Calibration
to carbon build-up, torch cleaning and wear on sample-introduction components, particularly in high- volume ICP-OES laboratories. Selecting calibration standards can also be limiting. Organometallic standards have long been the practical choice for metals-in-oil analysis, but laboratories may still have to manage shorter shelf lives, narrower element options, sulphur-specific calibration steps, supplier limitations and solvent-handling concerns. In many other areas of elemental analysis, aqueous certified reference materials can offer broad element availability, customisation options and the advantage of a longer shelf life. For oil testing, however, they have historically been difficult to use for one simple reason: aqueous standards and oil samples are not naturally compatible. That is why hybrid aqueous/bio-based organic solvent standards are gaining attention as a new calibration option for metals-in-oil testing. Rather than replacing established metals-in-oil methods, these systems are designed to give laboratories a way to use aqueous standards in oil analysis while preserving the ICP-OES workflow they already know.
WHERE THE WORKFLOW BECOMES COMPLICATED
The difficulty of metals-in-oil analysis is not limited to calibration. Used-oil samples can vary widely. One may be relatively clean and fluid, while another may be dark, viscous or loaded with particulate matter. These differences can affect sample introduction, internal-standard correction and the ability to maintain accuracy throughout a long run. “There is a wide range of viscosities, and for ICP, since you have to introduce the sample into the plasma, that presents a challenge for achieving accuracy,” says Dr Sergei Leikin, managing director of Texas Scientific Products. The analytical requirements also vary by application. In wear-metals testing, laboratories are often monitoring trends. A gradual increase or sudden spike in iron, copper, aluminium or another metal may indicate abnormal wear in an engine, gearbox, turbine or other lubricated system. For additive metals, the challenge can be different. Elements such as calcium, magnesium, zinc and barium may be present at much higher concentrations, and relatively small percentage errors can affect lubricant formulation and quality control. Maintenance is another pressure point in high- volume oil analysis.
“Carbon build-up is one of the major things that oil-analysis laboratories are facing,” Leikin says. “People are always asking how to deal with it and what can be improved.”
BRINGING AQUEOUS STANDARDS INTO OIL ANALYSIS
The idea of using aqueous standards in oil analysis has appealed to analytical chemists for years. The challenge has been finding a solvent chemistry that makes them practical for oil-based samples.
Instrumentation Monthly September 2026
More than two decades ago, Leikin saw an opportunity to address this need. With decades of experience in ICP and ICP-MS applications, including work with petroleum-related samples, he recognised that laboratories had limited options for metals-in-oil standards. In conversations with Inorganic Ventures founder Dr Paul Gaines, the question was not whether another organometallic standard could be produced. It was whether the chemistry could be approached differently.
The technical requirement was specific. The solvent system had to dissolve oil-based samples while allowing aqueous inorganic standards to remain compatible with the calibration workflow. In simple terms, it had to bridge two chemistries that would usually separate.
That idea has now progressed from a long- running technical discussion into an emerging calibration approach. Hybrid aqueous/bio-based organic solvent systems are designed to make aqueous CRMs usable in oil-based analysis while still meeting the expectations of laboratories that already use ICP-OES methods for metals in oils. One example is Inorganic Ventures’ ASOSolv, a hybrid aqueous/bio-based organic solvent system developed for the ICP-OES analysis of wear metals, additive elements, sulphur and contaminants in lubricating and edible oils. The product gives laboratories a way to use aqueous CRM chemistry without abandoning their existing metals-in-oil practices. Leikin views the shift as more than an incremental change.
“I usually try to avoid using this word, but I think it is a revolutionary approach,” he says. “It is not just innovative. It can change the industry.”
WHAT CHANGES FOR THE LABORATORY For a laboratory manager, the value begins with greater choice. Traditional organometallic standard sets are useful, but they can be limited by available element combinations, source chemistry and supplier options. A hybrid aqueous/organic approach can provide access to broader elemental coverage, more customised mixtures and the longer shelf-life advantages often associated with aqueous CRMs, while allowing laboratories to continue working within a familiar ICP-OES environment. Sulphur is another area in which hybrid aqueous/organic calibration can reduce complexity. Sulphur analysis by ICP is already possible with organometallic standards, but it often requires additional calibration considerations. “With organometallic standards, the starting materials are often sulphonated compounds,” Leikin says. “With a hybrid aqueous approach, those issues are eliminated because the solvent does not contain sulphur, so sulphur can be included in the same calibration operation.” Cleaner operation is a third consideration. Solvent chemistry designed to burn more cleanly may help
limit carbon residue in the sample-introduction system. This does not necessarily mean that a laboratory will process more samples per hour. The more realistic benefit is reduced maintenance pressure: less build-up, fewer cleaning interruptions and potentially less wear on components over time.
Hybrid solvent systems should not be presented as shortcuts around method discipline. They are calibration options for laboratories seeking to reduce known constraints while maintaining analytical control.
VALIDATION COMES BEFORE ADOPTION A new calibration approach must do more than work in principle. It must produce comparable results, remain reproducible and fit the realities of established laboratory methods.
As Leikin explained, a laboratory manager evaluating a new technology needs confidence that changing methods will produce the same value within an acceptable statistical range—not only once, but consistently.
Inorganic Ventures evaluated its hybrid aqueous/organic calibration approach against traditional organometallic standards and NIST SRM 1085c, a standard reference material for wear metals in lubricating oil. The reported results for the evaluated organometallic standards, run as unknown samples, were largely within two per cent of the certified values. The validation also included NIST SRM 1085c. For an oil-testing laboratory, this type of comparison addresses the first question behind any method change: will the new approach produce figures that agree with trusted reference materials?
“NIST reference materials are the gold standard internationally,” Leikin adds. “If you hit the number within two per cent to three per cent, that puts the question to bed in terms of whether the validated method of analysis can provide an accurate number.” Adoption will still require evaluation by individual laboratories. Laboratories will need to review accuracy, reproducibility, matrix behaviour, internal-standard performance, method compatibility, cost, logistics, shipping classification and waste handling. Laboratories that closely follow ASTM methods may also look for clearer recognition within established method frameworks. Hybrid aqueous/organic calibration does not remove the need for method validation, nor does it make established organometallic workflows obsolete. It gives laboratories another option to consider when carbon-related maintenance, limited elemental flexibility, sulphur calibration or standard stability become persistent constraints. For laboratories that have traditionally had to keep aqueous CRM chemistry separate from oil-based analysis, the ability to bring the two together could be one of the most significant advantages.
Inorganic Ventures
www.inorganicventures.com 57
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