ABSTRACT
OBJECTIVE@#To compare the performance of the GE cyclotron MINItrace system before and after the upgrade.@*METHODS@#The upgrade of the MINItrace system included replacing the silver target with the Nb syetem and adopting the latest RF control and management system and lastest ion source system.The failrue rate and production efficiency were retrospectively analyzed before and after the upgrade.@*RESULTS@#After the upgrade, the cyclotron failure rate decreased by 86.2%, the average capacity increased by 45%.@*CONCLUSIONS@#After the upgrade of MINItrace cyclotron, the failure rate is sharply reduced, and the production efficiency is grately improved.
Subject(s)
Cyclotrons/standards , Equipment Failure , Retrospective StudiesABSTRACT
Dielectric barrier discharge ion source-mass spectrometry ( DBDI-MS) can achieve in-situ and efficient detection of samples without tedious pretreatment, and has become a popular analytical method. To improve the detection sensitivity, a novel mass spectrometric method based on gold nanoparticles ( AuNPs)-assisted paper-based injection mode and DBDI-MS technology was developed for the fast determination of four veterinary drugs. The detection signal strength was improved by 8-31 times compared to the veterinary drugs which were tested without AuNPs-assisted paper based injection. Under the optimal conditions, the experimental data of four veterinary drugs showed a good linear relationship between the signal and the concentration in the respective range, with correlation coefficient ( r ) of 0. 951-0. 996. Moreover, the recoveries were between 79. 4% and 96. 5% at three spiked levels. This method has many distinct advantages, such as low detected limitation, low cost and high efficiency, and is also very suitable for fast on-site detecting, showing great potential in feed quality control.
ABSTRACT
Based on the electric field shielding and insulation technology, the single electrode dielectric barrier discharge ion source ( DBDI ) has the characteristics of uniform discharging, stability, and high ionization energy, and thus can be used to detect various samples with a large range of polarity. However, the ionization energy is too high to reduce the background signal noise, and thus affects the detection effectiveness to low polarity and low boiling point samples. To enhance the detection effectiveness to these samples, a method of eliminating electrons of single electrode DBDI by using external metal electrodes was developed in this study. Then, the single electrode DBDI was improved by an external needle electrode and an external metal net, respectively. The mechanism of those external metal electrodes was discussed, and the experimental studies were carried out. The results showed that the external metal net technology had an advantage in improving signal to noise ratio ( SNR ) , and the enhancement of SNR for the detection of isoprocarb, perfluorooctanoic acid and SudanⅢwas about 5-6 times. Based on the technology, a method for determination of Sudan Ⅲ in chili powder was developed. The recoveries, RSD and LOD were 83. 7%-94. 6% , 5. 6%-9. 0% and 23 mg/kg, respectively. The external metal electrode technique has broadened the detection range of single electrode DBDI to the field of low polarity, low boiling point and complex samples.
ABSTRACT
Currently, rapid detection of effective components in synthetic drugs and herbal medicine remains an important and difficult issue of medicine research. A novel ionization technique, called dielectric barrier discharge ionization ( DBDI ) , has strong ionization ability, and is suitable for weak polar substances. Besides, this technique possesses many intrinsic advantages, such as simplicity, rapidity, no complicated sample pretreatment, etc. In this study, a new DBDI ion source, based on single electrode technique, was used to detect four weak polar synthetic drugs. The results showed that the protonated molecular ions [ M+H]+of four weak polar synthetic drugs were observed obviously. What′s more, the DBDI ion source was also used for the rapid analysis of Radix Aconiti and Radix Aconiti Preparata pieces without any sample pretreatment. The result showed that the protonated molecular ions [M+H]+ and fragment ions [M+H-60]+of aconitine, hypaconitine, and mesaconitine were detected in Radix Aconiti. And only the fragment ions [M+H-60]+were detected in Radix Aconiti Preparat. The researches indicated that diester aconitine and monoester aconitine were the main effective components of Radix Aconiti Radix and Aconiti Preparat, respectively. The new DBDI ion source provided a fast and reliable method to identify effective components of medicine, showing a broad application prospects in synthetic drugs and herbal medicine research.
ABSTRACT
Currently, rapid detection of effective components in synthetic drugs and herbal medicine remains an important and difficult issue of medicine research. A novel ionization technique, called dielectric barrier discharge ionization ( DBDI ) , has strong ionization ability, and is suitable for weak polar substances. Besides, this technique possesses many intrinsic advantages, such as simplicity, rapidity, no complicated sample pretreatment, etc. In this study, a new DBDI ion source, based on single electrode technique, was used to detect four weak polar synthetic drugs. The results showed that the protonated molecular ions [ M+H]+of four weak polar synthetic drugs were observed obviously. What′s more, the DBDI ion source was also used for the rapid analysis of Radix Aconiti and Radix Aconiti Preparata pieces without any sample pretreatment. The result showed that the protonated molecular ions [M+H]+ and fragment ions [M+H-60]+of aconitine, hypaconitine, and mesaconitine were detected in Radix Aconiti. And only the fragment ions [M+H-60]+were detected in Radix Aconiti Preparat. The researches indicated that diester aconitine and monoester aconitine were the main effective components of Radix Aconiti Radix and Aconiti Preparat, respectively. The new DBDI ion source provided a fast and reliable method to identify effective components of medicine, showing a broad application prospects in synthetic drugs and herbal medicine research.
ABSTRACT
A thermal desorption low temperature plasma (TD-LTP) ionization was developed for rapid and sensitive detection of pesticides by direct mass spectrometry.The thermal desorption sampler was added in fount of the plasma generator.The sample was desorbed in the thermal desorption sampler firstly,and then the gas molecules were transported to the plasma generator by the carrier gas to be ionized.The utilization of thermal desorption sampler helps to shift the interaction of the gas phase plasma with the sample form gas-solid or gas-liquid to gas-gas,which increases the sensitivity and stability especially for non-volatile sample (e.g.pesticides) greatly compared with the traditional LTP ionization source.Under the optimal parameters of the thermal desorption LTP ionization source,the characteristic ions of 12 kinds of pesticides were investigated.Then the thermal desorption LTP ionization source was connected with the commercial ACQUITY TQD mass spectrometer to evaluate the pesticide residue level in broomcorn.