KR100955773B1 - Automatic titration method using PC camera in acidity analysis - Google Patents

Abstract

The present invention relates to a method of automating acidity titration using a PC camera. That is, the average value of the resting values of the 144 pixels selected from the camera image of the titrant is repeatedly calculated by the control algorithm until the titration is completed, and the end point is detected by tracking the change from the initial value of the average value to supply the titrant. How to stop automatically.

Auto titration, PC camera, pH analysis

Description

Automatic titration method using PC camera {Automatic titration method using PC camera in acidity analysis}

The present invention relates to a method for automating acid titration using a PC camera and belongs to the field of chemical analysis automation.

Background art of the present invention is a conventional technique using a PC camera in the analysis of volatile basic nitrogen using a PC camera for automation of titration (Patent No. 10-0667651).

First, the conventional technique of using PC cameras for the automation of titration, 'Automatic titration method using PC camera in volatile basic nitrogen analysis' (Patent No. 10-0667651), shows clear and uniform color of the titrant solution at the end point as in volatile nitrogen analysis. In the present invention, the present invention is applied to a case of changing from one grape red to a clear and uniform green color, but it cannot be applied to any kind of color from colorless to many other titrations such as acidity titration. Second, in the case of the conventional technique 'automatic titration method using PC camera in volatile basic nitrogen analysis' (Patent No. 10-0667651), the green value and the red value in which the information on the brightness of light is not separated by the color information of the pixel. Since it was used to solve the problem affected by the brightness of the surroundings in the present invention.

First, in the conventional technique 'automatic titration method using PC camera in volatile nitrogen analysis' (Patent No. 10-0667651), only the color information of one pixel is used, but in the present invention, the end point is obtained by using the average value of the color information of several pixels. Previously, it could be applied even when there was no specific color. Second, in the prior art, since the change of the green value and the red value of the pixel is tracked for the end point detection, the color is affected by the ambient brightness, and thus the reproducibility of the color information is decreased, and the accuracy of the end point detection is decreased. The use of a pause value that does not include information on increases the reproducibility of the color information so that the present invention can be used for more automated automation.

With the technique of the present invention, it was possible to efficiently automate acid titration which could not be automated by the conventional technique 'PCR camera in volatile basic nitrogen analysis' (Patent No. 10-0667651), and color change in addition to acid titration. It is believed that the technique of the present invention can be applied to most of the titrations for detecting the endpoint using

The configuration of the automatic titration system manufactured and used for automatic titration in the present invention is as shown in FIG. PC camera (LG, LPC-U30) (101), personal computer (Samsung, M2700) (102), LCD monitor (Samsung, CX931B; resolution setting 1280 × 1024 pixels), digital-to-analog converter (Advantech, PCL812PG) (103), Tubing Pump (Eyela, SMP-23S) (104), Teflon Tubing (0.8 mm Inner Diameter) (105), Tubing Adapter (Upchurch Scientific) (106), Stainless Steel Tube (Inner Diameter 2 mm) (107) , Magnetic stirrer (GmbH, ECM5) 108, burette (50 ml) 109 and beaker (50 ml or 100 ml) 110.

The automatic titration method reads the red, green, and blue values of the selected 144 pixels from the image of the titrated solution, converts them into idle values, calculates the average value of the 144 idle values, stores the first average value of the idle values, and then ends the titration. The difference between the average value of the resting value and the first resting value calculated by the control algorithm (difference difference value) is calculated. The difference is less than 5 for milk and less than 70 for Takju. If semen is supplied and the difference value is 5 or more in case of milk, and in case of Takju, the supply of titrant is stopped.The difference value is 5 or more in case of milk and 70 or more in case of Takju. If it was maintained for 50 seconds, it was determined that the end point of titration was reached, and the operation of terminating the titration was automatically performed. The 144 pixels have the perimeter of the bottom of the beaker when the top and bottom of the rectangular image 201 formed by the PC camera coincide with the top and bottom of the original image 202 formed by the periphery of the titrant solution (titration) as shown in FIG. In the square included in the original image 203 to be formed (the diagonal of the square coincides with the diameter of the circle) 204, both sides were selected at regular intervals. The difference in pixel numbers between neighboring pixels among the selected pixels was 15. The formula for calculating the hue value from the red value R, the green value G, and the blue value G is as follows.

The technique of the present invention was applied to the titration of acidity of milk and Takju. First, the acidity analysis method is described as follows. In the case of milk, take 10 ml of the sample into a beaker (50 ml), add 10 ml of boiled and cooled water, add 5 drops of phenolphthalein indicator, and add 0.1 N sodium hydroxide solution with a burette manually or automatically until the scarlet color is maintained for 50 seconds. Results are shown as the amount of 0.1 N sodium hydroxide solution consumed (ml). In the case of Takju, 20 ml of the sample is taken in a beaker (100 ml), boiled, 30 ml of cooled water is added, 1 ml of neutral red bromine thimol blue mixed indicator is added, and 0.1 N sodium hydroxide solution is added manually or automatically with a burette (50 ml). Results are shown as the amount of 0.1 N sodium hydroxide solution (ml) consumed until green is maintained for 50 seconds.

3 is a flowchart of an automatic titration program for analyzing acidity of milk and vinegar. First, the red, green, and blue values of 144 pixels are read (301), and the average value of the 144 idle values is calculated (302), and the average value of the idle values is stored (303). do. If the average value of the resting value is not the first value (304), the difference between the average value of the resting value and the first resting value is calculated (305). In the case of milk, if the difference value is less than 5 (306), the titrant (0.1 N sodium hydroxide solution) is supplied at a flow rate of 3.12 ml / min (307), and if the difference value is 5 or more (308), the pump is stopped. After repeating the operation 309, the titration is finished (311) when the resting difference value is maintained at 5 or more for 50 seconds (310). In the case of Takju, when the difference value is less than 70 (306), the flow rate of the titrant (0.1 N sodium hydroxide solution) is 3.12 ml / min (307), and when the difference value is 70 or more (308), the pump is stopped. (309) is repeated, and titration is terminated (311) when the difference value is maintained at 70 or more for 50 seconds (310). The automatic titration program was written in Visual Basic 6.0.

Manual titration and automatic titration were performed five times for each milk sample and Takju sample, and the experimental results are shown as the requirements of 0.1 N sodium hydroxide solution as shown in Tables 4 and 5. For the milk sample (Table 4), the result of manual titration was 1.390 ± 0.025 mL and the result of automatic titration was 1.388 ± 0.027 mL. The t-test of this data showed that the p-value of the two-sided test was 0.907, so there was no significant difference between the data of manual titration and automatic titration (p> 0.05). appear. In the case of Takju sample (Table 5), the result of manual titration was 4.738 ± 0.028ml and the result of automatic titration was 4.752 ± 0.037ml. The data in was found to agree well with each other. Therefore, it was considered that the automatic titration method of the present invention can be applied to acid titration, and that it can be applied to most titrations for detecting the end point using color change.

1 is a block diagram of an automatic titration system

2 is a schematic diagram of a PC camera image (a square included in the original image formed by the bottom of the beaker when the top and bottom of the rectangle formed by the PC camera coincide with the top and bottom of the original image formed by the titration solution before titration). Calculates the average value of the resting values of 144 pixels selected at regular intervals within

3 is a flow chart of the acidity automatic titration program of milk sample and Takju sample

4 is a table comparing titration requirements of 0.1 N sodium hydroxide solution with manual titration and automatic titration in acidity analysis of milk samples.

5 is a table comparing titration requirements of 0.1N sodium hydroxide solution of manual titration and automatic titration in acidity analysis of Takju sample

Claims (1)

Automatic pH titration using PC camera reads the red, green, and blue values of selected pixels from the image of the titrated solution, converts them to rest values, calculates the average value of the rest values, and stores the initial resting average value. Until the end of the period, the difference between the average value of the resting value and the first resting value calculated repeatedly by the control algorithm is calculated.If the difference is less than 5 for milk and less than 70 for Takju, the titrant is supplied. If the difference is 5 or more for milk and 70 or more for Takju, the supply of titrant is stopped.The difference value is 5 or more for Milk and 70 or more for Takju for 50 seconds. When the end point is reached and the operation to end the titration is automatically performed.

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