Sample Pre-treatment by Solid-Phase Eextraction

Pesticide residue analysis in Grains, Beans, Nuts, Seeds
(my own method I)

Sample Pre-treatment
(1) Place about 10 g of sample, accurately weighted, in 100-mL volumetric flask, add 20 mL of D.I H2O, let it still 1 min.
(2) Homogenize 20 mL of Acetontrile with frequent shaking, then filter. Wash the residues on the filter paper by 20 mL of Acetontrile. Combine all the filtrate, dilute to volume with Acetonitrile.
(3) Piper 20 mL of filtrate into 250 mL flask, mix 10 g of NaCl and 20 mL of 0.5 mol/L Phosphoric Acid Buffer. Allow the solution cool, still, discarding the aqueous phase.
SPE Column Solvation/Pre-equilibration
(A) Activation: Activate the Bond Elut C18( 1 g ) by washing 10 mL of Acetonitrile.
(B) Load Sample: Pipet 20 mL of the filtrate, collect the elute.
(3) Rinse / Analyte Elution: Use 2 mL of Acetonitrile.
(4) Concentrate: under 40 degree C, use rotary Evaporator. Add 10 mL of a mixture solution of Acetonitrile/Methylbenzene (3:1) for further pre-treatment.
Column Purification by Carbon/NH2 SPE
(1) Column solvation: Activate the Bond Elut Carbon/NH2 (500mg/500mg) by 10 mL of a mixture solution of Acetonitrile/Methylbenzene(3:1).
(2) Apply sample: Pipet 2 mL of the above solution.
(3) Interference elution: Analyte elution by using 20 mL of Acetonitrile/Methylbenzene (3:1), collect the elute.
(4) Concentrate: All 5 mL of Acetone to re-dissolve eluates again. Under 40 degree C, evaporate on a stream bath to dryness (or with Nitrogen blowing Instrument) and dissolve the residue in 1 mL with Acetone/Hexane (1:1).
Now ready for GC-MS or GC-MS/MS.
To my best knowledge, my own method meets assay requirement for hundreds of pesticides, antiseptic, herbicides, feed additives, Veterinary Drugs that required by Japanese Ministry of Health, Labor "food maximum residue limits of pesticides in the interim standards".

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Bond Elut C18 (1g, 6mL, PN.12256001)
Bond Elut Carbon/NH2 (500mg/500mg, 6mL, PN.12252202 )