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Amini S, Nohooji MG, Khani M, Labbafi MR, Khalighi-Sigaroodi f. 2019. Biological activity of some essential oil constituents in four Nepeta L. species against Sitophilus oryzae L.. Biodiversitas 20: 338-343. Recently, there has been a growing interest in research concerning the possible use of plant extracts as alternatives to synthetic insecticides. Essential oils are among the best-known natural substances with insecticidal properties. These compounds may act as fumigants, contact insecticides, repellents, antifeedants and may affect growth and development of the insects. In an attempt to find a natural and inexpensive method for the control of stored-product pests, contact toxicity of essential oils of Nepeta cataria, Nepeta pogonosperma, Nepeta glomerulosa. and Nepeta binaloudensis. were investigated on adult insects of Sitophilus oryzae L. (Coleoptera, Curculionidae) in vitro condition. Chemical Composition, repellency and fumigant toxicity of the essential oils were investigated. Chemical composition of the essential oils of above plants were identified by GC-MS. 4aα,7α,7aβ-nepetalactone (82.74 %) was major component of N. cataria and also different isomers of nepetalactone were among the major compounds in N. Pogonosperma and N. binaloudensis oils. In fumigants bioassay, N. glomerulosa (124.318μL/L air) showed the highest toxicity against S. oryzae adults, followed by N.pogonosperma (150.49μL/L air) and N. cataria (152.630μL/L air), respectively. Also, the S. oryzae was repelled by N. cataria (91.61%) and N. binaloudensis (91.50 %), respectively.

Sitophilus oryzae (L) were subjected to essential oils extracted from Mentha piperita L, Rosmarinus officinalis L and Hyssopus officinalis L. Chemical structure, repellency, fumigant toxicity and f...

A simple and selective method was developed for the preconcentration, separation, and determination of trace amounts of As(III) in an aqueous solution by solid phase extraction combined with graphite furnace atomic absorption spectrometry. Activated carbon (AC) was modified by sodium diethyldithiocarbamate (NaDDTC) and then used as a new, stable and easily prepared solid sorbent in a mini column for the extraction of As(III) in aqueous solution. Factors influencing the sorption and desorption of As(III), such as volume and concentration of eluent, sample pH, flow rate and effect of interfering ions on the recovery of As(III) have been systemically investigated. At pH 2.0 As(III) could be adsorbed quantitatively by NaDDTC-AC, and then eluted completely with 2 mL of 3.0 mol·L−1 HNO3. The amount of eluted As(III) was measured using graphite furnace atomic absorption spectrometry. The detection limit of As(III) was 0.04 ng·mL−1 with enrichment factor of 100 and the relative standard deviation (RSD, n=8) was 1.58% at 10 ng·mL−1 level.

A simple and sensitive method using mini-column packed with multi-walled carbon nanotubes (MWCNTs) combined with graphite furnace atomic absorption spectrometry (GFAAS) for preconcentration and determination of ultra trace amounts of As(III) in an aqueous medium is proposed. The procedure is based on the solid phase extraction of the As(III)-sodium diethyldithiocarbamate (As-NaDDTC) chelate on MWCNTs. Various parameters such as the effect of pH, eluent type and volume, amount of sorbent, and matrix effects on the quantitative recoveries of analyte ions were evaluated. It was found that sorption is quantitative and desorption occurs with 4.0 mL of 3.0 mol L−1 HNO3 in acetone. The limit of detection of the method was 0.008 ng mL−1 for GFAAS with enrichment factor of 125 and the relative standard deviation (RSD) 0.97% (n = 8, C = 10 ng mL−1). This method has been applied to the determination of ultra trace As(III) in water and rice plant and its ash successfully.