Improved sampling bag with filter

Abstract

Plastic sampling bag 1 intended for use in a blender for the preparation of samples for the purpose of carrying out analyses and / or microbiological tests, the bag comprising a bottom 5, lateral walls

Description

Technical Field 5 The present invention relates to the field of sampling and to the preparation of samples for analysis, and in particular to the preparation and collection of a filtrate from a solid sample. The solid sample may be fibrous, non-homogeneous, insoluble. In this case a liquid, for example physiological or a culture medium, is placed in the bag. The sample, placed in its compartment, is in contact with the liquid. The quantity 10 of liquid used is generally one tenth of the solid sample weight and generally represents only a low volume located at the bottom of the bag. The filtrate may be viscous or pasty and the analysis of the filtrate is in particular microbiological. The present invention relates to a sampling bag with a filter, of the flat bag type 15 made of a transparent plastic material sub-divided with the aid of a filtering partition that delimits a sampling chamber in which the sampling is performed and which may be used to prepare a filtrate from the potentially contaminating solid or liquid sample. Background Art 0 Sampling bags with a filter are principally used when the sample to be analysed is solid and is slightly soluble and / or difficult to handle and / or potentially pathogenic and / or that the sample taken ‘on site’ must not be contaminated. Generally speaking, microbiological analytical procedures require that the solid or 25 liquid samples to be analysed have to be diluted in order to obtain a liquid form. In most cases, the sampling bags with a filter comprise two compartments separated by a filter, wherein one compartment is intended to receive the solid sample, and the other is intended to receive the filtrate and forms the sampling chamber. According to one possibility, the filter can be of the full-page type and separates the 30 bag into two identical compartments. One compartment is intended to receive the sample and the diluent, the other for withdrawing the filtered mixture by means of a pipette. According to another possibility, the filter can be of the lateral type and forms a lateral chimney that divides the bag into two compartments. The largest compartment 35 receives the sample and the diluent. The bag can then be inserted into a blender in order to promote the suspension of the sample and / or the solubilisation of objects of the solid sample in the liquid. After blending, the compartment designed to receive the filtrate and forming the sampling chamber allows the suspension obtained after filtration to be sampled. All or a part of 5 the filtrate is then sampled for analysis. In order to avoid any ascent due to capillarity and leaks from the top of the bag during blending, the bag must be held closed by pinching with the door of the blender at a predetermined height. Typical dimensions of the sampling bags are 95x180 mm for a maximum blending 10 volume of 100 ml, 190x200 mm for a maximum blending volume of 400 ml, 250x380 mm fora maximum blending volume of 2000 ml, 380x600 mm fora maximum blending volume of 3750 ml, The applicant proposes mixers with a special closure, such as the specialized mixers sold by Interscience SARL of Saint-Norn La Breteche, France under the trademark Q-Tight®, to eliminate any risk of leakage from the top of the sampling bag during mixing. A lever ensures that the door of the blender is locked when closed, wherein the door closes the bag. After the blending step it may be necessary to temporarily close such a bag, for example so as to place it on a bag rack with a view to its storage. In this regard, after blending, the operator may have to make a fold on the width of the bag, then install a bag fastener on said fold, or any other pinching device. As the analysed products are often greasy, they facilitate the circulation of the liquid in the bag during blending. As the walls of the bag are greasy, they do not adhere to each other, and the liquid may therefore ascend high up in the bag during blending. The blending thus causes the liquid contained in the bag to rise and impregnate the filter that acts as a blotter and absorbs the contaminated medium. In this step, if the closure is too low and below the pinching zone of the blender door that holds it together by pressing during the blending step, then this often causes the medium contained in the bag to spill out of the bag. The spillage may be more or less 30 rapid and the error when the fold was made may not be immediately noticed by the operator. Furthermore, the volume of the liquid increases due to the heat and the development of the bacteria to be analysed in the enrichment and incubation stage. Also, with a bag according to the prior art, it frequently occurs that the potentially contaminating medium contained in the bag spills out of the bag. An object of the invention is to overcome all or some of the disadvantages highlighted above. Disclosure of the invention According to a first aspect of the invention, there is proposed a sampling bag made of a preferably flat, preferably transparent plastic material, possessing a bottom, lateral walls and an opening, the bag being sub-divided with the aid of a filtering partition that delimits a reception chamber for a sample and a sampling chamber for carrying out withdrawals, said bag comprising a visual indicator of a correct, predetermined fold line closing position along which the sampling bag may be folded after mixing to prevent leakage via capillary action and wherein the fold line visual indicator is placed at a distance from the opening. With such a fold line indicator the operator knows where to make a fold on the bag to close it whilst avoiding that the medium contained in the bag spills out of the bag. According to one possibility, the visual indicator is located on the bag at a distance from the opening substantially equal to one third of the height of the bag. Preferably, the distance is equal to the third of the height of the bag, plus or minus five per cent of the height of the bag (between 28% and 38% of the height). According to a second aspect of the invention, there is proposed a sampling assembly or sampling kit comprising a blender for preparing samples for the purpose of carrying out analyses and / or microbiological tests, and a sampling bag made of plastic material according to the first aspect of the invention. According to a further aspect of the invention, there is proposed a method for the production of a sampling bag intended for use in a blender for the preparation of samples for the purpose of carrying out analyses and / or microbiological tests, said bag possessing a bottom, lateral walls and an opening, and sub-divided with the aid of a filtering partition that delimits a reception chamber for a sample and a sampling chamber in which the sampling is performed, comprising marking said bag before use, with a visual indicator for a correct, predetermined closure position to form a fold line to prevent leakage via capillary action of the bag after mixing in use. The method according to the invention may moreover comprise, prior to the step of marking, a step for determining the position for the visual indicator, the position being between a nip line defined by closure of the bag in a blender during blending and the opening. Description of the Figures 5 Other advantages and distinguishing features of the invention will be revealed when reading the detailed description of the non limitative implementations and embodiments, by referring to the appended Figures, in which: [Fig. 1] Figure 1 is a schematic representation of an open sampling bag according 10 to the prior art, prior to a blending step, [Fig. 2] Figure 2 is a schematic representation of the sampling bag of Figure 1, pinched along a nip line in the blending step, [Fig. 3] Figure 3 is a schematic representation of the sampling bag of Figure 2, unpinched, after the blending step, 15 [Fig. 4] Figure 4 is a schematic representation of the sampling bag of Figure 3, Xl closed after closing along a fold line located under the nip line, after the step C\J represented in Figure 3, [Fig. 5] Figure 5 is a schematic representation of a sampling bag according to the invention, after a blending step as in Figure 3, ¢^20 [Fig. 6] Figure 6 is a schematic representation of a sampling bag according to the invention, closed after closing along a fold line, after the opening step represented in Figure 5. [Fig. 7] Figure 7 is a schematic representation of another embodiment of a sampling bag according to the invention. 25 Description of the embodiments As the embodiments described below are not exhaustive, in particular it is possible to consider variants of the invention which comprise only a selection of the described 30 characteristics, subsequently isolated from the other described characteristics, if this selection of characteristics is sufficient to provide a technical advantage or to differentiate the invention from the prior art. This selection comprises at least one characteristic, preferably functional without structural details, or with only a part of the structural details if this part alone is sufficient to provide a technical advantage or to 35 differentiate the invention from the prior art. In the Figures, an element that appears in a plurality of Figures retains the same reference number. Figure 1 illustrates a sampling bag made of polyethylene intended for use in a blender in order to prepare samples for the purpose of carrying out analyses and / or 5 microbiological tests. The samples may be solid and / or liquid materials. The sampling bag comprises two walls 2, 3 that extend from the top downwards between an opening 4 and a bottom 5 and extend laterally between two lateral interior edges 6. 10 According to the embodiment shown, the lateral interior edges 6 are principally parallel with each other. The sampling bag is manufactured by thermoforming two polyethylene sheets by forming a fold 7 connecting two lateral ends 8, 9 of the opening 4, and extending along the length of a first lateral interior edge 6 then the length of the bottom 5 of the bag 15 then the length of a second lateral interior edge 6. The bag is subdivided with the aid of a of a filtering partition 10 that delimits a receiving chamber 11 fora sample and a withdrawal chamber 12 in which the sampling is performed. The filtering partition 10 is made of polypropylene, whose filter porosity is £\|20 approximately 280 microns. The wall 3 may display a scale 13 that, for example, displays a maximum level of the scale 14 to be met for the correct utilisation of the bag in the blender. With reference to Figure 2, when the sampling bag is inserted into the blender, the bag is pinched along a nip line 15, drawn as a dashed line, thereby making the bag 25 liquid-tight during the blending. Of course, air can escape from the bag by the nip line, for example during its blending. The nip line 15 delimits the bag’s upper portion 16, facing towards its opening 4, and the bag’s lower portion 17, facing towards the bottom 5. The portion 16 is shown with a fill pattern with diagonal stripes extending from a top left portion towards a lower 30 right portion. When the sampling bag 1, made liquid-tight by pinching, is shaken in the blender, the sample becomes suspended in its liquid or possibly in an added diluent. In Figure 2, there is shown a soiled area 18. The area 18 is symbolised by a fill pattern of alternating vertical lines of stripes. In the diagram, the upper level of the impregnated area 18 is drawn at a level somewhat below the nip line 15, although it may also be possible for it to be at the same level as the nip line 15. Although the area 18 is shown only on the sole width of the filtering partition 10, 5 the width of the soiled area extends all through the bag, the liquid having circulated in the lower portion 17 as a result of the blending. Figure 3 is a schematic illustration of the state of impregnation of a bag after its passage in the blender, after having been removed from the blender. The bag is then no longer pinched along the nip line 15. 10 The filtering partition 10 acts as a blotter and the suspension present at the level of the soiled surface 18 may ascend by capillarity along the filtering partition 10, possibly invisibly. The upper level of the soiled surface 18 containing a potentially contaminating liquid may be found, again due to capillarity, slightly above the nip line 15. It can be seen that a closure of the bag at the level of the fold line 19 located below the top level of the nip line 15 will result in a spillage of potentially contaminated matter outside of that which is illustrated in Figure 4. In the example illustrated in Figure 4, an upper portion of the bag 1 is folded onto the wall 3 along the fold line 19. According to another possibility, the upper portion of the bag could be folded onto the wall 2 (Figure 3). When folded once along the fold line 19 the part 20 above this fold line of the filtering partition 10 is folded down and contains that part of the liquid contained in the bag in the filtering partition above the fold line 19. Under the force of gravity this part of the contaminated liquid flows through the not 25 yet impregnated portion 21 of the filtering partition 10 until it spills out of the bag through the opening 4. This flow creates a reduced pressure in the filtering partition 10 and may initiate a siphon, thereby causing the flow to continue until the contents of the bag are almost entirely emptied. 30 Referring to Figure 5, in order to mitigate this risk of the medium in the bag from spilling out of the bag, the bag 1 according to the invention is marked with a visual indicator 24 for a correct position of closure of the bag after blending. 10 When the bag 1 according to the invention is closed along a fold line at the level of the visual indicator 24, as shown in Figures, there is no risk of contamination beyond the closure of the bag. Accordingly, the bag is marked with a visual indicator 24 of a correct, predetermined fold line closing position of the sampling bag after mixing. In the present description, an indicator for a correct closure is an indicator that allows a closure of the bag, thereby avoiding potentially contaminating leaks / capillary rises and their spillage out of the bag. The position of the line of the visual indicator 24 can be determined by knowing the line of closure of the bag in the blender. For example, the visual indicator 24 may be placed between the nip line 15 of the bag and the opening 4, for example in the middle. It may also be placed below the opening at a distance of one third of the height of the bag, plus or minus 5% of the height. Of course, other types of visual indicators may also be provided. For example, the visual indicator 24 may comprise two distinct lines, a lower line 25 and an upper line 26, which indicate the fold position, as illustrated in Figure 7. In this way a check can be made that the fold is neither too low nor too high. A sampling assembly is also proposed that comprises a blender for preparing samples for the purpose of carrying out analyses and / or microbiological tests, and a sampling bag 1 made of plastic material as described above. The height of the fold in the blender is thus exactly known. Finally, a method is proposed for the production of a sampling bag 1 intended for use in a blender for the preparation of samples for the purpose of carrying out analyses and / or microbiological tests, said bag possessing a bottom 5, lateral walls 2, 3 and an opening 4, and sub-divided with the aid of a filtering partition 10 that delimits a reception chamber 11 for a sample and a sampling chamber 12, in which the sampling is performed, comprising a step for marking said bag with a a visual indicator 24 of a correct, predetermined closing position of the bag after mixing. The method moreover comprises, prior to the step of marking, a step for determining the position of the visual indicator based on the position of closure of the bag when in the blender. Of course, the invention is not limited to the examples that have just been described and numerous modifications can be made to these examples without departing from the scope of the invention. Furthermore, the different characteristics, forms, variants and embodiments of the invention can be combined with one another 5 according to diverse combinations insofar as they are not incompatible or exclusive to one another. 20 02 24

Claims

1. Plastic sampling bag (1) intended for use in a blender for the preparation of samples for the purpose of carrying out analyses and / or microbiological tests, 5 said bag possessing a bottom (5), lateral walls (2, 3) and an opening (4), andsub-divided with the aid of a filtering partition (10) that delimits two chambers side by side and open from above, one chamber being a reception chamber (11) for a sample and the other chamber being a sampling chamber (12), in which the sampling is performed,10 characterised in that the bag is marked with a visual indicator of a correct,predetermined fold line closing position along which the sampling bag may be folded after mixing to prevent leakage via capillary action, and wherein the visual indicator is marked at a distance from the opening.15 2. A sampling bag according to the preceding claim, wherein the fold line visualindicator is located on the bag below the opening at a distance less than or | substantially equal to one third of the height of the bag.

3. Sampling kit comprising a blender for the preparation of samples for the purpose 20 of carrying out analyses and / or microbiological tests and a plastic sampling bag(1) according to one of claims 1 or 2.

4. Method for the production of a sampling bag (1) intended for use in a blender for the preparation of samples for the purpose of carrying out analyses and / or 25 microbiological tests, said bag possessing a bottom (5), lateral walls (2, 3) andan opening (4), and sub-divided with the aid of a filtering partition (10) that delimits a reception chamber (11) for a sample and a sampling chamber (12) in which the sampling is performed, comprising marking said bag before use, with a visual indicator for a correct closure position to form a fold line to prevent 30 leakage via capillary action, for the bag in use after the blending.

5. A method according to claim 4 also comprising, prior to the step of marking, a step for determining the position of the visual indicator, the position being between a nip line, defined by closure of the bag when in the blender during 35 blending, and the opening.

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