A dynamic titration method for volumetric Karl Fischer titrator

Abstract

The invention discloses a dynamic titration method applied to a volumetric Karl Fischer titrator, comprising: S101, starting titration, adding at the longest time interval; S102, potential stabilization stage: the titration interval changes regularly by regularly increasing the titration volume; S103, potential transition stage: the titrated volume decreases regularly, and the titration interval is regularly extended at this time; S104, termination stage: reaching the termination condition, the titration ends. According to the invention, a simple, fast and accurate method is provided for titrating water content.

Description

Technical Field

[0001] The invention relates to the technical field of potentiometric titration, and in particular to a dynamic titration method applied to a volumetric Karl Fischer titrator. Background Art

[0002] Moisture content testing is one of the important quality indicators. All industries have relevant regulations and standards. If the moisture content exceeds or falls below a certain level, both the quality and economic benefits will be greatly affected.

[0003] There are many methods to determine the water content in a substance, the most common methods are drying method, spectral chromatography and Karl Fischer method. Karl Fischer water determination method is not only cost-effective but also highly accurate. It is recognized as a classic method for high-accuracy water detection.

[0004] When testing water samples with volumetric method, the accuracy of samples with lower water content is often not high, which makes the repeatability of volumetric moisture meter poor when used with cassette furnace to measure blank. Therefore, its titration mode needs to be improved.

[0005] In the past, when the volumetric method was used to measure samples with high water content, the test time was relatively long and the dynamic titration mode was relatively complicated. Summary of the invention

[0006] In view of the shortcomings of the prior art, the object of the present invention is to provide a dynamic titration method applied to a volumetric Karl Fischer titrator, which provides a simple, fast and accurate method for titrating water content. In order to achieve the above-mentioned purpose and other advantages according to the present invention, a dynamic titration method applied to a volumetric Karl Fischer titrator is provided, comprising:

[0007] S101, start titration, and add at the longest time interval;

[0008] S102, potential stabilization stage: the titration interval changes regularly by regularly increasing the titration volume;

[0009] S103, potential transition stage: the titration volume is reduced according to the rule, and the titration interval is extended according to the rule;

[0010] S104, termination phase: the termination condition is reached and the titration ends.

[0011] Preferably, when titration starts in step S101, the added volume is performed at the minimum added volume, the titration interval is performed at the maximum time interval, and this process is performed up to 10 times.

[0012] Preferably, in step S102, the addition is performed with the minimum addition volume. After the addition, the potential values ​​before and after the addition are determined. If the potential change is below 3 mV, the potential stabilization stage is entered, at which time the addition volume begins to increase, and the change pattern is carried out according to the potential stabilization stage. The titration interval time begins to decrease, and the pattern is carried out according to the time interval change pattern of the stabilization stage.

[0013] Preferably, after adding the titrant in step S103, the potential value before and after the addition is determined; if the potential drops by more than 3 mV for three consecutive times, the potential transition stage is entered. The volume change added in this stage refers to the volume change law of the transition stage, and the titration interval begins to increase, and the law is followed by the time interval change law of the transition stage.

[0014] Preferably, after continuing to add the titrant in step S104, when the endpoint potential is reached, the termination phase begins, the added volume is added according to the last addition of the previous phase, the time interval is added according to the last time interval of the previous phase, and when the endpoint judgment condition is reached, the entire titration ends.

[0015] Compared with the prior art, the present invention has the following beneficial effects: a simple, fast and accurate titration method, and the dynamic titration method provided by the present invention can be applied to a moisture meter combined with a volumetric method and a card furnace, and can accurately measure the blank value and measure low-moisture samples very accurately. When measuring high-concentration moisture, the test time is greatly shortened without affecting its accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 The present invention is a flow chart of a dynamic titration method applied to a volumetric Karl Fischer titrator. DETAILED DESCRIPTION

[0017] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Reference Figure 1 , a dynamic titration method applied to a volumetric Karl Fischer titrator, comprising: S101, starting titration, adding at the longest time interval;

[0019] S102, potential stabilization stage: the titration interval changes regularly by regularly increasing the titration volume;

[0020] S103, potential transition stage: the titration volume is reduced according to the rule, and the titration interval is extended according to the rule;

[0021] S104, termination phase: the termination condition is reached and the titration ends.

[0022] Furthermore, when titration starts in step S101, the added volume is performed at the minimum added volume, and the titration interval is performed at the maximum time interval. This process is performed up to 10 times.

[0023] Furthermore, in step S102, the addition is performed with the minimum addition volume. After the addition, the potential values ​​before and after the addition are determined. If the potential change is below 3 mV, the potential stabilization stage is entered. At this time, the addition volume begins to increase, and the change pattern is carried out according to the potential stabilization stage. The titration interval time begins to decrease, and the pattern is carried out according to the time interval change pattern of the stabilization stage.

[0024] Furthermore, after adding the titrant in step S103, the potential value before and after the addition is determined; if the potential drops by more than 3 mV for three consecutive times, the potential transition stage is entered. The volume change added in this stage refers to the volume change law of the transition stage, and the titration interval begins to increase, following the change law of the time interval in the transition stage.

[0025] Furthermore, after the titrant is continuously added in step S104, when the endpoint potential is reached, the termination phase begins, the added volume is added according to the last addition of the previous phase, the time interval is added according to the last time interval of the previous phase, and when the endpoint judgment condition is reached, the entire titration ends.

[0026] The variation pattern of the titration volume is as follows: the maximum added volume Vmax: 0.015 mL, the minimum added volume Vmin: 0.005 mL, and the addition coefficient F1: 10%.

[0027] Change rules of potential stability stage:

[0028] Each time adding: Vno = Vmin + (Vmax - Vmin) * 0.01 * No

[0029] Transition stage stage change rules:

[0030] The added volume is obtained by the last added volume and F1.

[0031] VNO=Vno-(VMax-VMin)*F1*0.01

[0032] Note: When the added volume is too small, the minimum added volume will be automatically selected.

[0033] When the added volume is too large, the maximum added volume is automatically selected.

[0034] Titration interval time variation rule: maximum interval time Tmax: 2s, shortest interval time Tmin: 50ms, parameter F2: 0.05.

[0035] Initial stage rule: add at the longest time interval, up to 10 times.

[0036] a) Change rules in the stable stage:

[0037] Tno=Tmax-(Tmax-Tmin)*F2*No.

[0038] b) Change rules of excessive drop stage:

[0039]

[0040] Note: When the time interval is too short, the shortest time interval is automatically selected.

[0041] When the time interval is too large, the maximum time interval is automatically selected.

[0042] The number of devices and processing scales described here are used to simplify the description of the present invention, and the application, modification and variation of the present invention will be obvious to those skilled in the art.

[0043] Although the embodiments of the present invention have been disclosed as above, they are not limited to the applications listed in the specification and implementation modes. They can be fully applied to various fields suitable for the present invention. For those familiar with the art, additional modifications can be easily implemented. Therefore, without departing from the general concept defined by the claims and the scope of equivalents, the present invention is not limited to the specific details and the illustrations shown and described herein.

Claims

1. A dynamic titration method applied to a volumetric Karl Fischer titrator, characterized in that: The following steps are involved: S101, start titration, and add at the longest time interval; S102, adding with the minimum addition volume, after adding, judging the potential value before and after adding, if the potential change is below 3mV, entering the potential stabilization stage, at this time, the addition volume begins to increase, the change rule is carried out according to the potential stabilization stage, the titration interval time begins to decrease, and the rule is carried out according to the time interval change rule of the stabilization stage; S103, potential transition stage: the titration volume is reduced according to the rule, and the titration interval is extended according to the rule; S104, termination stage: the termination condition is reached and the titration ends; Among them, the change rule of titration volume: maximum added volume Vmax: 0.015mL; minimum added volume Vmin: 0.005mL; addition coefficient F1: 10%; Change rules of potential stability stage: Each time adding: Vno=Vmin+(Vmax-Vmin)*0.01*No Change rules in the transition phase: The added volume is obtained by the last added volume and F1. VNO=Vno-(VMax-VMin)*F1*0.01; Note: When the added volume is too small, the minimum added volume will be automatically selected; When the added volume is too large, the maximum added volume will be automatically selected; Titration interval time variation rule: maximum interval time Tmax: 2s, minimum interval time Tmin: 50ms, parameter F2: 0.05; Initial stage rule: add at the longest interval, up to 10 times; a) Change rules in the stable stage: Tno =Tmax-(Tmax-Tmin)*F2*No; b) Change rules in the transition phase: TNo =Tno+ *F2* No; Note: When the time interval is too short, the shortest time interval is automatically selected; When the time interval is too large, the maximum time interval is automatically selected.

2. A dynamic titration method for a volumetric Karl Fischer titrator as claimed in claim 1, characterized in that: When titration starts in step S101 , the added volume is performed at the minimum added volume, and the titration interval is performed at the maximum time interval. This process is performed up to 10 times.

3. A dynamic titration method for a volumetric Karl Fischer titrator as claimed in claim 1, characterized in that: After adding the titrant in step S103, the potential value before and after the addition is determined; if the potential drops by more than 3 mV for three consecutive times, the potential transition stage is entered. The volume change in this stage refers to the volume change law in the transition stage, and the titration interval begins to increase, following the time interval change law in the transition stage.

4. A dynamic titration method for a volumetric Karl Fischer titrator as claimed in claim 1, characterized in that: After continuing to add titrant in step S104, when the endpoint potential is reached, the termination phase begins, the added volume is added according to the last addition of the previous phase, the time interval is added according to the last time interval of the previous phase, and the entire titration ends when the endpoint judgment condition is reached.

Images