||Ambient ionization mass spectrometry, which has witnessed a flurry of recent developments, is a set of useful techniques for the analysis of samples under open-air conditions. It allows direct, rapid, real-time, high-throughput analysis with little or no sample pretreatment for the chemicals in solids or liquids. In this study, thermal desorption electrospray ionization mass spectrometry ( TD-ESI/MS ) involving direct insertion probe ( DIP ), thermal desorption ( TD ) and electrospray ionization ( ESI ) was used for the rapid screening of various types of samples. The source mainly consists of the sampling probe device, thermal desorption heating device, electrospray ionization device, ion source and temperature controller. A novel strategy involved in TD-ESI/MS processes where sampling, desorption, and ionization are separated as three independent events. The sampling probe is first used for the sampling of analytes and then inserted into a heat unit for thermal desorption. The desorbed analytes are finally carried into a reaction region with a stream of nitrogen gas, where charged methanol droplets were generated continuously by electrospray for post-ionization. Total analysis time is less than 10 seconds.|
Traditionally, three standard methods are used for the analysis for pesticide residues, biochemical, immunoassay and instrument. And, the instrument analysis is the most widely used because it provides lots of advantages in particularly accurate quantitative approach. However, its complicated steps take a long period of time for preparation. Here, we used TD-ESI/MS to rapidly screen the pesticide residues on the surface of fruits and vegetables. The MS/MS analysis was also performed to confirm those detected compounds. The experimental results of the standard deviation for reproducibility is 13.2% (n = 10), and the detection limit is approximately 10 ppb. Furthermore, several fruits and vegetables purchased from local market were used as test samples and pesticide residues on the surface of samples can be successfully detected via TD-ESI/MS. In addition, the TD-ESI/MS technique was also applied to the analysis of illegal additives or phthalates in food. In this study, the TD-ESI/MS technique emerges lots of advantages such as direct, rapid, real-time analysis of sample surface and sample pretreatment is not necessary, and shows highly potential for rapid screening of chemicals in food safety.