JP2732320B2 - Differential refractive index detector for liquid chromatography - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a differential refractive index detector for liquid chromatography, and more particularly, to a high sensitivity region for analysis and a medium sensitivity for fractionation. The present invention relates to a differential refractive index detecting device for liquid chromatography which can be used for both the region and the region.

[Prior Art] Differential refractive index detectors for liquid chromatography are widely used as general-purpose detectors of the solution physical type, and there are two types, a Fresnel type and a polarization type.

FIG. 3 is an explanatory view showing a schematic configuration of a conventional polarization type differential refractive index detecting device for liquid chromatography.

According to the figure, a slit light R emitted from a light source 1 formed by a filament type lamp is condensed by a lens 3 via an entrance slit 2 and then a flow cell comprising a sample side cell 5 and a control side cell 6. The light passes through 4 and reaches the mirror 7. The slit light R reflected from the mirror 7 passes through the flow cell 4 again, reaches the light receiving elements 8 and 9 divided into two, and is converted into an electric signal by these light receiving elements 8 and 9, and performs predetermined processing. By doing so, the refractive index can be detected.

In this case, when a change occurs in the refraction of the passing light in the flow cell 4, the slit images reaching the light receiving elements 8, 9 deviate from the reference positions, and the deviation at that time can be output electrically. It has become.

Therefore, the electrical output value needs to have linearity. For this reason, the width of the slit of the entrance slit 2 is set to be narrow, for example, about 0.5 mm, and the deviation width of the slit image on the light receiving elements 8 and 9 is changed. Is made smaller.

Further, since the cell block including the flow cell 4 and the mirror 7 is formed relatively large, the distance l 'from the lens 3 to the mirror 7 becomes relatively long.
The entrance slit 2 must also be formed with a narrow slit width of about 0.5 mm to maintain a necessary light amount for the slit light R.

In addition, the distance m 'from the lens 3 to the light receiving elements 8, 9
Is the same as the focal length of the lens 3, the distance m ′ is also relatively long, 150 to 200 mm, and the temperature adjusting frame for accommodating these optical systems is also relatively large. As a result, the volume was large.

Furthermore, in the case of the differential refractive index detecting device for liquid chromatography having the above-described configuration, the refractive index to be detected has temperature dependence, so that it is necessary to adjust the temperature. Therefore, the optical system has a large heat capacity. It is necessary to be accommodated in a temperature control frame made of aluminum so as not to be affected by the external ambient temperature. For this reason, a large temperature control frame is used.

[Problems to be Solved by the Invention] By the way, since the entrance slit 2 in the conventional differential refractive index detecting device has a narrow slit width of about 0.5 mm, it is difficult to measure a high sensitivity region for analysis. Even if it is suitable, it is not possible to cope with the measurement in the medium sensitivity region for preparative separation under the same configuration.

For this reason, when the same apparatus is to be used for the measurement of the medium-sensitivity region for preparative separation, the flow angle of the flow cell 4 is reduced from a commercial product having a cell angle of 45 ° to 30 °, for example. It has to be replaced with a specially ordered product, which has the disadvantage of increasing costs accordingly.

In addition, the use of a temperature control frame having a large capacity (including a heat capacity as well as a volume) due to the necessity described above has a large gap between the present internal temperature and a desired set temperature. In this case, it means that it takes a lot of time to rise to the set temperature, and usually it takes 2 to rise to the state where it can be actually measured.
There is an inconvenience that workability is deteriorated because a standby time of about time is required.

Means for Solving the Problems The present invention has been made in view of the above-mentioned problems found in conventional devices, and has a structural feature that includes a light emitting unit for emitting slit light, and a light emitting unit for emitting slit light. An optical system consisting of a polarized light reflecting portion for polarizing and reflecting the slit light and a light receiving portion for photoelectrically converting the reflected polarized slit light is accommodated in the internal space of the temperature adjusting frame. The light emitting unit has a light emitting diode equivalent to a point light source and a slit having a width of 1 to 1.5 mm corresponding to analysis and preparative use, and a first light emitting unit for equalizing the amount of irradiation. A condenser lens is formed close to each other between the slit and
The polarizing reflector has a collimator lens having a focal length of 90 to 130 mm between a second slit section having a slit capable of removing scattered light from the slit light that is passing light and a reflection mirror, and a cell angle of 45. ° and the light receiving unit is formed so that the distance between the second slit unit and the light emitting unit is equal to the distance between the second slit unit and the light emitting unit. Using a two-part photoelectric conversion element set and arranged, the width of the slit image having a width of 1 to 1.5 mm can be freely formed, and the size of the slit image is reduced in response to the reduction in the optical path length of the slit light. The frame for temperature control is
PID control means for controlling temperature having a transistor installed in an internal space is provided, and the temperature in the internal space can be controlled while using the transistor as a heat source for temperature control.

[Effects] The present invention can irradiate slit light by uniformly adjusting the amount of light through a slit having a width of 1 to 1.5 mm, which is wider than a conventional slit, and furthermore, a light emitting diode and a condenser lens in a light emitting unit. And the first slit part, the second slit part, the collimator lens, the flow cell, and the reflection mirror in the polarization reflection part are arranged close to each other, and further, the separation distance between the polarization reflection part and the light reception part. Since the optical path length is shortened by making the distance between the light emitting unit and the polarized light reflecting unit equal, even if the slit light emitted from the light emitting unit has a wide width of 1 to 1.5 mm, The image can be formed as a slit image without widening the horizontal width of the two-part photoelectric conversion element in the section, so that the measurement covers from the high-sensitivity area for analysis to the middle-sensitivity area for fractionation. It can be.

To make the entire optical system compact in this way means that the temperature control frame itself can be correspondingly reduced in size, and therefore, the volume of its internal space is also reduced. Conventionally, the temperature of the internal space of the temperature control frame is controlled by the highly responsive PID control means, and the transistor incorporated in the PID control means is used as the heat source to set the temperature in the past. What took about 2 hours to start up to the temperature can be reduced to about 15 minutes,
Work efficiency can be significantly improved.

[Example] Hereinafter, an example of the present invention will be described in detail with reference to the drawings.

FIG. 1 is an explanatory diagram showing an outline of the overall configuration according to the apparatus of the present invention.

According to the figure, the entire device includes a light emitting unit 12 for irradiating slit light R, a polarization reflecting unit 17 for polarizing and reflecting the irradiated slit light R, and the reflected light after polarization. An optical system 11 including a light receiving unit 31 for performing a photoelectric conversion process on the slit light R is housed in an internal space of a temperature adjusting frame C made of aluminum.

Among them, the light emitting unit 12 has a light emitting diode 13 having a light emitting surface equivalent to a point light source whose length is about 1 mm immediately after.
And a first slit portion 15 having a slit 16 having a width of 1 to 1.5 mm to make the amount of irradiation uniform, and a light-emitting diode 13 and the first slit portion 15 The optical lens 13 is formed by interposing and interposing each other close to each other.

In addition, the polarization reflection section 17 has a second slit section having a width of about 1 mm, for example, capable of removing unnecessary scattered light from slit light that is passing light at the time of incidence and reflection. A collimator lens 20 and a flow cell 21 composed of a sample-side cell 22 and a control-side cell 23 partitioned at a cell angle of 45.degree. ing. The sample cell 22 has an introduction passage 25 and a discharge passage 26 arranged so as to allow efficient heat exchange, and the control cell 23 has an introduction passage capable of efficient heat exchange. 27 and a discharge path 28 are respectively piped.

Further, the light receiving section 31 is a second section in the polarization reflection section 17.
The distance m between the slit section 18 (m is equal to the focal length of the collimator lens 20 and is set to 90 to 130 mm) is the distance between the second slit section 18 and the light emitting section 12. In addition to the two-segment photoelectric conversion element 33 arranged in the same manner as described above, it is formed to have a null glass 32 arranged on the light incident side. Note that the two-part photoelectric conversion element 33 is
Corresponding to the fact that the slit 16 of the first slit portion 15 in 12 is formed wide, it is formed with a relatively large light receiving area.

In addition, the temperature of the temperature adjusting frame C is controlled by PID control means 37 having a temperature detecting element 39.
A transistor 38 constituting the ID control means 37 is used as a heat source for temperature control.

Next, the operation of the present invention will be described with reference to FIG.

That is, the temperature control frame C in which the optical system 11 for detecting the differential refractive index, which includes the light emitting unit 12, the polarization reflection unit 17, and the light receiving unit 31, is housed, is provided with the second slit unit 18 and the reflection mirror
And the distance m between the second slit section 18 in the polarization reflection section 17 and the two-segment photoelectric conversion element 33 in the light receiving section 31 is relatively short, so that the optical path length of the slit light R is short. Along with the miniaturization, a smaller one is used. Therefore, the volume of the internal space of the temperature adjusting frame C can be reduced accordingly. Therefore, the temperature adjustment of the internal space of the temperature adjusting frame C can be smoothly performed by the PID control means 37 having high responsiveness while using the transistor 38 as a heat source for temperature control.

On the other hand, in the light emitting unit 12 of the optical system 11, light emitted from a light emitting diode 13 equivalent to a point light source is collected by a condenser lens.
The light is condensed through 14 and passed through a first slit portion 15 having a slit 16 having a width of 1 to 1.5 mm, so that the slit light R having a uniform light amount is emitted toward the polarization reflection portion 17. .

The slit light R that has reached the polarization reflector 17 in this manner
Is introduced as slit light R from which unnecessary scattered light has been removed by passing through the slit 19 of the second slit portion 18, and the collimator lens 20 disposed immediately after this is introduced.
The slit light R converted into a parallel light beam by passing through the sample cell 22 in the flow cell 21 partitioned at a cell angle of 45 °.
And the control side cell 23 in order, and reaches the reflection mirror 24 disposed immediately after the flow cell 21 to be reflected.

The reflected slit light R is again transmitted to the flow cell 21.
Conversely, the light passes through the control-side cell 23 and the sample-side cell 22 in this order, and enters the collimator lens 20 from the opposite direction, so that the position of the two-part photoelectric conversion element 33 is focused while being focused. It reaches the slit 19 of the second slit section 18.

In the second slit portion 18, the unnecessary scattered light is adjusted again to the slit light R from which the unnecessary scattered light has been removed through the slit 19, and thereafter, the gap between the second slit portion 18 and the first slit portion 15 is adjusted. Is sent out toward the light receiving section 31 which is disposed with a separation distance m equal to the distance m.

The slit light R sent out toward the light receiving section 31 is converted into a two-part photoelectric conversion element 33 such as a two-part photodiode.
The light reaches the upper side and is formed as a slit image on the first photoelectric conversion unit 34 and the second photoelectric conversion unit 36. In this case, since the slit 16 of the first slit portion 15 in the light emitting section 12 is formed to have a relatively large width, the two-divided photoelectric conversion element 33 has a relatively large area corresponding to this. The measurement area can be widened,
The measurement can be performed from the high sensitivity region for analysis to the medium sensitivity region for fractionation without particularly changing the configuration.

The two-division photoelectric conversion element 33 is used to determine the image formation ratio of the first photoelectric conversion unit 34 in the slit image and the second photoelectric conversion unit.
By converting them into electric quantities corresponding to the 35 imaging ratios and comparing these, the concentration of the solute in the mobile phase is measured, and its refractive index can be detected.

[Effects of the Invention] As described above, according to the present invention, the width is 1 to 1.5 mm.
It is possible to irradiate the slit light by adjusting the light amount uniformly through the slits corresponding to the analysis and the preparative use.

In addition, the optical system includes a collimator lens having a focal length of 90 to 130 mm and a collimator lens having a focal length of 90 to 130 mm and a cell angle of 45, in addition to the light emitting diode, the condenser lens, and the first slit in the light emitting unit. The flow cell and the reflection mirror are placed close to each other, and the distance between the polarization reflection unit and the light reception unit is the same as the distance between the light emission unit and the polarization reflection unit. Can be shortened.

For this reason, even if the slit light emitted from the light emitting unit is of a wide width, the slit image can be formed without changing the flow cell to one having a different cell angle, particularly by making the two-part photoelectric conversion element in the light receiving unit relatively wide. Therefore, the measurement can be performed with the same apparatus while covering from the high sensitivity region for analysis to the medium sensitivity region for fractionation at low cost.

In addition, since the entire optical system is made compact in this way, and since there is no heat generated from the light source, it is possible to control the temperature of the temperature control frame, which is small and has a small internal space, with responsiveness. By using high PID control means, and using the transistor of the PID control means, which was conventionally disposed outside and exerting a thermal adverse effect on the side of the temperature control frame, as the heat source, the conventional apparatus can set the set temperature. It took about 2 hours to start up to about 15 minutes, but it can be reduced to about 15 minutes, and the work efficiency can be significantly improved.

[Brief description of the drawings]

FIG. 1 is an explanatory view showing an example of a schematic configuration of an apparatus according to the present invention, FIG. 2 is an explanatory view showing an interrelationship of optical systems in the present invention, and FIG. It is explanatory drawing which shows a relationship. 11 optical system, 12 light emitting unit, 13 light emitting diode,
14 ... Condenser lens, 15 ... First slit part, 16 ... Slit, 17 ... Polarized reflection part, 18 ... Second slit part, 19 ...
... Slit, 20 ... Collimator lens, 21 ... Flow cell, 22 ... Sample side cell, 23 ... Control side cell, 24 ... Reflection mirror, 25,27 ... Introduction path, 26,28 ... Exhaust path , 31 ……
Light receiving section, 32: Null glass, 33: Two-part photoelectric conversion element, 34: First photoelectric conversion section, 35: Second photoelectric conversion section, 37
... PID control means, 38, transistor, 39, temperature detecting element, C, temperature control frame, R, slit light.

Continuation of the front page (56) References JP-A-61-226640 (JP, A) JP-A-63-27733 (JP, A) JP-A-52-105878 (JP, A) JP-A-58-62565 (JP) JP-A-48-40043 (JP, A) JP-A-60-112120 (JP, A) JP-A-62-119664 (JP, U)

Claims (1)

(57) [Claims] 1. A light emitting section for emitting slit light, a polarization reflecting section for polarizing and reflecting the emitted slit light, and a light receiving section for photoelectrically converting the reflected polarized slit light. The light emitting unit is configured to accommodate a light emitting diode equivalent to a point light source and a width of 1 to 1.5 mm for analysis and fractionation. A condensing lens is formed so as to be close to each other between the first slit portion for equalizing the irradiation light amount with the corresponding slit, and the polarized light reflecting portion is formed from slit light that is transmitted light. The focal length is between the second slit portion having the slit capable of removing the scattered light and the reflection mirror.
A collimator lens having a diameter of 90 to 130 mm and a flow cell having a cell angle of 45 ° are formed so as to be close to each other. The width of the slit image having a width of 1 to 1.5 mm is freely formed by using a two-part photoelectric conversion element arranged and set to be equal to the distance between the unit and the light emitting unit, and the optical path of the slit light The frame for temperature control, which is miniaturized in accordance with the reduction in length, includes a PID control means for temperature control having a transistor installed in an internal space, and the transistor is a heat source for temperature control. A differential refractive index detecting device for liquid chromatography, wherein the temperature in the internal space can be controlled while maintaining the above-mentioned conditions.