JPS6326330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an atomic absorption spectrometer for automatic multi-element analysis using a hollow cathode lamp as a light source.

In an automatic atomic absorption spectrometer, hollow cathode lamps (abbreviated as HCL) for each element to be measured are arranged circumferentially on a disk and mounted on a turret.
The HCL can be replaced, and when measuring a certain element, the HCL for that element is placed on the measurement optical path.

As the name suggests, HCL emits light inside a hole, so the light can be used most efficiently when the center line of the hole is aligned with the optical axis of the measurement optical path. However, in the above-mentioned turret-type exchange mechanism, the center of each HCL mounting seat does not necessarily coincide with the optical axis of the measurement optical path due to machining and assembly errors of the exchange mechanism, and even if this could be done, it would be difficult to manufacture the HCL itself. Because the center line of the HCL envelope does not match the emission center of the cathode due to the error, it is difficult to match the emission center of the HCL with the optical axis of the measurement optical path.

Therefore, the present invention was made with the object of making it possible to adjust the position of HCL in a turret type HCL exchange mechanism in an automatic atomic absorption spectrometer.

In the present invention, the HCL is rotatably attached to a turret disk, the HCL at the measurement position is rotated to detect the point at which the output of the photodetector of the analyzer is maximum,
The present invention provides an automatic atomic absorption spectrometer that performs elemental analysis by stopping HCL at that position.

According to the present invention, each HCL can be used with the highest light utilization efficiency within the possible range, improving the S/N ratio in measurements. If such adjustments were to be made manually, automated analysis would be Before starting, it is necessary to adjust the position of all the HCLs for each element on the turret disk in advance, and in that case, the wavelength of the spectrometer must be matched to the wavelength of the HCL one by one, so the adjustment work is very troublesome and time-consuming. It's starting to grow. However, according to the present invention, the position adjustment of the HCL is automatically performed when changing the element to be measured during automatic analysis without having to be done in advance, so the wavelength of the spectrometer is automatically matched to the wavelength of the HCL, and the adjustment There is no such thing as troublesome operation. The present invention will be explained below with reference to Examples.

FIG. 1 shows an HCL exchange mechanism in one embodiment of the present invention. 1 is a turret base plate, 2 is a turret face plate, and both are connected by a connecting column 3 to be integrated. HCL holders 4, 4, . . . are provided on the substrate 1 along one circumference. Bearings (not visible in the figure) are interposed between these holders and the substrate 1, and each holder can rotate around an axis perpendicular to the substrate 1 at that position. A receiving hole 5 for supporting the head of the HCL is bored in the face plate 2 at a point where the extensions of the central axes of the respective holders 4 on the base plate 1 intersect. The leg pins of the HCL are inserted into the holder 4, the head is supported in the receiving hole 5, and when the holder 4 is rotated, the HCL also rotates. Board 1
The integrated structure of the face plate 2 and the turret axis X is rotatably supported, and a transmission wire 7 is connected between the outer periphery of the face plate 2 and a pulley attached to the rotating shaft of the drive motor 6. It's spread over. In addition, pins 8 are set up on the outer periphery of the board 1 in correspondence with each HCL, and pins 8 are placed across the path of pin 8.
A detector 9 is arranged to detect. This pin 8
and detector 9 determine the turret rotation stop position during HCL replacement. There is also one pin 10 standing on the back side of the substrate 1, and a detector 11 for detecting this pin is arranged. The position where the pin 10 is detected by the detector 11 is the origin of the turret exchanging device, and the HCL is designated as the number of HCL counting counterclockwise from the origin. Further, a single transmission wire 12 is stretched around the HCL holder 4, and this wire is hung on a pulley 14 attached to the rotating shaft of a motor 13. Therefore, when the motor 13 is rotated, the holder 4
rotate in unison. In the figure, L is the optical axis of the measurement optical system, and HCL, which is located at the top, is on this optical axis L.

FIG. 2 is a front view of the face plate 2 in the above embodiment. C is a rotation locus of the center of the receiving hole 5 and is concentric with the face plate 2. Point L indicates the optical axis of the measurement optical system. In design, the optical axis L should intersect with the rotation locus C of the receiving hole 5, but due to manufacturing and assembly errors, the two are separated as shown in the figure. Needless to say, 5 is a receiving hole, and only one of the holes at the measurement position is shown in the figure. D is HCL
Due to the manufacturing error of HCL, D is the hole 9 at the center of light emission.
does not coincide with the center of (located on the circumference C).
When the motor 13 in Fig. 1 is rotated with this relationship,
As the HCL rotates, point D in Figure 2 can move along a trajectory like the arrow circle R. Therefore, by this rotation, the position where point D is optically closest to point L can be determined.

FIG. 3 shows an entire embodiment of the present invention. F is the flame that atomizes the sample, M is the spectrometer, S1, S
2 are an entrance slit and an exit slit, respectively.
P is a photodetector, A is a preamplifier, Q is a signal processing circuit, and CPU is a control circuit that controls the entire device, and a microcomputer is used. The operation of adjusting the position of the HCL in this configuration will be explained.
Now, to measure element x in the sample,
Suppose that HCLx is brought to the measurement position. This operation is performed by rotating the motor 6. HCL is the xth position counted from the turret's origin, and the CPU counts the detection signal every time pin 8 is detected from the turret's origin, so the rotation of the motor 6 is controlled so that the count becomes x. Control. When HCLx comes to the measurement position, the CPU energizes the motor 13 to rotate HCLx. At this time, HCLx is emitting light, and the CPU is controlling the spectrometer M.
It has already been set to the wavelength position of the light emitted by HCLx. In this state, the signal processing circuit Q detects the peak of the output of the photodetector P and sends a peak detection signal to the CPU, which causes the motor 13 to stop rotating.
This completes the HCLx position adjustment. Figure 4 shows HCLx
This figure shows how the output of the photodetector P changes when it is rotated.If the rotation is stopped at the peak position, the HCL light can be used most efficiently within the possible range, and the S/N ratio will be reduced. Good analysis becomes possible.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of an HCL exchange mechanism according to an embodiment of the present invention, FIG. 2 is a front view of the turret face plate of the same embodiment, and FIG. 3 is a block diagram showing the overall configuration of the same embodiment. Figure 4 is a graph showing how the output of the photodetector changes when the HCL is rotated. 1... Turret board, 2... Turret face plate, 4
…HCL holder, 7…wire, 6…motor,
8... Positioning pin, 9... Detector for detecting pin 8, 12... Wire, 13... Motor, M... Spectrometer,
P...Photodetector, CPU...Control circuit.

Claims (1)

[Claims] 1. A plurality of hollow cathode lamps are arranged in a row along one circumference on a rotatable disk, and by rotating the disk, any one hollow cathode lamp can be positioned on the measurement optical path. In the turret type light source exchange mechanism, each hollow cathode lamp is rotatably attached to the disk and connected to a rotation drive mechanism, and the maximum value of the output of the photodetector of the photometric system for atomic absorption spectrometry is detected. A detection means is provided, the disk is rotated to position one hollow cathode lamp on the measurement optical path, the hollow cathode lamp is then rotated, and the maximum is detected from the change in the output of the photodetector at that time. An automatic atomic absorption spectrometer characterized in that it is provided with a control circuit that stops the rotation of the hollow cathode lamp when the hollow cathode lamp is turned off.