A thermostated flow cell for use in a liquid chromatograph

Abstract

A kind of constant-temperature flow cell applied to liquid chromatograph analyzer belongs to the technical field of detection auxiliary equipment, including flow cell body, semiconductor refrigeration / heat mechanism, thermistor, also have temperature control circuit, the front and rear side ends of the shell of semiconductor refrigeration / heat mechanism are fixedly installed with magnet piece A, the outside end of flow cell body has fixed groove, magnet piece B is fixedly installed in fixed groove, semiconductor refrigeration / heat mechanism is installed at the outside end of flow cell body;Thermistor is fixedly installed at the outside of flow cell body, temperature control circuit is installed in electric control box.The novel type passes through semiconductor refrigeration / heat mechanism as cold source and heat source, staff can conveniently attract the cold end or cold end of semiconductor refrigeration / heat mechanism in front and rear outside end of flow cell body by magnet, and then application, can control flow cell body to be in suitable constant high temperature or low temperature according to the sample and surrounding environment temperature needs of detection, guarantee the sample analysis detection effect.

Description

Technical Field

[0001] This utility model relates to the technical field of supporting equipment for liquid chromatography analyzers, and in particular to a constant temperature flow cell for the application of liquid chromatography analyzers. Background Technology

[0002] Liquid chromatography (LC) is an instrument that utilizes the difference in the partition ratio of a mixture between a liquid and a solid or between two immiscible liquids to separate the mixture before analysis and identification. During detection, the mobile phase carries the solution to be analyzed to the stationary phase. The components in the analytical solution are separated sequentially due to the different effects of the stationary phase. These separated components then flow sequentially with the mobile phase to a flow cell. The flow cell then performs optical detection on the different components that enter the analytical solution sequentially, obtaining the component information of each component. Currently, optical detection of solution components in flow-through cells is generally achieved using optical fibers. A flow-through cell includes the cell body, a light-reflecting flow tube inside the cell body, an optical path outside the cell body, two optical fibers connected to the light-reflecting flow tube, an inlet pipe connected to the mobile phase tube, and an outlet pipe connected to the reservoir (the inlet and outlet pipes are connected to the inlet and outlet on the left and right sides of the light-reflecting flow tube, respectively). Specifically, after the mobile phase flows into the flow-through cell, it flows in and out through the light-reflecting flow tube. The control system of the liquid chromatograph collects the signal changes of the light signals transmitted by the two optical fibers after passing through the light-reflecting flow tube, and thus obtains the component information of the solution in the mobile phase flowing through the light-reflecting flow tube.

[0003] As a crucial component of a liquid chromatography (LC) analyzer, the flow cell is subject to stringent temperature requirements during operation. Maintaining a constant temperature throughout the analysis process is essential to prevent adverse effects from temperature fluctuations. Firstly, temperature variations alter the viscosity of the mobile phase, affecting its flow behavior within the column. Unstable flow cell temperatures can lead to viscosity fluctuations, impacting separation efficiency and peak shape. To mitigate this, the flow cell is typically insulated to ensure a stable temperature range. Secondly, temperature changes also affect detector performance. Fluctuations in flow cell temperature can alter detector sensitivity, leading to signal instability. Insulation reduces these fluctuations, ensuring stable detector operation and improving analytical accuracy and repeatability. Furthermore, insulation minimizes the impact of ambient temperature changes on internal components of the flow cell, preventing mechanical stress caused by temperature variations and extending its lifespan. In existing technologies, the flow cell of a liquid chromatograph is typically placed in a temperature-controlled laboratory. While this method meets the requirement for constant temperature detection, it requires relatively high-power air conditioning, increasing detection costs. More importantly, if the liquid chromatograph needs to be moved to another location for sample testing (e.g., transported by vehicle to a vegetable farm to test for pesticide residues), and that area lacks air conditioning or similar equipment, the normal operation of the flow cell will be adversely affected, leading to inaccurate sample detection data. Therefore, it is essential to provide a low-cost, easy-to-use insulated flow cell. Utility Model Content

[0004] To overcome the drawbacks of existing insulated flow cells in liquid chromatography (LC) analyzers, which are limited by their structure and described in the background section, this invention provides a flow cell body for LC analyzers. This body utilizes a semiconductor cooling / heating mechanism as both a cold and heat source, offering advantages such as convenient installation and use, low cost, and flexible application. In practice, the flow cell body can be controlled at a suitable constant high or low temperature based on the sample being tested and the ambient temperature, ensuring optimal sample analysis and detection results.

[0005] The technical solution adopted by this utility model to solve its technical problem is: A constant-temperature flow cell for a liquid chromatography analyzer includes a flow cell body, a semiconductor cooling / heating mechanism, a thermistor, and a temperature control circuit. Magnets A are fixedly mounted on the front and rear ends of the housing of the semiconductor cooling / heating mechanism. A fixing groove is located on the outer end of the flow cell body, and a magnet B is fixedly mounted within the fixing groove. The semiconductor cooling / heating mechanism is mounted on the outer end of the flow cell body by magnets A attracting magnet B. The thermistor is fixedly mounted on the outer side of the flow cell body, with its sensing surface in contact with the outer side of the flow cell body. The temperature control circuit has at least two circuits, both of which are installed in an electrical control box. The two ends of the thermistor are electrically connected to the signal input terminals of the two temperature control circuits, and the power output terminals of the two temperature control circuits are electrically connected to the power input terminals of the two semiconductor cooling / heating mechanisms.

[0006] Furthermore, the rear end polarity of magnet A is opposite to that of magnet B's front end, and the outer and inner diameters of magnet A and magnet B are the same.

[0007] Furthermore, after the semiconductor cooling / heating mechanism is attracted to the front and rear ends of the flow cell body, its cold end or hot end is respectively attached to the outer side of the flow cell body.

[0008] Furthermore, the thermistor is equipped with an adjustable resistor, one end of which is electrically connected to one end of the thermistor.

[0009] Furthermore, the two temperature control circuits are identical in construction, each including an electrically connected relay, a power switch, an adjustable resistor, a resistor, and a transistor. One end of the power switch is connected to the positive power input terminal and the control power input terminal of the relay. The collector of the transistor is connected to the negative power input terminal of the relay. One end of the adjustable resistor is connected to one end of the first resistor and one end of the second resistor. The other end of the second resistor is connected to the base of the transistor. The emitter of the transistor is connected to the other end of the first resistor.

[0010] Furthermore, the normally closed contact of the relay in the first temperature control circuit is connected to one power input of the two sets of semiconductor cooling / heating mechanisms, and the normally open contact of the relay in the second temperature control circuit is connected to one power input of the two sets of semiconductor cooling / heating mechanisms.

[0011] Compared with the prior art, the advantages of this utility model are: This new flow cell body is based on the application of liquid chromatography analyzer. It uses a semiconductor cooling / heating mechanism as the cold source and heat source, which has the characteristics of convenient installation and use, low cost and flexible use. Specifically, the operator can easily use a magnet to attract the cold end of the semiconductor cooling / heating mechanism to the front and rear outer ends of the flow cell body. In application, the flow cell body can be controlled at a suitable constant high temperature or low temperature according to the sample being tested and the ambient temperature, thus ensuring the analytical detection effect of the sample. Attached Figure Description

[0012] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0013] Figure 1 This is a schematic diagram of the structure of this utility model.

[0014] Figure 2 This is the circuit diagram of this utility model. Detailed Implementation

[0015] Figure 1 , 2 As shown, a constant-temperature flow cell for a liquid chromatography analyzer includes a flow cell body 1, a semiconductor cooling / heating mechanism B, a power module A1, a thermistor RT, and a temperature control circuit 2. The semiconductor cooling / heating mechanism B has at least two sets. Each set of the semiconductor cooling / heating mechanism B has a U-shaped permanent magnet A3 fixedly installed (e.g., glued) on its front and rear ends. The front and rear ends of the flow cell body each have a U-shaped fixing groove 4 with a rearward and a forward concave design, respectively. The fixing groove 4 contains fixedly installed (e.g., glued) permanent magnets. (Adhesive) There is a U-shaped permanent magnet B5, and two sets of semiconductor cooling / heating mechanisms are attracted to magnet B by magnet A and respectively installed on the front and rear sides of the flow cell body 1; the thermistor RT is fixedly installed on the outer side of the upper middle part of the flow cell body 1 (for example, the Π-shaped fixing clip is welded to the upper part of the flow cell body, and the thermistor RT is tightly clamped inside the fixing clip), and its temperature sensing surface is in close contact with the outer side of the upper part of the flow cell body 1; the temperature control circuit 2 has at least two paths, and the two temperature control circuits 2 and the power module A1 are installed in the electrical control box 6 of the liquid chromatograph.

[0016] Figure 1 , 2As shown, the polarity of the rear end of magnet A3 is opposite to that of the front end of magnet B5, and the outer and inner diameters of magnets A3 and B5 are the same. Two sets of semiconductor cooling / heating mechanisms B are respectively attracted to the front and rear ends of the flow cell body 1, with their cold or hot ends respectively attached to the front and rear ends of the flow cell body 1. A thermistor RT is equipped with an adjustable resistor RP1, with one end of the adjustable resistor RP1 connected to one end of the thermistor RT via a wire. The first temperature control circuit includes a relay J, a power switch S, an adjustable resistor RP, resistors R1 and R2, and a transistor Q, all connected via circuit board wiring. One end of the power switch S is connected to the positive power input terminal and the control power input terminal of relay J. The collector of transistor Q is connected to the negative power input terminal of relay J. One end of the adjustable resistor RP is connected to one end of the first resistor R1 and one end of the second resistor R2. The other end of the second resistor R2 is connected to the base of transistor Q, and the emitter of transistor Q is connected to the other end of the first resistor R1. The second temperature control circuit includes a relay J1, a power switch S1, an adjustable resistor RP2, resistors R3 and R4, and a transistor Q1, all connected via circuit board wiring. One end of the power switch S1 is connected to the positive power input and control power input of relay J1. The collector of transistor Q1 is connected to the negative power input of relay J1. One end of the adjustable resistor RP2 is connected to one end of the first resistor R3 and one end of the second resistor R4. The other end of the second resistor R4 is connected to the base of transistor Q1, and the emitter of transistor Q1 is connected to the other end of the first resistor R3. The normally closed contact of the relay J1 in the first temperature control circuit is connected to the positive power input of the two sets of semiconductor cooling / heating mechanisms B. The normally open contact of the relay J1 in the second temperature control circuit is connected to the positive power input of the two sets of semiconductor cooling / heating mechanisms B. The power input terminals 1 and 2 of power module A1 are connected to the two poles of AC 220V power supply via wires. The power output terminals 3 and 4 of power module A1 are connected to the other end of power switch S and the emitter of transistor Q, the other end of power switch S1 and the emitter of transistor Q1 via wires. The two ends of the thermistor RT are connected to the other end of power switch S and the other end of adjustable resistor RP, the other end of power switch S1 and the other end of adjustable resistor RP2 via wires. The normally closed contact of relay J and the emitter of transistor Q, the normally open contact of relay J1 and the emitter of transistor Q1 via wires, and the two power input terminals of the two sets of semiconductor cooling / heating mechanisms B are connected via wires.

[0017] Figure 1 , 2As shown, during liquid chromatography analysis, the mobile phase carries the solution to be analyzed to the stationary phase. The components in the solution are separated sequentially due to the different effects of the stationary phase. The different components separated by the stationary phase flow with the mobile phase to the flow cell body 1. Then, the flow cell body 1 performs optical detection on the different components that enter with the mobile phase to obtain the component information of each component in the solution to be analyzed. The flow cell performs optical detection of solution components using optical fibers 101, etc. The flow cell includes a flow cell body 101, a light-reflecting flow tube within the flow cell body 101, an optical path located outside the flow cell body 101, two optical fibers 101 communicating with the light-reflecting flow tube, an inlet pipe 102 connected to the mobile phase pipe, and an outlet pipe 103 communicating with the reservoir (the inlet and outlet pipes are respectively connected to the inlet and outlet on the left and right sides of the light-reflecting flow tube). Specifically, after the mobile phase flows into the flow cell, it flows in and out through the light-reflecting flow tube. The control system of the liquid chromatograph collects the signal changes of the light signals transmitted by the two optical fibers 101 after passing through the light-reflecting flow tube, thus obtaining the component information of the solution components in the mobile phase flowing through the light-reflecting flow tube. The above-mentioned flow cell body 1, in conjunction with the liquid chromatograph, detects sample components using existing mature technology. Therefore, this application does not elaborate on the structure and working principle of the flow cell body 1, nor does it provide any protection for the above technical solution.

[0018] Figure 1 , 2As shown, after the 220V AC power enters the power input terminal of power module A1, pins 3 and 4 of power module A1 output a stable 12V DC power supply, which enters the power input terminals of the two temperature control circuits. In practical applications, when it is necessary to maintain a relatively low or relatively high temperature inside the flow cell body 1, the operator attaches the cold or hot ends of the two semiconductor cooling / heating mechanisms B to the front and rear outer ends of the flow cell body 1, respectively. When it is necessary to maintain a relatively high temperature inside the flow cell body 1, the operator turns on the power switch S (turns off the power switch S1), and the first temperature control circuit is powered on. When the temperature inside the flow cell body 1 is relatively high, the resistance value of the thermistor RT is relatively low, and the voltage drop between it and the adjustable resistor RP1 is low. Conversely, when the temperature inside the flow cell body 1 is relatively low, the resistance value of the thermistor RT is relatively high, and the voltage drop between it and the adjustable resistor RP1 is high. Specifically, when the temperature inside the flow cell body 1 (the outer shell temperature of the flow cell body directly affects the heated surface of the thermistor) is lower than the temperature set by the adjustable resistor RP (e.g., below 25℃), the temperature detected by the thermistor RT is relatively low and the resistance value is high. The thermistor RT and the adjustable resistor RP1 divide the voltage (the voltage division is large), and the power supply then passes through the adjustable resistor RP, resistor R1, and resistor R2 to reduce the voltage and limit the current. When the base voltage of transistor Q is below 0.7V, transistor Q is cut off, and the collector does not output a low level. Relay J is de-energized and does not engage, closing its control power input terminal and normally closed contact. Thus, the two semiconductor cooling / heating mechanisms B will operate, and the high temperature generated by their hot ends will act on the flow cell body, causing the temperature inside the flow cell body to gradually increase. When the temperature inside the flow cell body 1 is higher than the set temperature by the adjustable resistor RP, the resistance value of the thermistor RT is relatively low and the resistance value is high. The voltage of the thermistor RT and the adjustable resistor RP1 are then divided by the adjustable resistor RP, and the power supply is further divided by resistor R1. The current then decreases due to the voltage drop and current limitation. When the temperature set by the resistor RP is adjusted (e.g., above 25°C), the temperature detected by the thermistor RT is relatively high and the resistance value is low. After voltage division by the thermistor RT and the adjustable resistor RP1 (smaller voltage division), the power supply is further divided by the adjustable resistor RP, the resistor R1, and the resistor R2 reduces the voltage and limits the current to the base of the transistor Q, which is higher than 0.7V. The transistor Q conducts, and the collector outputs a low level, which enters the negative power input terminal of the relay J. The relay J is energized and its control power input terminal and normally closed contact terminal are opened. In this way, the two sets of semiconductor cooling / heating mechanisms B stop working, and their hot ends stop outputting high temperature to act on the flow cell body. The temperature inside the flow cell body no longer rises. Through the above, this new type can maintain a relatively high constant temperature (e.g., around 25°C) inside the flow cell body 1 in heating mode.

[0019] Figure 1 , 2As shown, when the flow cell body 1 needs to be kept at a relatively low temperature, the operator turns on the power switch S1 (turns off the power switch S), and the second temperature control circuit is powered on. When the temperature inside the flow cell body 1 is lower than the temperature set by the adjustable resistor RP2 (for example, below 10℃), the temperature detected by the thermistor RT is relatively low and the resistance value is large. It and the adjustable resistor RP1 divide the voltage (the voltage division is large). The power supply then passes through the adjustable resistor RP2, the resistor R3, and the resistor R4 to reduce the voltage and limit the current to the base of the transistor Q1. When the voltage is lower than 0.7V, the transistor Q1 is cut off and the collector does not output a low level. The relay J1 is de-energized and does not engage. Its control power input terminal and normally open contact terminal are open. In this way, the two sets of semiconductor cooling / heating mechanisms B will not work, and the low temperature generated by its cold end will not be... The flow cell body experiences a gradual increase in temperature. When the temperature inside the flow cell body 1 exceeds the temperature set by the adjustable resistor RP2 (e.g., above 10°C), the thermistor RT detects a relatively low resistance value. Its voltage is then divided by the adjustable resistor RP (resulting in a smaller voltage division). The power supply then passes through the adjustable resistor RP2, resistor R3, and resistor R4, which reduces the voltage and limits the current. The voltage at the base of transistor Q1 exceeds 0.7V, causing transistor Q1 to conduct. The collector outputs a low level, which enters the negative power input terminal of relay J1. Relay J1 is energized and its control power input terminal and normally open contact close. This activates the two semiconductor cooling / heating mechanisms B, whose cold junctions generate a low temperature that acts on the flow cell body, gradually lowering its temperature. Through this process, the novel design maintains a relatively low and constant temperature (e.g., around 10°C) inside the flow cell body 1 during cooling mode.

[0020] Figure 1 , 2 As shown above, this new invention uses a semiconductor cooling / heating mechanism as a cold or heat source, which is convenient to install and use, low in cost, and flexible in application. The operator can easily use a magnet to attract the cold end of the semiconductor cooling / heating mechanism to the front and rear outer sides of the flow cell body. In application, the flow cell body can be controlled at a suitable constant high or low temperature according to the sample being tested and the ambient temperature, thus ensuring the analytical and testing effect of the sample. Figure 2As shown, power module A1 is a finished product of AC 220V to DC 12V power module; power switches S and S1 are toggle switches (the operating handles are located outside the openings at the front of the control box for easy operation by staff); the thermistor RT is a negative temperature coefficient thermistor of model NTC103D; relays J and J1 are DC12V; resistors R1, R2, R3, and R4 have resistance values ​​of 4.7K, 10K, 4.7K, and 10K respectively; transistors Q and Q1 are model 9013; adjustable resistor RP1 has a resistance value of 1... K; The adjustable resistors RP and RP2 have a resistance of 47K (in this embodiment, they are adjusted to 25K and 10K respectively). The handles of the adjustable resistors RP and RP2 are located outside the opening at the front of the control box, making it convenient for the testing personnel to adjust and set the temperature inside the flow cell (the handles of the adjustable resistors RP and RP1 are marked with numbers representing temperature data on the front outer side of the control box); the semiconductor cooling / heating mechanism B is a finished product with a power of 100W (cold end temperature -10 to -20℃, hot end temperature between 40℃ and 60℃). The electronic components or circuit modules used in this application are all existing mature products, therefore, this application will not elaborate on their working principles, etc.

[0021] The foregoing has shown and described the basic principles, main features, and advantages of this utility model. It will be apparent to those skilled in the art that this utility model is limited to the details of the exemplary embodiments described above, and that it can be implemented in other specific forms without departing from the spirit or basic characteristics of this utility model. Therefore, the embodiments should be considered exemplary and non-limiting in all respects. The scope of this utility model is defined by the appended claims rather than the foregoing description, and thus all variations falling within the meaning and scope of equivalents of the claims are intended to be included within this utility model.

[0022] Furthermore, it should be understood that although this specification describes the embodiments, the embodiments do not necessarily contain only one independent technical solution. This way of describing the specification is only for clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in the embodiments can also be appropriately combined to form other embodiments that can be understood by those skilled in the art.

Claims

1. A constant temperature flow cell for liquid chromatography applications, comprising a flow cell body for liquid chromatography applications, a semiconductor refrigeration / heating mechanism, a thermistor, characterized in that, It also has a temperature control circuit. Magnets A are fixedly installed on the front and rear ends of the housing of the semiconductor cooling / heating mechanism. A fixing groove is provided on the outer end of the flow cell body, and a magnet B is fixedly installed in the fixing groove. The semiconductor cooling / heating mechanism is installed on the outer end of the flow cell body by magnet A attracting magnet B. The thermistor is fixedly installed on the outer side of the flow cell body, and its temperature sensing surface is in contact with the outer side of the flow cell body. The temperature control circuit has at least two circuits, and the two temperature control circuits are installed in the electrical control box. The two ends of the thermistor are electrically connected to the signal input terminals of the two temperature control circuits, and the power output terminals of the two temperature control circuits are electrically connected to the power input terminals of the two semiconductor cooling / heating mechanisms.

2. The constant temperature flow cell for use in liquid chromatography as claimed in claim 1, wherein, The polarity of the rear end of magnet A is opposite to that of the front end of magnet B. The outer diameter and inner diameter of magnet A and magnet B are the same.

3. The constant temperature flow cell for use in liquid chromatography as claimed in claim 1, wherein, After the semiconductor cooling / heating mechanism is attached to the front and rear ends of the flow cell body, its cold end or hot end is respectively attached to the outside of the flow cell body.

4. The constant temperature flow cell for use in liquid chromatography as claimed in claim 1, wherein, The thermistor is equipped with an adjustable resistor, one end of which is electrically connected to one end of the thermistor.

5. The constant temperature flow-through cell for use in a liquid chromatograph according to claim 1, wherein, The two temperature control circuits have the same structure, both including an electrically connected relay, a power switch, an adjustable resistor, a resistor, and a transistor. One end of the power switch is connected to the positive power input terminal and the control power input terminal of the relay. The collector of the transistor is connected to the negative power input terminal of the relay. One end of the adjustable resistor is connected to one end of the first resistor and one end of the second resistor. The other end of the second resistor is connected to the base of the transistor. The emitter of the transistor is connected to the other end of the first resistor.

6. The constant temperature flow-through cell for use in a liquid chromatograph according to claim 5, wherein, The normally closed contact of the relay in the first temperature control circuit is connected to one power input of the two sets of semiconductor cooling / heating mechanisms, and the normally open contact of the relay in the second temperature control circuit is connected to one power input of the two sets of semiconductor cooling / heating mechanisms.

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