Improve Productivity for Pesticides Analysis with Resprep FL + CarboPrep Plus SPE

• Dual-bed Florisil and carbon cartridge removes more coextracted matrix components than Florisil alone.
• Cleaner extracts mean less GC downtime and >10x higher sample throughput.

When analyzing complex soil and water samples for organochlorine pesticides, coextracted matrix components can contaminate the inlet and column, forcing analysts to take instruments offline for time-consuming, unplanned maintenance. Effective sample extract cleanup is the key to keeping your instruments running and generating accurate, reliable data. Pass-through SPE using Florisil cartridges (e.g., EPA Method 3620) is a common cleanup technique, but Resprep FL + CarboPrep Plus SPE cartridges (Resprep FL+CPP)—which contain both Florisil and carbon in a dual-bed, single-cartridge format—provide a much more effective cleanup. Better cleanup means that columns last longer and instruments stay running, which increases sample throughput and lab profitability.

The Florisil used in Resprep FL + CarboPrep Plus SPE cartridges undergoes special moisture-control processing to ensure full activation of the sorbent material and effective removal of polar contaminants. While it is quite good for capturing polar compounds, Florisil does not remove the high molecular weight contaminants that typically foul GC inlets and bring instruments down for maintenance.

Fortunately, the CarboPrep Plus sorbent bed is extremely efficient at removing the most troublesome coextracted matrix components. For example, if humic acids from the sample remain in the final extract, they cause DDT to break down and fail performance requirements for inlet degradation (<15% breakdown) and continuing calibration checks. The high-quality carbon in Resprep FL + CarboPrep Plus SPE cartridges removes these acids, producing visibly cleaner extracts that meet performance requirements longer and allow many more sample injections compared to extracts cleaned with Florisil alone (Figure 1).

Same Procedure, Cleaner Extracts

Not only do Resprep FL + CarboPrep Plus SPE cartridges remove more coextracted sample matrix contaminants but they also do so using the same solvents and volumes that are commonly used in Florisil cleanup methods. As shown in Figure 2, the same cartridge conditioning; sample loading; and 10 mL hexane:acetone (90:10) elution steps were performed, and the Resprep FL + CarboPrep Plus SPE cartridges produced visibly cleaner final extracts that produced excellent chromatography. In addition to being a drop-in replacement for Florisil cleanup procedures, Reprep FL + CarboPrep Plus SPE cartridges further simplify workflows because the same cartridge effectively cleans most sample types—there is no need to decide whether to use Florisil or carbon for potentially dirty samples.

Improve Data Quality and Reporting Accuracy

In addition to reducing downtime, improving sample throughput, and simplifying workflows, Resprep FL + CarboPrep Plus SPE cartridges help improve analytical performance, so you can be confident that you are reporting accurate results. Powerful, effective removal of coextracted matrix components eliminates sample-based interferences and prevents them from reducing quantitative accuracy. As shown in Table I, recoveries for all compounds in laboratory control samples were within the acceptance range of 80-110%. In addition, due to the presence of Florisil, no breakthrough of trichlorophenol (TCP) was observed. Method requirements are reliably met because the ultra-clean sorbents and tightly controlled manufacturing procedures ensure low background and consistent lot-to-lot performance (Figure 3).

Table I: Effective cleanup with Resprep FL + CarboPrep Plus SPE cartridges helps ensure accurate, reliable results (n=8).

*Meets requirement of <5% breakthrough.

Figure 3: Resprep FL + CarboPrep Plus cartridges have consistently low background due to proprietary manufacturing procedures and strict quality controls. (Eight injections per lot are shown.)

	Peaks	tR (min)
1.	2,4,5,6-Tetrachloro-m-xylene	5.65
2.	Biphenyl, decachloro-	10.00

Column	Rtx-CLPesticides, 30 m, 0.32 mm ID, 0.32 µm (cat.# 11141)
Standard/Sample
	2,4,5,6-Tetrachloro-meta-xylene (cat.# 32027)
	Decachlorobiphenyl (BZ #209) (cat.# 32029)
Diluent:	Hexane
Conc.:	5 ng/µL
Injection
Inj. Vol.:	4 µL pulsed splitless
Liner:	Topaz single taper inlet liner w/wool (cat.# 23303)
Inj. Temp.:	250 °C
Pulse Pressure:	35 psi (241.3kPa)
Pulse Time:	0.74 min
Purge Flow:	50 mL/min
Oven
Oven Temp.:	70 °C (hold 0.5 min) to 320 °C at 25 °C/min (hold 2 min)
Carrier Gas	He, constant flow
Flow Rate:	3.5 mL/min

Detector	Micro-ECD @ 330 °C
Make-up Gas Flow Rate:	60 mL/min
Make-up Gas Type:	N2
Data Rate:	50 Hz
Instrument	Agilent 7890B GC
Sample Preparation	Conditioned a Resprep FL + CarboPrep Plus SPE cartridge (cat.# 28899) by adding one cartridge volume of hexane:acetone (90:10) and letting it stand for five minutes before drawing the solvent down to frit level. Then, 1 mL of sample extract was loaded onto the cartridge and eluted with 9 mL of hexane:acetone (90:10).

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Enhance Your Florisil Cleanup—Switch to Resprep FL+CPP SPE Cartridges to Reduce Downtime, Improve Data Quality, and Increase Lab Productivity!