Elsevier

Analytica Chimica Acta

Volume 429, Issue 2, 23 February 2001, Pages 257-268
Analytica Chimica Acta

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

https://doi.org/10.1016/S0003-2670(00)01290-3Get rights and content

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.

Introduction

Unlike in mass spectrometry, ions can be measured by an aspiration type ion mobility spectrometry (IMS) at normal atmospheric temperature and pressure. This technique is based on ion mobility which is dependent to the molecular weight, charge and shape [1]. Naturally, the mobility of ions increases with decreasing molecular weight and increasing charge. Using the IMS model MGD-1 vapor analyzer, it is possible to analyze volatile or semi-volatile organic compounds that have a high proton affinity or electronegativity in the gas phase [2], [3]. Such compounds are e.g. aldehydes, ketones, halogens, halogenated hydrocarbons, cyanides, nitrogen compounds, ammonia, and some polyaromatic compounds [1], [4], [5]. In addition, organophosphorus (OP) compounds generally form protonated molecules, and the compounds that contain electronegative functional groups, such as halogen atoms or nitrogen groups produce more negative ions than normally in traditional IMS [5], [6].

The first multichannel IMS was developed for on-line gas detection of chemical warfare agents in 1992 [7], [9]. With this technique, it is possible to detect chemical warfare nerve agents such as sarin, soman, tabun and VX [1], [7], [9], [10], but also OP and carbamate pesticides [8]. This technique has also been used as a civil application for on-line monitoring of ethanol concentration from beer and yeast fermentation processes [11]. However, the IMS cannot be used for detecting those compounds that are difficult to ionize and produce product ions (e.g. hydrocarbons, heavy metals).

Pesticide intoxications are very widely occurred in agriculture, especially in the developing countries. Acute pesticide poisonings are known to be a major public health problem, for example, in Sri Lanka [12]. On a world-wide scale, there are approximately 3,000,000 and 100,000 cases of acute pesticide and OP intoxications, respectively, and approximately 220,000 deaths per year [13], [14]. For this reason, rapid, simple and sensitive field methods are required to check the presence of these compounds. Traditional methods such as gas chromatography (GC), high-performance liquid chromatography (HPLC) and GC coupled with mass spectrometry (GC-MS) are the best available methods. However, these methods are known to be expensive and quite laborious. In this paper, we describe the use of an aspiration type IMS for the detection of pesticides such as sulfotep, propoxur and nicotine from a liquid matrix.

Section snippets

Instrumentation

A ceramic evaporator was used to vaporize pesticide solutions. IMS model MGD-1 (Environics Oy, Kuopio, Finland) contains two different sensors: an open type ionization cell (ImCell™) and a commercial semiconductor cell (SCCell). The ImCell™ which has no membranes was used in this study. The detection system was composed of a commercially available MGD-1 and a personal computer. More information about the IMS model MGD-1 can be found from http://www.environics.fi. The MGD-1 was equipped with a

Results and discussion

In this study, the responses from 2-propanol background differed clearly from the responses of pesticides. Table 1 shows the detection limits of the IMS for used pesticide compounds. On the basis of projections, the sensitivities of detection for different insecticide compounds decreased in the order: sulfotep (6.4 μg/ml), propoxur (20.9 μg/ml) and nicotine (32.4 μg/ml).

Typical responses of different detector channels of MGD-1 for 2-propanol and two concentrations of sulfotep are presented in Fig.

Conclusions

Based on these results, it was concluded that the IMS model MGD-1 with ASPRM and neural network methods can be used to detect and identify some of the semi-volatile insecticide compounds even if they are present in liquid samples. The instrumentation required is simple and inexpensive and the analysis time is rapid compared to other traditional detection techniques, and due to that this technique would seem to make it potentially valuable for the analysis of pesticides even at residue levels.

References (20)

  • Z. Karpas et al.

    Anal. Chim. Acta

    (1992)
  • K. Tuovinen et al.

    Anal. Chim. Acta

    (2000)
  • T. Kotiaho et al.

    Anal. Chim. Acta

    (1995)
  • W. Van der Hoek et al.

    Soc. Sci. Med.

    (1998)
  • P. Törönen et al.

    FEBS Lett.

    (1999)
  • G.A. Eiceman, Z. Karpas, Ion Mobility Spectrometry, CRC Press, Boca Raton, FL, 1994, p....
  • H.H. Hill et al.

    Anal. Chem.

    (1990)
  • G.A. Eiceman

    Crit. Rev., Anal. Chem.

    (1991)
  • W. McGann et al.

    SPIE

    (1994)
  • H. Paakkanen et al.

    Finnish Air Pollut. Prevention News

    (1994)
There are more references available in the full text version of this article.

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