Determination and identification of pesticides from liquid matrices using ion mobility spectrometry

Abstract

A flow-through type ion mobility spectrometry (IMS) model MGD-1 has been used to detect different pesticide compounds from liquid matrices. This gas detection technique depends on ion mobility which is dependent to the molecular weight, charge and shape. With IMS technique, it is possible to measure mobility distribution changes of positive and negative ion clusters simultaneously in six different electrodes. Each measuring electrode detects a different portion of the ion mobility distribution formed within the cell’s radioactive source, and each measuring electrode represents one measuring channel. Unlike in our previous studies, the neural network method was also used to visualize and facilitate construction of the present results. Based on these results, the IMS model MGD-1 with the advanced signal pattern recognition method (ASPRM) or neural network method can be used to measure semi-volatile pesticides even if they are present in liquid samples. Especially, the results can be rapidly handling with the neural network method. On the basis of projection calculation, the profiles for 2-propanol and pesticides can be easily separated from each other. The strongest responses for all these pesticides were seen in the second positive channel, whereas only minor background signals were measured in the first and second positive channels. The detection limits/total injected amounts for different pesticides decreased in the order: sulfotep (6.4 μg/ml; 64 ng), propoxur (20.9 μg/ml; 209 ng) and nicotine (32.4 μg/ml; 324 ng). As a summary, the main advantages of the IMS detection method are its fast response and easy interpretation of the results. Moreover, the cell can detect high chemical concentrations after which the cell recover within some minutes. The rising and recovering times of the signal is immediate because the cell size is small and there is no membranes in the air input.