Oil in Water/Soil Analyzers

With over 4,000 oil and grease monitors in world-wide use today, InfraCal 2 Analyzers, originally developed by Wilks, have become a standard for the petrochemical industry.  These essential tools ensure that oil content levels are below the regulated limit in water, drill cuttings, and soil.  Both the InfraCal 2 TRANS-SP and InfraCal 2 ATR-SP are recommended for measuring oil in water, TPH in soil or FOG in wastewater.

The fact that InfraCal Analyzers over 10 years old are still operating in the corrosive environment of offshore oil rigs attests to their rugged, dependability. The analysis procedure takes less than 15 minutes and can be done by minimally trained personnel. They use field proven infrared technology for measuring oil in water, oil content in drilling mud or drill cuttings, TPH (total petroleum hydrocarbons) in soil and FOG (fats, oil and grease) in wastewater.

The InfraCal 2, the latest introduction to our easy to use analyzers, uses the same measurement technology as our InfraCal TOG/TPH Analyzers with added features such as data storage and transfer, multiple calibrations and password protection for instrument settings. The InfraCal Analyzers are stand-alone fixed filter infrared instruments that give results that are comparable to EPA 1664 and ISO 9377-2 and comply with ASTM D7066, EPA 413.2 and 418.1.

    Models INFRACAL 2 ATR-SP
    MDL Water 0.3 ppm 0.1 ppm
    MDL Soil 3 ppm 1 ppm
    Solvent Hexane Perchloroethylene, S-316

    New High Range Measurement of Oil In Water or Soil

    The InfraCal 2 analyzer with an ATR sample stage can now be used for measuring the 0.5-10% range of oil in water or soil. The sample is extracted using a solvent that does not have an infrared absorbance at the hydrocarbon wavelength and, therefore, does not require evaporation. Measuring the extract directly in the solvent, instead of evaporating off the solvent, allows for percent range measurements with the same ATR sample stage used to measure the ppm levels.

    • Measurement Range Water: 0.5 – 10%
    • Measurement Range Soil: 0.5 – 10%
    • Solvents: S-316, Tetrachloroethylene


    Oil in water analysis is a global issue that crosses many industries, analytical methods, and regulatory agencies. Due to the negative effects of oil on the environment, there are strict limits on the amounts of oil allowed in water. Failure to meet these limits can lead to heavy fines. While any industry that discharges produced water needs to test for oil in water, their specific needs can differ from industry to industry. The petroleum industry is most concerned with measuring Total Oils and Grease (TOG) in both their upstream and downstream wastewater. For industrial pretreatment of wastewater, public water treatment plants, and most other non-petroleum industries discharging produced water, it is most important to test for Fats, Oils and Grease (FOG) in their effluent. FOG differs from TOG in that it tends to contain large amounts of animal and vegetable components in the oil. FOG can be especially concerning in effluent streams because it can lead to clogged sewer lines which causes Sanitary Sewer Overflows (SSOs).

    The people responsible for conducting oil in water measurements understand that the measurement can be quite challenging. Wastewater from different sources can contain many different types of hydrocarbons, each with different chemical make-ups. On top of the lack of chemical uniformity in different oils, there has been a large variety of methods developed to quantify the oil in the wastewater. While none of the following methods is perfect, each will have its own advantages and disadvantages for oil in water analysis.


    Oil In Water Testing Techniques


    Emulsion Breaking Techniques for Oil in Water Solvent Extractions


    Certain types of samples, such as those containing detergent, may form emulsions when doing an oil in water extraction into a solvent. The boundary between the solvent and the sample will have an emulsion layer that has a cloudy or milky appearance as shown in this photo. According to U.S. EPA Method 1664, “if the emulsion is greater than one-third the volume of the solvent layer, the laboratory must employ emulsion-breaking techniques to complete the phase separation.” This is relevant to all oil in water measurements that use liquid-liquid extraction whether the analysis is done by infrared, gravimetric or UV. If such an emulsion cannot be broken by any attempted means, the test method may not give representative results for the problem sample. The best way to break or reduce the emulsion depends on the sample matrix.


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    Solvent Choices for Infrared Testing of Oil and Grease in Water


    Water is a very strong absorber in the mid infrared (IR) region where oil is measured. We see the effect of infrared absorbance when a cold bucket of water left in the sun is quite warm by afternoon due to the absorption of infrared energy as heat. When measuring part per million (ppm) oil levels with mid IR, the water absorbs so much of the infrared energy that the signal becomes saturated and low oil levels cannot be detected. The oil in the sample needs to be separated from the water in order to make a measurement. Typically, the oil is extracted into a solvent and then measured either directly in the solvent or the residual oil is measured after solvent evaporation.

    There are a number of different solvents which dissolve the oil and are hydrophobic so they form a separate solvent layer that can be conveniently used for the analysis. Some of the solvents are heavier than water which requires a separatory funnel or a syringe and an inverted vial with a septum cap to get to the solvent layer. The solvents lighter than water are easier to access from the top of the container. A summary of the solvents and their properties is in the chart in the next section.


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    ASTM Method D7066-04 for Measurement of Oil and Grease in Water


    A quick and easy field analysis method for determining oil and grease concentration levels is important for offshore oil platforms, soil remediation sites and industrial wastewater measurement of Fats, Oils and Grease (FOG) . Prior to the Montreal Protocol, infrared (IR) analysis using Freon as an extraction solvent was a widely used field and laboratory method. In 1999, the U.S. EPA promulgated Method 1664A to replace existing Freon methods. Method 1664A uses gravimetric analysis and hexane for the extraction process rather than Freon. Gravimetric analysis is a laboratory method and cannot be transported to the field for onsite measurements. In addition, hexane is not a suitable solvent for infrared analysis using transmission sampling techniques as it contains hydrocarbons. Therefore, the hexane must be removed through evaporation. If not, the hydrocarbons in the hexane will contribute to the oil and grease concentration measurement. Because of the measurement capabilities, simplicity and portability of infrared analysis, the ASTM felt it was important to find an alternate solvent to Freon and develop a suitable infrared oil and grease method. 


    Click for more information about ASTM Method D7066-04




    The InfraCal 2 Analyzers for measuring oil in water or soil can be used for a number of different applications.
    Our primary applications are listed below:


    Oil Level in Produced Water


    As offshore oil wells age, the increase of produced water challenges wastewater treatment systems. In order to  ensure oil levels in the water are under the regulatory limit, it is important to do regular testing. Infrared analysis has been used for off-shore oil in water measurements for over 50 years. Infrared is an accepted oil content measurement as it is least affected by changes in produced water composition. EPA 413.2 & 418.1 are infrared methods for measuring oil & grease using now-banned Freon to extract the hydrocarbons from the effluent.  EPA 1664, using hexane as the extraction solvent and gravimetric analysis is now the standard method, replacing the Freon methods.  This gravimetric procedure requires a skilled laboratory technician, is costly and a time and equipment intensive process. 

    The InfraCal 2 Analyzers are the petroleum industry standard for the field measurement of oil and grease and total petroleum hydrocarbons due to its reputation for excellent correlation with EPA 1664 results.


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    FOG in Wastewater


    Industrial and food processing plants that have high levels of fats, oil and grease (FOG)  in their effluent face strict wastewater regulations. The InfraCal 2 Analyzer is used for industrial wastewater and water entering public water treatment plants. Spectro Scientific offers this simplified procedure for monitoring FOG discharges to help customers avoid fines or regulators to catch high FOG discharges that can result in sanitary sewer overflows (SSOs). In most cases, treatment plants are forced to wait for days or even weeks before receiving off-site laboratory results. Now, they can have results in a mere 15 minutes.

    The InfraCal 2 Analyzer is a compact, lightweight and battery operated, making it an ideal solution for operating in the range of ambient conditions typically found in field environments. The measurement by infrared absorption makes use of the fact that hydrocarbons such as fats, oils, and grease are extracted from wastewater or soil through the use of an appropriate solvent. 


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    TPH in Soil at Remediation


    The InfraCal 2 Analyzers allow for TPH (Total Petroleum Hydrocarbons) in soil testing at remediation sites such as leaking underground storage tanks, frac water holding ponds, produced water evaporation ponds or oil spills. Site managers can avoid having costly soil remediation equipment sit idle while waiting for off-site lab results. Sampling takes less than 15 minutes and requires a few simple steps that can be performed by non-technical personnel. The soil is mixed with the extraction solvent, shaken, filtered, and then presented to the InfraCal 2 Analyzer for measurement.

    With no moving parts, the InfraCal 2 Analyzers are rugged and portable making them ideal for operation at a remediation site. They are 6.5 inches (127mm) square, weigh less than 5 lbs (2 kg) and can be operated from a 12 volt battery. Different sample stages and solvent choices allow for a measurement range from ppm to percent levels of oil in soil or oil in water. The InfraCal 2 can be calibrated for ppm levels of oil in water or mg/kg to percent levels of TPH in soil. 


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    Oil Content in Frac Water


    Whether flowback and produced water from a hydraulic fracturing site is getting cleaned up for the next fracture, going to an off-site treatment facility, evaporation ponds or going through thermal or membrane desalination for agricultural use or surface discharge, removing the oil is typically the first step. Testing the effectiveness of the oil removal system can be especially important if the risk is fouling a membrane or incurring a regulatory fine. 


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    Hydrocarbons in Drill Cuttings


    The large amounts of drill cuttings produced in offshore drilling require meeting an allowable limit on total petroleum hydrocarbons (TPH) for ocean disposal. Transporting cuttings to shore is labor intensive, costly, and could cease drilling activities due to bad weather. Limit requirements also must be met for onshore disposal or reuse. To evaluate hydrocarbon levels in drill cuttings or drilling mud, oil is extracted into the solvent for measurement. The InfraCal 2 Analyzer’s capability for multiple calibrations allow for ppm to percent levels.

    Whether onshore or offshore, the InfraCal 2 Analyzer can determine if oil levels have exceeded the allowable limit in less than 15 minutes. The InfraCal 2 Analyzer is a compact, fixed-filter, mid-infrared analyzer with no moving parts. Hydrocarbons are measured at 3.4 mm (2930 cm-1). It is rugged and portable, weighing less than 5 pounds, and the user interface is specifically designed for non-technical operators.  


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