Digital Titrator

Abstract

DIGITAL TITRATOR, for application in chemical instrumental analysis, comprising a transparent vertical tube (burette) (1), which contains the titrant, monitored by a contact image sensor (CIS) (2), parallel to the tube. A titrant reservoir (3) communicates with said burette, with solution transfer by means of a pump (4). The release of said solution is made by a valve (5) to the reaction flask (6), where a sensor (7) collects and transmits information about the progress of monitored reaction to a computer (8). Analytical data is stored, processed and displayed to the user on a screen, and/or printed. A flexible tube communicates the upper ends of tube and reservoir and transfers saturated internal atmosphere conversely, according as pressure change, caused by meniscus movement, without gas exchange with atmosphere, preventing evaporation of solvent and consequent changes in titrant concentration. For the same purpose, the inlet air from atmosphere to the reservoir goes by a saturation bottle (9) containing pure solvent. A PCI (10) controls operations, assisted by a computer, and an agitator (11) homogenizes reaction flask's content.

Claims

1) DIGITAL TITRATOR, instrument for chemical analysis, particularly applicable to quantitative determination of chemical species by volumetry, provided with titrant solution reservoir, volumetric burette, reaction vessel and controlled transfer means of said solution, characterized by the fact that it presents a contact image sensor for reading of liquid column level contained in the burette.

2) DIGITAL TITRATOR, instrument for chemical analysis, particularly applicable to quantitative determination of chemical species by volumetry, characterized by the fact that it presents, in accordance with claim 1, a pump for transfer of said titrant between said reservoir and burette.

3) DIGITAL TITRATOR instrument for chemical analysis, particularly applicable to quantitative determination of chemical species by volumetry, characterized by the fact that it presents, in accordance with claim 1, an electromechanical valve for controlling the transfer of said titrant from burette into reaction vessel.

4) DIGITAL TITRATOR, instrument for chemical analysis, particularly applicable to quantitative determination of chemical species by volumetry, characterized by the fact that it presents, in accordance with claim 1, a connecting means to exchange internal atmosphere between said reservoir and burette.

5) DIGITAL TITRATOR, instrument for chemical analysis, particularly applicable to quantitative determination of chemical species by volumetry, characterized by the fact that it presents, in accordance with claim 1, means to saturate external air admitted into reservoir with solvent vapor.

Description

[0008] FIG. 1 shows a preferred construction of proposed digital titrator. The instrument detects meniscus position in a transparent vertical tube by means of a high resolution contact image sensor (CIS). It comprises said vertical transparent tube (burette) (1), which contains the titrant monitored by a contact image sensor (2), parallel to the tube. A titrant reservoir (3) communicates with said burette with solution transfer by a pump (4), and release is controlled by an electromechanical valve (5) to the reaction flask (6), wherein a sensor (7) collects and transmits information on reaction progress to the computer (8). Analytical data is stored, processed and displayed to the user on a screen, and/or printed. A communication between the upper end of said burette and the top of said reservoir transfers saturated internal atmosphere conversely, as pressure changes due to meniscus movement, without gas exchange with atmosphere, preventing evaporation of solvent and consequent changes in titrant concentration. For the same purpose, inlet air from atmosphere to the reservoir goes through a saturation bottle (9) containing pure solvent. A PCI (10) controls operations, assisted by a computer, and an agitator (11) homogenizes reaction vessel's content.

[0009] Adoption of image sensor as reading system eliminates moving parts that usually are determinant of instrument's accuracy, while pump and valve are used only to titrant transfer, resulting in a device with no mechanical complexity and low cost. Resulting volumetric burette eliminates procedures for mechanical calibration and maintenance related to accuracy. The CIS sensor has low cost and long life.

CONSULTED REFERENCES

[0010] 1. Kuroda, T., Essential Principles of Image Sensors, CRC Press: Boca Raton (Fla.), 2014.

[0011] 2. Harvey, D. T., Modern Analytical Chemistry, 1.sup.st ed., McGraw-Hill: New York, 1999, p. 273.

[0012] 3. Carter K. N., Huff, R. B., Second derivative curves and end-point determination, J. Chem. Educ., 1979, 56 (1), p 26.

[0013] 4. Gran, G, Analyst, 77, 661 (1952).

[0014] 5. Oehme, F, Richter, W. Instrumental Titration Techniques. Verlag: Heidelberg, 1987.

[0015] 6. Hach C. C., Digital Titration Device, U.S. Pat. No. 088,062 A, Apr. 26, 1978, Hach Chemical Co.

[0016] 7. Hoffmann, W., Computer controlled titration with piston burette or peristaltic pumpa comparison, Fresenius' Journal of Analytical Chemistry, 1996, 356 (3-4), pp 303-305.

[0017] 8. Zimmerli, F. H., Automatic gravimetric titrator for batch operation, U.S. Pat. No. 3,447,906 A, Jun. 3, 1969, Rohm & Haas.

[0018] 9. Skoog, D. A., West, D. M., Holler, F. J., Fundamentals of Analytical Chemistry, 6.sup.th Edition, Saunders: Philadelphia, 1992; pages 94, 113-114, 809-810, 841-842.