Patent Description:
From the viewpoint of environmental sanitation and food hygiene, the establishment of technology for measuring the concentrations in liquids of various substances that may have toxicity is required.

Of these substances, measuring the concentration of a gas is particularly difficult because the concentration of a gas dissolved in a liquid is very low. In addition, if the liquid contains a compound other than the gas, removal of the compound or concentration of the liquid is required.

<CIT> discloses a method for detecting volatile organic content in water using a specific sampling and detection device also disclosed therein, the method comprising the steps of (<NUM>) placing a sampler in the to-be-detected water body, introducing a purge gas into the sampler and then into a gas detector for detection and (<NUM>) obtaining the concentration of volatile organic compounds in the to-be-detected water body according to detection results obtained by the gas detector and a standard sample concentration curve.

<CIT> relates to a method for determining the total petroleum hydrocarbon (TPH) content in soil and groundwater, comprising the steps of (A) collecting a sample from an environment contaminated with oil; (B) obtaining a first oil-containing extract by adding an extraction solvent to the sample and then shaking it; (C) stirring and leaving a mixed solution in which a standard solution is added to the first oil-containing extract obtained in step (B) and obtaining a first oil concentration by measuring the turbidity of the left mixed solution; (D) obtaining a second oil-containing extract from the sample according to <CIT> of a soil contamination process test standard; (E) obtaining a second oil concentration by performing gas chromatography (GC) analysis on the oil concentration in the second oil-containing extract; (F) obtaining a concentration value difference between the first and second oil concentrations; and (G) obtaining the oil concentration of a new sample by correcting the first oil concentration obtained in the steps (A)-(C) with the concentration value difference obtained in step (F) with respect to the new sample.

In light of the above circumstances, an object of the present invention is to provide a method for predicting the concentration of a gas dissolved in a compound-containing liquid, without removing the compound in the liquid or concentrating the liquid.

As a result of extensive research to achieve the above object, the inventors found that the step of removing a compound or concentrating a liquid can be omitted by calculating a predetermined coefficient. Based on this finding, the inventors conducted further research, and the present invention was accomplished.

Specifically, the present invention provides a method for predicting a gas concentration, comprising:.

Preferred embodiments of the invention are as defined in the appended dependent claims and/or as disclosed in the following detailed description.

According to the present method, the concentration of a gas dissolved in a liquid containing a compound can be predicted without removing the compound in the liquid or concentrating the liquid.

The present method comprises the steps (<NUM>)-(<NUM>) as set out above and explained in more detail below:.

In step (<NUM>), the gas is exposed, under the same conditions X, to a specimen A comprising a liquid that contains a compound; and to a specimen B comprising a liquid that contains the compound in a concentration lower than the concentration of the compound in the specimen A.

In the liquid containing a compound, the compound may be completely dissolved, may not be completely dissolved, or may be present as a solid in the liquid without being dissolved at all.

Examples of specimen A include one or more members selected from cell culture liquids (medium), river water, industrial waste water, foods, specimens derived from a living subject, and plant extracts. The same applies to the specimen B. In other words, it is preferable that both the specimens A and B are each one or more of cell culture liquids (medium), river water, industrial waste water, foods, specimens derived from a living subject, and plant extracts. The specimens derived from a living subject may be derived from a human or an animal. There is no limitation thereto; examples include blood, plasma, serum, urine, saliva, spinal fluid, bile, sweat, and tears.

The specimen A comprises the liquid containing a compound, as mentioned above. The specimen A is preferably the liquid containing a compound itself; however, the specimen A may be formed by adding other component(s) to the liquid containing a compound.

In the specimens A and B, the liquid containing a compound is preferably a substance that is liquid at room temperature. There is no limitation thereto. Examples include one or more of inorganic solvents, such as water (pure water) and liquid ammonia; and organic solvents, such as alcohols, ethers, and ketones.

The specimen B comprises a liquid in which the concentration of the compound is lower than the concentration of the compound contained in the specimen A. The specimen B may not contain the compound at all. When the specimen A comprises component(s) other than the above compound, it is preferable that the specimen B also contains the same component(s) in the same concentration(s).

As conditions for gas exposure, the same conditions X are used for the specimen A and the specimen B.

Conditions X may be suitably determined according to the purpose of the measurement and the like, without limitation. For example, the temperature condition is preferably between -<NUM> and <NUM>. The exposure may be performed in a closed system or an open system; if the exposure is performed in a closed system, it is preferable to set the pressure to ≥ <NUM> kPa.

The gas is not limited. Examples include one or more gases selected from inorganic gases, fuel gases, exhaust gases, and other organic compounds (gaseous organic compounds) whose main skeleton has a carbon number of <NUM> or less.

Examples of inorganic gases include helium, hydrogen, oxygen, nitrogen, carbon monoxide, nitrogen, fluorine, chlorine, bromine, phosgene, phosphine, hydrogen sulfide, hydrogen chloride, hydrogen fluoride, and ammonia.

Examples of fuel gases include methane, propane, butane, and acetylene.

Examples of exhaust gases include hydrocarbons, nitrogen oxides, and sulfur oxides.

Examples of organic compounds (gaseous organic compounds) whose main skeleton has ≤ <NUM> carbon atoms include acetone, benzene, toluene, xylene, formaldehyde, and dichloromethane.

There is no limitation to the method of exposing the gas to the specimens A and B, and a wide range of known methods can be used. Examples include a method of bubbling a gas into a specimen, a method of flowing a gas onto the liquid surface of a specimen, and a method of placing a specimen under a gas atmosphere.

The conditions X are conditions that are set for exposing the gas to the specimens A and B. Examples of conditions X include the exposure time; and the gas concentration, gas pressure, and temperatures of specimens A and B, in the exposure.

In Step (<NUM>), the concentration (a) of the gas in the specimen A obtained in step (<NUM>) and the concentration (b) of the gas in the specimen B obtained in step (<NUM>) are measured, thus obtaining the correction coefficient α by calculating the relationship between (a) and (b) based on the equation α =(a)/(b).

There is no limitation to the method for measuring the gas concentration in the specimens A and B. A wide variety of known methods for measuring the concentration of a gas dissolved in a liquid can be used. Specifically, a method selected from gas chromatography, mass spectrometry, visible UV spectroscopy, absorption spectroscopy, infrared spectroscopy, Raman spectroscopy, and nuclear magnetic resonance can be used.

In step (<NUM>), the gas is exposed, at conditions Y, to a specimen B' comprising a liquid containing the compound in the same concentration as the specimen B.

The specimen B' comprises the liquid that contains the compound in the same concentration as the specimen B. The specimen B' containing the compound in the same concentration as the specimen B is defined as the concentration of the compound in the specimen B' being within the ±<NUM> mass% range of error of the concentration of the compound contained in the specimen B.

In step (<NUM>), the gas to be exposed to the specimen B' is the same as the gas used in step (<NUM>).

As a method for exposing the gas, it is preferable to use the same method as that employed in step (<NUM>).

In order to accurately predict the gas concentration, the conditions Y are preferably the same as the conditions X in step (<NUM>); however, the conditions Y may be different from the conditions X.

In step (<NUM>), the concentration (b') of the gas in the specimen B' obtained in step (<NUM>) is measured.

Although there is no limitation to the method of measuring the gas concentration, widely known methods can be used. From the viewpoint of accurately predicting the gas concentration, it is preferable to use the same method as the gas concentration measuring method used in step (<NUM>).

In step (<NUM>), based on the gas concentration (b') and the correction coefficient α, the concentration (a') of the gas in a specimen A' obtained when the gas is exposed to the specimen A' comprising a liquid containing the compound under the conditions Y is predicted.

The specimen A' comprises the liquid containing the compound. The liquid containing the compound in step (<NUM>) may be substantially formed of the same composition as the liquid containing the compound in step (<NUM>). The substantially same composition in this specification is defined as the concentration of a compound contained in the specimen A' being within the ±<NUM> mass% range of error of the concentration of the compound contained in the specimen A.

The gas concentration (a') is calculated by using the gas concentration (b') and the correction coefficient α, i.e. , when the correction coefficient α is obtained by the calculation equation α = (a)/(b) in step (<NUM>), the gas concentration (a') can be obtained by multiplying the gas concentration (b') by the correction coefficient α.

The present method as described above can accurately predict the concentration of a gas dissolved in a liquid containing a compound while omitting the step of directly measuring the concentration of the gas dissolved in the liquid containing the compound by utilizing the correction coefficient α above.

Thus, embodiments of the present invention are explained by way of examples.

Based on the following example, embodiments of the present invention are described in more detail below.

The gas shown in Table <NUM> was bubbled at <NUM>/min for <NUM> minute in <NUM> of a cell culture medium (liquid containing <NUM>/L of sodium chloride, <NUM>/L of D-glucose, <NUM>/L of sodium bicarbonate, L-lysine hydrochloride, <NUM>/L of L-arginine hydrochloride, <NUM>/L of L-glutamine, and <NUM>/L of calcium chloride) or in <NUM> of purified water, at a liquid temperature of <NUM>; and dissolved. Subsequently, the concentration of the gas dissolved in the cell culture liquid or pure water was measured by gas chromatography (Shimadzu Corporation). Each measurement was repeated three times, and the average gas concentration was calculated. The correction coefficient α was then obtained by dividing the average gas concentration in the cell culture liquid by the average gas concentration in the pure water.

At a later date, the same measurements as above were performed, and the correction coefficient was calculated in the same manner. The results are shown in Table <NUM>.

Claim 1:
A method for predicting a gas concentration, comprising:
(<NUM>) exposing a gas, under the same conditions X,
- to a specimen A comprising a liquid containing a compound, and
- to a specimen B comprising a liquid containing the compound in a concentration lower than that in the specimen A,
(<NUM>) measuring the concentrations (a) and (b) of the gas in the specimens A and B, respectively, obtained in step (<NUM>), and calculating a correction coefficient α based on the equation α = (a)/(b),
(<NUM>) exposing, under conditions Y, the gas to a specimen B' comprising a liquid containing the compound in the same concentration as the specimen B,
(<NUM>) measuring the concentration (b') of the gas in the specimen B' obtained in step (<NUM>), and
(<NUM>) predicting the concentration (a') of the gas in a specimen A' obtained when the gas is exposed to the specimen A' comprising a liquid containing the compound under the conditions Y, based on the equation (a') = α·(b').