JP2701771B2 - Atomic absorption photometer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an atomic absorption spectrophotometer having a plurality of lamps as light sources, and more particularly to a mechanism for preliminarily lighting a lamp.

[0002]

2. Description of the Related Art In order to stably obtain accurate data with an atomic absorption spectrophotometer, it is necessary to wait for the output to stabilize after turning on a hollow cathode lamp serving as a light source. In order to eliminate this waiting time, it is common practice to preliminarily turn on a light source to be used for the next photometry while performing photometry with one light source.
This is called preliminary lighting. The time required for this pre-lighting depends on the type of lamp and its usage history, but the pre-lighting time, which is conventionally expected to be sufficient for any lamp, is set uniformly, and the time required for all lamps is fixed. On the other hand, it was lit for the same time.

[0003]

However, in this method,
In the multi-element automatic analysis in which the light source lamp is automatically switched and photometry is performed, preliminary lighting is performed for the same time even for lamps that are sufficiently stable with a pre-lighting time shorter than the set pre-lighting time. You. In the multi-element automatic analysis in which the lamp is switched according to the element to be measured, the preliminary lighting of the lamp used for the measurement of the next element is usually started at the same timing as the start of the measurement of the element to be measured. If the set pre-lighting time is longer than the time required for the current measurement and longer than the pre-lighting time required for the pre-lit lamp, the lamp is ready to start measurement. Nevertheless, since the preliminary lighting is continued, wasteful time is wasted, and unnecessary lighting of the lamp also shortens the time that can be used for measuring a lamp having a limited life. SUMMARY OF THE INVENTION It is an object of the present invention to shorten the actual time required for a series of measurements by preliminarily lighting a lamp for a minimum necessary time, and at the same time, to extend the substantial life of the lamp.

[0004]

SUMMARY OF THE INVENTION In order to solve the above-mentioned problems, the present invention provides an atomic absorption spectrometer provided with a plurality of light sources which are selectively used while the photometry is performed with one light source. Preliminary lighting means for preliminary lighting the light source, time limiting means for setting the preliminary lighting time to a predetermined time, drift detection means for detecting a drift of the light source output, And stabilizing state determination means for determining whether the drift amount of the light source output is within a predetermined allowable range when the light source output is within the allowable range. The metering was started immediately after the timed operation was canceled.

[0005] In the above, when a plurality of lamps are generally inserted into the optical path in a switching manner and used, the preliminary lighting means generally interlocks with the lighting switch of the currently used lamp to be used next (to be analyzed next). (Known in advance depending on the type of element to be used). The time limit means is constituted by a timer or the like for controlling the preliminary lighting time, and empirically determines a necessary and sufficient time for all the lamps to stabilize based on the characteristics of the lamps, etc. Is desirable.

The drift detecting means measures the intensity fluctuation of light emitted from the light source, and is preferably composed of a light detector and its amplifier. The stabilization state determination means determines whether or not the fluctuation state of the output from the photodetector is within a predetermined allowable range, and presets the difference between the minimum value and the maximum value of the optical output. And outputs the result of the determination.

To cancel the timed operation means that the timer for determining the time for performing the pre-discharge is in operation and the timed time has not elapsed, and the timed operation is stopped and the operation is switched to a normal main lighting (photometric operation). This means that, specifically, the control circuit issues a signal for forcibly terminating the timer, terminates the preliminary lighting, starts the lamp itself, and starts the measuring operation.

[0008]

The pre-lighting of the lamp to be used next is started while the current measurement is being performed, and is preliminarily turned on for a predetermined time. However, after the current measurement is completed, the next measurement is performed. At the stage when the lamp is turned on, the drift of the lamp output that has been preliminarily lit is checked, and if the drift is small, the preliminary lit is stopped and the measurement is started immediately. That is, using the presence or absence of the drift of the output signal as an indicator of whether or not the preliminary lighting is sufficient, even if the predetermined preliminary lighting time does not elapse, the output drift of the lamp that has been preliminary lit is within an allowable range. If so, the next measurement is started immediately, so that unnecessary preliminary lighting is not performed, so that the required time for the entire measurement can be shortened and the life of the lamp can be substantially extended.

[0009]

FIG. 1 shows an embodiment of an atomic absorption photometer according to the present invention. Holographic cathode lamps for each element measurement are mounted on the lamp turret 1, and each lamp is set at the position of the optical axis by rotating the lamp turret 1. The atomized solution sample is atomized in the atomization unit 2 by a burner or the like, and the amount of light from the lamp absorbed by the atomized sample atoms is measured by the spectral detection unit 3 for each light wavelength. In this way, elemental analysis of the sample is performed. In the multi-element automatic analysis, the hollow cathode lamp serving as the light source is automatically switched.

Since it takes a while for the output of the hollow cathode lamp to be stabilized after the lighting is started, preliminary lighting must be performed. Typically, to save time, pre-lighting is performed on the lamp used in the next measurement while the current measurement is being performed. Current lamp Lp
Assuming that the measurement by No. 1 is being performed, the preliminary lighting of the lamp Lp2 to be used in the next measurement is started simultaneously with the start of the measurement. The maximum time of the pre-lighting is set in advance, and when the time has elapsed, a signal is passed from the time limiter 6 to the photometry start means 9 to start the measurement.

Actually, the time at which the output stabilizes differs depending on the type of lamp and the usage history of the lamp. Therefore, if pre-lighting is performed only for the maximum pre-lighting time that is uniformly set in advance for all lamps,
The time required for measurement by the lamp Lp1 and the lamp Lp2
If the time until the output stabilizes is shorter than the maximum pre-lighting time set by the user, the lamp Lp2 will continue the meaningless pre-lighting, and the whole measurement time will be prolonged accordingly. In order to prevent this, in the apparatus of the present invention, when the measurement by the lamp Lp1 is completed and the lamp Lp2 is set to the measurement position, the drift detection means 7 checks the drift amount of the output of the lamp Lp2, and the stabilized state judgment means 8 already outputs the output. If it is determined that is stable, the timed operation of the timed means 6 is immediately canceled and the photometric start means 9 starts the measurement.

The flow of operation from the start of measurement by the lamp Lp1 to the start of measurement by the lamp Lp2 will be described with reference to the flowchart shown in FIG. As the symbols used here, the maximum preliminary lighting time set by the user is WTmax, and the preliminary lighting time up to the present is WTcur. This WTcur is updated every moment during the preliminary lighting operation as the time elapses, and is equal to the time required for the measurement currently being performed immediately after the lamp switching.
The time required for line search is LT, the time required for beam balance is BT, the photometric time for checking for drift is DT, the allowable value of the drift is Dmax, the measured drift value is Dmes, and the drift measurement is performed. Is performed N times. DT and Dmax can be set by the user. LT and BT are preset values.

First, the measurement by the lamp Lp1 is started and the preliminary lighting of the lamp Lp2 is started (S1).
1, S2). In this description, it is assumed that the preliminary lighting of Lp1 is sufficient, and the measurement by Lp1 is performed next (S
3). When this is completed, Lp1 is turned off (S4), and Lp1 is turned off.
2 is set at the measurement position (S5). Here, immediately after switching of the lamp, a counter N for counting the number of times of drift measurement of Lp2 is initialized to zero (S6). This is because the line search and beam balance are performed only once in S10 before the drift measurement of Lp2. In the next steps S7 to S14, it is determined whether the preliminary lighting of Lp2 is sufficient. First, in S7, it is determined whether or not drift measurement is the first time based on whether N = 0. If Yes in S7, the process proceeds to S8, and in S8, WTmax ≦ WTcur + LT + BT
Check whether + DT is satisfied. This is the preliminary lighting time WTcur performed up to now and the time L required for line search.
If the sum of T, the time BT required for beam balance, and the time DT required for drift measurement exceeds the preset maximum preliminary lighting time WTmax, drift measurement does not save time. This is to prevent the drift measurement from being performed. If the judgment of S8 is Yes
If so, the process proceeds to S9, and waits until the current preliminary lighting time WTcur exceeds (or becomes equal to) the maximum preliminary lighting time WTmax (S9). It starts (S16). If the determination in S8 is No, S10
After performing line search and beam balance (S10), photometry for drift measurement is performed (S1).
1), 1 is added to the drift measurement counter N (S1)
2). At this time, the measured drift, that is, the fluctuation range Dmes of the photometric value is compared with a preset allowable value Dmax (S13). -After performing beam balance (S15), measurement is started (S16). If not, return to S7 again.

From the second time, the determination in S7 is No.
Proceed to 14. In S14, it is checked whether WTmax ≦ WTcur + DT is satisfied. This is to prevent the drift measurement from being performed if the sum of the preliminary lighting time WTcur performed up to the present and the time DT required for the drift measurement exceeds the preset maximum preliminary lighting time WTmax. . If the determination in S14 is Yes, the process proceeds to S9, where the preliminary lighting time WTcur up to the present is the maximum preliminary lighting time WT.
After waiting until the value exceeds max (or becomes equal) (S
9) In S15, line search and beam balance are performed,
The measurement by Lp2 is started (S16). If the determination in S14 is No, the process proceeds to S11, where photometry for drift measurement is performed (S11), and 1 is added to the drift measurement counter N (S12). The drift measured at this time, that is, the fluctuation range Dmes of the photometric value and the preset allowable value D
max is compared (S13). If the drift is smaller, the preliminary lighting is considered to be already sufficient, and the line search and beam balance immediately before the measurement are immediately performed (S1).
5) The measurement is started (S16). If not, return to S7 again and repeat the above. Immediately after the measurement by Lp2 is started in S16, the lamp Lp3 to be used next is used.
Is started (S17).

Among the terms used in the above description, the line search is to search for a wavelength indicating the maximum intensity of the hollow cathode lamp and to allow light of that wavelength to enter the detector. Beam balance is the result of subtracting the background signal from the measurement signal by first determining the detector gain and adjusting the signal levels of the measurement signal and the background signal so that they are the same by adjusting the amplifier gain. Set the resulting current signal level to zero. In the drift measurement, the fluctuation of the lamp output is recorded for a predetermined time DT, and the fluctuation width is defined as the drift. If the fluctuation width is within a predetermined width, it is determined that the drift is sufficiently small.

[0016]

According to the apparatus of the present invention, the lamp to be used next is preliminarily turned on for a predetermined time, while the current measurement is completed and the next measurement can be started. The output of the lamp, which has been preliminarily illuminated until now, is checked, and if the drift is small, the preliminary illumination is stopped and the measurement is started immediately. Therefore, even if the predetermined preliminary lighting time has not elapsed, the next measurement is started immediately if the drift of the output of the preliminary lit lamp is within the allowable range, so that unnecessary preliminary lighting is not performed. This has a remarkable effect that the required time for the entire measurement can be shortened and the life of the lamp can be substantially extended.

[Brief description of the drawings]

FIG. 1 shows an embodiment of the atomic absorption photometer according to the present invention.

FIG. 2 is a flowchart illustrating the operation of the atomic absorption photometer according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Lamp turret 2 ... Atomization part 3 ... Spectral detection part 4 ... Preliminary lighting means 5 ... Controller 6 ... Time limit means 7 ... Drift detection means 8 ... Stabilized state determination means 9 ... Photometry start means

Claims (1)

(57) [Claims] 1. An atomic absorption spectrophotometer provided with a plurality of light sources which are switched, a preliminary lighting means for preliminary lighting a next light source to be used while measuring light with one light source, and this preliminary lighting. A time limiter for setting the time to a predetermined time, a drift detector for detecting a drift of the output of the light source, and a drift amount of the output of the light source when the preliminarily turned on light source is switched to the photometry position. And a stabilization state determination means for determining whether the value is within the range,
An atomic absorption spectrometer characterized in that when the drift of the light source output is determined to be within an allowable range, the timed operation of the timed means is canceled and photometry is started immediately.