ABSTRACT
An atmospheric pressure chemical ionization mass spectrometry (APCI-MS) method was developed for the direct analysis of triglycerides in edible oils.The edible oil sample was dissolved in acetonitrile.Under the optimal conditions such as positive ion detection,800 μL/h of sample flow rate,250℃ of vaporizer temperature and 5000 nA of corona needle current,the repeatability (RSD) of peak intensity rate of m/z 857.76 to m/z 881.76 was less than 5％.Then,different kinds of oil from different manufacturers were analyzed by the proposed method.After a principal component analysis for the analytical results,the peak intensity rate of m/z 857.76 and m/z 881.76 was selected for oil identification.The adulteration of 5％ lard in corn oil could be recognized directly using the peak intensity rate.Three characteristic triglycerides in edible oil were preliminarily identified by collision induced dissociation (CID) experiments.The method was applied to analyze the swill oil and fried oil samples,and the results showed that the swill oil contained both vegetable oil and animal fat,and the fried oil was also different with commercial vegetable oil.
ABSTRACT
The paper presents a flexible and simple direct analysis in real-time ( DART) device without grid electrode for mass spectrometer injection. It contained inert carrier gas, ionizer, heater and temperature-controller etc. Excluding the grid electrode and then reducing the structure units, the device could be easy to build up in low cost and flexible to connect with a variety of mass spectrometers. The experimental conditions like the kind of carrier gas, flow rate and temperature were investigated for the device. By using argon as carrier gas, flow rate as 7. 5 L/min, and temperature of heat tape as 300 ℃, the device was used to analyze benzene alcohol, linoleic acid, dichlorvos emulsion, mosquito coils, citrus peel, and sample ( propranolol hydrochloride) on thin-layer plate combined with mass spectrometer. The results were accurate and the device was stable and reliable.