[Simultaneous determination of nine preservatives in fruits using gas chromatography-mass spectrometry].

A gas chromatography-mass spectrometry (GC-MS) method was established for the simultaneous determination of nine typical preservatives (pyrimethanil, chlorothalonil, chlorpyrifos, triadimefon, thiabendazole, imazalil, myclobutanil, iprodione, prochloraz) in fruits. The fruit samples were subjected to ultrasonic extraction with hexane/ethyl acetate (1/1, v/v), and followed by purification using diatomite column chromatography with hexane/ethyl acetate (1/3, v/v) eluant. Qualitative and quantitative analysis of the nine preservatives were performed on the GC-MS at full-scan (SCAN) and selected ion monitoring (SIM) modes, in which triphenylphosphate was used as the internal standard. The detection limits obtained for the nine preservatives were ranged from 0.10 microg/kg to 2.16 microg/kg. The average recoveries were in the range of 75.3% to 128% at the spiked levels of 50, 100 and 200 microg/kg with the relative standard deviations (RSDs) of 1.57% to 11.6% (n = 5). The results showed that the developed method is sensitive and accurate for the determination of the nine preservatives in fruits.

[Determination of 29 pesticide residues in tobacco by gas chromatography-electron impact ionization mass spectrometry].

A method was developed for rapid determination of 29 pesticide residues in tobacco based on gas chromatography coupled with electron impact ionization mass spectrometric detection (GC-EI/MS). After the optimization of different parameters, such as the extraction solvent, elution solvent, purificant, pesticides were extracted from tobacco with hexaneacetone (1: 1, v/v) in an ultrasonic bath, cleaned-up on a column, packed with Florisil and neutral alumina, eluted with dichloromethane-hexane (95:5, v/v), and then determined by GC-EI/MS in the selected ion monitoring mode (SIM) with triphenyl phosphate (TPP) as internal standard. The recoveries were performed at 20, 50 and 100 microg/kg fortification levels for each pesticide, and the recoveries ranged from 70% to 110% with the relative standard deviations between 2% and 8%. The detection limits were less than 0.8 microg/kg for 26 pesticides except for the fenpropathrin, deltamethrin and permethrin. The method was linear over the range of 5.0-500.0 microg/kg with the correlation coefficients between 0.9994 to 0.9999. The method was successfully applied to the analysis of these pesticides in tobacco.

[Simultaneous determination of 14 phthalate ester residues in animal innards by gas chromatography-mass spectrometry with electron impact ionization].

An analytical multiresidue method was developed for the simultaneous determination of 14 phthalate esters (PAEs) in animal innards by gas chromatography-mass spectrometry with electron impact ionization (GC-EI/MS). After the optimization of different parameters such as the extraction solvent, PAEs were extracted from animal innards with hexane-dichloromethane (1:1, v/v) in an ultrasonic bath and cleaned up on a Florisil column, then were determined by GC-EI/MS in selected ion monitoring mode with diphenyl phthalate (DPhP) as internal standard. The recovery studies were performed at 100, 200 and 400 microg/kg levels for each PAE, and the recoveries ranged from 60% - 110% with the relative standard deviations between 0.8% and 10.3% for different PAEs. The detection limit of the method was less than 1.74 microg/kg for most of PAEs except dimethoxyethyl phthalate (DMEP) and di(2-ethoxyethyl) phthalate (DEEP). The method was linear over the range of 50.0 - 800.0 microg/kg with the correlation coefficients larger than 0.999 4. The method has been successfully, applied to the determination of 14 PAEs in six animal innards.

[Determination of five polybrominated diphenyl ether residues in deep-sea fish oil using gas chromatography-negative chemical ionization/mass spectrometry].

Polybrominated diphenyl ethers (PBDEs) are a kind of brominated flame retardants (BFRs), which refer to compounds used in some plastics to impede or even suppress the combustion process. As the emission or disposal of plastics, PBDE residues have been found in both environment and biota. In this work, an analytical method was developed for the simultaneous determination of 5 PBDE residues in deep-sea fish oil. PBDEs were extracted from deepsea fish oil with n-hexane, cleaned up on a silical gel column, and determined by using gas chromatography-negative chemical ionization/mass spectrometry (GC-NCI/MS) in the selected ion-monitoring (SIM) mode, with PCB103 as the internal standard. Meanwhile, the characteristic ion and fragmentation mechanism of some PBDEs in NCI/MS were evaluated. Recovery studies were performed at 20. 0 and 100.0 g/kg fortification levels for each PBDE, and the recoveries ranged from 88. 6% to 111. 3% with relative standard deviations between 3. 8% and 13.5% for different PBDEs. The limits of detection (LOD) were from 0.77 to 1. 34 1g/kg for different PBDEs. The developed method was linear over the range assayed, 1. 0 - 500. 0 g/kg, with correlation coefficients larger than 0. 999 2. The developed method has also been successfully applied to the determination of PBDEs in several deep-sea fish oil samples and the three most abundant PBDEs (PBDE-47, PBDE-99 and PBDE-100) were found.

[Determination of multiple pesticide residues in honey using gas chromatography-mass spectrometry].

An analytical method was developed for the simultaneous determination of 23 pesticide residues in various commercial honeys. Meanwhile, the characteristic ions and fragmentation mechanism of three pesticides in the process of electron ionization mass spectrometry (EI/MS) were evaluated. After the optimization of different parameters such as the extraction solvent, pesticides were extracted from honey with ethyl acetate in an ultrasonic bath, cleaned up on a Florisil column by an elution of mixture of hexane and ethyl acetate (7:3, v/v), and analyzed by gas chromatography-electron ionization mass spectrometry (GC-EI/MS) in the selected ion monitoring mode (SIM) with PCB103 as internal standard. Recovery studies were performed at 50, 100 and 200 microg/kg fortification levels for each pesticide, and the recoveries ranged from 82% to 120% with relative st0ndard deviations between 1.8% and 11.0% for different pesticides. The limit of detection was less than 10.0 microg/kg for all the pesticides. The developed method was linear in the range of 10-500 microg/kg, with correlation coefficients larger than 0.995. Finally, the developed analytical method has been successfully applied to the determination of pesticide residues in several honey samples.

[Multiresidue determination of organophosphorus pesticide residues in vegetables and fruit by gas chromatography-negative ion chemical ionization-mass spectrometry].

An analytical method of gas chromatography coupled with negative ion chemical ionization-mass spectrometry for simultaneous determination of nine organophosphorus pesticide residues in vegetables and fruit has been developed, and the negative ions structure and partition mechanism of the nine organophosphorus pesticides were interpreted. Meanwhile, the matrix effect for sample analysis was discussed, and matrix-matched calibration for quantification was introduced to reduce the matrix effect in this method. Pesticides were extracted from sample with ethyl acetate in an ultrasonic bath, then determined by gas chromatography-mass spectrometry operated in negative chemical ionization mode and quantified in selective ion monitoring mode, and ethion was used as an internal standard. The detection limits of the method were 0.12-1.0 microg/kg for the nine organophosphorus pesticides, and the relative coefficients were higher than 0.9993. A blank sample (tomato) was spiked at 100, 400, 800 microg/kg for each pesticide, and the recoveries were determined to be from 78% to 126% with relative standard deviations from 0.58% to 14.7% for the pesticides.