Determination of Pesticides Residues in Eggplant and Tomatoes from Central Marked in Khartoum State Using Quechers Method and Gas Liquid Chromatography-Mass Spectrometry

Determination of Pesticides Residues in Eggplant and Tomatoes from Central Marked in Khar toum State Using Quechers Method and Gas Liquid Chromatography-Mass Spectrometry. Biomed Abstract Pesticides are widely used in food production to increase food security, but they can have negative health effects on consumers. Both raw and processed vegetables have been found to be contaminated with pesticide residues. Consumers can be exposure to pesticides via food consumption. In this paper, we present the investigation of 30 pes ticides in total of 90 samples of tomatoes and 27 samples of eggplant from central markets in Khartoum state using the quick easy cheap effective rugged and safe (QuEChERS) multi-residue extraction, followed by gas chromatography-mass spectrometry (GC-MS). Pesticide residues were not detected in 9 samples (8%), while 108 samples (92%) contained detectable amount of pesticide residues. The percentage of contaminated vegetable samples was high for both tomatoes (91.2%) and eggplant (96.3%). Multiple pesticides residues were detected on 65samples with percentage of (55.6%) from total analyzed samples. Multiple residues with four pesticides were present in two samples of tomatoes. Sixteen pesticides chloropyrifos, diazinon, cypermethrin, deltamethrin, omethoate, lamdacyhalothrin, dimethoate, fenvlarate, fenpropathrin, pendimethalin, endosulfan, imidacloprid, carbaryl, permethrin, malathion and profenofos were detected in the analyzed vegetable samples with concentration range between 0.008-1.882 mg/kg and mean range between 0.0225- 0.8631mg/kg. Summer and autumn were the most seasons contaminated with pesticides residues. It is concluded that the continu ous monitoring and strict regulation of pesticide use on food crops, especially vegeta -bles, are necessary.

applied directly to the soil or sprayed over crop fields and hence are release directly to the environment. However, the continued use of pesticides specially insecticides increases the possibility of residues to be found in some vegetables, threatening the alimentary security.
Pesticide residue refers to the pesticides that may remain on or in food after they are applied to food crops [3]. Pesticide residues in agriculture have been a crucial worldwide problem that directly threatened the environment and people's health. Over 1000 compounds may be applied to agricultural crops in order to control undesirable moulds, insects or weeds to ensure the safety of food for consumers, numerous legislations such as codex directives and European Commission have established Maximum Residue Limits (MRLs) for pesticides in foodstuffs [4,5].
The determination of pesticide residues in agricultural products, plant and environmental samples has been a major subject for many years because of their toxic potential risk for human health, persistence and tendency to bioaccumulate. For many years, analysis of fruit and vegetable samples for organophosphorus, organochlorine, and pyrethroids pesticides at low levels were by gas chromatography (GC) using selective detectors: flame photometric, nitrogen phosphorus, and electron capture detectors (FPD, NPD, and ECD). Although these detectors are sufficiently sensitive for compliance with maximum residues limits (MRLs) in European Union regulations, they provide poor specificity for confirmation in these matrixes; therefore, GC coupled with mass spectrometry (MS) was required [6,7]. Many investigations studies form many areas were reported that different type of pesticides left residual amounts in fruit and vegetables with residues levels in rang of mg/kg [8][9][10], also many methods and studies have reported the use of GC/MS and LC/MS with either full scan or selected ion monitoring (SIM) to control pesticide residues in matrixes such as fruit, vegetables, milk, and soils [11,12]. During the last years, the Quick, Easy, Effective, Cheap, Rugged, and Safe (QuEChERS) approach, has become very popular for the determination of pesticides on diverse food matrices include fruits and vegetables, this method has been readily accepted by many pesticide residue analysts because of its low organic solvent consumption, low cost per sample, fast, the accurate procedures non time consuming, and have high analyte recoveries [13,14]. Vegetables are commonly used to fulfill the balance diet requirement as they are a vital source of vitamins and fiber, tomato (Lycopersicon esculentum) and eggplant (Solanum melongena) are from the most popular and widely grown vegetables in the world, tomato and eggplant crops are much susceptible to insect attack and disease infestation from seedling to fruiting stage. Eggplant helps to prevent colon cancer, reduces cholesterol level, helps in the type 2 diabetes management, is very rich in antioxidant, and helps to control weight [15,16].

Study Area and Time
The tomatoes and eggplants samples were collected from

Sample Collection and Treatment
A total of 117 vegetables samples were collected for pesticide residue analysis. The vegetable samples included 90 samples of tomatoes and 27 samples of eggplants. The sampling was performed in accordance with the general principles and methods of the European Commission (EC) directive 2002/63/EC [17]. Each representative vegetable sample was a composite of 6 to10 subsamples of the same commodity collected through random sampling. All the samples (1-2 kg each) were placed in polythene bags, in box contain ice, to avoid contamination and deterioration, labeled, and transported to the laboratory and stored at −20˚C until analysis.

Chemicals and Reagents
Pesticide reference standards including malathion, diazinon,

Sample Extraction and Cleanup Procedure
Ten grams of properly homogenized vegetable sample was taken in a 50-mL screw-capped polypropylene centrifuge tube, and 10 ml acetonitrile (MeCN) contain 1% acetic acid was added into the centrifuge tube. The centrifuge tube was closed properly and shaken vigorously for 30 s by vortex mixer. Then, 4g anhydrous MgSO4, 1g sodium chloride, 1g trisodium citrated dehydrate and 0.5g disodium hydrogen citrated sesquihydrate were added into the centrifuge tube, and it was shaken by vortex mixer for 1 min. afterward, the extract was centrifuged for 5 min at 5,000 rpm. An aliquot of 1 mL of the MeCN layer was transferred into a micro centrifuge tube containing 150mg anhydrous MgSO4, 25mg PSA, 2.5mg GCB for tomatoes or containing 150mg anhydrous MgSO4 and 25mg PSA for eggplants. The content of the centrifuge tube was thoroughly mixed by vortex for 30 s and centrifuged for 5 min at 4,000 rpm. A one mL supernatant was taken into a clean test tube, and one drop of toluene was added into the test tube. The test tube containing the extract was stored at −20 °C until analysis.

Quality Control
The performance of the QuEChERS method was evaluated by performing recovery studies. The recovery rate and precision of the method (expressed as relative standard deviation (RSD), %) were measured by analyzing replicate pesticide-free samples of each type of vegetable, which were fortified at a concentration of 0.01 or 0.05 mg/kg for each pesticide. Sensitivity was evaluated by determining the limit of detection (LOD) and limit of quantification (LOQ), using the signal-to-noise ratio (S/N) of 3:1 and10:1, respectively [18].

Pesticide Residues and Multiple Residues in Analyzed Samples
The level of pesticide residues in 117 vegetable samples was de-

Pesticides residues in different Markets and Seasons in Analyzed Samples
In eggplant only five samples (18.5%) contain pesticides residues more than codex maximum residues limits, carbaryl has been detected in nine samples( 33.3%) from each seasons and markets and only one sample from khartoum north market in autumn has been found above the codex maximum residues limits , cypermethrin has been detected in six samples(22.2%)and only one sample from omdurman market in summer has been found above the codex maximum residues limits, endosulfan has been detected in five samples(18.8%)and only two sample from khartoum central and omdurman in summer and autumn respectively have been found above the codex maximum residues limits, imidacloprid has been detected in six samples(22.2%) and only one sample from omdurman market in summer has been found above the codex maximum residues limits. Each permethrin and fenpropathrin has been detected in 7 (25.9%) and 8 (29.6%) samples respectively but no sample contains permethrin above the codex maximum residues limits Table 2.   Table 3. This study shows the evidence of contamination of vegetables specially tomatoes and eggplant with pesticides residues in Khartoum state markets.
Slightly more than 92% of the samples analyzed contained pesticides residues and from present samples more than 18. MRLs set by Codex, in previous studies some vegetables from Ghana [20], Saudi Arabia [21] and China [22] contain organochlorine pesticides which were banned or restricted in majority of countries.
Most of pesticides residues found in tomatoes in winter are similar to that found by Magdoleen especially for Malathion, Chloropyrifos and Dimethoate [23]. In study by Safiqul and other there were detected different organophosphorus like diazinon, malathion and chloropyrifos in eggplant from retail markets of some town in Bangladesh and there result show little different from our study specially in pesticides residues exceeded the MRLs which was dimethoate [24].In the analysis of pesticides on fresh vegetables using GC, interference and contamination resulting from plant pigments and the matrix are often encountered. Although silica gel and florisil are commonly used to reduce the matrix effects, in this study activated carbon were another material used to remove the pigments from fresh vegetables. Activated carbon is often used because it is cheap and strongly adsorbs many organic compounds in some fresh vegetables [25]. Table 3: Comparison between markets and seasons in pesticides residues found in Tomatoes.

Conclusion
This study investigated the levels of pesticide residues in vegetable samples (tomatoes and eggplant) and compared this level between seasons and markets in Khartoum state in Sudan.
The results indicated that most of the tomatoes samples were contaminated with pesticide residues, some pesticides residues concentrations in few samples of tomatoes and eggplant have been found above the MRLs established by Codex. The observed levels of pesticide residues may pose a potential health risk to consumers. Therefore, to reduce this risk, farmers should be sensitized to better pesticide safety practices and the need for continuous pesticide residue monitoring is highly recommended.