EP1559478A1 - Contamination shield - Google Patents

Abstract

A contamination barrier contains at least one water-insoluble hydrocarbon compound or hydrocarbon mixture. An independent claim is also included for a process for avoiding contamination when processing aqueous solutions in open and/or automatic systems.

Description

The present invention relates to a contamination barrier and a method for Avoiding contamination of aqueous solutions, which in particular by Carrying out and / or aerosol formation, for example when pipetting on open Systems arise.

In the field of biotechnology in particular, automation solutions, for safe and efficient processing, especially for a large one Number of samples, such as those incurred in HIV virus monotoring, searched. Preferably, this more and more fully automatic high-throughput workstations asked, which work in a very short time a very high number of samples, and always is dispensed with an additional manual use, but at the same time least Quantities of biological material to be detected.

However, currently common robot systems exhibit when working with biological material especially in the field of molecular biology and / or diagnostics a fundamental Problem on. Since the samples are usually in a plate-shaped body (such as For example, a rack), the individual sample containers open standing side by side, it comes, mainly by aerosol formation, but always again by mechanical carryover of sample material, during processing too Contamination of predominantly adjacent samples.

To avoid such (cross) contamination are already in the art some add-on modules and / or consumables for robotic systems known. So For example, hoods or, as in the Gebrausmusterschrift DE 200 06 546 U1 shown covering mats to protect multiple in a plate-shaped body trained and upwardly open reaction vessels disclosed. This kind of cover protects only the samples of a rack, for example, during transport and / or in the Bearing condition. However, when editing the individual samples on the rack occur continue to contaminate.

Further, the use of sterile consumables known in the art may also be used such as specially coated disposable pipettes and / or disposable filter tips the cross-contamination rate is reduced only, but not completely eliminated. So contaminations are still mainly in the ppm range also continue (for example in the field PCR diagnostics, where single molecules are detected) is a fundamental problem.

Furthermore, methods are known in which, such as in the European Patent EP 0011327 B1, the aqueous solution of water-soluble compounds be incorporated to avoid aerosol formation. Since these, however, with the Mix sample liquid and this may even change or to could cause undesirable side reactions, their use is extremely disadvantageous and especially conceivable in PCR diagnostics.

Furthermore, the most diverse were to protect against contamination of the samples Closure options, such as various lids, septa and / or filters etc. developed for single or multiple sample vessels. However, these have disadvantages in the Handling, especially in the field of automation on, for example, the opening and closing of caps, etc., especially individual samples, very time consuming and depending on the closure system is hardly feasible by machine. In addition, there is still the risk that the aerosols produced in the sample vessel escape during processing and thereby in the subsequent step when opening the adjacent sample vessel whose sample can be contaminated with sample material.

In addition, sample vessels with septa and / or thin filter materials are not in each Robotic or automatic pipetting variable, since only few pipette tips and / or pipette needles for the use of such sample containers suitable.

Since the state of the art does not disclose any known devices and / or a known method which could be used satisfactorily to avoid contamination, in particular in the field of automated PCR diagnostics, such a device or such a method is also disclosed can not derive from this, the present invention has the object to enable an efficient and reproducible processing of a high number of samples while avoiding contamination in the solutions to be analyzed in open and / or automated systems.

This object is achieved by providing a contamination barrier to avoid contamination of aqueous solutions in open and / or automated systems, which has at least one water-immiscible hydrocarbon and / or a hydrocarbon mixture. Thus, the object of the present invention is achieved by providing a method for preventing contamination in that, for processing aqueous solutions in open and / or automated systems, they are overcoated with at least one water-immiscible hydrocarbon or a hydrocarbon mixture.

The contamination barrier according to the invention is characterized in particular by its flexible use in a wide variety of sample vessels. It is particularly advantageous that the contamination barrier of the invention easily and quickly even in very small Sample vessels formed and can be removed again. In particular, can on a increased time-consuming and costly, manual or even mechanical use of Caps and / or septa etc. are dispensed with. Another advantage of Contamination barrier according to the invention is their flexible introduction into the Sample vessel, which, in contrast to the use of septa and / or filter materials, which are fixed in the sample vessel, the volume of the aqueous solution at any time can be varied without forming a cavity in which it is a Contamination-induced aerosol formation comes. Very particularly advantageous is the Use in very small volumes of aqueous solutions (eg in the ppm range and smaller).

Furthermore, results for the overlay of the contamination barrier according to the invention due to the water-immiscible hydrocarbons or hydrocarbon mixtures an advantageous field of use on almost any aqueous solution.

To process aqueous solutions in open and / or automated systems To avoid contamination is at least one solution to be analyzed Water immiscible hydrocarbon, applied by overcoating. The like The contamination barrier according to the invention applied to the aqueous solution settles like a film completely on the aqueous solution, thus preventing the penetration as well as the formation of aqueous aerosols. Advantageously, the inventive Contamination barrier preferably at least one substituted or unsubstituted, branched or unbranched hydrocarbon. Furthermore, the inventive Contamination barrier of a cyclic, saturated or unsaturated Hydrocarbon (such as cyclohexane, etc.) or from an aromatic hydrocarbon (such as benzene or toluene, etc.) exist or are formed, however, only those hydrocarbons are used which are not with Water are miscible. In addition, the hydrocarbons used according to the invention as substituents, for example, one or more halogen atom (s), nitro group (s) and / or amino group (s).

All of the abovementioned (hydrocarbon) compounds can be used individually or else in Mixtures (eg a hydrocarbon mixture such as mineral oil) are present.

For the purposes of the present invention, mineral oil is understood as meaning the liquid distillation products obtained from mineral raw materials, such as, for example, crude oil, lignite and hard coal, wood or peat, which consist essentially of mixtures of long-chain, aliphatic and saturated hydrocarbons.
Particularly suitable are distillation products or hydrocarbon mixtures, such as white oil and / or other paraffin oils containing mainly long-chain alkanes, preferably having 13 to 20, particularly preferably 14 to 16 carbon atoms.

For the purposes of the invention, hydrocarbons are, in the first place, branched or branched understood unbranched hydrocarbons, the 5 to 20, preferably 6 to 16, more preferably 8 to 12 carbon atoms. Very particularly preferred branched or unbranched alkanes having 8 to 12 carbon atoms are used, including, in turn, octane, nonane, decane and / or dodecane and mixtures thereof particularly preferred.

According to an advantageous embodiment of the present invention, the Contamination barrier according to the invention preferably for the coating of aqueous Solutions in open and / or automated systems with biological sample material used. For the purposes of the present invention, biological sample material is used Biopolymers understood that, on the one hand, naturally occurring macromolecules, such as For example, nucleic acids, proteins or polysaccharides, on the other hand may be synthetically prepared polymers, as long as they are the same or similar Blocks contain, like the natural macromolecules.

Surprisingly, it turned out that by a coating of aqueous Solutions containing preferably biological sample material with Hydrocarbons of the aforementioned type, in particular in the form of the invention Contamination barrier, especially in open, automated systems an efficient and reproducible avoidance of mainly aerosol contamination takes place.

Hereinafter, the present invention with reference to the accompanying drawings and Embodiments will be explained in more detail.

Fig. 1

die Bildung von Aerosolen aus einer wässrigen Lösung bei im Stand der Technik bekannten offenen Probengefäßen;

Fig. 2

eine auf eine wässrige Lösung überschichtete erfindungsgemäße Kontaminationsbarriere in einem offenen Probengefäß;

Fig. 3

einen schematischen aus dem Stand der Technik bekannten Pipetiervorgang aus einem offenen Probengefäß, bei dem ein Teil einer wässrigen Lösung unter Aerosolbildung entnommen wird;

Fig. 4

einen schematischen Pipetiervorgang aus einem offenen Probengefäß, bei dem ein Teil einer wässrigen Lösung unterhalb einer erfindungsgemäßen Kontaminationsbarriere ohne Aerosolbildung entnommen wird;

Fig. 5

einen schematischen Pipetiervorgang aus einem offenen Probengefäß, bei dem einer wässrigen Lösung unterhalb einer erfindungsgemäßen Kontaminationsbarriere ohne Aerosolbildung ein weiterer wasserlöslicher Teil hinzugegeben wird.

It shows:

Fig. 1

the formation of aerosols from an aqueous solution in open sample vessels known in the art;

Fig. 2

a contamination barrier superimposed on an aqueous solution according to the invention in an open sample vessel;

Fig. 3

a schematic pipetting process known from the prior art from an open sample vessel, wherein a portion of an aqueous solution is taken under aerosol formation;

Fig. 4

a schematic Pipetiervorgang from an open sample vessel, in which a portion of an aqueous solution is removed below a contamination barrier according to the invention without aerosol formation;

Fig. 5

a schematic Pipetiervorgang from an open sample vessel, in which an aqueous solution below a contamination barrier according to the invention without aerosol formation, a further water-soluble part is added.

It can clearly be seen from the prior art shown in FIGS. 1 and 3 that, for example by means of a pipetting device 6 or the like, by mechanical action during pipetting operations and / or mixing of the sample, etc., in a commercially available reaction vessel 1 a pipetting plate 2 (such as a microtiter plate, etc.) on a biological sample containing aqueous solution 3, the aerosols 4 form.
Such aerosol formation can, as soon as the aerosol 4 flows out of the reaction vessel 1, easily lead to contamination of adjacent reaction vessels.

By the contamination barrier 5 shown in FIGS. 2, 4 and 5 according to the invention Such a contamination-related aerosol formation is avoided because the aqueous Aerosols 4 can not penetrate the contamination barrier 5. The water-insoluble Contamination barrier 5 is in the reaction vessel 1 as a film on the aqueous Solution 3 in which the biological sample material is in dissolved form.

During the pipetting process, as shown in FIGS. 4 and 5, the one located in the reaction vessel 1 aqueous solution 3 or the sample in each case under the contamination barrier 5 processed. Due to the water-insoluble composition of the contamination barrier 5 The formation of aerosols 4 in both the immersion and retraction of the Pipetting device 6 excluded from the aqueous solution 3 and during mixing.

Also in the addition of a further aqueous solution to the sample shown in FIG. 5, when mixing the submitted aqueous solution 3 with the additional solution due to the contamination barrier 5 according to the invention not for aerosol formation of aqueous mixture 7.

Since the contamination barrier 5, as opposed to firmly introduced into reaction vessels Filters and / or septa, also very flexible, can at any time by means of a Pipetting device 6 the reaction vessel 1 variable amounts of aqueous solution. 3 taken or added without being between the surface of the aqueous solution 3 and the contamination barrier 5 forms a cavity, whereby in addition, the formation of aerosols 4 is avoided.

LIST OF REFERENCE NUMBERS

1

open reaction vessel

2

Pipetierplatte

3

aqueous solution

4

aerosol molecules

5

contamination barrier

6

pipetting

7

aqueous mixture (from sample solution added and added)

embodiments

On the basis of the following experimental procedures, the essential Contaminant sources (KQ) of open, automated pipetting systems, especially in fully automatic High-throughput workstations, so-called robotic systems (such as BioRobot Mdx / QIAGEN GmbH), and contaminations (K), mainly due to aerosol formation, but again and again by mechanical carryover of sample material arise, proven as well as the significant reduction of such contamination represented by the use of the contamination barrier according to the invention.

As evidence, cross-contamination tests were performed on samples with biological Sample material in the ppm range and smaller, as in common processes in the field of PCR diagnostics are used. The experiments were based on one common methods known in the art for the isolation and purification of Nucleic acids, in particular of viral RNA (used protocol: QIAamp 96 Virus Mdx V1.1 / QIAGEN GmbH).

As system accessories, reagents, consumables, etc. were also commercially available Kits (eg QIAamp 96 Virus BioRobot Kit / QIAGEN GmbH) etc., which are especially for the Use in robot systems are used.

For the experiment with alkane template (Examples 1b and 2b) was in common 96-well deepwell plates (hereinafter referred to as S-blocks) manually each 100 ul of dodecane submitted.

Evidence was not provided by mere observations during the individual Pipetting steps in the purification process, but also by the additional determination of actual nucleic acid contaminants in the negative samples in one subsequent downstream analysis (eg PCR, RT-PCR etc.). In addition to the essential Contamination sources of such systems show the following examples with reference to determined contamination rates (KR) significantly the effectiveness of the invention Contamination barrier.

Example 1:

a) mit einem Probenvolumen von 285 µl ohne Alkanvorlage und

b) mit einem Probenvolumen von 285 µl mit Alkanvorlage.

Cross-contamination tests performed

a) with a sample volume of 285 μl without alkane template and

b) with a sample volume of 285 μl with alkane template.

The automated process was started with the identification of the samples, the so-called loadcheck. As positive sample material (PP) hepatitis C virus material (arHCV) with an average concentration of 10 ⁸ - 10 ⁹ RNA copies / ml and as negative sample material (NP) negative plasma (eg citrated plasma / Breitscheid) was used. After the load check, 40 μl each of a commercially available protease (eg QIAGEN protease / QIAGEN GmbH) were pipetted into the S block and the system was heated to 56 ° C.
The addition of 285 .mu.l of sample material took place, as shown schematically below, in the "checkerboard pattern". In addition to each PP (+), an NP (-) was alternately pipetted into the S block (KQ 1!). Schematic representation of the plots of PP and NP in checkerboard pattern / S-block 1 2 3 4 5 6 7 8th 9 10 11 12 A + - + - + - + - + - + - B - + - + - + - + - + - + C + - + - + - + - + - + - D - + - + - + - + - + - + e + - + - + - + - + - + - F - + - + - + - + - + - + G + - + - + - + - + - + - H - + - + - + - + - + - +

Subsequently, the individual reaction solutions 305 .mu.l of a commercially available lysis buffer (eg Lysis Buffer AL / QIAGEN GmbH) added, this then by up and down Pipette mixed (KQ 2!) and then incubated for 10 minutes. In conclusion, were at intervals of about one minute per row of each reaction solution in each case twice 360 μl Ethanol (p.a. or at least 96%) to be pipetted (KQ 3!).

For the separation or purification of the nucleic acids isolated in this way, in each case 910 μl of lysate automatically into appropriate filter systems (eg QIAamp 96 plate / QIAGEN GmbH) transferred (KQ 4!) and under vacuum for 5 minutes at 25 ° C filtered (KQ 5!).

According to the experimental protocol (see above) loaded with the nucleic acid filters (B. Wash Buffer AW2 / QIAGEN GmbH z.) Were subsequently under vacuum with 800 μ l of a commercially available wash buffer (KQ 6) and then in a second washing step with 930 μ l of ethanol (pa or min 96%) (KQ 7!) and then dried the membranes to remove ethanol under vacuum and 60 ° C in an automated vacuum device (eg RoboVac / QIAGEN GmbH) (KQ 8!) ,

The purified nucleic acid was finally eluted from the filter system under vacuum for one minute with 50 μl and once with 100 μl of at least one commercially available elution buffer (eg Elution Buffer AVE / QIAGEN GmbH) (KQ 9!). The collected eluate was processed outside the automated pipetting system for the subsequent amplification process. To the eluate prepared for the RT-PCR, a commercially available enzyme mix (eg Mastermix / QIAGEN GmbH) was pipetted (KQ 10!), An RT-PCR was carried out to determine the nucleic acid contamination and the results were evaluated.

The two experimental runs (run 1al and 1all) without the introduction of dodecane were carried out with the following ar HCV dilution: 1x10 11 IU / ml + 148.5 ml NP = 1x10 9 IU / ml

Up to the addition of the elution buffer no observations could be made either in run 1al or in run 1all, which would have pointed to contamination in particular at the sources of contamination (KQ) 1-4.
Only in the course of the elution (KQ 7) could observations be made in this regard. Thus, for example, a distinct blistering was observed in the addition of the elution buffer, especially in row 12. Partially the bubbles burst when immersing and pulling out the pipette tips.
After elution, the outlet openings of the filter system (Nozzles) were as yellow as those of the PP in row 1 at the NP positions B, D, F (as well as in run 1al also H).

Lauf 1al: 9 K /48 NP ⇒ KR_{Lauf 1al} = 18,75 %

Lauf 1all: 2 K /48 NP ⇒ KR_{Lauf 1all} = 4,17%

After carrying out the RT-PCR, the following cross-contamination was determined:

Run 1al: 9 K / 48 NP ⇒ KR _{Run 1al} = 18.75%

Run 1all: 2 K / 48 NP ⇒ KR _{Run 1all} = 4.17%

This results in an average contamination rate (CR) of 11.46%.

The three experimental runs (runs 1bl, 1bII and 1bIII) with the introduction of dodecane were also carried out with the abovementioned ar HCV dilution: 1x10 11 IU / ml + 148.5 ml NP = 1x10 9 IU / ml

Run 1bIII was followed after, in Run 1bII, Row B due to the lack of PP task could not be evaluated. During the experiment could however, no specific incidents due to carryover of sample material during pipetting operations or aerosol formation.

Lauf 1bl: 1 K /42 NP ⇒ KR_{LauF 1bI} = 2,38 %

Lauf 1bll: 3 K /48 NP ⇒ KR_{Lauf 1bII} = 6,25 %

Lauf 1bIII: 3 K /48 NP ⇒ KR_{Lauf 1bIII} = 6,25 %

After carrying out the RT-PCR, the following cross-contamination was determined:

Run 1bl: 1 K / 42 NP ⇒ KR _{LauF 1bI} = 2.38%

Run 1bll: 3 K / 48 NP ⇒ KR _{Run 1bII} = 6.25%

Run 1bIII: 3 K / 48 NP ⇒ KR _{Run 1bIII} = 6.25%

This results in an average contamination rate (CR) of 4.96%.

After comparing the determined contamination rates it could be shown that by the use of dodecane the cross-contamination rate for the entire insulation and Separation method can be reduced by more than double (factor of 2.3).

Example 2:

a) mit einem Probenvolumen von 570 µl ohne Alkanvorlage und

b) mit einem Probenvolumen von 570 µl mit Alkanvorlage.

Cross-contamination tests performed

a) with a sample volume of 570 μl without alkane template and

b) with a sample volume of 570 μl with alkane template.

The automated process was started with the identification of the samples, the so-called loadcheck. As positive sample material (PP) hepatitis C virus material (arHCV) with an average concentration of 10 ⁸ - 10 ⁹ RNA copies / ml and as negative sample material (NP) negative plasma (citrated plasma / Breitscheid) was used. After the loadcheck, 80 μl each of a commercially available protease (eg QIAGEN Protease / QIAGEN GmbH) were pipetted into the S block and the system was heated to 56 ° C.
The addition of each 570 .mu.l of sample material was carried out, as already schematically shown in Table 1, in the "checkerboard pattern". In addition to each PP (+), an NP (-) was alternately pipetted into the S block (KQ 1!).

Subsequently, the individual reaction solutions 610 .mu.l of a commercially available Lysis buffer (eg Lysis Buffer AL / QIAGEN GmbH) was added, this then on and from pipette mixed (KQ 2!) and subsequently incubated for 10 minutes. Finally were each time twice each at a distance of one minute per row of each reaction solution 720 μl of ethanol (p.a or min. 96%) to be pipetted (KQ 3!).

To separate or purify the nucleic acids isolated in this way, in each case two times 910 μl of lysate were transferred automatically into appropriate filter systems (eg QIAamp 96 plate / QIAGEN GmbH) (KQ 4!) And filtered under vacuum for 5 minutes at 25 ° C. (KQ 5 !).
According to the experimental protocol (see above), the filters loaded with the nucleic acid were subsequently under vacuum in each case with 800 μl of a commercially available washing buffer (eg Wash Buffer AW2 / QIAGEN GmbH) (KQ 6!) And then in a second washing step with 930 μl ethanol (pa or at least 96%) (KQ 7!) and then dried the membranes to remove ethanol under vacuum and 60 ° C in an automated vacuum device (eg RoboVac / QIAGEN GmbH) (KQ 8!).
The purified nucleic acid was finally eluted under vacuum for one minute with 50 μl and once with 100 μl of at least one elution buffer (eg Elution Buffer AVE / QIAGEN GmbH) from the filter system (KQ 9!). The collected eluate was processed outside the automated pipetting system for the subsequent amplification process. To the eluate prepared for the RT-PCR, a commercially available enzyme mix (eg Mastermix / QIAGEN GmbH) was pipetted (KQ 10!), An RT-PCR was carried out to determine the nucleic acid contamination and the results were evaluated.

The two experimental runs (run 2al and 2all) without the introduction of dodecane were carried out with the following ar HCV dilution: 15ml 1x10 9 IU / ml + 22.5 ml NP = 4x10 8th IU / ml

Already with the addition of the lysis buffer in the S-block, the bubbles are already piling up to the Upper edge of the individual reaction vessels. In addition, the Pipetierspitzen (Tips) drove like that quickly out of the reaction vessels that partially the resulting bubbles burst (especially in position H5 and H10). Also with the second addition of the lysate caused by mixing in the S-block increased bubbles, which when removing the tips with were pulled up and / or burst.

Even with the addition of the elution buffer, both in the course 2al and in the run 2all Observations regarding contamination are made. For example, one was significant blistering during and after the addition of the elution buffer, in particular Series G as well as in position H6. Partly the bubbles burst here too when dipping and / or pulling out the tips. After elution, there were 1 in series the NP positions B, D, F and H the Nozzles under the QIAplate also yellow as in the PP.

Lauf 2al: 31 K /48 NP ⇒ KR_Lauf2al = 64,58 %

Lauf 2all: 34 K /48 NP ⇒ KR_{Lauf 2all} = 70,08 %

After carrying out the RT-PCR, the following cross-contamination was determined:

Run 2al: 31 K / 48 NP ⇒ KR _Run2al = 64.58%

Run 2all: 34 K / 48 NP ⇒ KR _{Run 2all} = 70.08%

This results in an average contamination rate (CR) of 67.33%.

At this point, it clearly shows that the pipetting steps increase with increasing sample volume are much more susceptible to cross-contamination, since here the S-block volume is fully exploited.

The two experimental runs (runs 2bI and 2bII) with the introduction of dodecane were also carried out with the abovementioned ar HCV dilution: 15ml 1x10 9 IU / ml + 22.5 ml NP = 4x10 8th IU / ml

In order to better observe the effect of dodecane coating on the reduction or prevention of blistering, etc., the dodecane used was previously stained with Sudan black.
During the entire experiment, however, no special incidents with regard to contamination could be observed. Also, the Nozzles on the QIAplate had no residues or discoloration after elution as already mentioned under Example 1b).

Lauf 2bl: 6 K /48 NP ⇒ KR_{Lauf 2bl} = 12,50 %

Lauf 2bII:10 K/48 NP ⇒ KR_{Lauf 2bII} = 20,83 %

After carrying out the RT-PCR, the following cross-contamination was determined:

Run 2bl: 6 K / 48 NP ⇒ KR _{Run 2bl} = 12.50%

Run 2bII: 10 K / 48 NP ⇒ KR _{Run 2bII} = 20.83%

This results in an average contamination rate (CR) of 16.67%

After comparing the calculated contamination rates, it could thus be shown that through the use of dodecane, the cross contamination rate for the entire insulation and separation processes with higher sample and reaction volumes even by at least the factor 4 can be reduced.

However, as already mentioned above, such an overall process has quite a few Error or contamination sources on. To get the effect of the invention To determine contamination barrier for a single pipetting step were over In this series of experiments, individual samples (preferably NP) taken and by RT-PCR analyzed. Based on the observations made in Examples 1b and 2b, that by overlaying with dodecane the formation of bubbles respectively Aerosols in particular in the first process steps (in the field of Contamination sources 1 to 4) by the immersion and extraction of the pipetting tips was prevented, samples were taken at these points of the overall process and analyzed. None of these samples had nucleic acid contaminants. For individual Process steps can thus by the use of dodecane (cross) contamination even avoided altogether.

Further experiments showed that the use of dodecane also in the pipetting steps Downstream analyzes (such as RT-PCR) have been successful in reducing this of (cross) contamination can be achieved. For example, in others Cross-contamination tests the commercially available enzyme mixture necessary for an RT-PCR (eg Mastermix / QIAGEN GmbH) to a sample coated with dodecane. Again, the negative samples in the test series with the invention Contamination barrier significantly less to no contamination.

However, overlaying with the contamination barrier according to the invention is suitable not just for any kind of pipetting. According to a further embodiment of the present invention, the contamination barrier according to the invention in other Modules of sample processing, in which (cross) contamination occur, used become. Thus, the use of the contamination barrier according to the invention prevents For example, in an equally advantageous manner, cross-contamination caused by aerosol formation, when overturning with wash buffers, by dispensing with a dispenser he follows.

Claims (18)

Contamination barrier to avoid contamination of aqueous solutions in open and / or automated systems that do not have at least one with water having miscible hydrocarbon or a hydrocarbon mixture. Contamination barrier according to claim 1, characterized in that it comprises an unsubstituted hydrocarbon. Contamination barrier according to claim 1, characterized in that it comprises a substituted hydrocarbon. Contamination barrier according to one of claims 1 to 3, characterized in that it comprises a cyclic, saturated or unsaturated hydrocarbon. Contamination barrier according to one of claims 1 to 3, characterized in that it comprises a branched and / or unbranched acyclic hydrocarbon. Contamination barrier according to one of claims 1 to 5, characterized in that the hydrocarbon has 5 to 20, preferably 6 to 16, particularly preferably 8 to 12 carbon atoms. Contamination barrier according to one of claims 1 to 6, characterized in that it has as a hydrocarbon particularly preferably a branched or unbranched alkane, preferably having 8 to 12 carbon atoms. Contamination barrier according to claim 7, characterized in that it has as alkane preferably octane, nonane, decane and / or dodecane and mixtures thereof. Contamination barrier according to one of claims 1 to 8, characterized in that it comprises mineral oil as a hydrocarbon mixture. A process for the prevention of contamination, characterized in that when processing aqueous solutions in open and / or automated systems, these are overcoated with at least one water-immiscible hydrocarbon or a hydrocarbon mixture. A method according to claim 10, characterized in that for overlaying an unsubstituted hydrocarbon is used. A method according to claim 10, characterized in that a substituted hydrocarbon is used for the overlay. Method according to one of claims 10 to 12, characterized in that a cyclic, saturated or unsaturated hydrocarbon is used. Method according to one of claims 10 to 12, characterized in that a branched and / or unbranched acyclic hydrocarbon is used. Method according to one of claims 10 to 14, characterized in that a hydrocarbon having 5 to 20, preferably 6 to 16, particularly preferably 8 to 12 carbon atoms is used. Method according to one of claims 10 to 15, characterized in that as the hydrocarbon is particularly preferably a branched or unbranched alkane, preferably having 8 to 12 carbon atoms is used. A method according to claim 16, characterized in that as alkane preferably octane, nonane, decane and / or dodecane and mixtures thereof are used. Method according to one of claims 10 to 17, characterized in that mineral oil is used as the hydrocarbon mixture.

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