GC Analysis of Pesticides in Spinach on SLB®-5ms after QuEChERS Extraction then SPE Clean-up using Supelclean™ ENVI-Carb/NH2 Dual Layer
Materials
related product
used together
CONDITIONS
sample preparation
Solid Phase Extraction (SPE)
sample/matrix
Spinach extract by QuEChERS, as described in the pretreatment step
SPE tube/cartridge
Supelclean ENVI-Carb/NH2 SPE Cartridge, 6 mL (54035-U)
extraction process
to 10 g homogenized spinach, add 10 mL acetonitrile, shake 1 min, add contents of Supel QuE acetate tube (55234-U), shake 1 min, centrifuge, transfer extract to dSPE tube, (add 1 g anhydrous MgSO4, shake 1 min and centrifuge, transfer 5 mL extract to glass tube, evaporate to 1 mL, add 250 μL toluene for a final volume of 1.25 mL QuEChERS extract)
condition
10 mL acetonitrile:toluene (75:25), discard
sample addition
1.25 mL spinach QuEChERS extract
elution
20 mL acetonitrile:toluene (75:25), gravity elution
eluate post-treatment
adjust volume of sample extract to 21.25 mL
column
SLB-5ms, 20 m x 0.18 mm I.D., 0.36 μm (28576-U)
oven
50 °C (0.5 min), 25 °C/min to 125 °C (0 min), 10 °C/min to 300 °C (5 min)
inj. temp.
60 °C (0.28 min), 600 °C/min to 325 °C (5 min)
detector
MSD
MSD interface
325 °C
scan range
SIM
carrier gas
helium
injection
10 μL, PTV solvent vent, purge flow to split vent 60 mL/min at 2.78 min, vent flow 100 mL/min
liner
4 mm I.D., split/splitless type, wool packed single taper FocusLiner design (2877505-U)
Description
Analysis Note
Pigments, sterols, sugars, organic acids and fatty acids when extracted from leafy greens such as spinach, pose problems for long term GC performance. An effective clean-up technique is required that will isolate/retain matrix interferences without effecting the pesticide analytes of interest. Solid Phase Extraction is a common and efficient approach to effectively clean up extracts and reduce interferences for low concentration residue analysis. A 6 mL Supelclean ENVI-Carb/ NH2 (54035-U) SPE tube is used for clean-up of spinach extract for GC/MS analysis and produces good recoveries with very low background.
Sample pretreatment: to 10 g homogenized spinach add 10 mL acetonitrile and shake 1 min, add contents of Supel QuE acetate tube (55234-U), shake 1 min and centrifuge, transfer extract to dSPE tube, add 1 g anhydrous MgSO4, shake 1 min and centrifuge, transfer 5 mL extract to glass tube, evaporate to 1 mL, add 250 μL toluene for a final volume of 1.25 mL QuEChERS extract
Legal Information
SLB is a registered trademark of Merck KGaA, Darmstadt, Germany, Supelclean is a trademark of Sigma-Aldrich Co. LLC