On-Site Analysis, Inc. 

Analysis Methods Used in OSA

Wear Metals

OSA measures the individual concentrations of twenty-one metal elements often found in used lubricating oils.  These originate from wear metals, additives and contaminants.  The phenomenology used is arc-spark optical emission spectroscopy wherein the sample oil is pumped between two, ultra pure, silver electrodes across which a high current spark is sustained to vaporize the metallic compounds entrained in the oil.  The optical emission spectrum resulting from electron transitions in the vaporized metals is collected via two solid-state fiber optic spectrometers.  Characteristic emission lines for each element appear in the spectra.  Their intensity is proportional to the elemental metal concentration(s) found in the oil for particles sizes in the fractional to ten mm range.  This is somewhat better than the five mm upper detection limit of ICP instruments used by many labs that are limited by both the sample dilution that is usually necessary and by the fine droplet size of the aerosol.  A further consideration is the ability of the particular sample oil to suspend large particles.  Because no dilution of the sample is necessary with OSA, larger metallic particles remain in suspension.

Each metal has multiple emission lines.  The lines chosen to quantify the metal concentration are those that present the least amount of mutual spectral interference with the other elements that may be present in the oil.  Two lines are used for many of the metals.  Most of the emission lines appear in the ultraviolet from 200 nm to 340 nm.  Several elements are quantified using emission lines in the visible and near infrared from 400 nm to 780 nm.  To accommodate this broad spectral range while maintaining adequate resolution, two spectrometers are used.  These are solid-state, diode array devices with diffraction gratings as the dispersive elements.  The emission spectra are collected through a single objective lens inserting into a bifurcated fiber optic cable that connects to each of two spectrometers.

The metals measured are: Al, Ba, B, Ca, Cu, Cr, Fe, Pb, Mg, Mn, Mo, Ni, P, K, Si, Na, Sn, Ti, V, Zn.  Concentration ranges measured for each element are appropriate to the source or purpose of each analyte.  Silver is not measured because the electrodes are silver.  A very strong silver spectrum results.  Certain silver lines are used in calibrating and normalizing the spectra.

A more comprehensive discussion of the OSA metals analysis is available separately.

Viscosity

OSA is available with an optional viscometer that measures kinematic viscosity at 100°C.  Instruments so equipped can measure viscosities in the range of 0 to 24 centistokes with ±0.5 centistokes accuracy.  The viscometer utilizes an oscillating piston driven by two solenoid coils.  The frequency of the piston is inversely proportional to viscosity.

Total Base Number

OSA incorporates a mid-infrared, liquid phase, absorbance spectroscopy module for measurement of a number of physical properties of used oils.  The unit measures absorbance of the sample in a 90 mm path length cell in the infrared spectrum between 2 and 15 mm wavelength.  The TBN value of the sample is predicted by a chemometric algorithm corresponding to ASTM method D4739.  The algorithm was generated by modeling a large matrix of lab-rated, used oils with diverse brand, type, application and usage.  All samples used in constructing the model were collected from laboratories that used ASTM method D4739 to measure TBN. 

A model for prediction of TBN corresponding to ASTM method D2896 is available as a substitution for D4739 when requested.

Oxidation

Oxidation is another property measured with the IR module.  A chemometric prediction model based on a large matrix of used oils lab-rated by ASTM method E168 is utilized.  As is common practice among laboratories using FTIR analysis to measure oxidation, the model gives emphasis to the large absorbance feature centered at 1730 wavenumbers.  This is a somewhat ambiguous peak resulting from a collection of carbonyl-containing, degraded and oxidized products of oil.  Ester-based synthetic oils can interfere strongly with correlation of this peak with oxidation.  Fortunately, synthetic oils are highly oxidation resistant and this property can usually be safely ignored when synthetic oil is used.  The OSA prediction model utilizes broad spectral information to correct for spectral interferences to the greatest extent possible.

Nitration

As with oxidation, OSA uses a prediction model developed from a sample matrix lab-rated using ASTM method E168.  Nitrogen oxide fixation, due mostly to nitrate esters, results in a strong absorbance at 1630 wavenumbers.  Again, the chemometric modeling process develops interference corrections and higher order correlations with other spectral features to minimize interference in this “busy” spectral region.

Soot

Soot suspended in diesel engine oils is measured by the IR module using a prediction model based upon a matrix of used oils lab-rated by thermo-gravimetric analysis (TGA).  Primary spectral information is obtained at 2220 wavenumbers where an absorbance window exists in hydrocarbons.  Other spectral information is used by the model to enhance accuracy.  With undiluted samples, OSA can measure soot concentrations up to approximately 4% before opacity occurs in the 90 mm path length sample cell.  For soot levels in excess of 4%, sample dilution procedures provided with OSA permit measurement of soot levels in excess of 12%.  OSA software will detect IR spectrum opacity from soot and will so indicate on the report.

Water

The infrared module can quantify water content with a ±0.2% accuracy between 0 and 3% concentration.  Higher amounts of water tend to separate from the oil.  The broad spectral peak centered at 3400 wavenumbers provides primary information to the water model developed based upon samples rated by E168.  As distinct from laboratory FTIR methods measuring peak height, spectral interference from glycol is substantially corrected.

Glycol

Glycol has infrared absorbance peaks at 3400, 1080,1040 and 880 wavenumbers.  The OSA prediction model uses all of these as well as other spectral information to correct for interferences from water, sulphation products, etc.  OSA measures glycol with approximately the same accuracy as water.  When glycol is indicated, a very reliable confirmation can be obtained by the presence of sodium or potassium coolant trace indicators present in the OES metals analysis.

Gasoline Fuel Dilution

The gasoline prediction model for the IR module in the OSA performs well.  It is based on a matrix of over 500 used oil samples lab-rated according to E168.  It can be expected to perform with an accuracy of ±1.7%. 

Diesel Fuel Dilution

It is difficult to accurately measure diesel fuel dilution in used oil by any analytical method.  This is especially so after the fuel has weathered under crankcase conditions.  OSA uses a mid-infrared chemometric model to predict diesel fuel dilution.  The accuracy of this model is no better than ±5%.  As such it is suitable only for screening. Both false negatives and positives are possible.  By comparison, FTIR lab methods are limited to measuring diesel fuel dilution only when the spectrum of the used oil can be directly compared to a spectrum of the same brand and type of oil.  Even as much as 20% diesel fuel dilution produces only minor changes in the spectrum of the diluted oil; less than the differences in the spectra that can be seen among a variety of undiluted oils.

For OSA’s equipped with viscometers, an indication of fuel dilution based upon viscosity depression can be provided on the report.  This method follows the common lab practice of indicating fuel dilution when the viscosity of the sample measure 15% or more below the bottom of the viscosity bracket for the original grade of the sample oil.  Upwards of 10% fuel dilution may be present before the viscosity depression reaches this threshold.

A2 Technologies

Headquartered in Danbury, Connecticut, A2 Technologies is taking FT-IR spectroscopy out of the lab and into the field. A2 Technologies manufacture and develop portable FT-IR spectrometers designed for the analytical needs of the petrochemical, environmental, metals and mining and general environments where there is a need for analysis. The portable FT-IR analyzers extend the proven capabilities of Fourier Transform infrared technology by rendering sample preparation obsolete and ensuring real time results.

SCAVINI, ITALY

Since 1956 Scavini & Co. manufacture petroleum testing apparatus. A well trained staff of electrical and mechanical engineers permits us to continuously update our products to the state-of-the-art technology and to the new requests coming from the market.

In the early 70's Scavini manufactured its first automatic analyzers. Today, after 40 years since its foundation, Scavini is a dynamic enterprise capable to realize hi-tech equipment.

OMNITEK v.o.f, the Netherlands

OmniTek was founded in 1979 by William Wagelaar. Over the course of the past decade, two strong product lines have emerged from our continuous effort to provide the industry with smart and innovative measuring solutions : our moisture analysers for plastics and viscometry systems for mineral oils both offer unique advantages to their users, that sets them apart from the competition entirely. The instruments we offer have all been developed from a direct need in the market.

ORBIS BV, the Netherlands

Orbis BV is specialized in production, development and selling of analytical instruments for chemical, petrochemical and petroleum industry. The ORBIS Precision Automated Distillation Unit (PAM-Distillation) is the final result of the "ORBIS Basic Line" Distillation Units.  NEW ORBIS  Revolutionary "Volume-Scan" System is accurately measuring the true recovered volume at the bottom line of the meniscus, eliminating volume measurement errors. Ring marks on receivers do not disturb the volume measurement using this technique - Automatic calibration of the volume measuring system is performed before each distillation start -Solid-state volume detection and receiver cooling technique. - Recovered volume and receiver temperature is displayed on a large display at the front panel of the receiver compartment.

C.I. Analytical

C.I. Analytical, provides innovative products used for chemical analysis. We develop, manufacture, sell, and service analytical instruments that detect, measure, analyze, and monitor chemicals in liquids, solids, and gases.

C.I. uses various technologies in its instruments, matching the technology to the application, ensuring that each analytical requirement of the client is met. Technologies include Dry Colorimetry (Tape Detection), Chemiluminescence (Sulfur and Nitrogen), Gas Chromatography (GC), Flame Ionization Detection (FID), Photo-Ionization Detection (PID), and UV-Fluorescence.

Our Products include laboratory and on-line analyzers to detect:
Arsine, Ammonia, Sulfur, Nitrogen, Chlorides, Phosgene, Hydrogen Sulfide, hydrogen cyanide and analyzers using GC-detectors.

CARVER, USA

For over 85 years, Carver hydraulic presses have set the standard for laboratories around the world. Here you'll find the widest array of standard choices for nearly any application. Find out more about us.

Our standard laboratory presses include two-column and four-column, benchtop and floor standing; manual and automatic presses. We have also just introduced our new "E" Series Electric Presses. Carver, Inc. also has a complete line of laboratory press accessories.

Real-Time, USA

C2V, the Netherlands

C2V is an international company specialized in fast micro GC. The versatile technologies and products provide value to industrial process applications, security, telecom and life sciences.

C2V's revolutionary micro GC (Gas Chromatograph) technology creates unique opportunities for fast volatile detection at any location. C2V offers a fast micro GC gas analyzer module and it can be ordered as a standard single instrument (the C2V-200), but we can also supply customized lower cost OEM modules in higher volumes.

Lamy Rheology, France

LAMY RHEOLOGY company is specialized in the trade of scientific materials since 1957, with very quickly , a dominating share given to the Rheology activity.

Since 2006, all the range of the rotative viscometers and rheometers of LAMY RHEOLOGY are developed and manufactured in France, in our buildings located close to Lyon; it is diffused in the whole world, thanks to effective partners.

SITE-LAB, USA

Sitelab Corporation manufactures portable test kits to measure petroleum contamination in soil, sediment and water.  Sitelab uses ultraviolet fluorescence technology (UVF) to detect concentrations of hydrocarbons commonly found in gasoline, jet fuel, diesel fuel, heating oils, waste oils, coal tars, coal ash, creosote, crude oils and many other petroleum products.

Physical Sciences Inc.

Physical Sciences Inc. (PSI), a leading developer of advanced aerospace technologies, announced the award of a contract to develop techniques and technologies that will allow next-generation MAVs to reliably operate in cluttered, harsh environments. This effort, funded through the Air Force's Office of Scientific Research (AFOSR), will focus on understanding and applying biomimetic principles observed in insects and birds to allow MAVs to recover from collisions with obstacles quickly, and undamaged.