Non-dry aqueous phase system, preparation method and application thereof, and trace solution system

Abstract

The invention discloses a non-dry water phase system, a preparation method and application thereof, and a trace solution system. At least one hygroscopic inorganic salt is dissolved in the water phase system; the total concentration of the hygroscopic inorganic salts is greater than or equal to 0.05 g / mL; under the conditions that RH is larger than or equal to 10% and T is smaller than or equal to 40 DEG C, the volume of the water phase system per unit volume is stabilized within a threshold volume range; the unit volume is V0, and the range of the threshold volume Vt is 0.20 V0 < = Vt < = 1.20 V0. The water phase system provided by the invention can keep the volume stable for a long time, and can effectively resist evaporation at low humidity and high temperature.

Description

Technical Field

[0001] This invention belongs to the field of solution preparation technology, specifically relating to a non-drying aqueous phase system, its preparation method, application, and micro-solution system. Background Technology

[0002] Water-based droplets, especially tiny ones, can rapidly shrink or even dry out completely in the air, particularly in low-humidity environments, due to water evaporation. This phenomenon is a pressing problem to be solved in many scientific research and industrial applications. For example, in chemical analysis, the evaporation of trace reaction droplets can lead to changes in reactant concentrations, affecting the accuracy of detection results; in fields such as microscopic observation, material self-assembly, and inkjet printing, rapid droplet evaporation limits the operating time window and the stability and uniformity of the final product. Currently, the main technologies to prevent droplet evaporation are as follows: (1) Oil-phase encapsulation method, which involves encapsulating water-phase droplets in an oil-phase medium to form an oil film to block water evaporation. This method is relatively complex to operate, and the presence of the oil phase may interfere with certain chemical reactions, biological experiments, or optical detection; the oil film may also be unstable or unsuitable for all application scenarios. (2) Humidification environment method, which involves placing droplets in a high-humidity environment, such as using a dedicated humidity control chamber, to slow down the evaporation rate. This method requires additional equipment to control and maintain a high-humidity environment, increasing the complexity and cost of the system, and is not suitable for scenarios that require operation in an open, low-humidity environment. (3) Adding polymers: Certain polymers are added to the droplets. These polymers can form a thin film on the droplet surface or change the physicochemical properties of the solution to slow down evaporation. However, the introduction of polymers may change the original properties of the droplets, such as viscosity and surface tension, and may even interact with the components within the droplets, affecting their original function. Moreover, the effect of slowing down evaporation is limited at extremely low humidity. (4) Replacing some water with other non-volatile solvents: For example, adding polyols such as glycerol. Although this can slow down evaporation, it changes the solvent system and may not be suitable for applications in pure water systems.

[0003] The four existing technologies mentioned above still have shortcomings in terms of ease of operation, cost, universality, and effectiveness under specific low humidity conditions. More seriously, these technologies may cause a significant deviation between the droplet environment and the pure water environment, thus affecting the final results of droplet experiments. Therefore, developing a method that can keep droplets stable for extended periods under low humidity and high temperature conditions has significant application value.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of the present invention, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0005] To address the aforementioned problems in the prior art, this invention provides a non-drying aqueous phase system, its preparation method, applications, and a trace solution system. The technical problem to be solved by this invention is achieved through the following technical solution: In a first aspect, the present invention provides a non-drying aqueous phase system, wherein at least one hygroscopic inorganic salt is dissolved in the aqueous phase system; the total concentration of the hygroscopic inorganic salt is greater than or equal to 0.05 g / mL; Under the conditions of RH≥10% and T≤40℃, the volume of the aqueous phase system per unit volume is stable within the threshold volume range; wherein, the unit volume is the liquid volume taken in the actual application of the aqueous phase system; The unit volume is V0, and the threshold volume is V. t The range is 0.20 V0≤V t ≤1.20 V0.

[0006] In one embodiment of the present invention, the threshold volume V t The range is 0.30V0≤V t ≤1.05 V0.

[0007] In one embodiment of the present invention, the hygroscopic inorganic salt is at least one of calcium chloride, lithium chloride, and magnesium chloride.

[0008] In one embodiment of the present invention, the hygroscopic inorganic salt is calcium chloride, and the concentration C1 of the calcium chloride is: 0.10 g / mL ≤ C1 < concentration of saturated calcium chloride solution.

[0009] In one embodiment of the present invention, the hygroscopic inorganic salt is lithium chloride, and the concentration C2 of the lithium chloride is: 0.05 g / mL ≤ C2 < concentration of saturated lithium chloride solution.

[0010] In one embodiment of the present invention, the hygroscopic inorganic salt is magnesium chloride, and the concentration C3 of the magnesium chloride is: 0.10 g / mL ≤ C3 < concentration of saturated magnesium chloride solution.

[0011] Secondly, the present invention provides a method for preparing the above-mentioned non-drying aqueous phase system, comprising the following steps: S1. Obtain the relative humidity RH1 of the target environment; the target environment is the actual application environment of the aqueous system; S2. Add at least one hygroscopic inorganic salt to water to obtain an aqueous phase system with a water activity of Aw1; wherein, the saturated water activity ≤ Aw1 ≤ 1.5 RH1.

[0012] Thirdly, the present invention provides a trace solution system comprising the above-mentioned non-dried aqueous phase system and a solute dissolved in the non-dried aqueous phase system.

[0013] Fourthly, the present invention provides an application of the above-mentioned non-dried aqueous phase system in a trace solution system.

[0014] In one embodiment of the present invention, the trace solution system is a contactless suspension solution system.

[0015] Compared with the prior art, the beneficial effects of the present invention are as follows: 1. This invention increases hydration by adding hygroscopic inorganic salts to water, enabling the aqueous system to maintain volume stability for extended periods even at relative humidity as low as 10% and temperatures as high as 40°C. The amount and type of hygroscopic inorganic salts added can be adjusted to ensure the prepared aqueous system remains volume stable over a long period, effectively resisting evaporation under low humidity and high temperature conditions.

[0016] 2. The preparation method of the non-drying aqueous phase system provided by the present invention uses low-cost and readily available raw materials, and the preparation process is simple and does not require complex and expensive equipment.

[0017] 3. The non-drying aqueous phase system provided by the present invention can be used, but is not limited to, as a solvent for trace solution systems. The application environment of this aqueous phase system is not limited to closed environments or special atmospheres. It can be used in open or semi-open low humidity environments. The application scenarios include, but are not limited to, various scientific research or industrial production processes that require maintaining a stable solution volume.

[0018] 4. The aqueous system provided by this invention has water-based characteristics, which is more suitable for many aqueous reactions or biological applications compared with water-in-oil solutions or solutions containing large amounts of organic solvents. Furthermore, the relative humidity of the prepared aqueous system can be adjusted by selecting inorganic salts with different hygroscopic properties to meet the requirements of the actual operating environment.

[0019] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments. Attached Figure Description

[0020] Figure 1 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.1 g / mL in an acoustic levitation device after 10 min, as provided in Embodiment 2 of the present invention. Figure 2 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.1 g / mL in an acoustic levitation device for 30 minutes, as provided in Embodiment 2 of the present invention. Figure 3 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.1 g / mL in an acoustic levitation device after 1 hour, as provided in Embodiment 2 of the present invention. Figure 4This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.1 g / mL after 12 hours in an acoustic levitation device, as provided in Embodiment 2 of the present invention. Figure 5 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.1 g / mL in an acoustic levitation device after 24 hours, as provided in Embodiment 2 of the present invention.

[0021] Figure 6 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in the initial stage of the acoustic levitation device, as provided in Embodiment 3 of the present invention.

[0022] Figure 7 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in an acoustic levitation device after 10 minutes, as provided in Embodiment 3 of the present invention. Figure 8 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in an acoustic levitation device after 30 minutes, as provided in Embodiment 3 of the present invention. Figure 9 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in an acoustic levitation device after 1 hour, as provided in Embodiment 3 of the present invention. Figure 10 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in an acoustic levitation device after 12 hours, as provided in Embodiment 3 of the present invention. Figure 11 This is a characterization diagram of droplets formed in an aqueous calcium chloride system with a concentration of 0.35 g / mL in an acoustic levitation device after 24 hours, as provided in Embodiment 3 of the present invention. Detailed Implementation

[0023] To further illustrate the technical means and effects adopted by the present invention to achieve the intended purpose, the following, in conjunction with the accompanying drawings and specific embodiments, provides a detailed description of a non-drying aqueous phase system, its preparation method, applications, and micro-solution system based on the present invention.

[0024] The foregoing and other technical contents, features, and effects of the present invention will be clearly presented in the following detailed description of specific embodiments in conjunction with the accompanying drawings. Through the description of the specific embodiments, a more in-depth and concrete understanding can be gained of the technical means and effects adopted by the present invention to achieve its intended purpose. However, the accompanying drawings are for reference and illustration only and are not intended to limit the technical solutions of the present invention.

[0025] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified.

[0026] The terms “include,” “contain,” or any other variation are intended to cover non-exclusive inclusion, such that an article or device that includes a list of elements includes not only those elements but also other elements not expressly listed.

[0027] The term "not dry" means that, under the conditions of RH≥10% and T≤40℃ required by this invention, the volume change of a unit volume of the aqueous phase system is within a preset threshold volume range within a preset time period.

[0028] The term "micro-solution system" refers to a solution system in which a unit volume (e.g., 1 µL, 50 µL, or 1 mL, etc.) of a non-dried aqueous phase is used as the solvent.

[0029] This invention provides a non-drying aqueous phase system in which at least one hygroscopic inorganic salt is dissolved; the total concentration of the hygroscopic inorganic salt is greater than or equal to 0.05 g / mL. Under conditions of RH ≥ 10% and T ≤ 40℃, the volume of a unit volume of the aqueous phase system remains stable within a threshold volume range; wherein, the unit volume is the liquid volume taken in the actual application of the aqueous phase system. The unit volume is V0, and the threshold volume is V0. t The range is 0.20 V0≤V t ≤1.20 V0.

[0030] This invention enhances hydration by adding a hygroscopic inorganic salt to water, enabling the aqueous system to maintain long-term volume stability even at relative humidity as low as 10% and temperatures as high as 40°C. When a unit volume of liquid is taken from the aqueous system for practical application, the volume change per unit volume (V0) is controlled within 0.20 V0 to 1.20 V0, based on the water activity (Aw) of the prepared aqueous system and the relative humidity and temperature of the application environment. Excessive volume change per unit volume of the aqueous system solution is avoided, as it affects the concentration of the solute dissolved in that unit volume, potentially leading to inaccurate measurements, insufficient chemical reaction time, or a shortened application window for the material. Thus, by using a hygroscopic inorganic salt to improve the volume stability of the aqueous system under low humidity and high temperature conditions, a new trace solvent option is provided for various fields.

[0031] For example, in microchemical reactions, the non-drying aqueous phase system provided by this invention is used as a solvent, where unit volume refers to the volume of solvent required in each reaction vessel.

[0032] Furthermore, the threshold volume V of the aqueous phase solution with a unit volume of V0 in the application environment. t The range is 0.30V0≤V t ≤1.05 V0. By controlling the volume of the aqueous solution per unit volume within a small range, the aqueous system becomes more stable under application conditions.

[0033] In one example, the hygroscopic inorganic salt can be at least one of calcium chloride, lithium chloride, and magnesium chloride. That is, the hygroscopic inorganic salt in the non-dried aqueous phase system can be a single calcium chloride, lithium chloride, or magnesium chloride; it can also be a combination of calcium chloride and lithium chloride, lithium chloride and magnesium chloride, calcium chloride and magnesium chloride, or a combination of all three. The choice can be made based on the specific application environment.

[0034] In another example, the hygroscopic inorganic salt could also be potassium chloride, but potassium chloride has a high Aw even in saturated solutions (e.g., Aw is about 0.84 at 25°C). Therefore, potassium chloride can be used in combination with one or more of calcium chloride, lithium chloride, and magnesium chloride to achieve the preparation of a non-drying aqueous phase system.

[0035] In one example, under the conditions of RH≥10% and T≤40℃, the hygroscopic inorganic salt is a single calcium chloride, and the concentration of calcium chloride C1 is: 0.10g / mL≤C1<concentration of saturated calcium chloride solution.

[0036] Furthermore, the concentration of calcium chloride, C1, is: 0.20 g / mL ≤ C1 < 0.50 g / mL, which makes the threshold volume V of the aqueous phase system with a unit volume of V0 in the application environment... t The range satisfies 0.30 V0≤V t ≤1.05 V0.

[0037] In one example, under the conditions of RH≥10% and T≤40℃, the hygroscopic inorganic salt is a single lithium chloride, and the concentration of lithium chloride C2 is: 0.05g / mL≤C2<concentration of saturated lithium chloride solution.

[0038] Furthermore, the lithium chloride concentration C2 is: 0.10 g / mL ≤ C2 < 0.50 g / mL, which makes the threshold volume V of the aqueous phase system with a unit volume V0 in the application environment... t The range satisfies 0.30 V0≤V t ≤1.05 V0.

[0039] In one example, under the conditions of RH≥10% and T≤40℃, the hygroscopic inorganic salt is a single magnesium chloride, and the concentration C3 of the magnesium chloride is: 0.10 g / mL≤C3<concentration of saturated magnesium chloride solution.

[0040] Furthermore, the concentration of magnesium chloride, C3, is: 0.15 g / mL ≤ C3 < 0.40 g / mL, which makes the threshold volume V of the aqueous phase system with a unit volume of V0 in the application environment... t The range satisfies 0.30 V0≤V t ≤1.05 V0.

[0041] The present invention also provides a method for preparing the above-mentioned non-drying aqueous phase system, the method comprising the following steps: S1. Obtain the relative humidity RH1 of the target environment; the target environment is the actual application environment of the aqueous system; S2. Add at least one hygroscopic inorganic salt to water to obtain an aqueous phase system with a water activity of Aw1; wherein, the saturated water activity ≤ Aw1 ≤ 1.5 RH1.

[0042] For example, the water in step S2 can be deionized water, distilled water, or ultrapure water (resistivity > 18 MΩ·cm).

[0043] The preparation method provided by this invention enhances hydration by adding inorganic salt ions to water, offering a simple, economical, and efficient method for preparing an aqueous system that resists evaporation and maintains long-term volume and morphological stability under low relative humidity (e.g., 10%) and specific ambient temperatures (e.g., not exceeding 40°C). This allows even small volumes (e.g., less than 1 mL of aqueous solution) to maintain volume stability over extended periods. Thus, this invention significantly reduces the vapor pressure (or water activity Aw) of water in droplets by utilizing high concentrations of hygroscopic salts, making it difficult to evaporate under specific low-humidity conditions, and even achieving a dynamic equilibrium with ambient moisture.

[0044] For example, the hygroscopic inorganic salt can be at least one of calcium chloride, lithium chloride, and magnesium chloride. The hygroscopic inorganic salt used is an analytical grade inorganic salt raw material.

[0045] For example, in step S1, the relative humidity RH1 ≥ 10% and the ambient temperature is less than or equal to 40°C.

[0046] The present invention also provides a trace solution system, comprising the non-dried aqueous phase system disclosed in any of the above embodiments, and a solute dissolved in the non-dried aqueous phase system.

[0047] For example, the micro-solution system can be: 1. A solution system for a slow aqueous polymerization reaction based on calcium chloride, such as the polymerization reaction of acrylamide, acrylic acid, etc. 2. An enzyme-catalyzed reaction system within droplets, such as a solution system for peroxidation or hydroxide reactions. 3. A solution system for nucleic acid amplification reactions such as DNA / RNA, such as the PCR droplet reaction. 4. For printing biomaterials (such as proteins, hydrogels), where water evaporation can easily lead to protein denaturation, the aqueous system provided by this invention can buffer local moisture changes, improve printing stability, and at the same time, reduce the coffee ring effect caused by particle movement towards the edges, maintaining a more uniform humidity gradient.

[0048] The present invention also provides an application of a non-dried aqueous phase system in a trace solution system.

[0049] In one example, the trace solution system is a solution system suspended without contact. Suspension technology enables applications where a unit volume of non-dry aqueous phase system (the unit volume of non-dry aqueous phase system exists in the form of droplets) is suspended in a suspended state. For example, the suspension technology could be acoustic levitation or electromagnetic levitation, etc.

[0050] The following description, in conjunction with specific embodiments, provides further details.

[0051] Example 1 S1. The relative humidity of the target environment is 20% and the temperature is 25℃.

[0052] S2. Weigh 1g of anhydrous CaCl2 powder and slowly add it to about 4g of deionized water. Stir continuously until completely dissolved to obtain an aqueous phase system with a CaCl2 concentration of 0.2g / mL. The water activity Aw of this aqueous phase system is close to 0.20.

[0053] A unit volume (5 µL) of the aqueous phase system prepared in Example 1 was measured.

[0054] The testing process includes: Experimental group: Accurately pipette 5µL of the prepared aqueous system with a CaCl2 concentration of 0.2g / mL. Drop this 5µL aqueous system containing the CaCl2 concentration of 0.2g / mL onto the center of a pre-hydrophobic glass slide. Immediately transfer the glass slide with the droplet to a constant temperature and humidity chamber set to 20% relative humidity and 25℃.

[0055] Control group: A 5µL drop of pure deionized water was added to another identical pre-hydrophobic glass slide and placed together in a constant temperature and humidity chamber with a relative humidity of 20% and a temperature of 25℃.

[0056] The shape and size (diameter) of two droplets were observed and recorded every 30 seconds using a camera. The photos were then compiled and their volume changes were calculated and analyzed. The results are shown in Table 1.

[0057] Table 1. Percentage change in droplet volume over different time periods

[0058] Where - represents the percentage decrease in volume at the corresponding time point relative to the initial volume.

[0059] The control group of pure water droplets: In an environment of 20%RH and 25℃, the droplets of pure deionized water evaporated rapidly, and the droplets almost completely evaporated and disappeared within one hour.

[0060] The CaCl2 solution droplets in the experimental group exhibit a significantly slower evaporation rate due to their extremely low water activity (Aw ≤ 0.20) matching the ambient relative humidity (RH = 20%). Initially, a very slight volume adjustment (water loss or moisture absorption) may occur due to the minute difference between the water activity Aw and the relative humidity RH. Subsequently, the droplet volume tends to stabilize, maintaining its steady-state volume for 24 hours or even longer (losing only 40% of its volume), demonstrating a remarkable "non-drying" characteristic.

[0061] Example 2 S1. The relative humidity of the target environment is 20% and the temperature is 25℃.

[0062] S2. Weigh 0.5g of anhydrous CaCl2 powder and slowly add it to about 4.5g of deionized water. Continue stirring until completely dissolved to obtain a CaCl2 aqueous phase system with a concentration of 0.1g / mL.

[0063] A unit volume (5 µL) of droplets was taken from the aqueous system prepared in Example 2 for suspension detection.

[0064] The testing process includes: Experimental group: 5µL of CaCl2 with a concentration of 0.1g / mL was pipetted into an aqueous system and suspended in a constant temperature and humidity chamber (RH=20%, T=25℃) using an acoustic levitation device (40 kHz frequency).

[0065] Control group: 5µL of ultrapure water droplets were pipetted and suspended in a constant temperature and humidity chamber (RH=20%, T=25℃) using an acoustic levitation device (40 kHz frequency).

[0066] See Figures 1-5 The shape and size (diameter) of two droplets were observed and recorded every 30 seconds using a camera, and the changes in volume were calculated and analyzed by organizing the photos. The results are shown in Table 2.

[0067] Table 2. Percentage change in droplet volume over different time periods

[0068] Where - represents the percentage decrease in volume at the corresponding time point relative to the initial volume.

[0069] Combination Figures 1-5 The results in Table 2 show that the ultrapure water droplets in the control group were completely evaporated within 1 hour, while the 0.1 g / mL calcium chloride droplets in the experimental group had a larger initial volume change, and after 1 hour, they basically reached a dynamic equilibrium with the environment, maintaining the droplets in a non-drying state.

[0070] Example 3 The difference from Example 2 is that the relative humidity of the target environment in S1 is 50%; and in S2, a CaCl2 aqueous phase system with a concentration of 0.35 g / mL is obtained. The rest is the same as in Example 2.

[0071] The detection was performed using the same method as in Example 2, such as... Figures 6-11 As shown, the shape and size (diameter) of the droplets were recorded, and the images were organized to calculate and analyze their volume changes. The results are shown in Table 3.

[0072] Table 3. Percentage change in droplet volume over different time periods

[0073] Where - indicates the percentage decrease in volume at the corresponding time point relative to the initial volume, and + indicates the percentage increase in volume at the corresponding time point relative to the initial volume.

[0074] according to Figures 6-11 As shown in Table 3, the ultrapure water droplets in the control group completely evaporated within 1 hour. In the experimental group, Figure 6 The diagram illustrates the initial (0 min) droplet volume of the experimental group. It can be seen that... Figure 7 and Figure 8 The droplet volume increased slightly. This is because the 0.35 g / mL calcium chloride droplets in the experimental group initially expanded due to the Aw being lower than the ambient relative humidity (50%). After about 6 hours, the calcium chloride droplets reached an equilibrium with the ambient temperature and humidity, and maintained a basically constant volume from 24 to 48 hours, achieving the effect of the droplets not drying out for a long time.

[0075] In the application schemes of Examples 2 and 3, the droplets are freely suspended by acoustic radiation force, eliminating the influence of the substrate on the evaporation path. This verifies the effectiveness of the non-drying aqueous phase system provided by this invention in contactless scenarios, making it suitable for cutting-edge fields such as microgravity simulation and containerless chemical reactions, and providing a new option for the application of trace solvents in multiple fields. In addition, contactless operation avoids surface tension interference, the droplets can be freely observed at 360°, and the water activity is controlled only by salt concentration to maintain the characteristics of the pure water system, expanding the ability to stably control droplets from microliters (μL) to milliliters (mL) in open, low-humidity environments.

[0076] The above description, in conjunction with specific preferred embodiments, provides a further detailed explanation of the present invention. It should not be construed that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art, various simple deductions or substitutions can be made without departing from the concept of the present invention, and all such modifications and substitutions should be considered within the scope of protection of the present invention.

Claims

1. A non-drying aqueous phase system, characterized in that, The aqueous system contains at least one hygroscopic inorganic salt dissolved in it; the total concentration of the hygroscopic inorganic salt is greater than or equal to 0.05 g / mL. Under the conditions of RH≥10% and T≤40℃, the volume of the aqueous phase system per unit volume is stable within the threshold volume range; wherein, the unit volume is the liquid volume taken in the actual application of the aqueous phase system; The unit volume is V0, and the threshold volume is V. t The range is 0.20 V0≤V t ≤1.20 V0.

2. The non-drying aqueous phase system according to claim 1, characterized in that, The threshold volume V t The range is 0.30V0≤V t ≤1.05 V0.

3. The non-drying aqueous phase system according to claim 2, characterized in that, The hygroscopic inorganic salt is at least one of calcium chloride, lithium chloride, and magnesium chloride.

4. The non-drying aqueous phase system according to any one of claims 1-3, characterized in that, The hygroscopic inorganic salt is calcium chloride, and the concentration C1 of the calcium chloride is: 0.10 g / mL ≤ C1 < concentration of saturated calcium chloride solution.

5. The non-drying aqueous phase system according to any one of claims 1-3, characterized in that, The hygroscopic inorganic salt is lithium chloride, and the concentration C2 of the lithium chloride is: 0.05 g / mL ≤ C2 < concentration of saturated lithium chloride solution.

6. The non-drying aqueous phase system according to any one of claims 1-3, characterized in that, The hygroscopic inorganic salt is magnesium chloride, and the concentration C3 of the magnesium chloride is: 0.10 g / mL ≤ C3 < concentration of saturated magnesium chloride solution.

7. A method for preparing a non-drying aqueous phase system according to any one of claims 1-6, characterized in that, Includes the following steps: S1. Obtain the relative humidity RH1 of the target environment; the target environment is the actual application environment of the aqueous system; S2. Add at least one hygroscopic inorganic salt to water to obtain an aqueous phase system with a water activity of Aw1; wherein, the saturated water activity ≤ Aw1 ≤ 1.5 RH1.

8. A trace solution system, characterized in that, It includes the non-dried aqueous phase system as described in any one of claims 1-6, and the solute dissolved in the non-dried aqueous phase system.

9. The application of the non-dried aqueous phase system according to any one of claims 1-6 in trace solution systems.

10. The application according to claim 9, characterized in that, The trace solution system is a non-contact suspension solution system.

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