Waters Meteorological Chromatograph
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Waters Meteorological Chromatograph
Weather chromatograph is a kind of important instrument separation and determination of low boiling point mixed components, available for chemical, ShengGong, food for instrument analysis experiment, also can be used for research and routine analysis.
Weather chromatograph including six basic unit: 1) the carrier gas and its velocity control system; (2) sampling system; (3) chromatographic column system; (4) detector system; (5) the recorder system; (6) temperature control system. Commonly used in the gas chromatograph detector are: thermal conductivity detector (TCD), hydrogen flame ionization detector (FID), nitrogen and phosphorus detector (NPD), flame photometric detector (FPD), optical ionization detector (PID), electron capture detector (ECD), etc.
Each unit functions:
1) air supply system: gas source points of carrier and auxiliary two kinds, the carrier gas is carrying the analysis sample through chromatographic column, provide the sample run in the column of power, auxiliary gas combustion is to provide the detector or purging, some instrument using EPC system for digital control flow.
2) injection system: sample system function is to accept samples, make instant vaporization, transferred to the sample of the chromatographic column. Some instruments including sample pretreatment device, such as hot stripping device (TD) purge and trap, cracking device, device, headspace sampling device.
3) column chromatographic column system: sample run in the column at the same time needed to get separated. Chromatographic column with packed column and capillary column two kinds commonly, with packed column are 0.2 -- 0.6 cm inner diameter, 1-6 meters long, a u-shaped or spiral glass or stainless steel column, fills in a different polarity of stationary phase, such as OV - 17, OV - 101, 30, SE SE - - 54, etc; Capillary column is commonly, 0.05 0.53 mm inner diameter of 10 ~ 50 meters long column made of fused silica, its inner surface evenly coated with different polarity of stationary phase, generally with circular frame around the circle shape, to release the GC column in the box.
:4) detection system to test the column has been separated components, the role of the detector is indicating and measuring load has separation in gas of various components, namely the detector is the sensor of the mobile phase composition, so it is one of the key components of the chromatograph. After some instruments include column transformation (such as silicon alkylation device, hydrocarbon conversion device).
5) data acquisition and processing system, signal acquisition and processing system input, the last sample qualitative and quantitative results are given.
6) temperature control system: control and display the sample system, oven, the temperature of the detector and auxiliary parts.
All of the gas chromatograph should include more than six basic unit, and its function are the same, the difference of just the level of configuration, so a comprehensive understanding of the composition of each unit function of instrument use, development and fault analysis are necessary. Respectively under the gas circuit system is introduced in this paper, sampling system and testing system, column system and data acquisition processing system.
Working principle:
Principle is the mixed gas of various components by the speed of the chromatographic column.
Uv-visible absorption spectrum is due to molecules absorbed some of the groups after ultraviolet visible light radiation, the electron energy level transition and the absorption spectrum. It is a band spectrum, some groups reflects the molecular information. Can use the standard spectrogram and qualitative analysis combined with other means. (note that this section error!)
According to the Lambert - Beer's law: A = epsilon BC, (A is absorbance, epsilon as the molar absorption coefficient, as the thickness of the liquid pool, c solution concentration) can be the solution for quantitative analysis.
You can use the wavelength of three kinds of pesticide in a solution of minimum and maximum absorption wavelength.
Solutions - under spectrum detection test - adjust the spectral range and speed - scanning spectrum - maximize absorbance wavelength corresponding to maximum absorption wavelength, the absorbance of minimum corresponding to the wavelength of the department for the smallest absorption wavelength.
Note:
Hand don't take the needle and syringe to have sample parts, don't have a bubble (slower, fast discharge when inhaling the sample again slowly suck, repeated several times, 10 ul syringe needle metal part volume 0.6 ul, have can't see a bubble, sucked more 1-2 ul the syringe tip up walking on air bubble to the top and then push the needle bar to eliminate air bubbles, (10 ul syringe, with core syringes feel) sample faster (but not easy to express), each sample to keep the same speed, needle point to the middle of vaporizing chamber began taking samples.
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