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ERACHECK PRO and standard test method ASTM D7678 - A perfect combination

In 2011, ASTM International published the latest oil in water method D7678. It has been the first infrared standard method, which does not rely on CFC or carcinogenic solvents for ultra-precise quantification of hydrocarbons in water. Instead, an environmentally friendly cycloalkane (cyclohexane or cyclopentane) is used for extraction. Laser-based infrared absorption spectroscopy is the key to measure sub-ppm hydrocarbon concentrations in a hydrocarbon extraction solvent.

Recently, the standard test method was updated to D7678-17 and now includes several significant improvements:

  • Coverage of concentrations from 0.1 mg/L to 1000 mg/L oil in water
  • Total Oil & Grease (TOG) introduced as parameter additionally to Total Petroleum Hydrocarbon (TPH)
  • Validation of ready-made LiquiSpec® TOG and LiquiSpec® TPH cartridges for easiest clean-up 

A round robin study was conducted to show the unrivaled precision of the method and the analyzer. The ERACHECK PRO by QuantaRed Technologies is the only oil-in-water analyzer that fully complies with standard test method ASTM D7678-17.

 

Easy clean-up with LiquiSpec® TOG and LiquiSpec® TPH cartridges

TPH cartridgeDepending on the applied method, clean-up procedures have to be performed subsquently to the extraction to get rid of polar substances (often referred to as "grease") before measurement. This sample preparation step is time consuming, involves preparation and cleaning of equipment, and therefore, might lack of reproducibility. To circumvent these difficulties, a simple, automated clean-up procedure has been developed by QuantaRed Technologies for use with the ERACHECK PRO.

Ready-made solid phase extraction (SPE) cartridges are directly plugged to the instrument’s sample inlet port and connected with the inlet tubing. With an embedded pump, the ERACHECK PRO automatically primes the cartridge, performs the solid phase extraction, rinses the measurement cell and starts the measurement. Afterwards the cartridge is unplugged and disposed. Clear instructions are given on the screen.

Two types of LiquiSpec® cartridges are available:

  • LiquiSpec® TOG drying cartridges (filled with Na2SO4) to remove water residue from the sample
  • LiquiSpec® TPH cartridges (filled with Na2SO4/Florisil) to remove all polar substances from the sample

The use of LiquiSpec® cartridges with the ERACHECK PRO is optional. The cartridges simplify and speed-up the clean-up procedure while maximizing reproducibility and applicability of oil-in-water analysis. The use of LiquiSpec® cartridges is in full compliance with ASTM D7678-17.

 

Comparison to other methods

In comparison to other methods for oil-in-water detection, ASTM D7678 offers significant benefits. The most relevant methods, which are used world-wide are included in the following table:  

Methodenvergleich

Further methods for oil-in-water analysis rely on attenuated total reflection (ATR), fluorescence and membrane solid phase extraction. None of these techniques are able to provide accurate and reproducible results for TOG and TPH concentrations in the low ppm range. The results are jeopardized by slight changes in sample preparation or sample composition. This gets crucial whenever oils from different sources  have to be monitored.

 

QuantaRed service

Our service of QuantaRed chemical analysis for water samples supports clients with oil-in-water measurements using the CFC-free and reliable method ASTM D7678. Further, we offer comparison studies to alternative methods for oil-in-water detection.