SU798883A1 - Meter of chromatographic peak parameters - Google Patents

Description

one

The invention relates to automation and computing, in particular to the automatic processing of chromatographic information (measurement of the area or height of the chromatographic peak and retention time). The calculation of the concentration of a substance in a given mixture (chromatographic peak) is carried out over both peak areas and heights, and in the cases of unseparated peaks, the calculation of heights provides a higher accuracy than area calculations.

A known integrator is designed to measure the area of chromatographic peaks, which contains an amplifier, a voltage-frequency converter, a counter, a memory register, a correction unit.

An automatic integrator is also known for measuring the area of the chromatographic peak and the retention time, comprising an amplifier, a voltage-frequency converter, a counter, a memory register, a digital printer, a circuit determining the beginning and end of the integration, a control unit 2}.

However, these chromatographs have a large error in calculating the concentrations of unseparated peaks, since they do not measure the height of the chromatographic peak.

Closest to the proposed technical entity is a device for determining the height of chromatographic peaks, containing an amplifier, voltage-frequency converter, a control unit, the first output of which is connected to a pulse sensor, the second output of which is connected to the first input of the second memory register, the third the output of which is connected to the first input of the first memory register, the first pulse counter connected to the first display unit and the digital printing device through the first memory register, the second counter named Pulse coupled to the second display unit and the digital printer device via a second register memory and a second counter input coupled to the output of the pulse generator 3J.

A disadvantage of the known device is the small dynamic range (up to 10), determined mainly by the digital-to-analog converter unit. The purpose of the invention is to expand the dynamic range of the input signal without increasing the error. The goal is achieved by introducing a tilt detector, a quantizing pulse generator, a larger number detection circuit, an OR circuit, a correction unit, the first input of the OR circuit is connected to the fourth output of the control unit, the second input of the OR circuit, the second output of which is connected to the first input of the control unit, the output of the OR circuit is connected to the reset bus of the first counter, the output of the first counter is connected to the first input of the larger number detection circuit, the second input the output is connected to the output of the first memory register, and the output of the larger number detection circuit is connected to the second input of the control unit, the output of the amplifier is connected to the input of the voltage-frequency converter and to the input of the tilt detector, the output of which is connected to the third input of the control unit, the output of the voltage converter Frequency-frequency is connected to the first input of the correction unit, the second input of the correction unit is connected to the fifth output of the control unit, and the output of the correction unit is connected to the input of the first counter. The drawing shows a block diagram of the gauge parameters of chromatographic peaks. The chromatographic peak parameter meter contains an amplifier 1, the output of which is connected to the input of a voltage-frequency converter 2 and a slope detector 5. The output of the voltage-frequency converter is connected to the first input of the correction unit 3, the second input of the correction unit 3 is connected to the Fifth output of the control unit 6. The third input of the control unit 6 is connected to the tilt detector 5. The output of the correction unit 3 is connected to the first counter 4, which is connected to a larger number determining circuit 8 and through the first memory register 7 with the display unit 13 and the digital printing device 14. The first output of the control unit 6 is connected to the input of the pulse sensor 9, the output of which connected to the input of the second counter 10. The second counter 10 through the second memory register 11 is connected to the digitizer 14 and the second display unit 12. The second output of the control unit 6 is connected to the second memory register 11, the third output of the display unit 6 is connected to the first memory register 7. The fourth output of the control unit 6 is connected to the first 4 input of the OR circuit 15, the output of which is connected to the first counter 4. The second input of the OR circuit 15 is connected to the generator output of 16 quantizing pulses, the second output of which is connected to the first input of the control unit 6. The second input of control unit 6 is connected to the output of circuit 8 for determining a larger number. The meter works as follows. The signal from the chromatograph enters amplifier 1, from where it arrives at voltage-frequency converter 2 and tilt detector 5, from which pulses are taken to control unit 6. The control unit 6 generates control commands for the remaining blocks corresponding to the beginning, end and top of the chromatographic peak of pulses with a frequency corresponding to the input voltage from the output of converter 2 through the correction unit 3 to the meter 4. The device operates in two modes: measuring the area and retention time, measurement of chromatographic peak height and retention time. In the first mode, the counter 4 through the circuit 15 OR is torn off at the integration time (peak duration), and at the end of the chromatographic peak, information from counter 4 enters memory register 7 and then on digital display 13 and printing 14. In the second mode, on the counter reset bus 4, counter reset pulses are applied, the period of which is equal to the quantization time. The quantization time is specified by generator 16. The number of pulses counted during this time is transmitted to memory register 7, and from there to a larger number determination circuit. In the subsequent quantization time, the information stored in the memory register is compared in the scheme for determining a larger number with the current information in counter 4, from which information is sent to another input of the scheme for determining a larger number. In all cases, when the number in memory register 7 is less than the number coming from counter 4, the control pulse from the circuit. the determination of a larger number is not received by the control unit 6. When the chromatographic peak passes through the vertex, the number stored in memory register 7 is greater than the number coming from counter 4, and the larger number determination circuit generates a control signal to block 6. The control block 6 stops the reset pulses to the counter and registers 7 the memory stores the number that corresponds to the top of the chromatographic peak. From the memory register 7, information is fed to the display unit 13 and the digital printing device 14. At the time the sample is introduced into the chromatograph (start of analysis), the sensor 9 of time pulses is triggered. The pulses arrive at the counter 10, during the determination of the tip of the tilt detector 5, the control unit 6 issues a command to transfer information from the counter 10 to the memory register 11, then to the digital display 12 and print the device 14.

The proposed chromatographic peak parameter meter has a higher signal measurement range in height.

Tests of the prototype of the device when measuring the height of peaks with a duration of 2 to 20 s and more show the spread of the dynamic range of the input signal from 1 V to 1 μV (10), which significantly exceeds the dynamic range of the known, having 10, about 10 and 10. The proposed device can work with

with capillary columns (i.e., with a peak duration of up to 0.3-0.5 s), with a dynamic range of up to 10. The dynamic range of the device proposed is increased compared to the known one without an increase in the error. Roughly, the measurement error is 0.2-0.3%.

A scheme for measuring the height of the chromatographic peak is implemented on TTLlogs. A circuit for measuring the height of a chromatic peak is mounted on one board with an area meter measuring 160 x 240 mm.

Claims (3)

1. Integrator of chromatographic data a.s. USSR № 570066, cl. G 06 G 7 / 1.8. 2. US patent number 3506818, cl. 7D-23, 1967. 3. The patent of Germany N 1195073, C. 06 G 7/18, 1965 (prototype).