ABSTRACT
A new approach based on online coupled liquid chromatography-gas chromatography-mass spectrometry ( LC-GC / MS ) was developed for the rapid determination of 4-( methylnitrosamino )-1-( 3-pyridyl)-1-butanone (NNK) in mainstream cigarette smoke, in which a switching valve was employed to online switching between two-dimensional chromatography. The online LC-GC / MS system used in this study was built by using online gel permeation chromatography-gas chromatography-mass spectrometry except that the micro gel column was replaced by micro alkaline alumina column which was prepared by ourselves before. The NNK in mainstream cigarette smoke was collected by a Cambridge filter pad, then the pad was extracted with dichloromethane, and the extract was quantitatively analyzed by online LC-GC / MS with D4-NNK as an internal standard. Online LC-GC / MS allowed online pretreatment purification, and the sample was subjected to online LC-GC / MS without any prior purification, which reduced human error in analysis process. The injection volume of the present online LC-GC / MS could reach 40 μL, which was 20 times of that of the conventional GC / MS (2. 0 μL of injection volume), and thus significantly improved the sensitivity. Under the optimum conditions, good linearity ( r = 0. 9998) was obtained over the range of 1. 2 - 120 ng / mL. The recoveries at three spiked levels ranged from 93. 9% to 96. 0% , and the limits of detection for qualitative and quantitative detection were 0. 25 ng / mL and 0. 9 ng / mL, respectively. All the results obtained by the present method are comparable to those of standard method recommend by China National Tobacco Company.
ABSTRACT
The migration of two potential contaminants, formaldehyde and acetaldehyde, from two paper materials into food simulant Tenax was studied. A rapid and simple one-step extraction-derivatization method combined with ultra high performance liquid chromatography was established for the determination of formaldehyde and acetaldehyde in paper packaging materials and food stimulants. The linear correlation coefficients (R2) were greater than 0. 9999 in the range of 0. 14-35. 7 mg/m2 for both formaldehyde and 0. 20-49. 1 mg/m2 for acetaldehyde, with detection limits of 0. 03 mg/m2 for formaldehyde and 0. 04 mg/m2 for acetaldehyde. The recoveries were 90. 1%-108. 6% for paper sample and Tenax. The migration behaviors of formaldehyde and acetaldehyde at different temperatures and migration times were investigated. Both for formaldehyde and acetaldehyde, the amount of migration gradually increased with time first, then decreased, finally reached a steady value. The migration rates of formaldehyde and acetaldehyde were differently influenced by temperature. After reaching a steady value, the maximum migration rate for formaldehyde was at 30℃, and for acetaldehyde was at 70℃ and 50℃. The migration rates of formaldehyde and acetaldehyde greatly varied, and the migration rate of acetaldehyde was far more than the migration rate of formaldehyde when reaching a steady value.