GC/MS/MS Analysis of Pesticides in Ginseng on SLB®-5ms after QuEChERS Cleanup using SupelClean™ Ultra
Materials
analytical column
accessory
Certified Vial Kit, Low Adsorption (LA) QsertVial™
volume 0.3 mL, QsertVial, amber glass vial, natural PTFE/silicone septa, thread for 9 mmrelated product
sample prep
CONDITIONS
sample/matrix
powdered ginseng
extraction tube
Supel Que non-buffered extraction tube (4 mg NaSO4, 1 g NaCl in 12 mL tube) (55294-U)
extraction process
Add 10 mL ACN/IS Extraction Solvent and allow to sit 15 minutes, then shake or vortex 30 sec. Add contents of Supel Que nonbuffered extraction tube (55294-U). (Shake by hand immediately to prevent clumping. Shake on shaker for 30 minutes at 2250 rpm, centrifuge for 5 minutes at 4500 rpm. Draw off supernatant for cleanup.)
clean-up tube
SupelClean Ultra 2400, 3 mL (54281-U)
column
SLB-5ms, 30 m x 0.25 mm I.D. x 0.25 μm (28471-U)
oven
105°C (3 min), 10 °C/min to 130 °C, 4°C/min to 200°C, 8°C/min. to 300°C (10 min)
inj. temp.
programmed: 100 °C (.05 min), to 280 °C at 720°C/min, hold 45 min
detector
MS/MS
MSD interface
300 °C
scan range
MRM
carrier gas
helium, 1.4 mL/min constant
injection
2 μL splitless
liner
2 mm ID
sample
QuEChERS extract of ginseng powder
Description
Analysis Note
QuEChERS is a common method used for extraction of pesticide residues from dry botanicals. The resulting extracts are often very high in background, requiring a rigorous cleanup prior to analysis. The standard SPE cleanup approach uses a dual layer cartridge containing graphitized carbon (GCB) and PSA. In this application, Supelclean™ Ultra 2400 was used for SPE cleanup of ginseng extracts. Ultra offers several advantages over the standard cartridge: (1) smaller size and thus less solvent usage (2) does not require the use of toluene for elution (3) better recovery of planar structured pesticides.
Other Notes
This report summarizes the results of our participation in a multi-lab validation of a method protocol for the analysis of selected pesticides in dried botanicals by GC/MS/MS. The method protocol was developed by Wong et.al at the US Food and Drug Administration. This method uses QuEChERS extraction followed by SPE cleanup. The SPE cleanup uses a dual layer cartridge containing GCB and PSA. Our goal in participating in this study was to evaluate the use of the Supelclean™ Ultra 2400 alongside the standard dual layer cartridge.
Clean-up Process:
Cartridge: Top 3 mL Ultra 2400 SPE cartridge (54281-U) with ~0.10 g anhydrous Na2SO4
Condition: 3 mL of Acetonitrile
Load: 750 μl of QuEChERS extract
Elute: using 8 mL of acetonitrile containing 0.5% formic acid. Apply slight vacuum at end if needed.
Collect eluent in glass or plastic centrifuge tubes (glass preferred)
Concentrate: all eluent extracts in water bath at 45-50°C w/3 psi N2 purge to ~50-100 μL.
Legal Information
SLB is a registered trademark of Merck KGaA, Darmstadt, Germany
Supelclean is a trademark of Sigma-Aldrich Co. LLC