I. Introduction
Since the first creation of practical gas-liquid chromatography in the world in 1952, gas chromatographs, as a representative of modern analytical instruments in just a few decades, have developed into a fairly productive scale and have formed quite A wealth of materials for testing technical knowledge. By studying the development rules of gas chromatographs, it can give users useful enlightenment and bring some help to the work of relevant professionals.
For example, the gas chromatography series of Sakamoto Shimadzu, which is widely used in China, is used, such as GC-7A in 1983, GC-9A in 1985, GC-14A in 1990, GC-17A in 1995, etc. The main aspects of these instruments, namely heating unit control, furnace temperature control, flow control, data processing system, detector system, system control, etc., to explain the development of gas chromatograph technology advancement, and predict the future of gas chromatograph development trend.
Second, the development track of gas chromatograph technology progress
1. Inject and detector temperature control of the inlet and detector
Both GC-7A and GC-9A use a complete total heating block unit. The GC-14A inlet and detector each share a total heating block unit. GC-17A is changed to each inlet and detector. Independent heating unit system.
The total heating block unit means that the inlet and detector are all or part of a large heating block, and there is a heating rod, a temperature controller and a constant temperature block to control the temperature. Its advantages are simple structure, few components and low cost. Due to the large heat storage value, it is easy to stabilize the temple after reaching the temperature. Its disadvantage is that the temperature of each component on the heating block can only be set to be consistent, but can not be different, which limits the application of the detection means; because the heating block is large in volume, the temperature rise and fall is slow, and the changing conditions are difficult; The components are heated, and the unused components are subjected to thermal fatigue loss during the temperature rise and cool down process.
Independent heating unit means that any inlet and detector have independent heating, temperature control and constant temperature devices. The advantage is that any one component can be set to different temperatures, and because the heating block is small in volume, low in heat storage value, the temperature rise and temperature drop speed is greatly improved, and the functions of the inlet program temperature heating can be provided, enriching The means of chromatographic technology. Its shortcomings are that each is a separate system, the technical requirements for temperature control are high, and the components are increased, and the cost is relatively high.
Gas chromatographs using total heating block units typically employ "U" shaped columns (e.g., GC-7A, GC-9A, GC-14A) because the positions of the various components are limited to one heating block and must be compact. A gas chromatograph with a separate heating unit typically uses a circular column because its inlet and detector need to be separated by a certain distance because the cooling of each individual heating unit is achieved by ambient air cooling, such as the inlet and The detectors are too close together to affect each other's heat dissipation.
Is the heating from the total heating block unit to the individual unit a big beer?
2. Oven temperature contol
Gas chromatograph furnace temperature control often IH omnipotent level can often reflect the level and level of this instrument, the evolution of furnace temperature control technology can be seen from the change of the column oven exhaust port. GC-7A does not have a column oven exhaust port, and its temperature rise and fall is too slow, making the operator easily unable to change the conditions; GC-9A, GC-14A has a narrow slit type heat exhaust port, so that the effect has Certain improvement; GC-17A is further changed to two square heat exhaust ports, and the cooling effect is satisfactory.
In terms of operating system for furnace temperature control, the GC-7A uses a mechanical dial, which is very inconvenient. From the GC-9A, electronic control is used, and keyboard input parameters are used. It can be said that Shimadzu's gas color pre-existence from the GC-9A is considered to begin to modernize. The GC-17A is controlled by a workstation and can be easily temperature controlled.
3. Gas flow control (Flow COIltol)
The GC-7A, GC-9A, and GC-14A all use classic mechanical watch valve controls such as pressure wheat and rotor flow meters.
Generally, components that require precise control of the carrier gas flow rate use a rotameter, and pressure gauges are used only for the rough control. For example, hydrogen and air flow control as auxiliary combustion gases basically use pressure decay.
Mechanical watch valve control has the advantages of being reliable, durable and economical. Its disadvantages are: it should be slowly increased from zero at each turn-on, and then turned back to zero when it is turned off. Since there is inevitably a human difference in each adjustment, it is difficult to maintain the same flow each time. The flow cannot be changed during the test. The electronic pressure control uses a solenoid valve instead of a mechanical watch valve. It only needs to input a value to find a predetermined flow or pressure. It is convenient, accurate and rapid. It can also provide a program boosting method. It can be described as a revolution in flow control.
Electronically controlled flow overcomes the drawbacks of mechanically controlled flow, but it also brings new problems:
(1) If the pressure of the air source changes too much, it is easy to be damaged by strong impact, and the mechanical watch valve does not have this problem.
(2) In the event of an unexpected power outage, the solenoid valve stops working and stops supplying air. The column is easily damaged when no carrier gas passes through the high temperature.
(3) Theoretically speaking, the rotameter is the most stable and accurate component for measuring the carrier gas flow, and it is difficult to produce deviation; and the electronic pressure control must be an electronic simulation mechanical process, and there may be slight deviation after long-term use.
4. Data processing unit
GC-7A configuration plotter, GC-9A configuration integrator or data processor that can not store data, GC-14A configuration data processor to store data, GC-17A configuration ChemStation for data processing.
The data system data processing system is the fastest-growing and most profitable part of the gas chromatograph, making it easier to operate the instrument. Before inventing the integrator, measuring the peak area of ​​the chromatographic peak can only be manually measured by the integral ruler or paper-cut, and often a peak will take half a day. All chromatographic data is now available quickly after the test is completed.
From plotters to integrators, from data processors to ChemStations, the advances are mainly due to the rapid development of electronic technology.
5. Detector system (Detecωr)
Among the various components of the gas chromatograph, the detector is relatively stable, the internal structure and composition have not been revolutionized, and the detection performance is limited, but the stability speed has been greatly improved, such as the GC-17A electronic capture detector. It is 10 times faster than the GC-14A, and the cooling efficiency is as high as 100 degrees Celsius per 10 minutes.
6. Host system control part (Total system control)
Before the workstation appeared, you can only manually set various operating parameters of the host. Therefore, to start an instrument, you need to perform many trivial settings and adjustment steps, open and close many switches, and adjust many knobs. People who are not familiar with the device often make mistakes.
After using the workstation, the user can input various instrument parameters and running programs of different experiments into the computer. The next time you call directly, you can work, complete the steps from starting, detecting, processing, and so on. The parameters of each component are entered and determined item by item, making operation easier.
Shimadzu's gas chromatograph series is commonly used after GC-17A to directly control the instrument.
Third, the future development trend of gas chromatography
From the development of GC-7A to GC-17A, we can see a period of development from mechanical instruments to electronic instruments.
Due to the limitations of electronic technology and material science, the early gas chromatographs also limited the designers' ideas and exerted them. The chromatographic technology at that time was also greatly limited. The female daily temperature program and program boosting are now very easy. The technical means were very cumbersome and impractical at the time.
With the development of electronic technology and materials science, it not only strengthens the function of gas chromatograph, but also greatly enriches the methods and means of applying gas chromatograph technology, and at the same time brings profound influence to designers' design ideas. Promote, and thus advance the progress of gas chromatographs faster.
Extending from this trend, the author predicts the technical development path of the future gas chromatograph, and looks at what the future gas chromatograph will look like.
â’ˆ computer become standard <br> due to the extensive use of computer technology and computer prices continue to fall, the computer will become the standard configuration of the gas chromatograph. The control panels that are currently common on gas chromatographs will be eliminated, leaving only a few gas flow switches on the sides. The operating parameters of the various components of the instrument are completely controlled by the computer, making the gas chromatograph smaller, simpler in structure and lower in cost.
â’‰ flexible replaceable function module <br> Currently, GC sample inlet, the detector once it is difficult detachably mounted or replaced, because the interface portion thereof, the air passage connecting portions are not uniform in size, And the design does not take into account the need for frequent disassembly.
In the future, each module of the inlet and detector will adopt a square interface with uniform specifications, which is convenient for users to plug and unplug and select different conditions. The socketed air circuit connection is located at the bottom of the module and is secured by a hand-tight nut at the top of the module.
â’Š <br> data acquisition card of each company and is currently a wide range of expensive data acquisition card will gradually disappear, their place is a computer network card. The test data is transmitted to the computer through the network cable, which further reduces the cost of the instrument.
â’‹ appear to share control software <br> Currently, various gas chromatograph workstation is dedicated, which can only control a certain kind of model of a company's production of gas chromatography. With the high application of electronic components, it means that the instrument can be controlled as long as the electrical signal is controlled. Therefore, although the signal mode and range of each gas chromatograph are different, if a set of software stores the signal parameters of several instruments at the same time, the instruments produced by different companies can be controlled by selecting different models.
⒌ sharp decline in the price of parts can be reduced with intensive <br> imply that the cost reduction. In addition to the limited space for detector price reduction, considering the elimination of control panels, data acquisition cards, and the intensive design of other components, the price of the entire instrument (including computers) is estimated to be reduced by at least half.
The National Standard Material Resource Platform lists the national standard materials and the standards, reference materials and chemical reagents developed by the company, which facilitates the customer's inquiry of standard substances and chemical reagents! All the orders received were changed from door-to-door to express delivery, which not only speeded up the use of products by foreign customers, but also standardized the internal warehouse structure! Make the purchase of one-stop standard materials more precise and efficient!
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Since the first creation of practical gas-liquid chromatography in the world in 1952, gas chromatographs, as a representative of modern analytical instruments in just a few decades, have developed into a fairly productive scale and have formed quite A wealth of materials for testing technical knowledge. By studying the development rules of gas chromatographs, it can give users useful enlightenment and bring some help to the work of relevant professionals.
For example, the gas chromatography series of Sakamoto Shimadzu, which is widely used in China, is used, such as GC-7A in 1983, GC-9A in 1985, GC-14A in 1990, GC-17A in 1995, etc. The main aspects of these instruments, namely heating unit control, furnace temperature control, flow control, data processing system, detector system, system control, etc., to explain the development of gas chromatograph technology advancement, and predict the future of gas chromatograph development trend.
Second, the development track of gas chromatograph technology progress
1. Inject and detector temperature control of the inlet and detector
Both GC-7A and GC-9A use a complete total heating block unit. The GC-14A inlet and detector each share a total heating block unit. GC-17A is changed to each inlet and detector. Independent heating unit system.
The total heating block unit means that the inlet and detector are all or part of a large heating block, and there is a heating rod, a temperature controller and a constant temperature block to control the temperature. Its advantages are simple structure, few components and low cost. Due to the large heat storage value, it is easy to stabilize the temple after reaching the temperature. Its disadvantage is that the temperature of each component on the heating block can only be set to be consistent, but can not be different, which limits the application of the detection means; because the heating block is large in volume, the temperature rise and fall is slow, and the changing conditions are difficult; The components are heated, and the unused components are subjected to thermal fatigue loss during the temperature rise and cool down process.
Independent heating unit means that any inlet and detector have independent heating, temperature control and constant temperature devices. The advantage is that any one component can be set to different temperatures, and because the heating block is small in volume, low in heat storage value, the temperature rise and temperature drop speed is greatly improved, and the functions of the inlet program temperature heating can be provided, enriching The means of chromatographic technology. Its shortcomings are that each is a separate system, the technical requirements for temperature control are high, and the components are increased, and the cost is relatively high.
Gas chromatographs using total heating block units typically employ "U" shaped columns (e.g., GC-7A, GC-9A, GC-14A) because the positions of the various components are limited to one heating block and must be compact. A gas chromatograph with a separate heating unit typically uses a circular column because its inlet and detector need to be separated by a certain distance because the cooling of each individual heating unit is achieved by ambient air cooling, such as the inlet and The detectors are too close together to affect each other's heat dissipation.
Is the heating from the total heating block unit to the individual unit a big beer?
2. Oven temperature contol
Gas chromatograph furnace temperature control often IH omnipotent level can often reflect the level and level of this instrument, the evolution of furnace temperature control technology can be seen from the change of the column oven exhaust port. GC-7A does not have a column oven exhaust port, and its temperature rise and fall is too slow, making the operator easily unable to change the conditions; GC-9A, GC-14A has a narrow slit type heat exhaust port, so that the effect has Certain improvement; GC-17A is further changed to two square heat exhaust ports, and the cooling effect is satisfactory.
In terms of operating system for furnace temperature control, the GC-7A uses a mechanical dial, which is very inconvenient. From the GC-9A, electronic control is used, and keyboard input parameters are used. It can be said that Shimadzu's gas color pre-existence from the GC-9A is considered to begin to modernize. The GC-17A is controlled by a workstation and can be easily temperature controlled.
3. Gas flow control (Flow COIltol)
The GC-7A, GC-9A, and GC-14A all use classic mechanical watch valve controls such as pressure wheat and rotor flow meters.
Generally, components that require precise control of the carrier gas flow rate use a rotameter, and pressure gauges are used only for the rough control. For example, hydrogen and air flow control as auxiliary combustion gases basically use pressure decay.
Mechanical watch valve control has the advantages of being reliable, durable and economical. Its disadvantages are: it should be slowly increased from zero at each turn-on, and then turned back to zero when it is turned off. Since there is inevitably a human difference in each adjustment, it is difficult to maintain the same flow each time. The flow cannot be changed during the test. The electronic pressure control uses a solenoid valve instead of a mechanical watch valve. It only needs to input a value to find a predetermined flow or pressure. It is convenient, accurate and rapid. It can also provide a program boosting method. It can be described as a revolution in flow control.
Electronically controlled flow overcomes the drawbacks of mechanically controlled flow, but it also brings new problems:
(1) If the pressure of the air source changes too much, it is easy to be damaged by strong impact, and the mechanical watch valve does not have this problem.
(2) In the event of an unexpected power outage, the solenoid valve stops working and stops supplying air. The column is easily damaged when no carrier gas passes through the high temperature.
(3) Theoretically speaking, the rotameter is the most stable and accurate component for measuring the carrier gas flow, and it is difficult to produce deviation; and the electronic pressure control must be an electronic simulation mechanical process, and there may be slight deviation after long-term use.
4. Data processing unit
GC-7A configuration plotter, GC-9A configuration integrator or data processor that can not store data, GC-14A configuration data processor to store data, GC-17A configuration ChemStation for data processing.
The data system data processing system is the fastest-growing and most profitable part of the gas chromatograph, making it easier to operate the instrument. Before inventing the integrator, measuring the peak area of ​​the chromatographic peak can only be manually measured by the integral ruler or paper-cut, and often a peak will take half a day. All chromatographic data is now available quickly after the test is completed.
From plotters to integrators, from data processors to ChemStations, the advances are mainly due to the rapid development of electronic technology.
5. Detector system (Detecωr)
Among the various components of the gas chromatograph, the detector is relatively stable, the internal structure and composition have not been revolutionized, and the detection performance is limited, but the stability speed has been greatly improved, such as the GC-17A electronic capture detector. It is 10 times faster than the GC-14A, and the cooling efficiency is as high as 100 degrees Celsius per 10 minutes.
6. Host system control part (Total system control)
Before the workstation appeared, you can only manually set various operating parameters of the host. Therefore, to start an instrument, you need to perform many trivial settings and adjustment steps, open and close many switches, and adjust many knobs. People who are not familiar with the device often make mistakes.
After using the workstation, the user can input various instrument parameters and running programs of different experiments into the computer. The next time you call directly, you can work, complete the steps from starting, detecting, processing, and so on. The parameters of each component are entered and determined item by item, making operation easier.
Shimadzu's gas chromatograph series is commonly used after GC-17A to directly control the instrument.
Third, the future development trend of gas chromatography
From the development of GC-7A to GC-17A, we can see a period of development from mechanical instruments to electronic instruments.
Due to the limitations of electronic technology and material science, the early gas chromatographs also limited the designers' ideas and exerted them. The chromatographic technology at that time was also greatly limited. The female daily temperature program and program boosting are now very easy. The technical means were very cumbersome and impractical at the time.
With the development of electronic technology and materials science, it not only strengthens the function of gas chromatograph, but also greatly enriches the methods and means of applying gas chromatograph technology, and at the same time brings profound influence to designers' design ideas. Promote, and thus advance the progress of gas chromatographs faster.
Extending from this trend, the author predicts the technical development path of the future gas chromatograph, and looks at what the future gas chromatograph will look like.
â’ˆ computer become standard <br> due to the extensive use of computer technology and computer prices continue to fall, the computer will become the standard configuration of the gas chromatograph. The control panels that are currently common on gas chromatographs will be eliminated, leaving only a few gas flow switches on the sides. The operating parameters of the various components of the instrument are completely controlled by the computer, making the gas chromatograph smaller, simpler in structure and lower in cost.
â’‰ flexible replaceable function module <br> Currently, GC sample inlet, the detector once it is difficult detachably mounted or replaced, because the interface portion thereof, the air passage connecting portions are not uniform in size, And the design does not take into account the need for frequent disassembly.
In the future, each module of the inlet and detector will adopt a square interface with uniform specifications, which is convenient for users to plug and unplug and select different conditions. The socketed air circuit connection is located at the bottom of the module and is secured by a hand-tight nut at the top of the module.
â’Š <br> data acquisition card of each company and is currently a wide range of expensive data acquisition card will gradually disappear, their place is a computer network card. The test data is transmitted to the computer through the network cable, which further reduces the cost of the instrument.
â’‹ appear to share control software <br> Currently, various gas chromatograph workstation is dedicated, which can only control a certain kind of model of a company's production of gas chromatography. With the high application of electronic components, it means that the instrument can be controlled as long as the electrical signal is controlled. Therefore, although the signal mode and range of each gas chromatograph are different, if a set of software stores the signal parameters of several instruments at the same time, the instruments produced by different companies can be controlled by selecting different models.
⒌ sharp decline in the price of parts can be reduced with intensive <br> imply that the cost reduction. In addition to the limited space for detector price reduction, considering the elimination of control panels, data acquisition cards, and the intensive design of other components, the price of the entire instrument (including computers) is estimated to be reduced by at least half.
The National Standard Material Resource Platform lists the national standard materials and the standards, reference materials and chemical reagents developed by the company, which facilitates the customer's inquiry of standard substances and chemical reagents! All the orders received were changed from door-to-door to express delivery, which not only speeded up the use of products by foreign customers, but also standardized the internal warehouse structure! Make the purchase of one-stop standard materials more precise and efficient!
Http://
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