Mass spectrometry has a non-negligible role in experiments such as protein analysis and identification. This article introduces in detail the sample preparation reagent supplies, experimental operations, selection of mass spectrometers, and selection of samples. In addition, information on FAQs and famous websites in this area can be viewed by clicking the blue font. Utensils and instruments: Vacuum dryer, water bath, 10μ and 200μ pipettes, waste tank, ice making and ice loading equipment, 200μ tube rack, scissors, plastic box that can hold 200μ tube rack, 200μ tube centrifuge. ready: 1. Three sets of 0.2ml EP tubes. MilliQ water and methanol are rinsed once and vacuum dried. 2. Six 50ml EP tubes, rinse each with MilliQ water and methanol, and vacuum dry. 3. Preparation of pancreatin stock solution: make the pancreatin powder fall to the bottom of the bottle, dissolve it with 100 μ pancreatin vortex solution, and divide into 5 μl with 0.5 ml EP. 4. 50ml 100 mM NH4HCO3. Decolorization and digestion: 1. Cut the 200μl tip to a diameter of about 1.5mm at the suction port. Rinse with MilliQ water, poke the spots after sucking 100μl of water, put the rubber particles into a 0.2ml EP tube, absorb the water and then use MilliQ water Wash twice and blot dry. 2. Decolorize 180μl 50% MeOH / 50mM NNH4HCO3 for more than twice, half an hour each time; 180μl MilliQ water for 5 minutes, 180μ 50% ACN for 5 minutes, 180μl 100% ACN for 5 minutes; vacuum dry for half an hour. 3. Digestion ①Dilute pancreatin to 12.5 μg / μl with 25 mM NH4HCO3; add 3 μl of pancreatin to each tube of granules, wash away the excess pancreatin after 15 minutes in ice bath; then add about 3 μl of 25 mM NH4HCO3 to cover the colloid. ② Carefully turn the EP tube upside down, place the entire EP tube rack in a plastic box, and put it in a 37 degree water bath for 16 hours. ③ Remove the plastic box from the 37-degree water, take care not to pour the water, and cool to room temperature. ④ Add 10μl 25 mMNH4HCO3, shake for 15 minutes, centrifuge and collect in a new tube; Add 10μl 2.5% TFA, shake for 5 minutes, collect to the upper tube; Add 10μl 2.5% TFA-50% ACN, shake for 5 minutes, and collect to the upper tube; Add 10 μl of 100% ACN, shake for 5 minutes, and collect into the upper tube. ⑤ After concentrating the collected solution in vacuum to 5-10μl, add 20μl 0.5% TFA; continue to concentrate to 10-20μl. Peptide concentration and desalination: 1. Aspirate 10μl 100% ACN, discard it and repeat twice; 2. Aspirate 10μl 0.1% TFA, discard it and repeat twice; 3. Blow the sample 15 times; 4. Aspirate 10μl 0.1% TFA, discard, repeat twice; 5. Aspirate 3 μl of 0.1% TFA-50% ACN and transfer this eluent to a new EP tube. Types of mass spectrometry There are many types of mass spectrometers, and their working principles and application ranges are also very different. From an application perspective, mass spectrometers can be divided into the following categories: Organic mass spectrometer: due to different application characteristics, it is divided into: ①Gas chromatography-mass spectrometry (GC-MS) In this type of instrument, due to the different working principles of the mass spectrometer, there are gas chromatography-quadrupole spectrometer, gas chromatography-time-of-flight mass spectrometer, gas chromatography-ion trap mass spectrometry Instrument etc. ② Liquid chromatography-mass spectrometry (LC-MS) Similarly, there are liquid chromatography-quadrupole mass spectrometer, liquid chromatography-ion trap mass spectrometer, liquid chromatography-time-of-flight mass spectrometer, and various Liquid chromatography-mass spectrometry-mass spectrometry. ③ Other organic mass spectrometers include: matrix-assisted laser desorption time-of-flight mass spectrometer (MALDI-TOFMS), Fourier transform mass spectrometer (FT-MS) Inorganic mass spectrometer, including: ①Spark source dual focus mass spectrometer. ② Inductively coupled plasma mass spectrometer (ICP-MS). ③ Secondary ion mass spectrometer (SIMS) But the above classification is not very strict. Because some instruments have different accessories and have different functions. For example, if a gas chromatography-dual focus mass spectrometer is replaced with a fast atom bombardment ionization source, it is no longer a gas chromatography-mass spectrometer, but is called a fast atom bombardment mass spectrometer (FAB MS). In addition, some mass spectrometers can be connected to both gas chromatography and liquid chromatography, so it is not easy to fall into a certain category. Among the above types of mass spectrometers, organic mass spectrometers are the most numerous and most versatile. In addition to the above classification, the mass spectrometer can be divided into a dual-focus mass spectrometer, a quadrupole mass spectrometer, a time-of-flight mass spectrometer, an ion trap mass spectrometer, a Fourier transform mass spectrometer, etc. from the mass analyzer used in the mass spectrometer. Selection tips for mass spectrometers There are many types of mass spectrometers, and the application characteristics of different instruments are also different. Generally speaking, samples that can be vaporized at about 300C can be given priority for analysis by GC-MS, because GC-MS uses an EI source, and the mass spectrum information obtained is much more. Library search. The separation effect of the capillary column is also good. If it can not be vaporized at about 300 ℃, it needs to be analyzed by LC-MS. At this time, the molecular weight information is mainly obtained. If it is a tandem mass spectrometer, some structural information can also be obtained. In the case of biological macromolecules, LC-MS and MALDI-TOF analysis are mainly used to obtain molecular weight information. For protein samples, the amino acid sequence can also be determined. The resolution of a mass spectrometer is an important technical indicator. High-resolution mass spectrometers can provide compound composition formulas, which are very important for structural determination. Dual-focus mass spectrometer, Fourier transform mass spectrometer, time-of-flight mass spectrometer with reflector, etc. all have high-resolution functions. Sample selection in mass spectrometry Mass spectrometry requires certain samples. The sample for GC-MS analysis should be an organic solution. The organic matter in the aqueous solution cannot generally be determined. It must be extracted and separated into an organic solution, or headspace sampling technique is used. Some compounds are too polar and easily decompose during heating. For example, organic acid compounds can be esterified at this time, and the acid can be converted into an ester for GC-MS analysis. From the analysis results, the structure of the acid can be inferred. If the sample cannot be vaporized or esterified, it can only be analyzed by LC-MS. The sample for LC-MS analysis is preferably an aqueous solution or a methanol solution, and the LC mobile phase should not contain non-volatile salts. For polar samples, generally use ESI source, for non-polar samples, use APCI source. Acoustic Wall Panel ,Soundproof Wall Panels,Sound Panels For Walls ,Acoustic Insulation Panels Feat Top International(China) CO.,LTD , https://www.feattop.com