A measuring cuvette for measuring the concentration of a particle suspension and a measuring method

Abstract

The application discloses a measuring cuvette and a measuring method for the concentration of a particle suspension. The measuring cuvette has an L-shaped structure formed by removing a rectangular gap from a square cross section, and the difference between the length and the width of the rectangular gap is 1-4 mm. The measuring cuvette is made of a fully transparent material. The measuring method comprises the following steps: pouring the particle suspension to be measured into the measuring cuvette, and measuring the absorbance of the measuring cuvette at different light paths, wherein the maximum light path of the measuring cuvette is light path 1, the intermediate light path is light path 2, and the minimum light path is light path 3; the OD value weight of light path 1 is w1=X1 / (X1+bX2+cX3); the OD value weight of light path 2 is w2=bX2 / (X1+bX2+cX3); the OD value weight of light path 3 is w3=cX3 / (X1+bX2+cX3); and the final OD value of the particle suspension is X=w1X1+w2X2+w3X3; wherein X1 is the OD value corresponding to light path 1, X2 is the OD value corresponding to light path 2, and X3 is the OD value corresponding to light path 3. E +cX3 F +cX3 E +cX3 E +cX3 F +cX3 F +cX3 E +cX3 F ​

Description

Technical Field

[0001] This invention belongs to the field of particulate matter suspension detection and analysis technology, and relates to a cuvette and method for measuring the concentration of particulate matter suspension. Background Technology

[0002] The statements herein provide only background information in relation to this invention and do not necessarily constitute prior art.

[0003] The concentration of a particulate suspension refers to the content of particulate matter per unit volume. Common particulate suspensions include ink, mud, correction fluid, and various microbial culture media. The concentration of suspensions is generally determined using spectrophotometry. The principle of this method is that when a light beam passes through a suspension, its transmittance is reduced due to scattering or absorption. At lower suspension concentrations, light transmission follows Beer-Lambert's law; within a certain range, the concentration of particulate matter is directly proportional to optical density (OD value) and inversely proportional to transmittance.

[0004] Spectrophotometry is a simple and quick method, but it can only accurately measure the concentration of particulate suspensions with an OD value not exceeding 1.0. When the concentration of particulate matter is high, the Beer-Lambert law no longer applies due to the phenomenon of secondary reflection of light, resulting in an OD reading significantly lower than the actual value, with the deviation increasing as the concentration increases. Therefore, for suspensions with high OD values, dilution is required to bring the OD value down to within the aforementioned range for accurate measurement. This process is cumbersome, and the readings from diluted and undiluted suspensions can jump, resulting in poor stability and affecting accuracy. Furthermore, the process of opening the cap to sample and dilute microbial cultures can cause contamination and interfere with the growth conditions of microorganisms; this operation is completely unacceptable for anaerobic microorganisms. Summary of the Invention

[0005] To address the shortcomings of existing technologies, the present invention aims to provide a cuvette and method for measuring the concentration of particulate suspensions. This method allows for direct and accurate detection of liquid concentration without dilution, even when the actual OD value of the particulate suspension far exceeds 1.0, thereby significantly improving detection efficiency and accuracy.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] In a first aspect, the present invention provides a cuvette for measuring the concentration of particulate suspension, the cross-section of which is a square with a rectangular notch removed to form an L-shaped structure, the difference between the length and width of the rectangular notch being 1-4 mm.

[0008] The cuvette is made of a completely transparent material.

[0009] In some embodiments, the cuvette is made of polystyrene.

[0010] In some embodiments, the height of the cuvette is 4-5 cm.

[0011] In some embodiments, the width of the square cross-section of the cuvette is 0.8-1.2 cm.

[0012] Preferably, the cross-section of the cuvette has a square width of 1 cm, a rectangular notch length of 7-9 mm, and a width of 5-6 mm.

[0013] Secondly, the present invention provides a method for measuring the concentration of particulate matter suspension, comprising the following steps:

[0014] The suspension of the particulate matter to be tested is poured into the cuvette, and the absorbance of the cuvette at different optical paths is measured. The maximum optical path of the cuvette is optical path 1; the middle optical path is optical path 2; and the minimum optical path is optical path 3.

[0015] The OD value weight of optical path 1 is: w1 = X1 / (X1 + bX2) E +cX3 F );

[0016] The OD value weight for optical path 2 is: w2 = bX2 E / (X1+bX2 E +cX3 F );

[0017] The OD value weight for optical path 3 is w3 = cX3 F / (X1+bX2 E +cX3 F );

[0018] The final OD value of the particulate suspension is: X = w1X1 + w2X2 + w3X3;

[0019] Where X1 is the OD value corresponding to optical path 1; X2 is the OD value corresponding to optical path 2; and X3 is the OD value corresponding to optical path 3.

[0020] b and c are real numbers, ≥0; E and F are real numbers, ≥0.

[0021] Where b and c are real numbers, greater than or equal to zero, and their specific values ​​are given by experimental data. These two parameters determine at what concentration the weights of optical paths 2 and 3 exceed those of the previous optical path. E and F are positive real numbers, and their optimal specific values ​​are given by experimental data. These two parameters determine the rate at which the weights of the corresponding optical paths increase; the larger the exponent, the faster the increase. Generally, E and F can be positive integers.

[0022] In some embodiments, the specific values ​​of b and c are determined by pre-experimental calibration of the analyte, such that the maximum optical path has the greatest weight at low concentrations and the minimum optical path has the greatest weight at high concentrations.

[0023] In some embodiments, the specific values ​​of E and F are determined by pre-experimental calibration of the analyte, such that the maximum optical path has the greatest weight at low concentrations and the minimum optical path has the greatest weight at high concentrations.

[0024] The values ​​of b, c, E, and F were all determined through preliminary experiments on a specific analyte. The principle was that at low concentrations, the 1-cm optical path (maximum optical path) had the highest weight, and the weights of the 5-mm or 4-mm (intermediate optical path) and 2-mm or 1-mm (minimum optical path) optical paths gradually increased with increasing concentration, so that at high concentrations, the 2-mm or 1-mm (minimum optical path) optical path had the highest weight. In the examples, integer values ​​were used, which are empirical constants given by observational data, and the error under these conditions is already sufficiently small. More precise parameters can be obtained through numerical fitting. Once the values ​​of b, c, E, and F are determined, they can be directly used for subsequent measurements of similar particulate matter.

[0025] In some embodiments, when the particulate suspension to be tested is detected by spectrophotometry, its absorbance is greater than 1.0.

[0026] The beneficial effects achieved by one or more embodiments of the present invention described above are as follows:

[0027] Using the cuvette and detection method of this invention, when the concentration of the particulate suspension is low, the 1 cm optical path has the highest weight. As the concentration increases, the weight of the 1 cm optical path continuously decreases, while the weight of shorter optical paths continuously increases. The OD value of the particulate suspension is then the weighted average of the readings for each optical path. This solves both the problem of low OD readings at high concentrations and the problem of jumps between diluted and undiluted data. Attached Figure Description

[0028] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments of the invention and their descriptions are used to explain the invention and do not constitute an improper limitation of the invention.

[0029] Figure 1 This is a schematic cross-sectional view of the cuvette used in the method for accurately measuring particulate matter concentration according to the present invention. Detailed Implementation

[0030] It should be noted that the following detailed description is illustrative and intended to provide further explanation of the invention. Unless otherwise specified, all technical and scientific terms used in this invention have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains.

[0031] The present invention will be further described below with reference to the embodiments.

[0032] Example 1

[0033] Prepare LB medium suitable for culturing Escherichia coli: Take a 300 ml Erlenmeyer flask, add 1 g peptone powder, 0.5 g yeast extract, 1 g sodium chloride powder, and 100 ml distilled water, then seal the flask with aluminum foil. Place it in an autoclave and sterilize at 121°C for 20 minutes.

[0034] Take 100 μL of E. coli from the preserved E. coli culture and add it to the above-mentioned LB medium that has been brought back to room temperature, along with an appropriate amount of antibiotic. Place it in a constant temperature shaking incubator and incubate at 37°C and 220 rpm for 16 hours.

[0035] The above E. coli solutions were diluted a series of times with distilled water to obtain E. coli solutions numbered 1-11 in Table 1, with concentrations decreasing sequentially. 3 ml of each of the 11 different concentrations of E. coli solutions were added to a cuvette designed in this invention and placed in the cuvette well of a spectrophotometer. The wavelength was set to 600 nm, and the OD values ​​at three optical paths of 1 cm, 5 mm, and 2 mm were measured and designated as X1, X2, and X3, respectively.

[0036] Based on the experimental data, we set b = 4, c = 8, E = 2, F = 3, and w1 = X1 / (X1 + 4X2). 2 +8X3 3 w2 = 4 x 2 2 / (X1+4X2 2 +8X3 3 w3 = 8 x 3 3 / (X1+4X2 2 +8X3 3 Multiplying X1, X2, and X3 by the coefficients w1, w2, and w3 respectively, we can calculate the final OD value: w1X1 + w2X2 + w3X3.

[0037] In addition, the particulate matter suspension was diluted 2 times and 5 times, respectively, and the OD value at a 1 cm optical path was measured. This OD value was then multiplied by the dilution factor to obtain the particulate matter concentration detected by the dilution method, denoted as X. 1-2 and X 1-5 .

[0038] The test and calculation results are shown in Table 1.

[0039] Table 1

[0040]

[0041]

[0042] As shown in Table 1, by using a weighted method, different weights are assigned to different optical paths at different concentrations, which solves the problem of low OD readings at high concentrations and also solves the problem of jumps between diluted and undiluted data.

[0043] At low concentrations, the final OD reading is close to X1, and at high concentrations it is close to X3. This solves the problem of low X1 readings at high concentrations and eliminates the need for dilution. If the concentration is high enough, dilution will result in slightly lower concentrations, while slightly higher concentrations will not have this problem. This will cause anomalies in microbial growth curves around this point.

[0044] Example 2

[0045] Prepare BMGY medium suitable for culturing yeast: Take a 300 mL Erlenmeyer flask and add 400 μL of glycerol, 10 mL of 1 M pH 6.0 potassium phosphate buffer, and 80 mL of distilled water. Seal the flask with aluminum foil. Place it in an autoclave at 121°C for 20 minutes to sterilize. Then, in a laminar flow hood, add 10 mL of filtered and sterilized yeast nitrogen source basal medium stock solution with a concentration of 134 g / L to the above medium.

[0046] Take 100 μL of yeast from the preserved yeast culture and add it to the BMGY medium described above. Place the medium in a constant temperature shaking incubator and incubate at 30°C and 260 rpm for 24 hours.

[0047] The yeast solution was diluted a series of times with distilled water to obtain yeast solutions numbered 1-17 in Table 2, with concentrations decreasing sequentially. 3 ml of each of the 17 different concentrations of yeast solution was added to a cuvette designed in this invention and placed in the cuvette well of a spectrophotometer. The wavelength was set to 600 nm, and the OD values ​​at three optical paths of 1 cm, 4 mm, and 1 mm were measured and designated as X1, X2, and X3, respectively.

[0048] Based on the laboratory data, we set b = c = 4, E = 2, and F = 4. Then we have w1 = X1 / (X1 + 4X2) 2 +4X3 4 w2 = 4 x 2 2 / (X1+4X2 2 +4X3 4 w3 = 4 x 3 4 / (X1+4X2 2 +4X3 4 Multiplying X1, X2, and X3 by the coefficients w1, w2, and w3 respectively, we can calculate the final OD value: w1X1 + w2X2 + w3X3.

[0049] In addition, the particulate matter suspension was diluted 2.5 times and 10 times, respectively, and the OD value at a 1 cm optical path was measured. This OD value was then multiplied by the dilution factor to obtain the particulate matter concentration detected by the dilution method, denoted as X. 1-2.5 and X 1-10 .

[0050] The test and calculation results are shown in Table 2.

[0051] Table 2

[0052]

[0053]

[0054] As shown in Table 2, the weighted method, which assigns different weights to different optical paths at different concentrations, solves the problem of low OD readings at high concentrations and also resolves the issue of jumps between diluted and undiluted data. Furthermore, the low 1 cm optical path reading is more pronounced in yeast at high concentrations, thus the new method demonstrates a more significant improvement.

[0055] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for measuring the concentration of particulate matter suspension, characterized in that: Includes the following steps: The particulate suspension to be tested was poured into a cuvette, and the absorbance of the cuvette was measured at three different optical paths. The maximum optical path of the cuvette was optical path 1; the middle optical path was optical path 2; and the minimum optical path was optical path 3. The cross-section of the cuvette was a square with an L-shaped structure formed by removing a rectangular notch. The difference between the length and width of the rectangular notch was 1-4 mm. The cuvette was made of a completely transparent material. The OD value weight for optical path 1 is: w1 = X1 / (X1 + bX2) E +cX3 F ); The OD value weight for optical path 2 is: w2 = bX2 E / (X1+bX2 E +cX3 F ); The OD value weight for optical path 3 is w3 = cX3 F / (X1+bX2 E +cX3 F ); The final OD value of the particulate suspension is: X = w1X1 + w2X2 + w3X3; Where X1 is the OD value corresponding to optical path 1; X2 is the OD value corresponding to optical path 2; and X3 is the OD value corresponding to optical path 3. b and c are real numbers, ≥0; E and F are real numbers, ≥0; The specific values ​​of b and c are determined by the preliminary experiment of the substance to be tested, so that the maximum optical path has the greatest weight at low concentrations and the minimum optical path has the greatest weight at high concentrations. The specific values ​​of E and F are determined by the preliminary experiments of the substance to be tested, so that the maximum optical path has the greatest weight at low concentrations and the minimum optical path has the greatest weight at high concentrations. The values ​​of b, c, E, and F were obtained through data fitting.

2. The method for measuring the concentration of particulate matter suspension according to claim 1, characterized in that: When the particulate suspension to be tested is detected by spectrophotometry, its absorbance is greater than 1.

0.

3. The method for measuring the concentration of particulate matter suspension according to claim 1, characterized in that: The cuvette is made of polystyrene.

4. The method for measuring the concentration of particulate matter suspension according to claim 1, characterized in that: The height of the cuvette is 4-5 cm.

5. The method for measuring the concentration of particulate matter suspension according to claim 1, characterized in that: The width of the square cross-section of the cuvette is 0.8-1.2 cm.

6. The method for measuring the concentration of particulate matter suspension according to claim 5, characterized in that: The cuvette has a square cross-section with a width of 1 cm, and a rectangular notch with a length of 7-9 mm and a width of 5-6 mm.

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