ABSTRACT
An electrospray/ultraviolet lamp dual-source ion trap mass spectrometer was developed for the rapid detection of gas and liquid samples.The instrument used the discontinuous atmospheric pressure sampling technique that both the electrospray ions and gaseous analytes were sampled and transferred using a pinch valve device.The two ionization sources were generally suitable for different kinds of analytes and provided complementary applications.Electrospray was used for the ionization of polar compounds in solution, while the UV ionization source was mainly applied for the analysis of gaseous organic compounds.A variety of samples such as anisole, toluene, 2,4-dimethylaniline, arginine, reserpine and aspartame were employed to test the performance in different working mode of the instrument.The results showed that the two sources were feasible for ionization of different types of samples, and different types of molecular ions could be generated when 2,4-dimethylaniline was analyzed.The two ionization sources could be used alternately or simultaneously without interference, and the working mode was also switched to fit the application requirements.The dual-source configuration was an effective way to extend the applications for miniature mass spectrometers.It did not significantly increase the size of the instrument, but provided more versatile analysis to meet the need for the measurement of different types of samples.
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.