Gas Chromatograph Purchase Notes

　　Matters Needing Attention in Purchasing Gas Chromatographs From the guiding ideology of purchasing gas chromatographs, the following points should be considered:

　　1. Shop on demand and target your needs

　　"Buy what you need" seems to be a very simple principle, and everyone knows it. However, knowing is one thing, and doing is another, because many people have another "little trick" - "broad use for narrow use", that is, buying all the accessories that are not needed temporarily or may not be needed in the future. When units bought chromatographs several years ago, if the superiors allocated funds, they would buy all the accessories. This is actually a waste and trouble for themselves. For example, your actual work only needs a thermal conductivity detector and a hydrogen flame ionization detector, but when you order a chromatograph, you also buy an electron capture detector and a flame photometer, and you don't need to put them in the warehouse. So you should only buy those detectors and accessories that you need, which is shopping on demand and targeting. If you buy a new one with better performance when you need a certain accessory, isn't it both economical and practical? Especially now that various instruments are developing very fast, new functions are constantly being added, and existing functions are constantly being improved, so you should buy what you need at the time, and don't buy accessories that you don't need at the time.

　　2. Tailor your clothes to your body and do what you can

　　At present, there are many domestic manufacturers of gas chromatographs with medium-high-end and medium-low-end products. The book "Recommended Products of Domestic Scientific Instruments" published in 2002 lists a variety of analytical gas chromatographs. Most of these gas chromatographs from different manufacturers have many years of production experience, and the general price is around 20,000 to 80,000 yuan. If you are teaching or doing general routine tests, these gas chromatographs produced in China should be able to meet your requirements. If you are doing routine analysis in conjunction with production, choose a single-detector gas chromatograph with only one detector, such as a gas chromatograph equipped with only a thermal conductivity detector or only an electron capture detector, so that it can be more effective.

　　Of course, if you need to work, such as high sensitivity, high reproducibility, high reliability analysis and process control, such as electronic pressure control, automatic sample injector, large volume injection, non-stop operation on the production line for years, etc., and have financial support, you can choose high-end foreign gas chromatographs. At present, several well-known gas chromatograph manufacturers in the world have sales agencies in China. The instrument level is similar, each has its own characteristics, and it can be said that each has its own advantages. As for which one and which model to choose, you have to spend some time to examine it.

　　Here we classify and analyze several factors to consider when purchasing a gas chromatograph for your reference.

　　1. Samples to be analyzed

　　⑴ What is the composition and state of the sample itself? Is it gas, liquid, solid or mixed? Can it be directly analyzed by gas chromatography?

　　⑵ Is the measured component thermally unstable, easily decomposed, or easily catalyzed? Will changes in time, temperature, pressure, etc. cause changes in the measured component?

　　⑶Whether there is smoke, suspended matter, high-point components and corrosive components in the sample. Consider how to collect the sample and how to pre-treat the sample;

　　⑷ Is the sample source easy to obtain? Allowing sample consumption is conducive to selecting the injection method;

　　⑸ Components that do not need to be analyzed and their approximate concentration range;

　　⑹The number of times samples need to be analyzed each day and the interval between two analyses;

　　2. What is the purpose of the analysis?

　　⑴ Do qualitative analysis: Is the component being analyzed known or unknown? Is there a standard substance?

　　⑵ Quantitative analysis: In which range - constant (10-1`~10-3); semi-trace (10-3~10-5); trace (10-5~10-7); trace (10-6~10-9) or ultra-trace (≤10-9)

　　⑶ Quantitative precision and analytical accuracy. If it is semi-quantitative requirement, it will be much simpler.

　　3. Positioning of purchasing units

　　When choosing a unit, in addition to considering the price, the most important thing to consider is the quality of after-sales service.

　　⑵ Monitoring and analysis center - accurate and reliable;

　　⑶ For on-site analysis at the front line - repeated reproduction;

　　4. Theoretically, the same sample may be analyzed by a variety of instruments . Compare the performance/price ratio, operating characteristics, and maintenance services of the instrument, and list the reasons for choosing a gas chromatograph for analysis.

　　5. Consult and find out whether there are national standards, industry standards, enterprise standards or relevant foreign reference materials for the samples to be analyzed. If so, the standards will give the functions and technical requirements of the instruments that should be used in general situations.

　　6. Are there any analysts doing similar sample analysis around this work unit? If there are any, it will be of direct help to the selection and establishment of chromatographic analysis methods in the future;

　　7. Collect samples and information of various types of gas chromatographs (including accessories) to prepare for the final selection;

　　8 Is the mission long-term or short-term? How much investment and what equipment to choose will depend on the mission? Do you need to make long-term plans?

　　9. What are the existing conditions? For a new analytical task, many units have existing instruments that can be properly modified and re-established analytical methods to fully handle the work; if the conditions are met, there is no reason to make a large investment in purchasing new instruments and equipment;

　　10 Considering the working efficiency, operating cost, human resources (technical level) and financial conditions of the selected equipment, it is not easy to choose those so-called high-precision and cutting-edge products. In short, practicality and economy are the main considerations.

　　11. Chromatographic data processing device is an essential equipment for giving the final analysis results. You should choose it according to the specific requirements of the type and format of information required for the analysis results. You must not choose those chromatographic workstations with excessive prices and functions without considering financial resources. Some samples have few components and good separation. The work can be completed by a recorder and chromatographic data processing machine of several thousand yuan. Why spend tens of thousands of yuan to buy a computer with low efficiency and time-consuming operation for data processing?

　　12. Application and installation location of the instrument:

　　Although the installation location requirements for gas chromatographs are not strict compared to optical instruments, the following conditions should be noted when operating certain detectors and high-sensitivity work:

　　⑴ Occasions of use: temperature, humidity, atmospheric pressure, vibration, electromagnetic interference, presence or absence of corrosive gases, ventilation, stray light, water sources, dust, etc. that may affect the operation of the instrument;

　　(2) Whether the installation base of the instrument is stable and earthquake-resistant, and whether its area, location, and maintenance are convenient;

　　⑶ Whether the gas supply method, installation operation, purity, etc. can meet the requirements.