Thermal dissociation atmospheric chemical ionization ion trap mass spectrometry with a miniature source for selective trace detection of dimethoate in fruit juices

Abstract

A miniature thermal dissociation atmospheric chemical ionization (TDCI) source, coupled with LTQ-MS, has been developed for rapid trace detection of pesticide residues such as dimethoate in highly viscous fruit juice samples. Instead of toxic organic solvents and the high electric field used in the conventional ionizations, an ionic liquid, a "green solvent", was employed to directly generate reagent ions in the TDCI process, followed by the proton or charge transfer with the analytes prior to the LTQ instrument for mass analysis. Trace amounts of dimethoate in fresh orange juices have been quantitatively detected, without any sample pretreatment or aid of high-pressure gas. A low limit of detection (LOD = 8.76 × 10(-11) g mL(-1)), acceptable relative standard deviation (RSD = 3.1-10.0%), and reasonable recoveries (91.2-102.8%) were achieved with this method for direct detection of dimethoate in highly viscous orange juice samples. The average analysis time for each single sample was less than 30 seconds. These experimental results showed that the miniature TDCI developed here is a powerful tool for the fast trace detection of pesticide residues in complex viscous fruit juices, with the advantage of high sensitivity, high speed, and high-throughput, ease of operation, and so on. Because of no chemical contamination and high voltage damage to the analytes and the environment, the technique has promising applications for online quality monitoring in the area of food safety.

Ionic Liquids in Analytical Chemistry: Fundamentals, Advances, and Perspectives

“…224,225 The [C 4 MIM][Br] IL was applied as a solvent for the detection of dimethoate in fruit juices by thermal dissociation atmospheric chemical ionization ion trap mass spectrometry. 226 The [C 4 MIM][BF 4 ] IL was also employed as a matrix in the analysis of pharmaceuticals and pesticides by matrix-assisted corona beam ionization. 227 This allowed for the successful and reproducible quantitation of pharmaceuticals and pesticides in synthetic samples.…”

The Study of Titanium and Zirconium Ions in Water by MPT-LTQ Mass Spectrometry in Negative Mode

“…Based on the standard formula LOD = 3cσ/S [ 34 ], where c is the concentration of titanium or zirconium in the aqueous sample, σ is the standard deviation of all the measurements performed on the blank sample, and S is the mean value of the signals repeatedly measured, the calculated limit of detection (LOD) values for titanium and zirconium are 10 μg/L for titanium and 20 μg/L for zirconium, respectively. These quantitative data are summarized in Table 1 .…”

A Novel Integrated APCI and MPT Ionization Technique as Online Sensor for Trace Pesticides Detection

“…However, chromatography-mass spectrometry techniques are time-consuming, and the pretreatment process is laborious. In recent years, with the development of ambient MS, various atmospheric pressure ionization sources have been used for pesticide testing, including desorption electrospray ionization (DESI) [12][13][14], extractive electrospray ionization (EESI) [15,16], paper spray ionization (PSI) [17][18][19][20], probe electrospray ionization [21], and atmospheric plasma ionization sources, such as direct analysis on real time (DART) [22][23][24][25], atmospheric pressure chemical ionization (APCI) [26,27], and dielectric barrier discharge ionization (DBDI) [28][29][30][31]. These ion sources avoid complex pretreatment and chromatographic separation steps and offer multiple advantages.…”