WO2004029406A1

WO2004029406A1 - Soil sampling and extraction unit

Info

Publication number: WO2004029406A1
Application number: PCT/GB2003/004125
Authority: WO
Inventors: Timothy David Hart
Original assignee: Cybersense Biosystems Limited
Priority date: 2002-09-24
Filing date: 2003-09-18
Publication date: 2004-04-08
Also published as: AU2003267628A1; GB0222160D0

Abstract

Apparatus (1) for sampling and extracting solid or liquid/solids material includes a sampling section (2) adapted for connection to and communication with an extraction section (8), and a filter section (30) connectable to the extraction section (8) for flow communication therewith.

Description

SOIL SAMPLING AND EXTRACTION UNIT

[0001] This invention relates to sampling and extraction apparatus and in particular has reference to soil sampling apparatus incorporating a sample extraction unit.

[0002] A number of inventions have been disclosed that describe soil sampling tools but not combined with extraction systems. Most of these describe the general principle of removing a soil sample by pushing a container into the substrate, which then becomes filled with soil.

[0003] For example, US Patent No. 4848484 describes a soil sample extraction tool whereby an open-ended tube is pushed directly into the soil to remove a sample and a closure door seals the chamber when the sample is removed from soil.

[0004] Patent DE19625125 describes a similar invention, but here the soil is received into a specimen chamber, which is then frozen in situ .

[0005] Patent No. US6176326 describes an easy-to-use field-based soil sampling method. This is a volume-based method, but the user does not have to refer to a visual scale to check enough sample has been collected. When the sample container is full, resistance is felt on a plunger, which indicates that the sample has been taken. [0006] Patent No. US5937953 describes a hand-held sampler to be used for obtaining soil samples for VOC analysis where sealed samples -with no headspace are required.

[0007] One patent (WO0176782) describes a method of extracting oil- soluble contaminants from soil by using oil and water phase fluids. However, there is no suggestion that this could be field-based or part of a soil sampling system.

[0008] An object of the present invention is to provide an apparatus to facilitate the sampling of solid material, solubilise components of the sample and separate solids from the soluble into a defined volume.

[0009] A further object of the invention is to provide apparatus and a method for rapid on-site soil sampling and extraction of pollutants for toxicity testing.

[00010] According to the invention there is provided apparatus for sampling and extracting solid or liquid/solids material including sampling section adapted for connection to and communication with an extraction section, and a filter section connectable to the extraction section for flow communication therewith.

[00011] The sampling section may conveniently be in the form of a receptacle, for example a pot, for the receipt of material, the pot being so formed with a means of connection, for example a screw thread, interengageable with a mating thread on the extraction section. In practice a sample, for example a soil sample, is placed into the sampling section, i. e. the pot. [00012] The extraction section is adapted to contain an extractant for interaction with the sampled material to provide a solute for transfer to the filter section.

[00013] The filter section may include a syringe provided with an air vent and a filter unit, the body of the syringe being connectable to the filter unit by suitable means, for example Luer lock, and optionally being provided with graduations inscribed thereon to give an indication of the volume of its contents .

[00014] There is provided intermediate the extraction section and the syringe of the filter section the filter unit which may include three elements, namely a micropore filter sandwiched between two sintered permeable discs. The micropore filter may be made of an inert material such as polyether sulphone with a pore diameter of for example 0.45μm, and the sintered discs may be produced from an inert material, for example polypropylene or glass. The discs facing the extraction section, which may for example be two in number and be approximately 6 mm in thickness, act as a prefilter for the micropore filter which is provided to separate particulates and colloids from soluble components and the other disc supports and protects the filter. This other disc, e.g. 3.2 mm thick, may be replaced by another supportive and protective structure, for example plastics webbing, to hold the micropore filter in situ.

[00015] The value of the invention is that the system produces a solid sampling and extraction process, which is rapid, disposable and easy to use. The system has been designed to be simple to use and of minimal steps to allow rapid sampling and extraction in field-based situations. The filtered extracts could be used for toxicity testing or any other assay, for example enzyme or colorimetric assays, where the presence of particulates would otherwise interfere with the test or a filtrate is required for analysis.

[00016] All parts are made from an inert plastics material, such as polypropylene, unless otherwise indicated, to minimise adsorption of organic contaminants onto the sampling apparatus and/or to minimise degradation of the parts by the extractants.

[00017] One particular application of the present invention is for the monitoring of toxicity of soil samples and one example of apparatus employs the use of bioluminescent bacteria. The sampling and extraction apparatus of the present invention provides an effective and efficient precursor to such toxicity monitoring.

[00018] By way of example only one embodiment of sampling apparatus according to the invention is described below with reference to the accompanying drawings in which:

[00019] Figure 1 is an exploded external view of the apparatus;

[00020] Figure 2 is a part exploded view of the sampler in vertical cross section and in first operative mode;

[00021] Figure 3 is a vertical cross section of the apparatus in a second operative mode; and

[00022] Figure 4 is a vertical cross section of the apparatus in a third operative mode. [00023] Referring to the drawings, a sampler is shown generally at 1 and includes a sampling section 2 formed of a plastics receptacle such as a pot 4 provided with a male thread 6. The volume of the pot 4 is exactly defined (e.g. 5 cm³) .

[00024] A holding rack (not shown) comprises a plastic rack that holds 20 samplers according to the invention in a 4x 5 format. The rack is provided with a complementary cover (not shown) that holds the samplers in place to allow shaking of the rack, thus mixing the contents of the sampler all together.

[00025] The sampler further includes an extraction section 8 consisting of a plastic tube 10 one end of which has a female screw thread 12 that fits a male screw thread 14 on an end cap 16 which has a connecting section 18 provided with a female thread for engaging the thread 6 on the pot 4.

[00026] Towards the other end of the extraction tube 10 there is a central boss 20 internally threaded so as to engage the threaded section 22 of a shaft 24 of a plunger 26 provided with an operating knob 28. The plunger 26 operates within the tube 10 and in use turning of the shaft by the knob 28 causes movement of the plunger within the tube 10 for a purpose to be hereinafter described.

[00027] The sampler is further provided with a filter section 30 including a filter unit 32 that is interchangeable with the pot 4 and the end cap 16 and accordingly is provided with a male thread at 33 engageable with the female thread 12 in the tube 10. The filter unit 32 incorporates a micropore filter 34, e.g. 0.45 μm pore diameter, sandwiched between two sintered discs 36, 38 which are fitted within the filter unit 32. The innermost sintered discs 36, e.g. 6mm thick, act as a pre -filter. The sandwiched filter 34 acts to separate particulates and colloids from soluble components and the outermost sintered disk 38 supports and protects the sandwiched micropore filter 34. Beyond the outermost sintered disc 38, or in an alternative embodiment plastics webbing, the diameter of the tube as at 39 narrows acutely. At the narrow end 39 there is a Luer lock 40 on the inside of the tube.

[00028] The filter section 30 further includes a syringe 42 having a plunger 44, the tube 46 of the syringe having an air vent 48 and being connectable through the agency of a Luer fitting 50 onto the filter unit 32 at 39 of the filter section 30. Measurement markings (not shown) are provided on the syringe tube 46 to give an indication as to the volume of its contents.

[00029] The extraction tube 10 contains a defined volume (e.g. 10 ml) of extraction liquid (e.g. acetone or methanol or 0.1M HC1 or water) and has a defined volume of headspace above the liquid (e.g. 10 cm³) . The headspace acts as empty space to allow more forceful mixing of the solid material with the extractant when the two are shaken together in the tube which is repeatedly inverted end-over-end by hand.

[00030] Just below the plunger 44 when this is in its outermost position, there is a small hole in the tube, which functions as the air vent 48 to allow air to escape from the headspace when the plunger 26 of the extraction section 8 in the soil sampler 1 is pushed in. The air vent 48 can be closed by pushing down on the plunger 44 in the filter section 30. This acts to seal off the air vent 48 and thus the filter unit now functions as a pressurised syringe, such that when the syringe tube 46 is removed from the Luer fitting at 39 of the filter unit 32, the contents can be expelled. The measurement markings on the side of the syringe tube 46 allow the user to draw a precise volume (e.g. 1ml) of extractant into the syringe 42 of the filter section 30. When the filter section 30 is fitted onto the extraction tube 10, the user can screw the soil sampler plunger 26 in, thus forcing extractant which has been mixed with solid material (e.g. soil) through the filter unit 32 and up into the syringe 42, until the liquid in the filter unit 32 meets the marking, thus measuring a specified volume.

[00031] For smaller volumes of extract, e.g. 20 μl, the syringe of the filter section is not attached to the filter unit and as soon as the filtrate can be seen in the filter unit, a pipette is inserted through the Luer lock opening to remove a smaller volume. Different volumes of extract may need to be measured out with the sampler for different solvents (e.g. less methanol or acetone is needed from the sampler for use in a toxicity assay) .

[00032] In operation, the pot 4 is filled with solids, e.g. soil, by either pushing the open end of the sampling section 2 directly into the solid substrate or using a device such as a spatula to fill the sampler completely. Either technique gives a defined volume (e.g.

5 cm³) of solid material. The sample pot 4 is then screwed onto the end cap 16 which in turn is screwed into the end of the extraction tube 10. The end cap 16 functions as both a cap for the pot 4 to contain material prior to extraction and to seal the end of the extraction tube 10 and prevent extractant liquid from escaping prior to use. The entire sampler 1 can then be placed into a holding rack, while the pots 4 of other samplers 1 as required for a testing session are being filled with samples. [00033] When it is desired to commence the extraction step, each sampler 1 is lifted out of the holding rack and the end cap with the sample pot 4 are removed from the extraction tube 10 by unscrewing. The sample pot 4 is then separated from the end cap 16 by unscrewing and the sample pot 4 containing the sample is carefully screwed into the end of the extraction tube 10. Wet samples should be retained by inherent adhesiveness in the pot 4 whilst it is being screwed into the extraction tube 10, whereas dry samples require care to ensure that they are tipped into the extraction tube 10 without spillage. Each sampler 1 is then placed back into the holding rack with the plunger 26 downwards. This process is repeated for all the samplers 1. The previously mentioned top of the holding rack is then placed over all the samplers 1 and the entire rack is inverted end-over-end repeatedly using both hands for a defined time (e.g. 2 minutes) . This is done by holding the top and bottom sections of the rack at each end with each hand and tipping the rack over 180° and then back again using the wrists. The samplers 1 are then left standing for a few minutes to allow the solid material to settle to the bottom of the extraction tube due to gravity.

[00034] The holding rack thus functions as a means by which multiple (e.g. 20) samplers can be shaken all at once. This minimises variability in extraction between samplers compared to shaking each unit separately. It also allows more samples to be processed in one shaking period. However, the holding rack is not an integral part of the invention and if the user so desires, single samples can be processed individually by shaking each sampler by hand, although a stand or rack is still required to allow the solid contents of the extraction tube to settle prior to filtration. [00035] Each sampler 1 is carefully lifted out of the holding rack and held with the filter unit 32 uppermost. If the soil is not settled sufficiently to filter, the sample pot 4 can be unscrewed and a few grains of a flocculent such as Magnafloc^® may be added to aid settlement. The pot 4 is then screwed back onto to the tube 10 and the sampler 1 reshaken to dissolve the flocculent and then left for a few seconds for the soil to settle. The plunger 26 on the soil sampler is then screwed in such that the contents of the extraction section tube 10 are pushed through the filters 34, 36, 38 and into the filter unit 32. Firstly, this forces the headspace air out through the air vent 48 in the syringe tube 46. The plunger 26 is screwed in further until the extract reaches the mark defining the volume in the syringe tube 46. The plunger 44 in the syringe tube 46 is then pushed down to cover the air vent 48 and thus pressurise the section which now functions as a syringe. The syringe tube 46 can now be carefully removed from the filter unit 32 and the defined volume of filtered extract within syringe tube 46 dispensed by pushing down on the plunger 44 into an appropriate vessel to conduct further analysis on the filtrate. For example the sample may be placed in a toxicity monitor using bioluminescent bacteria to determine the toxicity of the sample taken.

[00036] The invention thus provides a simple sampler and extraction unit which is easily usable, disposable and portable for on-site analysis.

Claims

1. Apparatus (1) for sampling and extracting solid or liquid/solids material characterised by a sampling section (2) adapted for connection to and communication with an extraction section (8) , and a filter section (30) connectable to the extraction section (8) for flow communication therewith.

2. Apparatus according to Claim 1 characterised in that the sampling section (2) includes a receptacle (4) releasably connectable to the extraction section (8) and adapted in use temporarily to receive a sample therein.

3. Apparatus according to Claim 1 or 2 characterised in that a cap (16) is provided for the extraction section (8) and is adapted to receive the receptacle (4) in releasable manner.

4. Apparatus according to any one of the preceding claims characterised in that the extraction section (8) includes a tube (10) one end of which is adapted for connection to the sampling section, and the other end of which is provided with a plunger (26) .

5. Apparatus according to Claim 4 characterised in that the said other end of the tube (10) is provided with an internally threaded boss (20) for interengagement with a shaft (24) provided with a knob (28) for actuating the plunger (26) .

6. Apparatus according to Claim 5 characterised in that the filter section (30) includes a filter unit (32) and a syringe (30), the unit (32) and the syringe (30) being releasably interconnectable .

7. Apparatus according to Claim 6 characterised in that the releasable interconnection between the filter unit (32) and the syringe (30) is effected by a Luer connector (40, 50).

8. Apparatus according to Claim 6 or 7 characterised in that the syringe includes a tube (46) within which a plunger (44) is slidable, and the tube (46) is provided with a vent hole (48).

9. Apparatus according to any one of the preceding Claims 6 to 8 characterised in that the filter unit (32) includes a micropore filter (34) .

10. Apparatus according to Claim 9 characterised in that the micropore filter (34) is sandwiched between at least one primary filter (36) and a support element (38) .

11. Apparatus according to Claim 9 and 10 characterised in that the micropore filter (34), the primary filter (36) and the support element (38) are made of an inert material.

12. Apparatus according to Claim 11 characterised in that the micropore filter (34) is made of polyether sulphone.

13. Apparatus according to Claim 11 characterised in that the primary filter (34) and the support element (38) are made of polypropylene.

14. Apparatus according to Claim 11 characterised in that the primary filter (34) and the support element (38) are made of glass.

15. Apparatus according to Claim 11 characterised in that the primary filter (36) and the support element (38) are sintered filter discs.

16. Apparatus according to Claim 11 characterised in that the support element (38) is made of a plastics webbing.

17. Apparatus according to any one of the preceding claims characterised in that a rack is provided for accommodating a plurality of the apparatus, and a top for the rack is provided for registration with the plurality of the apparatus whereby the apparatus is held between the rack and the top.

18. A method of sampling and extracting a solids or liquid/solids material using the apparatus claimed in the preceding claims characterised by the steps of inserting a set volume of a sample of the said material into the receptacle (4) of the sampling section (2) , providing a predetermined volume of an extractant medium in the extraction tube (10) of the extraction section (8), causing the sample to mix with the extractant medium to solubilise the sample to provide an extract, forcing the mixture from the extraction tube (10) by use of the plunger (26) through the filter unit (32) and into the syringe (42), allowing the expulsion of any entrapped air to escape through the vent hole (48), moving the syringe plunger (44) to seal the vent hole (48) , removing the syringe (42), and expelling the filtered extract into a further receptacle for assay.

19. A method according to Claim 18 as dependent upon Claim 17 characterised in that more than one apparatus is employed for acquiring a batch of samples, and in that the mixing of the samples with the extraction medium in the extraction tubes (10) is effected simultaneously by placing the said plurality in the rack and holding the extraction tubes (10) between the rack and the top.

20. A method according to Claim 19 characterised in that the mixing of the samples and the extractant medium is effected by appropriate movement of the apparatus held between the rack and the top.