Automated analysis of discrete sample aliquots

• US 8,663,561 B2
• Filed: 02/19/2010
• Issued: 03/04/2014
• Est. Priority Date: 11/18/2005
• Status: Active Grant

• Current Assignee: Segmented Solutions
• Original Assignee: Charles J. Patton
• Inventors: Patton, Charles J.
• Primary Examiner(s): Warden, Jill
• Assistant Examiner(s): Kingan, Timothy G
• Application Number:
  US12/660,033
• Publication Number:
  US 20100159601A1
• Time in Patent Office: 1,474 Days
• US Class Current: 422/82.05
• CPC Class Codes: B01F 2035/99 Heating
• CPC Class Codes: B01F 25/433 Mixing tubes wherein the shape of the tube influences the mixing, e.g. mixing tubes with varying cross-section or provided with inwardly extending profiles
• CPC Class Codes: B01F 25/4331 Mixers with bended, curved, coiled, wounded mixing tubes or comprising elements for bending the flow
• CPC Class Codes: B01F 35/92 for heating the outside of the receptacle, e.g. heated jackets or burners
• CPC Class Codes: B01L 3/5027 by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip B01L3/5023 takes precedence; micromixers B01F33/30; microreactors for synthesis B01J19/0093; microcapillary devices in general B81B1/00
• CPC Class Codes: G01N 2035/1032 Dilution or aliquotting
• CPC Class Codes: G01N 33/18 Water
• CPC Class Codes: G01N 35/08 using a stream of discrete samples flowing along a tube system, e.g. flow injection analysis
• CPC Class Codes: G01N 35/1097 characterised by the valves valves in general F16K
• CPC Class Codes: Y10T 436/11 Automated chemical analysis
• CPC Class Codes: Y10T 436/117497 with a continuously flowing sample or carrier stream
• CPC Class Codes: Y10T 436/12 Condition responsive control
• CPC Class Codes: Y10T 436/2575 Volumetric liquid transfer

Abstract

An automated apparatus and method for analyzing liquid samples by forming discrete sample aliquots (boluses) in an elongated conduit which contains a hydrophobic carrier liquid. Aliquots may be analyzed by adding at least one reagent to the sample aliquot that reacts selectively with an analyte contained therein. The reaction product, which is selective for the analyte of interest and proportional to its concentration, is measured with an appropriate detector. Intrinsic sample properties of the sample may also be measured without the need for adding chemical reagents. The invention enables simple and accurate testing of samples using time honored wet-chemical analysis methods in microliter volume regimes while producing remarkably small volumes of waste.

Claims

1. A method of analyzing discrete sample aliquots for an analyte which is capable of detection by the addition of at least two reagents, said method involving bidirectional flow of a hydrophobic carrier fluid comprising the steps of:

(a) introducing a discrete sample aliquot into an elongated analytical conduit which contains a hydrophobic carrier fluid by closing a downstream shutoff valve in fluid communication with the analytical conduit, opening a sampling port and aspirating said sample aliquot into said analytical conduit by reverse flow of the hydrophobic carrier fluid, said sample aliquot being essentially immiscible with the hydrophobic carrier fluid, thereby forming said discrete sample aliquot;

(b) controlling the flow of the carrier fluid in the analytical conduit to position the discrete sample aliquot to receive a first reagent from a first dosing unit that is in communication with the analytical conduit;

combining the first reagent with the discrete sample aliquot, by dispensing the reagent through a first dosing port,

(c) controlling the flow of the carrier fluid in the analytical conduit to position the discrete sample aliquot, which includes the first reagent, to receive a second reagent from a second dosing unit that is in communication with the analytical conduit, and combining the second reagent with the discrete sample aliquot by dispensing the reagent through a second dosing port,

wherein steps (b) and (c) include closing a downstream shutoff valve, opening doser ports and aspirating said reagents into said sample aliquot in said analytical conduit by reverse flow of said hydrophobic carrier fluid;

(d) conveying the discrete sample aliquot by forward flow of said hydrophobic carrier fluid to a detection zone, which is positioned on the analytical conduit and includes a detector adapted to measure an analyte in the aliquot,

whereby steps (a) through (d) require bidirectional flow of the carrier fluid; and

(e) measuring the amount of analyte in the discrete sample aliquot with the detector.

2. The method according to claim 1, wherein the sample aliquot comprises a polar solvent.

3. The method according to claim 2, wherein the sample aliquot is aqueous.

4. The method of claim 1, wherein the time between the introduction of the first reagent and the introduction of the second reagent is controlled to be in the range of from 1 second to 30 minutes.

5. The method of claim 1, wherein the time between the introduction of the first reagent and the introduction of the second reagent is controlled to be in the range of from 10 seconds to 10 minutes.

6. The method of claim 1, wherein the flow through the analytical conduit is controlled so that the discrete sample aliquot is conveyed in both a forward and reverse direction in the conduit prior to being measured by the detector.

7. The method of claim 1, further comprising the step of positioning the discrete sample aliquot, which has been dosed with at least one reagent into a mixing zone and conveying the reagent-dosed sample aliquot in both a forward and reverse direction within the mixing zone to promote mixing of the sample and reagent.

8. The method of claim 1, further comprising the step of parking the discrete sample aliquot, which has been dosed with at least one reagent in a heated zone for a predetermined amount of time prior to being measured by the detector.

9. The method according to claim 1, further comprising the steps of separating the sample aliquot from the carrier fluid after the aliquot is measured in the detection zone, and recycling the carrier fluid to the analytical conduit.

10. The method of claim 1, wherein air segments are not added to the conduit.

11. A method for analyzing water for an analyte which is selected from the group consisting of nutrients, trace metals, major cations, major anions, and combinations thereof, said method involving bidirectional flow of a hydrophobic carrier fluid comprising the steps of:

(a) introducing a discrete sample aliquot of the water into an analytical conduit which contains a the hydrophobic carrier fluid, by closing a downstream shutoff valve, opening a sampling port in fluid communication with the analytical conduit and aspirating said sample aliquot into said analytical conduit by reverse flow of the hydrophobic carrier fluid, wherein the discrete aliquot has a volume of from about 1 to about 500 microliters;

(b) controlling the flow of the carrier fluid in the analytical conduit to position the discrete sample aliquot adjacent to a dosing port which is in communication with a reagent reservoir having a first reagent;

(c) combining the first reagent with the discrete sample aliquot, by dispensing the reagent through the dosing port including closing a downstream shutoff valve, opening the doser port and aspirating said reagent into said sample aliquot in said analytical conduit by reverse flow of said hydrophobic carrier fluid;

(d) controlling the flow of the carrier fluid in the analytical conduit to position the discrete sample aliquot in a detection zone which includes a detector by way of providing forward flow of said hydrophobic carrier fluid,

whereby steps (a) through (d) require bidirectional flow of the carrier fluid; and

(e) using the detector to measure the amount of analyte in the sample aliquot.

12. The method according to claim 11, wherein the nutrient analytes are selected from the group consisting of nitrate, nitrite, ammonium, orthophosphate, urea, organic carbon, organic nitrogen, organic phosphorous, sugars, amino acids, proteins and combinations thereof.

13. The method according to claim 11, wherein the trace metal analytes are selected from the group consisting of iron, manganese, cadmium, and combinations thereof.

14. The method according to claim 11, wherein the major cation analytes are selected from the group consisting of calcium, magnesium, potassium, sodium, and combinations thereof.

15. The method according to claim 11, wherein major anion analytes are selected from the group consisting of chloride, sulfate, and combinations thereof.

16. The method of claim 11, wherein the flow through the analytical conduit is controlled so that the discrete sample aliquot is conveyed bidirectionally in both a forward and reverse direction in the conduit after combination with said first reagent and prior to being measured by the detector.

17. A method for analyzing water, said method involving bidirectional flow of a hydrophobic carrier fluid comprising the steps of:

(a) introducing a plurality of discrete sample aliquots of the water into an analytical conduit which contains a the hydrophobic carrier fluid by closing a downstream shutoff valve in fluid communication with the analytical conduit, opening a sampling port and aspirating said sample aliquot into said analytical conduit by reverse flow of the hydrophobic carrier fluid, wherein the discrete aliquots have a volume of from about 1 to about 500 microliters;

(b) controlling the flow of the carrier fluid in the analytical conduit to position a first discrete sample aliquot adjacent to a dosing port which is in communication with a reagent reservoir having a first reagent;

(c) combining the first reagent with the first discrete sample aliquot, by dispensing the reagent through the dosing port by closing the downstream shutoff valve, opening a first doser port and aspirating said reagent into said sample aliquot in said analytical conduit by reverse flow of said hydrophobic carrier fluid;

(d) controlling the flow of the carrier fluid in the analytical conduit to (i) position the first discrete sample aliquot, which includes the first reagent, to receive a second reagent from a second dosing unit that is in communication with the analytical conduit or (ii) positioning a second sample aliquot to receive a second reagent from a second dosing unit that is in communication with the analytical conduit wherein (i) and (ii) further include closing the downstream shutoff valve, opening a second doser port and aspirating said reagent into said aqueous sample aliquot in said analytical conduit by way of reverse flow of said hydrophobic carrier fluid;

(e) controlling the flow of the carrier fluid in the analytical conduit to position the plurality of discrete reagent-dosed sample aliquots in a detection zone which includes a detector by forward flow of said hydrophobic carrier fluid,

whereby steps (a) through (e) require bidirectional flow of the carrier fluid; and

(f) using the detector to measure the amount of analyte in the reagent-dosed sample aliquots.

18. The method according to claim 17, wherein the first discrete sample aliquot, which includes the first reagent, is positioned to receive a second reagent from a second dosing unit that is in communication with the analytical conduit.

19. A method for analyzing water, said method involving bidirectional flow of a hydrophobic carrier fluid comprising the steps of:

(a) introducing a plurality of discrete sample aliquots of the water into an analytical conduit which contains a hydrophobic carrier fluid by way of closing a downstream shutoff valve in fluid communication with the analytical conduit, opening a sampling port and aspirating said sample aliquot into said analytical conduit by reverse flow of the hydrophobic carrier fluid, wherein the discrete aliquots have a volume of from about 1 to about 500 microliters;

(b) controlling the flow of the carrier fluid in the analytical conduit to position the plurality of discrete sample aliquots in a detection zone which includes a detector, by forward flow of said hydrophobic carrier fluid

whereby steps (a) and (b) require bidirectional flow of the carrier fluid; and

(c) using the detector to measure the amount of analyte in the sample aliquots without the use of chemical reagents.

20. The method according to claim 19, wherein the analyte is chlorophyll measured by a fluorescence detector.

21. The method according to claim 19, wherein the analyte is nitrate measured by a UV detector.

22. A method of water column depth-profiling for an analyte at a plurality of predetermined depths of a water source comprising:

(a) drawing a series of discrete sample aliquots from a plurality of predetermined depths of a water sampling source into an analytical conduit which contains a hydrophobic carrier fluid, wherein the discrete aliquots have a volume of from about 1 to about 5000 microliters;

(b) controlling the flow of the carrier fluid in the analytical conduit to position the plurality of discrete sample aliquots in a detection zone which includes a detector; and

(c) using the detector to measure the amount of analyte in the sample aliquots.