Study area The study area included major ten markets of Mymensingh Sadar, Mymensingh. Brinjals were collected from 10 markets: K.R market, Mesua bazar, Paurashava bazar, Shankipara bazar, Charpara bazar, Shambhuganj bazar, Sutiakhali bazar, Kewatkhali bazar, Khagdahar bazar and Chorkhai hat. These markets are famous for vegetables. The vegetables of these markets comes from different places covering a large area such as Char Gobadia, Char Nilakshmia, Kalibari char, Baganbari Char, Bobar Char, Bhabanipur, Gafargaon, Fulbaria, Ishwarganj, Paranganj, Char Khaircha, Char Gavindapur, Nuldug, Jailkhana road, Nandina, Joy bangla bazar, Konaparar Char,Jamalpur, Nurondi, Bidyagaon etc. Sample collection A total of 50 brinjal were collected for this study. Five samples of brinjal were collected from each market. Samples were collected in two steps. On 14 December 2015, first 50 samples were collected from K.R market; Mesua bazar; Paurashava market; Shankipara bazar and Charpara bazaar. On 16 January 2016, the other 50 samples were collected from Shambhuganj bazar; Sutiakhali bazar; Kewatkhali bazar; Khagdahar bazar and Chorkhai hat. The sources of the vegetables were encoded from the shopkeepers.The amount of eggplant for each sample was 800gm and was collected in transparent clean air tight polyethylene bag and each bag was properly labeled with sample number and sources. Individual numbers of sample was collected in individual polyethylene bag to avoid cross contamination. Chemicals and reagents The standard of chlorpyrifos, acephate, diazinon, dimethoate, quinalphos, malathion and fenitrothion were obtained from Sigma-Aldrich Laborchemikalien (St Louis, MO, USA) via Bangladesh Scientific Pvt. Ltd. Dhaka, Bangladesh. Standards of all the pesticides contained >99.6% purity.Methanol, acetone, gradient grade acetonitrile, sodium chloride (NaCl), anhydrous magnesium sulphate (MgSO4) and primary secondary amine (PSA) were purchased from Bangladesh Scientific Pvt. Ltd. Dhaka, Bangladesh. Preparation of pesticide standard solution Pesticide standard stock solutions of chlorpyrifos, acephate, diazinon, dimethoate, quinalphos, malathion and fenitrothion were prepared separately in acetone at a concentration of 1000 mg/l and stored at -20°C until use. A mixed standard solution of 50 mg/l in acetone containing all the aforementioned pesticides was prepared by adding the appropriate volume of each individual stock solution in a 50 ml volumetric flask and made to volume by addition of acetone. An intermediate mixed standard solution of 10 mg/l in acetone was prepared from the mixed standard solution of 50 mg/l. Then working standard solutions of 0.1, 0.2, 0.5, 1.0,2.0, 3.0, and 5.0 mg/l in methanol were prepared by transferring the appropriate amount from 10 mg/l intermediate mixed standard solution into ten separate 10 ml volumetric flasks. All the standard solutions were kept in a freezer at -200C until use. Extraction and clean up In this study the QuEChERS extraction technique was used which was modified by Prodhan et al., 2015. The chopped samples were grounded thoroughly with the fruit grinder (Handmixer M-122, Bamix, Switzerland). A representative 10 g portion of thoroughly homogenized sample was weighted in a 50 ml polypropylene centrifuge tube. Then 10 ml of acetonitrile (MeCN) was added into the centrifuge tube. The centrifuge tube was closed properly and shaken vigorously for 30 s by the use of a vortex mixer. Then, 4 g of anhydrous MgSO4 and 1 g of NaCl were added into the centrifuge tube, and it was shaken immediately by the vortex mixer for 1 minute to prevent the formation of magnesium sulfate aggregates. Afterwards, the extract was centrifuged for 5 min at 5000 rpm. An aliquot of 3 ml of the acetonitrile layer was transferred into a 15 ml micro centrifuge tube containing 600 mg anhydrous MgSO4 and 120 mg primary secondary amine (PSA). Then it was thoroughly mixed by vortex for 30 s and centrifuged for 5minutes at 4000 rpm. (Laboratory Centrifuges, Sigma-3K30, Germany). After centrifuge, a 1 ml supernatant was filtered by a 0.2 μm PTFE filter, and then it was taken in a clean HPLC vial for injection. Detection and quantification of pesticide residue in samples The concentrated extracts were subjected to analysis by GC-2010 (Shimadzu) with flame thermonized detector (FTD) for the detection of acephate, dimethoate, diazinon, fenitrothion, malathion, chlorpyrifos and quinalphos. The capillary column was AT-1, length was 30m, ID was 0.25mm and film thickness was 0.25μm. Helium was used as carrier and make up gas for FTD. The identification of suspected pesticide was performed by peak retention times in samples to those of peaks in the pure analytical standards. Calibration curve preparation Prior to the injection of the sample extract, standard solutions of different concentrations of each pesticide group were prepared and injected with suitable instrument parameters.