CN116637664A - Ocean total alkalinity measuring device and method based on micro-flow control - Google Patents
Ocean total alkalinity measuring device and method based on micro-flow control Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 25
- 239000013535 sea water Substances 0.000 claims abstract description 63
- 230000031700 light absorption Effects 0.000 claims abstract description 10
- 238000005259 measurement Methods 0.000 claims description 36
- HEDRZPFGACZZDS-UHFFFAOYSA-N Chloroform Chemical compound ClC(Cl)Cl HEDRZPFGACZZDS-UHFFFAOYSA-N 0.000 claims description 34
- 238000010521 absorption reaction Methods 0.000 claims description 18
- PZBRPDUUWGYUTE-IWSIBTJSSA-M sodium;2-[(z)-(3,5-dibromo-4-hydroxy-2-methylphenyl)-(3,5-dibromo-2-methyl-4-oxocyclohexa-2,5-dien-1-ylidene)methyl]benzenesulfonate Chemical compound [Na+].CC1=C(Br)C(=O)C(Br)=C\C1=C(C=1C(=CC=CC=1)S([O-])(=O)=O)/C1=CC(Br)=C(O)C(Br)=C1C PZBRPDUUWGYUTE-IWSIBTJSSA-M 0.000 claims description 16
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 claims description 16
- 239000000243 solution Substances 0.000 claims description 15
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 14
- 229910052799 carbon Inorganic materials 0.000 claims description 14
- 238000004364 calculation method Methods 0.000 claims description 11
- 239000011259 mixed solution Substances 0.000 claims description 10
- 239000012895 dilution Substances 0.000 claims description 9
- 238000010790 dilution Methods 0.000 claims description 9
- 238000010494 dissociation reaction Methods 0.000 claims description 9
- 230000005593 dissociations Effects 0.000 claims description 9
- 238000003801 milling Methods 0.000 claims description 9
- WYTGDNHDOZPMIW-RCBQFDQVSA-N alstonine Natural products C1=CC2=C3C=CC=CC3=NC2=C2N1C[C@H]1[C@H](C)OC=C(C(=O)OC)[C@H]1C2 WYTGDNHDOZPMIW-RCBQFDQVSA-N 0.000 claims description 8
- 239000000463 material Substances 0.000 claims description 8
- 238000002835 absorbance Methods 0.000 claims description 6
- 229920003229 poly(methyl methacrylate) Polymers 0.000 claims description 6
- 239000004926 polymethyl methacrylate Substances 0.000 claims description 6
- 230000003287 optical effect Effects 0.000 claims description 5
- KRHYYFGTRYWZRS-UHFFFAOYSA-M Fluoride anion Chemical compound [F-] KRHYYFGTRYWZRS-UHFFFAOYSA-M 0.000 claims description 4
- QAOWNCQODCNURD-UHFFFAOYSA-L Sulfate Chemical compound [O-]S([O-])(=O)=O QAOWNCQODCNURD-UHFFFAOYSA-L 0.000 claims description 4
- 238000002474 experimental method Methods 0.000 claims description 4
- 239000007788 liquid Substances 0.000 claims description 4
- 239000002699 waste material Substances 0.000 claims description 4
- 239000012267 brine Substances 0.000 claims description 3
- 238000013461 design Methods 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 3
- 238000005286 illumination Methods 0.000 claims description 3
- 230000002572 peristaltic effect Effects 0.000 claims description 3
- 238000005498 polishing Methods 0.000 claims description 3
- 238000002360 preparation method Methods 0.000 claims description 3
- HPALAKNZSZLMCH-UHFFFAOYSA-M sodium;chloride;hydrate Chemical compound O.[Na+].[Cl-] HPALAKNZSZLMCH-UHFFFAOYSA-M 0.000 claims description 3
- 239000000126 substance Substances 0.000 claims description 3
- BVKZGUZCCUSVTD-UHFFFAOYSA-M Bicarbonate Chemical compound OC([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-M 0.000 claims description 2
- BTBUEUYNUDRHOZ-UHFFFAOYSA-N Borate Chemical compound [O-]B([O-])[O-] BTBUEUYNUDRHOZ-UHFFFAOYSA-N 0.000 claims description 2
- 238000001914 filtration Methods 0.000 claims description 2
- 230000001678 irradiating effect Effects 0.000 claims description 2
- 238000004321 preservation Methods 0.000 claims description 2
- 238000004891 communication Methods 0.000 claims 1
- 238000005516 engineering process Methods 0.000 abstract description 4
- 238000001514 detection method Methods 0.000 abstract description 3
- 238000009614 chemical analysis method Methods 0.000 abstract description 2
- 239000003153 chemical reaction reagent Substances 0.000 abstract description 2
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 12
- 239000001569 carbon dioxide Substances 0.000 description 6
- 229910002092 carbon dioxide Inorganic materials 0.000 description 6
- 238000012544 monitoring process Methods 0.000 description 6
- FRPHFZCDPYBUAU-UHFFFAOYSA-N Bromocresolgreen Chemical compound CC1=C(Br)C(O)=C(Br)C=C1C1(C=2C(=C(Br)C(O)=C(Br)C=2)C)C2=CC=CC=C2S(=O)(=O)O1 FRPHFZCDPYBUAU-UHFFFAOYSA-N 0.000 description 4
- BVKZGUZCCUSVTD-UHFFFAOYSA-L Carbonate Chemical compound [O-]C([O-])=O BVKZGUZCCUSVTD-UHFFFAOYSA-L 0.000 description 4
- FAPWRFPIFSIZLT-UHFFFAOYSA-M Sodium chloride Chemical compound [Na+].[Cl-] FAPWRFPIFSIZLT-UHFFFAOYSA-M 0.000 description 4
- 230000009919 sequestration Effects 0.000 description 3
- XDXJADAMHLVTDF-UHFFFAOYSA-N [Na].CC1=C(O)C=CC=C1Br Chemical class [Na].CC1=C(O)C=CC=C1Br XDXJADAMHLVTDF-UHFFFAOYSA-N 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 230000020477 pH reduction Effects 0.000 description 2
- 239000011780 sodium chloride Substances 0.000 description 2
- 238000006467 substitution reaction Methods 0.000 description 2
- 241001658044 Beata Species 0.000 description 1
- ZOXJGFHDIHLPTG-UHFFFAOYSA-N Boron Chemical compound [B] ZOXJGFHDIHLPTG-UHFFFAOYSA-N 0.000 description 1
- 235000014653 Carica parviflora Nutrition 0.000 description 1
- 241000243321 Cnidaria Species 0.000 description 1
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 description 1
- UCKMPCXJQFINFW-UHFFFAOYSA-N Sulphide Chemical compound [S-2] UCKMPCXJQFINFW-UHFFFAOYSA-N 0.000 description 1
- 239000005864 Sulphur Substances 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 201000009310 astigmatism Diseases 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 229910052796 boron Inorganic materials 0.000 description 1
- 150000001642 boronic acid derivatives Chemical class 0.000 description 1
- 238000004177 carbon cycle Methods 0.000 description 1
- 229910001748 carbonate mineral Inorganic materials 0.000 description 1
- 238000007796 conventional method Methods 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 230000007774 longterm Effects 0.000 description 1
- 238000000691 measurement method Methods 0.000 description 1
- 238000005375 photometry Methods 0.000 description 1
- 238000004313 potentiometry Methods 0.000 description 1
- 238000011160 research Methods 0.000 description 1
- 230000000630 rising effect Effects 0.000 description 1
- 235000015170 shellfish Nutrition 0.000 description 1
- 239000002904 solvent Substances 0.000 description 1
- 229910021653 sulphate ion Inorganic materials 0.000 description 1
- 238000004448 titration Methods 0.000 description 1
- 239000003643 water by type Substances 0.000 description 1
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
- B01L—CHEMICAL OR PHYSICAL LABORATORY APPARATUS FOR GENERAL USE
- B01L3/00—Containers or dishes for laboratory use, e.g. laboratory glassware; Droppers
- B01L3/50—Containers for the purpose of retaining a material to be analysed, e.g. test tubes
- B01L3/502—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures
- B01L3/5027—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip
- B01L3/502769—Containers for the purpose of retaining a material to be analysed, e.g. test tubes with fluid transport, e.g. in multi-compartment structures by integrated microfluidic structures, i.e. dimensions of channels and chambers are such that surface tension forces are important, e.g. lab-on-a-chip characterised by multiphase flow arrangements
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/25—Colour; Spectral properties, i.e. comparison of effect of material on the light at two or more different wavelengths or wavelength bands
- G01N21/31—Investigating relative effect of material at wavelengths characteristic of specific elements or molecules, e.g. atomic absorption spectrometry
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- B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
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- B01L2300/08—Geometry, shape and general structure
- B01L2300/0861—Configuration of multiple channels and/or chambers in a single devices
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- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N2021/0106—General arrangement of respective parts
- G01N2021/0112—Apparatus in one mechanical, optical or electronic block
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Abstract
The invention relates to the technical field of seawater detection, in particular to a device and a method for measuring total sea alkalinity based on micro-flow control. The ocean total alkalinity measuring device at least comprises a micro-fluidic wafer, wherein the micro-fluidic wafer comprises a sample mixing module and a light absorbing module; the light absorption module comprises an opaque layer A and an opaque layer B which are stacked up and down, wherein a first through hole pair and a second through hole pair are formed in the layer A, transparent connecting columns are arranged in all through holes of the two through hole pairs, and a sample channel is formed in one side of the layer A or/and the layer B, which is in contact with the other layer; one end of the transparent connecting column, which is positioned at the interface of the layer A and the layer B, is provided with a conical prism, an LED light source is arranged above the transparent connecting column through which the sample flows first in the through hole centering way along the flowing direction of the sample in the sample channel, and a photoelectric converter is arranged above the transparent connecting column through which the sample flows later. The present invention miniaturizes conventional chemical analysis methods by using microfluidic technology and is performed in small scale, using smaller amounts of sample and reagents.
Description
Technical Field
The invention relates to the technical field of seawater detection, in particular to a device and a method for measuring total sea alkalinity based on micro-flow control.
Background
Total alkalinity is a key parameter that determines the ability of the ocean to absorb and store carbon dioxide, and changes in total alkalinity may be indicative of changes in ocean carbonate chemistry. Measuring total alkalinity can help scientists track ocean carbon absorption and storage, which is critical to understanding global carbon circulation and predicting the impact of rising atmospheric carbon dioxide levels on ocean acidity and ecosystem. Continuous monitoring of the total alkalinity of the ocean is important in understanding the cycle of ocean carbon, predicting the impact of climate change on ocean chemistry, ecology and global climate.
The total alkalinity in the seawater can provide a warning signal of ocean acidification, a process threatening marine organisms and ecosystems. As the concentration of carbon dioxide in the atmosphere increases, more carbon dioxide dissolves into the seawater, resulting in a decrease in the pH of the seawater and an increase in acidity. Such acidification can cause damage to marine organisms including coral reefs, shellfish and other marine organisms that rely on carbonate minerals to build exoskeletons or shells. Continuous monitoring of total alkalinity can help detect changes in marine carbonate chemistry and alert in advance of potential impact on marine organisms and ecosystems. In addition, monitoring total alkalinity may evaluate the effectiveness of a carbon sequestration strategy. Carbon sequestration involves removing carbon dioxide from the atmosphere and storing it in a long-term reservoir, such as the deep sea. By measuring the total alkalinity, scientists can monitor the amount of carbon stored in the ocean and evaluate the effectiveness of different carbon capture and storage technologies.
Continuous monitoring of ocean total alkalinity is critical to understanding ocean carbon circulation, predicting the impact of climate change on the ocean and developing effective carbon sequestration strategies. By monitoring the total alkalinity, scientists can detect changes in marine carbonate chemistry, evaluate the effectiveness of carbon capture and storage technologies, and alert in advance of potential impact on marine organisms and ecosystems.
There are many methods for measuring the total alkalinity of the ocean, including titration, photometry and potentiometry. However, conventional methods of measuring total alkalinity are time consuming, expensive, and do not have continuity. This is particularly challenging for marine research because high frequency measurements are required to capture the dynamic changes in the marine carbon cycle.
Disclosure of Invention
Aiming at the technical problems that the traditional ocean total alkalinity measuring method is time-consuming, expensive and not continuous, the invention provides the ocean total alkalinity measuring device and the measuring method based on the micro-flow control, the traditional chemical analysis method is miniaturized by using the micro-flow control technology and is carried out in a small scale, and a smaller amount of samples and reagents are used.
In a first aspect, the invention provides a microfluidic-based ocean total alkalinity measuring device, which at least comprises a microfluidic wafer, wherein the microfluidic wafer comprises a sample mixing module and a light absorbing module; the light absorption module comprises a layer A and a layer B which are stacked up and down, the layer A and the layer B are opaque, a first through hole pair and a second through hole pair are formed in the thickness direction of the layer A, transparent connecting columns are arranged in the through holes of the two pairs of through holes, a sample channel is arranged on one side of the layer A or/and the layer B, which is in contact with the other layer, a sample inlet end of the sample channel is communicated with an outlet of the sample mixing module, the sample channel is connected with the two transparent connecting columns in the first through hole pair through a first light measurement channel, the sample channel is connected with the two transparent connecting columns in the second through hole pair through a second light measurement channel, and the length of the first light measurement channel is shorter than that of the second light measurement channel; one end of the transparent connecting column, which is positioned at the interface of the layer A and the layer B, is provided with a conical prism, an LED light source is arranged above the transparent connecting column through which the sample flows first in the through hole centering way along the flowing direction of the sample in the sample channel, and a photoelectric converter is arranged above the transparent connecting column through which the sample flows later.
Further, the layer A and the layer B are made of black opaque PMMA materials.
Further, the preparation method of the light absorption module comprises the following steps:
(1) Milling four through holes on the layer A, and cutting out four transparent connecting columns with the same size specification as the through holes by using transparent PMMA material;
(2) Preheating the chloroform solution until chloroform steam is generated, and then placing the layer A and four transparent connecting columns above the chloroform solution to enable the chloroform solution to be contacted with the chloroform steam;
(3) Then, correspondingly inserting the four transparent connecting columns into the four through holes of the layer A, heating to 115 ℃ under vacuum condition, and then carrying out heat preservation for material bonding;
(4) Polishing the outer surface of the assembled layer A, milling a sample channel on the upper surface or the lower surface of the layer A (namely the surface where the end part of the transparent connecting column is positioned) according to the design, milling a cone shape on the end part of the transparent connecting column on the same side, and forming a prism;
(5) Then the A layer and the B layer are treated in chloroform vapor, and then bonded at 85 ℃ under the bonding pressure of 625N/cm 2 The sample channel and conical prism are enclosed in a microfluidic wafer.
Further, the sample mixing module is a serpentine pipeline, and an inlet of the serpentine pipeline is respectively communicated with the water sample storage tank and the titrant storage tank.
Further, a filtering device is arranged at the outlet of the water sample storage tank, and an electromagnetic valve and a peristaltic pump are respectively arranged on connecting pipelines of the water sample storage tank, the titrant storage tank and the inlet of the serpentine pipeline.
Further, a sample outlet end of the sample channel is connected with a waste liquid tank.
In a second aspect, the invention provides a method for detecting total alkalinity of a seawater sample by adopting the ocean total alkalinity measuring device, which is characterized in that LED light is put into a microfluidic chip, reflected by two conical prisms, and LED out of the chip after passing through a solution (seawater sample, mixed solution of seawater sample and titrant) with a certain distance, and the voltage of the LED-out light is measured by using a photoelectric converter, so that the absorbance of the light is calculated, and finally the total alkalinity of the sample to be detected is calculated.
Further, the specific steps are as follows:
(1) Introducing 1mL of seawater sample into the microfluidic chip, and measuring the voltage V of the seawater sample under dark condition by using a photoelectric converter d ；
(2) Turning on the LED light source, irradiating the transparent connecting columns of the first light measuring channel and the second light measuring channel with light of different wavelengths, and measuring the voltage V of the seawater sample under the illumination condition by using the photoelectric converter ow ；
(3) Introducing a mixed solution of a seawater sample and a titrant into a microfluidic chip, controlling the sum of the flow rates of the seawater sample and the titrant to be 1-5 mL/min, and measuring the voltage V of the mixed solution under different seawater dilution degrees, wherein the total addition amount of the seawater sample and the titrant is 1 mL;
(4) According to the measurement data and formula of the first optical measurement channel and the second optical measurement channelCalculation of [ HI ] of the Mixed solution]And [ I ] - ]Concentration, wherein epsilon represents a molar absorption coefficient, L represents an absorption distance, and c represents a solution concentration;
(5) By bromocresol green dissociation equationAccording to the formula->Calculation [ H ] + ]；
(6) Controlling the sum of the flow rates of the seawater and the titrant to be unchanged, continuously changing the flow rates of the seawater and the titrant, and calculating the [ H ] under different seawater dilution degrees R + ]The concentration of the water in the water is higher,；
(7) According to the formula
Calculating total alkalinity of seawater, wherein R is seawater dilution degree, A T Is the total alkalinity of seawater, C T K is the total concentration of dissolved inorganic carbon in seawater 1 、K 2 First-order and second-order dissociation constants of carbonic acid ion, C a F for the concentration of HCl in the titrant T B is the total concentration of fluoride in seawater T 、S T 、C [HI] Respectively the concentration of borate, sulfate and bromocresol green sodium in the titrant, K [HI] 、K B 、K W 、K F 、K S Dissociation constants of the respective substances or elements;
（8）multiple groups of R and H obtained by the above experiment + ]The data and parameters are substituted into the formula, and then a nonlinear least square method is used to calculate the closest A T And C T From which the total alkalinity in the brine can be obtained.
Further, in step (4), absorbance A of channel one is measured optically S The calculation formula is thatIn the formula->Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel one, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel one, L s Representing the absorption light distance of the first light measurement channel;
absorbance a of light measurement channel two L The calculation formula is thatIn the formula->Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel two, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel two, L L Representing the absorption light distance of the second light measurement channel.
The invention has the beneficial effects that:
the ocean total alkalinity measuring device provided by the invention has the advantages of small use size, few samples, low cost and energy consumption and high stability, has the potential of being manufactured into a portable detector or being directly deployed in the ocean, and can be used for continuously monitoring ocean carbon circulation.
The micro-fluidic chip is provided with the paired transparent connecting columns and connected through the sample channel, a reflection path of light in the chip is prepared, and the A layer and the B layer are arranged to be opaque, so that the astigmatism and the reflection effect in the detection process can be reduced. Two light measuring channels are arranged, and the measuring precision and accuracy are further improved by a dual-wavelength measuring method.
The photoelectric converter in the ocean total alkalinity measuring device can convert the light intensity signal into voltage, and the light intensity and the voltage are in linear proportion, and the voltage is used for replacing the light intensity to calculate the solvent absorbance. The photoelectric converter is used for replacing light and other equipment to measure the light intensity, so that experimental equipment is more stable.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings that are required to be used in the description of the embodiments or the prior art will be briefly described below, and it will be obvious to those skilled in the art that other drawings can be obtained from these drawings without inventive effort.
Fig. 1 is a schematic view of the structure of the total marine alkalinity measuring apparatus of example 1.
Fig. 2 is a schematic diagram of the operation of the light absorbing module in embodiment 1.
In the figure, a 1-microfluidic chip, a 2-sample mixing module, a 3-light absorption module, a 4-A layer, a 5-B layer, a 6-transparent connecting column, a 7-conical prism, an 8-water sample storage tank, a 9-titrant storage tank, a 10-waste liquid tank, a 11-40 μm filter element, a 12-LED light source and a 13-photodiode are arranged.
Detailed Description
In order to make the technical solution of the present invention better understood by those skilled in the art, the technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention, and it is apparent that the described embodiments are only some embodiments of the present invention, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the present invention without making any inventive effort, shall fall within the scope of the present invention.
Example 1
The device for measuring the total ocean alkalinity based on the micro-flow control comprises a micro-flow control wafer 1 and a computer;
the microfluidic chip 1 comprises a sample mixing module 2 and a light absorbing module 3;
the sample mixing module 2 is a serpentine pipeline with the depth of 500 mu m and the width of 600 mu m, the inlet of the serpentine pipeline is respectively communicated with the water sample storage tank 8 and the titrant storage tank 9, a 40 mu m filter core 11 is arranged at the outlet of the water sample storage tank 8, and electromagnetic valves and peristaltic pumps are respectively arranged on connecting pipelines of the water sample storage tank 8, the titrant storage tank 9 and the inlet of the serpentine pipeline;
the light absorption module 3 comprises an A layer 4 and a B layer 5 which are stacked up and down, wherein the A layer 4 and the B layer 5 are black light-proof PMMA blocks, a first through hole pair and a second through hole pair are formed in the thickness direction of the A layer 4, the distance between the two through holes of the first through hole pair is 10mm, the distance between the two through holes of the second through hole pair is 25mm, transparent connecting columns 6 are arranged in each through hole, one side, in contact with the B layer 5, of the A layer 4 is provided with a sample channel, the sample inlet end of the sample channel is communicated with the outlet of the sample mixing module 2, the sample channel is connected with the two transparent connecting columns 6 in the first through hole pair through a first light measuring channel (the length of the sample channel is 10 mm), the sample channel is connected with the two transparent connecting columns 6 in the second through hole pair through the second light measuring channel, and the sample outlet end of the sample channel is connected with a waste liquid tank 10;
one end of the transparent connecting column 6, which is positioned at the interface between the layer A4 and the layer B5, is provided with a conical prism 7, an LED light source 12 is arranged above the transparent connecting column 6 through which the sample flows in the through hole centering along the flowing direction of the sample in the sample channel, a photodiode 13 is arranged above the transparent connecting column 6 through which the sample flows after the sample flows, and a computer receives a voltage signal measured by the photodiode 13 and analyzes and processes the data.
The preparation method of the light absorption module comprises the following steps:
(1) Milling four through holes with the diameter of 5-8 mm on the layer A, and cutting out four transparent connecting columns with the same size specification as the through holes by using a transparent PMMA material;
(2) Preheating chloroform solution until chloroform steam is generated, and then placing the layer A and four transparent connecting columns above the chloroform solution to make the layer A and four transparent connecting columns contact the chloroform steam for 1min;
(3) Then, correspondingly inserting the four transparent connecting columns into the four through holes of the layer A, heating to 115 ℃ under vacuum condition, preserving heat for 2.5h, and bonding materials;
(4) Polishing the outer surface of the assembled layer A, milling a sample channel on the upper surface or the lower surface of the layer A (namely the surface where the end part of the transparent connecting column is positioned) according to the design, milling a cone shape on the end part of the transparent connecting column on the same side, and forming a 45-degree prism;
(5) Then the A layer and the B layer are treated in chloroform steam for 1min, and then bonded at 85 ℃ under 625N/cm bonding pressure 2 The sample channel and conical prism are enclosed in a microfluidic wafer.
Example 2
The total alkalinity of the seawater sample was detected using the ocean total alkalinity measuring apparatus of example 1, the method steps were as follows:
(1) Introducing 1mL of seawater sample into the microfluidic chip, and measuring the voltage V of the seawater sample under dark condition by using a photoelectric converter d ；
(2) The LED light source of the light measuring channel one (wavelength 620nm, mainly measuring unprotonated bromocresol sodium green [ I ] - ]) The LED light source of the light measurement channel two (wavelength 450nm, mainly measuring protonated bromocresol sodium green [ HI ]]) The two LED light sources are not mutually interfered, and the photoelectric converter is used for measuring the voltage V of the seawater sample under the illumination condition ow ；
(3) And introducing a mixed solution of a seawater sample and a titrant into the microfluidic chip, wherein the titrant comprises HCl with the concentration of 0.01mol/kg, bromocresol green sodium with the concentration of 10-20 mu mol/kg and NaCl with the concentration of 0.5-0.8 mol/kg, and the concentration of the NaCl depends on the salinity of the local seawater.
Controlling the sum of the flow rates of the seawater sample and the titrant to be 1-5 mL/min, and measuring the voltage V of the mixed solution under different seawater dilution degrees, wherein the total addition amount of the seawater sample and the titrant is 1 mL;
(4) From the measurement data and formulas of the first and second optical measurement channels, according to Beer-Lambert law:
calculation of the [ HI ] of the Mixed solution]And [ I ] - ]Concentration of (1)Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel one, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel one, L s Represents the absorption light distance of the first light measuring channel, for example>Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel two, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel two, L L The absorption light distance of the second light measuring channel is represented, and the molar light absorption coefficient of each substance can be obtained through a light absorption experiment;
(5) By bromocresol green dissociation equationAccording to the formula->Calculation [ H ] + ]；
(6) Controlling the sum of the flow rates of the seawater and the titrant to be unchanged, continuously changing the flow rates of the seawater and the titrant, and calculating the [ H ] under different seawater dilution degrees R + ]The concentration of the water in the water is higher,；
(7) The total alkalinity of the seawater is calculated according to the following formula:
wherein R is the dilution degree of seawater;
A T is the total alkalinity of the seawater;
C T the total concentration of dissolved inorganic carbon in the seawater;
K 1 、K 2 the primary and secondary dissociation constants of carbonate ions, respectively, are available from "Instrument and method Spectrophotometric procedures for determination of sea water alkalinity using bromocresol green";
B T as the total concentration of borates in seawater, "Anomaly of total boron concentration in the brackish waters of the Baltic Sea and its consequence for the CO", by Karol and Beata, can be mentioned 2 system calculations "or other measurement methods;
C a is the concentration of HCl in the titrant;
F T the total concentration of fluoride in seawater can be calculated or measured by the method described in "Normal fluoride content of seawater" by THEODORE;
S T the total concentration of sulfate in seawater can be calculated or measured by the method described in Neoarchaean seawater sulphate concentrations from sulphur isotopes in massive sulphide ore of Jamieson and Farquhar;
C [HI] the concentration of bromocresol green sodium in the titrant;
K [HI] for dissociation constants, available from article "Spectrophotometric procedures for determination of sea water alkalinity using bromocresol green" of Breland and Byrne;
remaining dissociation constant (K) B 、K W 、K F 、K S ) Are closely related to the temperature and salinity of seawater and can be obtained from a book of Handbook of methods for the analysis of the various parameters of the carbon dioxide system in sea water;
(8) The above experiment was carried outMultiple sets of R and H + ]The data and parameters are substituted into the formula, and then a nonlinear least square method is used to calculate the closest A T And C T From which the total alkalinity in the brine can be obtained.
Although the present invention has been described in detail by way of preferred embodiments with reference to the accompanying drawings, the present invention is not limited thereto. Various equivalent modifications and substitutions may be made in the embodiments of the present invention by those skilled in the art without departing from the spirit and scope of the present invention, and it is intended that all such modifications and substitutions be within the scope of the present invention/be within the scope of the present invention as defined by the appended claims.
Claims (9)
1. The ocean total alkalinity measuring device based on the micro-flow control is characterized by at least comprising one micro-flow control wafer, wherein the micro-flow control wafer comprises a sample mixing module and a light absorption module; the light absorption module comprises a layer A and a layer B which are stacked up and down, the layer A and the layer B are opaque, a first through hole pair and a second through hole pair are formed in the thickness direction of the layer A, transparent connecting columns are arranged in the through holes of the two pairs of through holes, a sample channel is arranged on one side of the layer A or/and the layer B, which is in contact with the other layer, a sample inlet end of the sample channel is communicated with an outlet of the sample mixing module, the sample channel is connected with the two transparent connecting columns in the first through hole pair through a first light measurement channel, the sample channel is connected with the two transparent connecting columns in the second through hole pair through a second light measurement channel, and the length of the first light measurement channel is shorter than that of the second light measurement channel; one end of the transparent connecting column, which is positioned at the interface of the layer A and the layer B, is provided with a conical prism, an LED light source is arranged above the transparent connecting column through which the sample flows first in the through hole centering way along the flowing direction of the sample in the sample channel, and a photoelectric converter is arranged above the transparent connecting column through which the sample flows later.
2. The marine total alkalinity measuring device of claim 1, wherein the a and B layers are made of black opaque PMMA material.
3. The marine total alkalinity measuring device of claim 2, wherein the preparation method of the light absorbing module comprises the steps of:
(1) Milling four through holes on the layer A, and cutting out four transparent connecting columns with the same size specification as the through holes by using transparent PMMA material;
(2) Preheating the chloroform solution until chloroform steam is generated, and then placing the layer A and four transparent connecting columns above the chloroform solution to enable the chloroform solution to be contacted with the chloroform steam;
(3) Then, correspondingly inserting the four transparent connecting columns into the four through holes of the layer A, heating to 115 ℃ under vacuum condition, and then carrying out heat preservation for material bonding;
(4) Polishing the outer surface of the assembled layer A, milling a sample channel on the upper surface or the lower surface of the layer A according to the design, and milling a cone shape on the end part of the transparent connecting column on the same side to form a prism;
(5) Then the A layer and the B layer are treated in chloroform vapor, and then bonded at 85 ℃ under the bonding pressure of 625N/cm 2 The sample channel and conical prism are enclosed in a microfluidic wafer.
4. The marine total alkalinity measuring device of claim 1, wherein the sample mixing module is a serpentine conduit having an inlet in communication with the water sample reservoir and the titrant reservoir, respectively.
5. The ocean total alkalinity measuring device according to claim 1, wherein the outlet of the water sample storage tank is provided with a filtering device, and the connecting pipelines of the water sample storage tank, the titrant storage tank and the serpentine pipeline inlet are respectively provided with an electromagnetic valve and a peristaltic pump.
6. The marine total alkalinity measuring device of claim 1, wherein the sample outlet end of the sample channel is connected to a waste liquid tank.
7. The method for measuring the total ocean alkalinity is characterized in that the device for measuring the total ocean alkalinity is adopted, according to any one of claims 1-6, LED light is put into a microfluidic chip, the light is reflected by a conical prism of a through hole pair, the light is LED out of the chip after passing through a solution with a certain distance, the voltage of the LED-out light is measured by using a photoelectric converter, the light absorption degree is calculated, and finally the total alkalinity of a sample to be measured is calculated.
8. The method for measuring total marine alkalinity according to claim 7, wherein the specific steps are as follows:
(1) Introducing 1mL of seawater sample into the microfluidic chip, and measuring the voltage V of the seawater sample under dark condition d ；
(2) Turning on the LED light source, irradiating the transparent connecting columns of the first light measuring channel and the second light measuring channel with light of different wavelengths, and measuring the voltage V of the seawater sample under the illumination condition ow ；
(3) Introducing a mixed solution of a seawater sample and a titrant into a microfluidic chip, controlling the sum of the flow rates of the seawater sample and the titrant to be 1-5 mL/min, and measuring the voltage V of the mixed solution under different seawater dilution degrees, wherein the total addition amount of the seawater sample and the titrant is 1 mL;
(4) According to the measurement data and formula of the first optical measurement channel and the second optical measurement channelCalculation of [ HI ] of the Mixed solution]And [ I ] - ]Concentration, wherein epsilon represents a molar absorption coefficient, L represents an absorption distance, and c represents a solution concentration;
(5) According to the formulaCalculation [ H ] + ]；
(6) Controlling the sum of the flow rates of the seawater and the titrant to be unchanged, continuously changing the flow rates of the seawater and the titrant, and calculating the [ H ] under different seawater dilution degrees R + ]The concentration of the water in the water is higher,；
(7) According to the formula
Calculating total alkalinity of seawater, wherein R is seawater dilution degree, A T Is the total alkalinity of seawater, C T K is the total concentration of dissolved inorganic carbon in seawater 1 、K 2 First-order and second-order dissociation constants of carbonic acid ion, C a F for the concentration of HCl in the titrant T B is the total concentration of fluoride in seawater T 、S T 、C [HI] Respectively the concentration of borate, sulfate and bromocresol green sodium in the titrant, K [HI] 、K B 、K W 、K F 、K S Dissociation constants of the respective substances or elements;
(8) Multiple groups of R and H obtained by the above experiment + ]The data and parameters are substituted into the formula, and then a nonlinear least square method is used to calculate the closest A T And C T Thereby obtaining the total alkalinity in the brine.
9. The method for measuring total marine alkalinity according to claim 8, wherein in step (4), absorbance a of the first light measuring channel is measured S The calculation formula is thatIn the formula->Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel one, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel one, L s Representing the absorption light distance of the first light measurement channel;
absorbance a of light measurement channel two L The calculation formula is thatIn the formula->Represents unprotonated bromocresol green sodium [ I ] - ]Molar absorption coefficient in light measurement channel two, +.>Represents protonated bromocresol green sodium [ HI ]]Molar absorptivity in light measurement channel two, L L Representing the absorption light distance of the second light measurement channel.
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