Simultaneous determination of pesticide multiresidues in white wine and rosé wine by SDME/GC-MS

Highlights

• It is a fast robust comprehensive and efficient method for the determination of pesticide residues in white and rosé wine samples.

• Tests showed that the extraction by SDME was comprehensive for use in aqueous or alcoholic matrix (alcohol content up to 15%).

• This methodology presents high sensitivity for detecting and quantifying eleven pesticides up to 65 μg L^− 1 in the samples.

Abstract

Pesticides have been applied in vineyards around the world in order to protect grapevines against different diseases. However, the indiscriminate use of these substances has aroused great concern regarding the health and safety of consumers due to toxicological risks that pesticides may present to human health. Thus, this study aims to determine simultaneously eighteen pesticide residues from different chemical classes in real white wine and rosé wine samples using single-drop microextraction (SDME), followed by gas chromatography coupled to mass spectrometry (GC-MS). The step of SDME was optimized, and it was found that the best experimental conditions were as follows: toluene, 30 min extraction, 1.0 μL drop volume, solution volume 10 mL, stirring speed 200 rpm, with acidification of the medium with HCl and without the addition of salt. The proposed extraction method was efficient for the extraction of pesticides, both from aqueous solutions and from alcoholic solutions, with an ethanol concentration of up to 15%. The method was applied to real white wine and rosé wine samples, and 11 pesticide residues were detected (carbofuran, molinate, diazinon, disulfoton, malathion, endosulfan, ethion, bifenthrin, permethrin I, permethrin II and azoxystrobin) with concentrations, which ranged from not detected to 65.3 μg L^− 1.

Introduction

Pesticides have been applied in vineyards around the world in order to protect grapevines from diseases caused by insects, fungi and other agents [1]. In this context, wineries have become increasingly dependent on synthetic chemicals, such as pesticides, to gain competitive advantage on the market. Although there are natural products and alternative techniques to the use of pesticides, many producers have chosen the use of these substances in grape crops, due to lower cost, time and ease of application [2].

The indiscriminate use of pesticides in agriculture has aroused great concern about the health and safety of consumers. During the process of wine production, pesticide residues in grapes can pass into the must and, therefore, into the drink, which can be a toxicological risk to the consumer [3].

Pesticides from different chemical classes have been used extensively in the treatment of diseases in grapes used for winemaking, such as azoxystrobin, carbendazim, cymoxanil, cyprodinil, dichlofluanid, fenhexamid, folpet, fludioxonil, metalaxyl, thiophanate methyl, penconazole, pyrimethanil, procymidone, vinclozolin, mepanipyrim, fluazinam and chlorpyrifos [4].

The winemaking process involves different steps that modify and reduce the concentration of pesticides in wine, although there is no total elimination of residues of these substances during the production of the drink. Thus, although the levels of pesticides are significantly lower in wines than in grapes, the concern about the possible presence of residues of these substances in the final product is extremely important [3], [5]. The knowledge of pesticide concentrations in wine allows to evaluate the risks of human exposure through the ingestion of the drink, as well as the dissipation rates during winemaking [6].

Several analytical methods have been proposed for the simultaneous determination of pesticide multiresidues in aqueous matrices. The development of these methods is often difficult since the compounds have different degrees of polarity, solubility and volatility, as well as different partition coefficients octanol/water, making their extraction and analysis difficult [7]. Hence, the routine methods for the determination of pesticide residues in the environment and in food usually require many steps of sample preparation before the instrumental analysis, such as extraction, clean-up and concentration [8].

In the analysis of pesticides in wine samples, both the complexity of the matrix, and the nature of the pesticide should be taken into account. The techniques of liquid or gas chromatography using different types of detectors have been used for the determination of these substances in food. In terms of selectivity and sensitivity, mass spectrometry, coupled to the chromatographic techniques mentioned above, has been used as one of the most efficient detection tools in the analysis of pesticides in food [1], [9].

Several studies have focused on the development of analytical methods which are economical, miniaturized and with low impact on the environment for the preparation of samples. In this context, the single-drop microextraction (SDME) has emerged as a sample preparation procedure which is simple, fast, cheap and virtually free of solvents. This technique is based on the distribution of analytes between the microdrop of organic solvent, on the tip of a microsyringe needle, and the aqueous phase (sample). The microdrop is exposed to an aqueous sample in which the analyte is extracted into the droplet. After the extraction, the microdrop is retracted into the microsyringe and injected into instruments for liquid or gas chromatography for analysis [8], [10]. This technique has been successfully used in the determination of different classes of substances, such as phenolic compounds [11], sulfur compounds [12], metals [13], [14] and amines [15], as well as for the extraction of pesticides [8], [16], [17], [18], [19] in different matrices.

Given the above, this study aims to determine eighteen pesticide residues from different chemical classes in real white wine and rosé wine samples using single-drop microextraction (SDME), followed by gas chromatography coupled to mass spectrometry (GC-MS).