The difficult way to explore the micro mass spectrometer

Mass spectrometry is an important method to determine the molecules in samples But if security personnel encounter an unknown, potentially dangerous substance, they may not be willing to waste time sending samples to the laboratory and waiting patiently for the results of mass spectrometry They would prefer a portable mass spectrometer to be brought into the field to help analyze samples quickly Miniaturization of mass spectrometers is nothing new For decades, researchers have been working on the miniaturization of this important instrument Although researchers have successfully built some small mass spectrometer systems and corresponding applications, these products have not been able to reach more users successfully R Graham cooks, a professor of chemistry at Purdue University, who is a leader in this field, believes that the problem facing the micro mass spectrometer is the user's "wrong expectations" People will be disappointed if they expect the data provided by the micro mass spectrometer to be the same as the high-end mass spectrometer used in the laboratory Daniel E Austin, a professor of chemistry at Brigham Young University who has been working on the development of micro ion traps for more than 15 years, said: "when we are striving for miniaturization, we often need to sacrifice some aspects of performance." Compared with those of the larger mass spectrometers in the laboratory, the micro mass spectrometers, which are close to the size of desktop computers, won't win, Ouyang Zheng said He is a professor at Tsinghua University and founder and President of purspec technologies The company focuses on commercializing micro mass spectrometers Compared with the general mass spectrometer in the laboratory, the resolution of micro mass spectrometer will be worse, the detection limit will be more, and the quality accuracy of detection will be worse But scientists don't necessarily need a micro mass spectrometer with more performance than the general specifications, because the micro mass spectrometer is made because of the demand for rapidity and portability "If a portable device can perform on-site analysis, a new application scenario will emerge," Austin said "For example, when you need to get answers or make decisions quickly; the samples are easy to deteriorate; or the amount of samples to be tested is large and it's difficult to send them back to the laboratory So the micro mass spectrometer is a good choice " This kind of micro mass spectrometer is very suitable for detecting toxic gases in transportation system or environmental detection in the field In the miniaturized mass spectrometer, the most common mass analysis component (the instrument component for separating and classifying molecular fragments) is ion trap In the ion trap, a variety of current with different voltage and frequency should be applied to the electrode to set the electric field of ion movement The smaller the device, the higher the current frequency required to capture ions "They are already quite compact compared to other quality analysis components." Austin said One of the advantages of miniaturization is that they can operate under higher pressure than other similar equipment, so the requirements of instruments for vacuum pump system will be reduced The reduction of the huge vacuum pump provides conditions for the miniaturization of the whole machine Other types of mass spectrometer usually need to reduce the pressure inside the system to 0.001 PA or even lower through the vacuum pump, so that the ions can easily travel through the interior to reach the detector This vacuum state usually needs to be delivered by multi-stage pump In contrast, ion traps can usually operate at pressures below 0.1 PA J Michael Ramsey, a professor of chemistry at the University of North Carolina at Chapel Hill, is another pioneer in the development of micro mass spectrometer He has successfully relaxed the pressure requirements of ion trap By using the micron scale ion trap driven by high frequency current, the micro mass spectrometer can operate at 133 PA or even higher pressure He called it high pressure mass spectrometry "This saves us a lot of volume, weight and power in the vacuum system," Ramsey said Ramsey licensed his technology to Boston's 908 devices for development The company sells miniature mass spectrometers weighing about 2-4 kg (including pumps and batteries) Vacuum system is the largest component of the instrument If the demand for vacuum can be reduced, a smaller instrument can be produced But the proper vacuum affects the performance of the instrument Another area of improvement for micro mass spectrometers is their sensitivity A smaller ion trap can only maintain a smaller ion current, so the mass range that can be detected at one time is narrow, and the sensitivity may be reduced The Ramsey and 908 instruments overcome these problems by using ion trap arrays, which improve the ability to capture ions Another approach, Austin says, is to use one-dimensional extended traps, such as linear or ring traps Ramsey and 908 also used this technique to stretch the length of the ion trap Austin also makes linear ion traps on micro ceramic plates PerkinElmer is interested in Austin's technology It has sold a 17 kg suitcase University gas chromatography / micro mass spectrometry system that uses a ring-shaped ion trap called TORION T-9 Austin wants to reduce Perkin Elmer's system by two to four times His team focuses only on quality analysis components, but PerkinElmer has more engineering support to make the system as a whole smaller Mr Ouyang of purspec hopes to develop a system to make it easier for people to get answers from samples Ouyang believes that the micro mass spectrometer can be used for personalized precise drug treatment The therapeutic window of many powerful drugs is very narrow and highly dependent on human metabolism He hopes the instrument can analyze blood or urine samples in time to obtain individual pharmacokinetic and pharmacodynamic information Then the medical staff can prescribe a prescription in the right dose Ramsey and 908 also focus on applications in life sciences Ramsey said a dedicated analyzer could be used to collect information about metabolites They have tried to diagnose phenylketonuria by measuring phenylalanine in the urine Ramsey and 908 combine the micro mass spectrometer with the chip based capillary electrophoresis device and the integrated nano electro spray launcher developed in Ramsey laboratory The device is called ZipChip, which can separate samples and spray them into the mass spectrometer by electrospray At present, the commercial version of the device can use full-scale mass spectrometry, and it has been successfully combined with high-pressure mass spectrometry It can analyze analytes from amino acids to complete monoclonal antibodies "We have a positive mindset to develop a small system that can be used in life science applications with a capillary electrophoresis chip and a micro mass spectrometer," said Christopher D brown, chief technology officer, 908 In the field of life science, biologists may be potential users, because they don't know much about mass spectrometry and don't want to know the whole contents of mass spectrometry, but they want to get the answer they are looking for Ouyang said that the micro mass spectrometer needs the company's efforts to find the corresponding vertical market This market is different from traditional mass spectrometer The general mass spectrometer usually needs experienced and trained personnel to operate The micro mass spectrometer must be guaranteed to operate without professional operators.