing a digester portion including at least one reaction coil having an input and an output, said at least one reaction coil adapted for receiving at its input a flow of a sample in a solvent and an acid suitable for partial digestion of the sample so as to partially mix and begin partial digestion in the reaction coil;arranging a heating element along a portion of the reaction coil;preheating at least a portion of the reaction coil proximate to its output by the heating element to a degree sufficient to convert a partially digested sample into vapor;collecting a vapor sample;providing an evaporator portion comprising an evaporation chamber including a cover with a first opening having the substantially vertically-oriented tube extending from the cover, and said evaporation chamber includes an axial opening longitudinally arranged therein, and said evaporation chamber adapted to contain fluid at a bottom portion;arranging said collected vapor sample in the top of the substantially vertically-oriented tube after a vapor sample has been collected from the digester portion;providing a gas supply tube with a preheated gas provided in a top of the substantially vertically-oriented tube and in the axial opening of the evaporation chamber so as to create a cyclonic gas flow into the chamber and carry the sample to a container area in a bottom portion of the chamber; andproviding the sample in an aqueous form for analysis by an output device.

13. The method according to claim 12, further comprising: coupling said digester portion to a flow from a High Performance Liquid Chromatography (HPLC) device.

14. The method according to claim 13, wherein the HPLC device is reverse phased.

15. The method according to claim 14, wherein the output device in fluid communication with the output of the evaporation chamber comprises an inductively coupled plasma-mass spectrometry (ICP-MS) device, the acid suitable for digestion of the sample comprises nitric acid, the solvent comprises an organic solvent, and the fluid contained in the container area of the chamber comprises water.

16. The method according to claim 14 further comprising: attaching a tee connector being in fluid communication with the input of said digester, said tee having one or more inputs and two outputs, said tee being adapted to receive at a first input a sample in a solvent and output from a high performance liquid chromatography (HPLC) system, and for receiving at a second input of said tee an acid used in a digestion process of said sample in the solvent, wherein the sample in the solvent and the acid both exit the tee connector at its output.

17. The method according to claim 16, wherein the at least one reaction coil is comprised of two portions of reaction coils, a first coil comprising a (polyetherketone) PEEK reaction coil connected to the output of the tee connector, and a second coil comprising a quartz reaction coil that includes a heater.

18. The method according to claim 17, wherein the gas supply tube carrying nitrogen gas is heated by the heater associated with the quartz reaction coil.

19. The method according to claim 18 further comprising pumping the sample in a solution of water at the bottom of the evaporation chamber to the ICP-MS for analysis with a first peristaltic pump, and pumping the acid into the tee connector for mixture with the HPLC flow with a second peristaltic pump.

20. The method according to claim 18, wherein the sample comprises selenium-containing proteins.

21. A digester device comprising: at least one reaction coil having an input and an output, said at least one reaction coil adapted for receiving at its input a flow of a sample in a solvent and an acid suitable for partial digestion of the sample so as to partially mix and begin partial digestion in the reaction coil;a heating element arranged along a portion of the reaction coil;at least a portion of the reaction coil proximate to its output being preheated by the heating element to a degree sufficient to convert a partially digested sample into vapor; anda collector spoon with carrier water for collecting sample vapor.

22. An evaporator device comprising: an evaporator portion comprising:an evaporation chamber including a cover with a first opening having the substantially vertically-oriented tube extending from the cover, and said evaporation chamber includes an axial opening longitudinally arranged therein, and said evaporation chamber adapted to contain fluid at a bottom portion;said collector spoon arranged in the top of the substantially vertically-oriented tube after a vapor sample has been collected from the digester portion;a gas supply tube for supplying a preheated gas provided in a top of the substantially vertically-oriented tube and in the axial opening of the evaporation chamber so as to create a cyclonic gas flow into the chamber and carry the sample to a container area in a bottom portion of the chamber;wherein said evaporator chamber evaporates substantially all of said acid and the solvent in-line; andwherein an output of said evaporation chamber is in fluid communication with an output device.