SU1068731A1 - Method and device for nuclear abosrption analysis - Google Patents

Abstract

1. A method for atomic absorption analysis of a substance, including sequential transmission through an atomizer containing atoms of the element under study, pulses of resonant and continuous radiation with subsequent photoelectric recording and comparison of the corresponding electrical signals, so that in order to reduce the measurement error, a change in the electrical signal proportional to the absorption of resonant radiation is compensated by a change in the duration of the pulse of continuous radiation, and the values for the signal of absorp- tion, they are determined by the change in the duration of the radiation pulse of a continuous radiation. | SG

Description

2. A device for atomic absorption analysis of a substance containing a series of resonant radiation sources with a pulsed power supply unit, a translucent plate at an angle of 45 ° to the optical axis, an atomizer, a monochromator, a series-connected photodetector, an amplifier, a switch, the outputs of which are connected to integrators associated with the comparison device, as well as a continuous spectrum radiation source, located at an angle of 90 ° to the optical axis, with a pulsed power supply unit.

the synchronizing device and the digital measuring device, the outputs of the synchronizing device are connected to the power supply unit of the resonant radiation source and the switch, characterized in that, in order to reduce the measurement error, the device is supplied with a device for controlling the duration of the power pulse, the inputs of which are connected to the calls of the comparison device and sync device as well. output - to the inputs of the power supply unit of the continuous spectrum radiation source and the digital measuring device

one

The invention relates to an analytical measurement technique and can be applied for the elemental analysis of liquid and solid substances.

A known method for the atomic absorption analysis of a substance is based on transmitting resonant radiation through an atomizer containing aroMj of the element under study, followed by photoelectric recording and measuring the change in intensity of resonant radiation 1.

However, single-beam atomic absorption spectrophotometers (AAS) based on this method are characterized by significant errors caused by non-selective absorption and drift.

A known method for atomic absorption analysis of a substance involves sequential transmission through an atomizer containing atoms of the element under study, pulses of resonant and continuous radiation with subsequent photoelectric recording and comparison of the corresponding electrical signals {2.

A device for the atomic absorption analysis of a substance is known, which contains successively located sources of resonant radiation with a pulsed power supply unit, a translucent plate located at an angle of 45 ° to the optical axis, an atomizer, a monochromator, a photodetector, an amplifier, a switch, two integrators and a comparator, as well as a radiation source a continuous spectrum, located at an angle of 90 ° to the optical axis with a pulsed power supply unit, a synchronizing device and a digital measuring device 2.

However, devices that implement these methods and devices have a differential structural measurement scheme that cannot provide long-term stability and high measurement accuracy. The purpose of the invention is to reduce measurement errors.

The goal is achieved. In accordance with the method of atomic absorption analysis of a substance, including sequential transmission through an atomizer containing the atoms of the element under study, pulses of resonant and continuous radiation, followed by photoelectric recording and comparing with the corresponding electrical signals, the change in the electrical signal is proportional to the absorption of resonant radiation. , compensated by changing the duration of the pulse of continuous radiation, and

the magnitude of the absorption signal is determined by the change in the pulse duration: emission of the splashin radiation.

A device for atomic absorption analysis of a substance, containing

5 consecutively located resonant radiation source with a pulsed power supply unit, a semitransparent plate located at an angle of the optical axis, an atomizer, a monochromator, a series-connected photodetector, an amplifier, a switch, the outputs of which are connected to integrators connected to the comparator, as well as a continuous source of radiation. spectrum, located on the optical axis of the optical axis, with a pulsed power supply unit, a synchronization device and a digital measuring device, and the sync outputs niziruyuschego ustroy0 CTBA connected to the power supply unit and the switch of the resonant radiation, introduced device controlled supply pulse duration, whose inputs are connected to the passages, you comparing device, and the synchronizing device, and output to the outputs of the power supply unit and the continuous spectrum of radiation Vågå digital measuring device. FIG. 1 kanaza AAS structural diagram implementing the proposed measurement method; in fig. 2 diagrams of forming electrically signals. AAS contains sources 1 and 2 of resonant and continuous radiation, respectively, pulsed blocks 3 and 4 of the power supply of sources of radiation, translucent plate 5, atomizer b, monochromator 7, photodetector 8, amplifier 9, switch 10, devices 11 and 12 of integration, device 13 comparison, a device 14 for regulating the duration of the power supply impulse of the block 4, an electronic synchronizing device 15, a digital measuring device 16, for example, a generator 17 of counting pulses, a key 18 and a recalcating counter 19 of pulses. The device works as follows. At the initial moment, a pulse of resonant radiation from source 1 passes a semitransparent plate 5, an atomizer 6 containing the atoms of the element under investigation, a monochromator 7 and is converted into an electrical signal by the photoreceiver 8, amplified by amplifier 9. The signal from the output of amplifier 9 through the switch 10 is fed to the input of the mouth Features 11 integration. The duration of the resonant radiation pulse is fixed, as determined by the duration of the supply pulse of power supply unit 3, which is constant during the measurement process. Therefore, during the course of integrator 11, a signal l appears. where t is the pulse duration K is the transfer coefficient of the blocks 6-11; f is the light flux of a source of resonant radiation. At the time tp, the synchronization device 15 sends a pulse to the synchronization input of the device 14 for regulating the duration, the pulse, which turns on the power supply unit 4, and the radiation from the source 2 of the continuous spectrum, reflected from the plate 5, successively passes the blocks 6-9. The device 15 supplies a clock pulse to KONWyTaTOp 10, which connects the output of the amplifier 9 to the input of the integrating device 12. At the same time, the comparison device 13 is turned on, which compares the voltages at the two inputs connected to the outputs devices 11 and 12 integration. The constant voltage U is compared with the current value of voltage U at the output of the integration device 12. At a certain point in time, equality takes place (Fig. 2a), i.e. “F-dt, And where C is the transfer coefficient of blocks 6 - 10 and 12; F- is the light flux of a continuous radiation source. Condition C1) can be replaced by the equality MlS (V4) At time tg, the output of the comparison device 13 is zero-signal, which is fed to the control and input of the device 14. At this moment the device 14 turns off the power supply 4. The pulse duration D 3 is recorded by the digital device 16. The synchronizing pulse at time t2 opens the key 18, and the counting pulses from the generator 17 counting pulses arrive at the input of the reversing 9 of the counter 19. At time t3, the device 14 turns off the power supply 4 and closes the key 18. Thus Thus, the counter-19 receives N counting pulses, where NQ 4i /, where f is the frequency of the counting pulses. The value is remembered as the initial value of the counter 19. In the presence of non-selective absorption, a voltage arises at the output of the device 11 -integrating (, t, where tH is the non-selective absorption coefficient. However, the presence of the Hexteric value does not cause the time interval at, since equality is maintained) 5 ) "2 O12 In the presence of atoms of the element under study in the atomizer 6, absorption of resonant radiation occurs, as a result of which the luminous flux Φ decreases by the magnitude of LF. This leads to a decrease in the input voltage of the device 13, therefore the equality of the stresses occurs at the time t (Fig. 2, c), which satisfies the condition (K) From which it follows that v; -and the change in the luminous flux is proportional to the change in duration Power pulse of a continuous radiation source. Over a period of time j-iy, N counting pulses arrive at the reversible counter. The counter reading, taking into account the initial value N.J (Fig. 2, b. D) m, -m.1a, df where K is the proportionality coefficient. Thus, in the invention, a zero signal is maintained at the output of the comparator device, which is, by processing the signal, by rebalancing an inverse relationship covering the continuous radiation source. The measurement of the measuring signal, the resonance absorption signal, proportional to the concentration of the element under study, is compensated for by a corresponding change in the duration of a continuous radiation pulse.

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Claims (2)

METHOD AND DEVICE FOR ATOMIC-ABSORPTION ANALYSIS OF SUBSTANCE. 1. The method of atomic absorption analysis of a substance, including sequential transmission through an atomizer containing the atoms of the element under study, pulses of resonant and continuous radiation, followed by photoelectric registration and comparison of the corresponding electrical signals, which is due to the fact that , in order to reduce the measurement error, a change in the electrical signal proportional to the absorption of the resonant radiation is compensated by a change in the pulse duration of the continuous radiation, and the signal absorption is determined by the change in the pulse duration of continuous emission radiation 6 -> 7 " t Fig 1 2. A device for atomic absorption analysis of a substance containing a sequentially located resonant radiation source with a pulsed power supply unit ', a translucent plate located at an angle of 45 ° to the optical axis, an atomizer, a monochromator, a photodetector connected in series, an amplifier, a switch, the outputs of which are connected to integrators associated with the comparison device, as well as a continuous spectrum radiation source located at an angle of 90 ° to the optical axis, with a switching power supply, synchronizing a device and a digital measuring device, and the outputs of the synchronizing device are connected to the power supply unit of the resonant radiation source and a switch, characterized in that, in order to reduce the measurement error, a device for controlling the duration of the power pulse, the inputs of which are connected to the outputs of the comparison and synchronizing devices, is introduced into the device devices as well. output - to the inputs of the power supply unit of the radiation source of a continuous spectrum and a digital measuring device.