CN2572406Y - Step coulombmeter - Google Patents

Abstract

The utility model relates to a step coulomb meter, belonging to analytical chemical instruments, comprising a clock pulse generator (1), a counter (2), a step potential setting circuit (3), a bidirectional analog switch A (4), a bidirectional analog It is composed of a switch B (6), a current amplification circuit (5) and a current integral operation circuit (7). The instrument is combined with a macrocyclic copper complex-platinum black modified platinum electrode to measure trace nitric oxide. The instrument has the advantages of stable performance, strong anti-interference, high sensitivity, low detection limit, convenient use, light weight, small size, and suitable for on-site analysis.

Description

Step Coulomb

The utility model relates to an analytical chemical instrument.

Voltammetry is a commonly used electroanalytical chemical method, but its sensitivity is not high enough, and it is difficult to determine some trace components in many occasions. For this problem, the inventor of the utility model has proposed and established step voltammetry, and has designed corresponding multifunctional microcomputer control step voltammetry. After years of application practice and research, it is found that its sensitivity can be further improved.

The purpose of this utility model is to establish a new electroanalytical chemical method and design a new electroanalytical chemical instrument----step coulomb instrument on the basis of the prior art. This new instrument can further improve the sensitivity, while being easy to operate, light in weight and small in size.

The main technical proposal of the utility model is that on the basis of the step voltammetry, the current measurement of the step voltammetry is changed to the electric quantity measurement, and a step coulomb is made. Among them, the power measurement uses the integration circuit of current versus time.

The utility model has the advantages of stable performance, strong anti-interference, high sensitivity, convenient use, light weight, small volume, suitable for on-site analysis, etc., and the concentration can be directly displayed in the digital meter.

Below in conjunction with accompanying drawing and embodiment the utility model is described further.

Fig. 1 is the basic structural diagram of the utility model.

Fig. 2 is a circuit diagram of a three-step electronic switch of the present invention.

3 is a circuit diagram of each step potential setting circuit of the present invention.

Fig. 4 is a circuit diagram of a three-step power and current amplifying circuit of the present invention.

With reference to Fig. 1, the utility model instrument is by clock pulse generator (1), counter (2), step potential setting circuit (3), two-way analog switch A (4), two-way analog switch B (6), current amplification The circuit (5) and the current integral operation circuit (7) are composed. The output of the clock pulse generator (1) is connected to the input terminal of the counter (2), and the output terminal of the counter (2) is connected to the control terminals of the bidirectional analog switch A (4) and the bidirectional analog switch B (6). The output end of the step potential setting circuit (3) is connected to the non-inverting input end of the operational amplifier through the bidirectional analog switch A (4), and the inverting input end and the output end of the operational amplifier are respectively connected to the reference electrode ( R) and opposite pole (C) connection. The input end of the current amplification circuit (5) is connected to the working electrode (W) of the electrochemical cell, and its output end is connected to the current integration operation circuit (7) through the bidirectional analog switch B (6), and the current integration operation circuit (7) outputs The terminal is connected with the display (digital ammeter).

The clock pulse generator (1) generates a pulse of a certain frequency and adds it to the counter (2), so that the counter (2) outputs the high and low levels of the corresponding frequency, and drives the bidirectional analog switch (4, 6) to turn on or off. Therefore, the voltages of the three steps generated by the step potential setting circuit (3) are sequentially applied to the opposite poles. The current obtained by each step is output directly after passing through the current amplification circuit (5) or converted into electric quantity through the current integration circuit (7) and displayed on the digital voltmeter in millivolts.

According to needs, three, five or seven step potential setting circuits (3) can be set, respectively connected to the bidirectional analog switch A (4) to make a three-step coulomb meter, a five-step coulomb meter or a seven-step coulomb meter. Step coulometer.

Below in conjunction with Fig. 2～4, take the three-step coulometer as an example, illustrate the working principle and working process of the present utility model.

Referring to Figure 2, the clock pulser is composed of IC1 (CC4069). The pulse frequency is determined by R.C. The clock frequency can be changed when R is changed. The pulse signal is sent to the CP of the decimal counting and decoding integrator IC2 (CC4017) through differentiation (R1C1) End (counting with pulse rising edge) and falling edge counting end EN connected to low level. When the first clock pulse acts on the CP end, Y0 becomes high level, and the analog switches SWA and SWA(1) are turned on. When the second clock pulse arrives (CP terminal), Y0 returns to low level, switches SWA and SWA(1) are turned off, Y1 becomes high level, and electronic switches SWB and SWB(2) are turned on. Similarly, when the third clock pulse arrives, Y2 becomes high level, and Y1 returns to low level; when the fourth clock pulse arrives, Y2 returns to low level, and Y3 becomes high level, immediately Drive the trigger pole of the thyristor, the thyristor conducts, drives the relay B to pull in, and the clock pulse stops. Input the CP terminal of IC2 (CC4017), the circuit can stop counting. Always keep Y3 at high level. SWA, SWB, SWC and SWA(1), SWB(2), SWC(3) are in the off state, so by adding different (set) potentials of the input signal A.B.C, the circuit completes a cycle. Three step (ladder) potentials appear at opposite extremes.

To re-scan the cycle again, just set the panel switch to reset first, and the reset terminal R of IC2 (CC4017) in the circuit becomes high level (the thyristor T goes out), and Y3 changes back to low level. The circuit is in the reset state, at this time the panel channel indicator light O emits red light, and the panel switch B is placed in the scanning position. The thyristor is not conducting, the relay B is not closed, and the normally closed point is connected to the clock pulse channel. The circuit performs a turn-on cycle until Y3 becomes high level, and completes a cycle again.

Referring to Figure 3, R11, R12, W3, W4, W5 and IC4, IC5, IC6, SWA, SWB, SWC form three channels (ladder) set (adjustable) voltage (constant voltage), IC4, IC5, IC6 constitute buffer amplifier. The setting potential of the first channel (that is, the first step) is adjusted by W3, and the output of IC4 is connected to point A (that is, the end of the switch SWA of the first channel), while the second and third channels (the second and third steps) The setting potential of the switch is also connected to the input terminals of IC5 and IC6 respectively by W4 and W5 (adjustable voltage), and its output terminals are respectively connected to points B and C of SWB and SWC, and the other ends of the switches SWA, SWB and SWC are respectively connected to Together and output to the input terminal of IC7, IC7 is connected to the counter electrode and reference electrode. When SWA, SWB, and SWC are sequentially turned on, the set potentials of each step appear in sequence at the opposite end.

Referring to Figure 4, the current obtained by each ladder is directly output after being amplified or converted into electricity by integration and displayed on the digital voltmeter in millivolts. The current amplifier is composed of IC8 (OPA128), and the working electrode (W pole) is connected to the operational amplifier IC8 (OPA128 ) of the inverting input terminal; R6, R7, R8 form the adjustment current amplification factor, resistors R3, R4, R5. and W1 form the zero point adjustment. Zeroing); IC9 (CA3130E) constitutes an integral operational amplifier. R13, C1, and C2 form an integral constant (by setting the size of C1 and C2, the integral rate can be adjusted to two levels of 0.1 second and 1 second, and K5 is the discharge switch of C1 or C2). To measure the integral of a certain channel, K3 is respectively connected to the beginning of electronic switches SWA(1), SW(2), SW(3); SWA, SWB, SWC and SWA(1), .SWB(2), SWC(3) ) is synchronous, that is, when SWA is turned on, SWA(1) is also turned on at the same time.

The utility model can carry out the multi-potential step process of oxidation, reduction and re-oxidation. Experiments show that this instrument has good performance and high sensitivity, and is especially suitable for systems with increased sensitivity during oxidation, reduction, and reoxidation. The detection limit can be reduced to 3.5×10 ^-10 mol/L, and the linear range is 1.5×10 ^-9 ～ 4.5×10 ^-6 mol/L. And it has the characteristics of small size, light weight, strong anti-interference ability, easy to use, and suitable for on-site measurement.

List the application examples of the present utility model below.

Nitric oxide (NO) is an important physiological endogenous biomolecule, which participates in many physiological processes and is one of the main small molecules that life depends on. The detection of NO is of great significance to the study of its physiological function. NO exists in many tissues in the body, and when the content of NO is 10 ^-9 mol/L, it plays the role of information transmission. In order to detect this level of NO, many methods have been proposed, but only electrochemical methods can detect living organisms in real time and provide time information of NO in living organisms, making research in this field develop rapidly. We applied a practical new three-step coulometer, combined with macrocyclic copper complex-platinum black modified platinum electrode catalytic oxidation determination, carried out oxidation, reduction and re-oxidation process, and successfully reduced the detection limit of NO to 3.5×10 ^-10 mol/ L, the linear range is 1.5×10 ^-9 ~ 4.5×10 ^-6 mol/L.

So far, the structure, working principle and application of the utility model have been described in detail. The utility model is not limited to the above-mentioned embodiments, and each component and parts in the circuit can be replaced by components and parts with the same function, equivalent or similar, and each circuit can also be replaced by a circuit with the same function, equal or similar, but all should be included in the present invention. Among utility models.

Claims (2)

1. a step coulomb meter, is characterized in that: by clock pulse generator (1), counter (2), step potential setting circuit (3), bidirectional analog switch A (4), bidirectional analog switch B ( 6), the current amplification circuit (5) and the current integration operation circuit (7) are composed; the output of the clock pulse generator (1) is connected to the input terminal of the counter (2), and the output terminal of the counter (2) is connected to the bidirectional analog switch A (4) and the control terminal of the bidirectional analog switch B (6); the output terminal of the step potential setting circuit (3) is connected to the non-inverting input terminal of the operational amplifier through the bidirectional analog switch A (4), and the negative input terminal of the operational amplifier The phase input terminal and output terminal are respectively connected with the reference electrode (R) and the opposite pole (C) of the electrochemical cell; the input terminal of the current amplification circuit (5) is connected with the working electrode (W) of the electrochemical cell, and its output terminal It is connected to the current integral operation circuit (7) through the bidirectional analog switch B (6), and the output terminal of the current integral operation circuit (7) is connected to the display (digital electric meter). 2. The step coulomb meter according to claim 1, characterized in that: three, five or seven step potential setting circuits (3) can be set, respectively connected to the bidirectional analog switch A (4).

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