Method Validation for the Extraction and Analysis of Spiromesifen in Cabbage , Tomato and Soil by GC and GC-MS

Spiromesifen is a non-systemic insecticidal/miticidal compound belonging to the chemical class of spirocyclic phenyl substituted tetronic acid. It is an effective compound for controlling whiteflies (Bemisia and Trialeuroides spp.) and numerous mite species (Tetranychus and Panonychus spp.) [1, 2]. It controls insects and mites which are resistance to other insecticide/miticide [3]. It is a lipid biosynthesis inhibitor, acts by inhibiting lipid metabolism enzyme acetyl Co-A carboxylase [4]. It does not exhibit cross resistance to the more commonly used neonicotinoids [5]. Cabbage (Brassica oleracea) is an annually grown leafy vegetable. The annual production of cabbage is 3 million metric tons [6]. Cabbage reported to have anti-carcinogenic agent. It is a good source of vitamin C, fiber and betacarotene [7]. Most common pests of cabbage are aphids [8]. Tomato is the important vegetable consumed throughout the world. It is good source of carotene and lycopene and acts as a natural antioxidant. Tomato reportedly gives preventive control of prostate, head and neck cancer [9]. Psyllid and whiteflies are the common pests of tomato. Spiromesifen can give effective control of psyllid, whiteflies and aphids of cabbage and tomato [10-13]. When the pesticides are used for the pest control on different crops, it may also reach the soil. Soil is the major source of entry of pesticides into food chain. QuEChERS is the most convenient method for the extraction of the broad range of pesticides. It is a single step buffered acetonitrile extraction and clean-up method using small amount of solvent [14-15]. Method validation is a process to provide the evidence that the method was suitable for the residue analysis of the intended compound. Method validation was carried out as per SANCO (2013) for analysis of spiromesifen in cabbage, tomato and soil [16]. The parameters of the method validation studied were accuracy, precision, limit of detection (LOD), limit of quantification (LOQ), linearity, range, selectivity and measurement uncertainty (MU). Abstract Spiromesifen (3-mesityl-2-oxo-1-oxaspiro [4.4] non-3-en-4-yl 3, 3-dimethylbutyrate) is a novel miticide/ insecticide that belong to the chemical class of spirocyclic phenyl tetronic acid. An analytical method was validated for the analysis of spiromesifen in cabbage, tomato and soil using gas chromatography (GC) and gas chromatography mass spectrometry (GC-MS). The sample extraction was carried out using acetonitrile and dispersive solid phase extraction (dSPE) clean-up was carried out using primary secondary amine (PSA). The recoveries were in the range of 72.56-103.37% with relative standard deviation (RSD) of 2.7-9.4%. The Limit of detection (LOD) was 0.003 μg mL -1 . The limit of quantification (LOQ) of the method, the lowest concentration at which the compounds could be analyzed in the samples, was 0.01 mg kg -1 , respectively. The measurement uncertainty was within 9.9-14.9%, indicating the true value remained within this range.