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Improve EPH Testing Accuracy and Efficiency with Resprep EPH Fractionation SPE Cartridges

Resprep Tubes
  • Method-specific performance for extractable petroleum hydrocarbon (EPH) analysis of soil and water samples.
  • Complete separation of aliphatic and aromatic compounds into distinct fractions.
  • Guaranteed background level under the strict reporting limits of MA and NJ EPH methods.
  • Superior lot-to-lot reproducibility and storage stability ensured by rigorous QC testing and moisture-resistant packaging.
  • Available in two formats: 5 g bed for higher loading capacity and 2 g bed for automated systems, time-saving, and solvent reduction.

Figure 1: Resprep EPH SPE cartridges offer consistent and complete separation between aliphatic and aromatic compounds from one lot to the next. A representative subset of compounds is shown here (40+ compounds were analyzed in total) to clearly illustrate the separation between fractions and the lack of breakthrough in every lot we produce.

Lot 1

Lot 2

Lot 3

Data shown produced using 5 g cartridges; similar results are obtained using 2 g cartridges because both formats are made with the same silica.

No guesswork, no worries.

Every lot of Resprep EPH cartridges you order will provide consistent and complete fractionation.

Figure 2: Restek guarantees a background level in each fraction of less than half the strict reporting limits of MA and NJ EPH methods. (Tables give average total extracted background for both formats; example chromatography used 5 g cartridge.)

Aliphatic Fraction

Average ppm (n = 3)
Format Lot # Region 1
(C9 - C18)
Region 2
(C18 - C36)
2 g 1 3.2 2.5
2 3.7 2.9
5 g 1 13.2 17.3
2 11.3 16.4
Restek aliphatic quality limits: <35 ppm each region

EPH Silica Cartridge Background Extraction Aliphatic Fraction on Rxi-5ms
GC_EV1437

Aromatic Fraction

Format Lot # Average ppm
C9-C36 (n = 3)
2 g 1 9.5
2 9.5
5 g 1 34.2
2 35.6
Restek aromatic quality limits: <50 ppm
EPH Silica Cartridge Background Extraction Aromatic Fraction on Rxi-5ms
GC_EV1438

For 5 g Cartridges: Column: Rxi-5ms, 30 m, 0.32 mm ID, 0.25 μm (cat.# 13424); Sample: MA EPH surrogate spike mix (cat.# 31479); Conc.: 5 μg/mL; Injection Inj. Vol.: 1 μL splitless (hold 1 min); Liner: Restek Premium 4.0 mm ID cyclo double taper inlet liner (cat.# 23310); Inj. Temp.: 300 °C; Purge Flow: 50 mL/min; Oven Temp.: 40 °C (hold 1 min) to 300 °C at 12 °C/min to 330 °C at 6 °C/min; Carrier Gas: He, constant flow; Flow Rate.: 2 mL/min; Linear Velocity: 41.0 cm/sec @ 40 °C; Dead Time: 1.12 min @ 40 °C; Detector: FID @ 330 °C; Make-up Gas Flow Rate: 45 mL/min; Make-up Gas Type: N₂ Hydrogen flow: 40 mL/min; Air flow: 450 mL/min; Data Rate: 50 Hz Instrument: Agilent 7890B GC; Notes: The area of the surrogate peak was excluded from the calculated total extracted background value.

For 2 g Cartridges: Column: Rxi-5ms, 30 m, 0.25 mm ID, 0.25 μm (cat.# 13423); Sample: MA EPH surrogate spike mix (cat.# 31479); Conc.: 5 μg/mL; Injection Inj. Vol.: 1 μL splitless; Liner: Topaz single taper inlet liner with wool (cat.# 23303); Inj. Temp.: 250 °C; Purge Flow: 50 mL/min; Oven Temp.: 40 °C (hold 1 min) to 300 °C at 12 °C/min to 330 °C at 6 °C/min; Carrier Gas: He, constant flow; Flow Rate.: 2 mL/min; Linear Velocity: 41.0 cm/sec @ 40 °C; Dead Time: 1.12 min @ 40 °C; Detector: FID @ 330 °C; Make-up Gas Flow Rate: 45 mL/min; Make-up Gas Type: N₂ Hydrogen flow: 40 mL/min; Air flow: 450 mL/min; Data Rate: 50 Hz Instrument: Agilent 7890B GC; Notes: The area of the surrogate peak was excluded from the calculated total extracted background value.

No background, no problems.

Resprep EPH cartridges are guaranteed clean—we certify our background levels will always meet method requirements.

Same High-Performance Silica Now Available in Two Formats

  • Use 5 g bed for higher loading capacity.
  • Use 2 g bed for automated systems, time-saving, and solvent reduction.

Figure 2: Performance indicator compounds demonstrate the elution profiles of 5 g and 2 g cartridges packed with the same silica lot so you know exactly where target analytes will elute.

5 g Format


2 g Format

Restek EPH cartridges have a sample concentration loading capacity of 5000 ppm per gram silica (10,000 ppm for 2 g cartridges and 25,000 ppm for 5 g cartridges). However, to ensure satisfactory fractionation and avoid breakthrough, actual elution volumes should be determined empirically prior to sample analysis. The procedure in Restek’s product instruction sheet is suitable for MA and NJ method QC levels; however, high-concentration samples may require dilution or modified solvent volumes.

Table I: Whether you use 5 g or 2 g formats, Resprep EPH fractionation SPE cartridges deliver accurate results consistently, even for the compounds most critical to method requirements as shown below.

Aliphatic Fraction


5 g Cartridges 2 g Cartridges
Compound Function Average %
Recovery
%RSD Average %
Recovery
%RSD
Nonane (C9) Most-retained aliphatic 109.1 2.1 102.8 0.2
1- Chlorooctadecane Surrogate 107.0 0.6 89.8 0.4
Octacosane (C28) Aliphatic loading capacity probe 109.2 1.0 101.6 0.0
Tetracontane (C40) Least-retained aliphatic 106.8 0.6 100.7 0.1


Aromatic Fraction


5 g Cartridges 2 g Cartridges
Compound Function Average %
Recovery
%RSD Average %
Recovery
%RSD
1,2,3-Trimethylbenzene Least-retained aromatic 85.3 6.7 101.9 0.5
Naphthalene Breakthrough probe 86.6 6.8 101.5 0.5
2-Methylnaphthalene Breakthrough probe 86.6 6.7 101.6 0.5
2-Fluorobiphenyl Surrogate 86.4 6.7 101.2 0.5
2-Bromonaphthalene Surrogate 86.2 6.7 101.7 0.5
Phenanthrene Aromatic loading capacity probe 86.2 6.7 101.4 0.6
o-Terphenyl Surrogate 86.2 6.7 99.7 0.4
Dibenzo(a,h)anthracene Most-retained aromatic 82.2 7.7 99.5 0.5
Fortified concentrations for all fractions were prepared per gram silica and were 800 ppm (C28 and phenanthrene) and 40 ppm (all other compounds) after accounting for the amount of silica in each cartridge format (n = 3). Method requirements: MA EPH and NJ EPH analyte recovery 40%–140%; Texas EPH analyte recovery 60%–140% and surrogate recovery 70%–130%.

Which Cartridge Format do I Need?

Table II: If your samples don’t require a higher loading capacity, you can save time and reduce solvent consumption by using 2 g cartridges instead of 5 g cartridges.

Solvent Consumption Comparison


Solvent Consumption (mL)
Extraction Steps 5 g Cartridge 2 g Cartridge
Cartridge conditioning Dichloromethane 6 3
Hexane 15 5
Aliphatic fraction Sample 1 1
Hexane 19 5
Aromatic fraction Dichloromethane 20 6
Total solvent used (mL) 60 20
Total chlorinated solvent used (mL) 26 9

Reduce solvent waste by ~66%!

Time-Saving Comparison


Extraction Time (min)
Extraction Steps 5 g Cartridge 2 g Cartridge
Cartridge conditioning Dichloromethane (5-min hold) 8 6.5
Hexane 7.5 2.5
Aliphatic fraction Sample loading 0.5 0.5
Hexane 9 2.5
Aromatic fraction Dichloromethane 10 3
Concentration time Two fractions 60 15
Miscellaneous steps Adding solvent, transferring glassware 8 8
Total process time 103 min 38 min

Save over an hour of sample prep time!

Figure 4: Regardless of which cartridge format you use, our moisture-resistant packaging prevents contamination from ambient moisture, ensuring outstanding performance even after storage.

No-risk, no-obligation trial.

Free samples of Resprep solid phase extraction (SPE) tubes are available. Contact us or your local Restek representative to request yours: www.restek.com/contact-us

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