Embracing IR

Dr Jerry Sellors examines recent technological advancements in IR and looks at how the technique is meeting diverse industry demands Infrared spectroscopy (IR) is a well established technique in analytical chemistry, but recently, many industries looking to perform rapid, accurate sample testing, both on-site and remotely, have also embraced IR. Today, the technique is proving to meet wide-ranging analytical needs in a number of diverse sectors – from examining petrochemical biodiesel blends to meeting the challenging investigative needs of industrial and academic researchers.

Across the board, these industries are looking to characterise and qualify materials as quickly and accurately as possible, with methods that can be employed by a wide selection of personnel – no matter what their level of experience. Confidence in results is key, as is the need to perform analyses in many different locations, whether in the laboratory or out in the field.

The fuel industry is governed by many international regulations. Blending biofuels with fossil fuels for use in diesel engines is now commonplace, necessitating regulation to assure biodiesel blend conformance. Strict testing procedures to measure biodiesel concentration are vital in the marine and aviation industries, where biodiesel is an undesirable fuel contaminant. Benzene levels must also be closely monitored in all types of fuels. Failure to comply with regulations can lead to serious repercussions. Analysing the concentration of biodiesel in distillate fuels is therefore becoming increasingly important; both to verify blend concentrations and to detect trace levels of FAME in supposedly pure distillate. As such, a rapid and precise method of quantification of FAME in diesel fuel blends is essential, and FT-IR spectroscopy offers just that.

Very low levels of biodiesel can be detected in diesel samples using FT-IR spectroscopy. Although both ASTM D7371 and EN 14078 methods are effective for standard blend measurements (1% to 30%), the better sensitivity attainable with a transmission measurement gives EN 14078 the edge over ASTM D7371 for trace measurements, with a detection limit of tens of ppm. Both methods are very easy to use with support from modern instruments and intuitive software.

Lubrication is a vital component of machinery and, as with any component, early detection of wear is essential for timely replacement. This helps avoid unnecessary maintenance while reducing the risk of catastrophic breakdowns. Oil inevitably degrades with use and is exposed to various sources of contamination, both internal and external, which can lead to its degradation and reduced effectiveness in protecting vital components. Early identification of impending lubricant failure can prevent costly damage.

Infared analysis is a rapid, inexpensive test that can provide specific information about the chemical condition of oil and lubricants, also allowing inferences about the state of the machine component from which the sample was taken. Trend data can be gathered by regular sampling to monitor engine performance and operating conditions. This allows the oil to be changed at optimal intervals, which has two major benefits. Costs are reduced by carrying out the oil change only when necessary, and problems are identified early, which allows the appropriate preventative steps to be taken. IR measurements are sensitive to a number of additives, degradation products and potential contaminants that can be found in oil.

Common contaminants include soot (a by-product of incomplete combustion), water and glycol (both indicating a leak from the cooling system) and unburned fuel (an indication of poor combustion). In terms of degradation, oxidation can occur when oil is exposed to oxygen at elevated temperatures. This leads to thickening, varnish formation, a build-up of carboxylic acids and eventual corrosion. Nitric oxides can oxidise oil and acidic sulphur compounds also have corroding effects. Plus, synthetic oils with a polyol ester base are susceptible to hydrolysis at elevated temperatures if water is present.

Dichloromethane near IR spectrum

Additives that confer desirable functional properties are often depleted during lubricants’ lifecycles, and monitoring this depletion can provide an early warning of impending failure. Anti-wear additives such as zinc di-alkyl or di-aryl dithiophosphates (ZDDPs) prevent direct metal-to-metal contact by forming a coating on metal surfaces activated by frictional heat. These additives can be depleted by hydrolysis or oxidation, and this can result in an increase in wear rate. Phenolic antioxidant compounds are often used in turbine lubricants. Depletion of the antioxidant is followed by a rapid increase in the rate of oxidation.

The benefits of oil condition monitoring can be further increased by complementing routine measurements at a centralised laboratory with more rapid on-site analysis using transportable instrumentation. Recent advances in IR technology mean it is now feasible to achieve the same high quality result both in the laboratory and out in the field.

In today’s academic laboratories, students and researchers alike need to collect accurate, reliable results. And for universities to continue to attract the highest calibre of students, it is important that they have up-to-date technologies accessible in teaching laboratories. Equipment is often required to meet the demands of performing everyday analyses in teaching laboratories, while also delivering the quality of data required for research applications.

“These industries are looking to characterise and qualify materials as quickly and accurately as possible, with methods that can be employed by a wide selection of personnel – no matter what their level of experience”

Recent technological advancements in IR are helping meet these needs. For example, new instruments on the market break new ground in operational simplicity without compromising performance, allowing novice users to perform analyses at the touch of a button, while delivering the quality of data required for research applications.

Dedicated resource packs for academic environments are also adding significant value in the academic sector. These guides save valuable experimental design time for course developers. Providing comprehensive experimental documentation, they help create a high quality, modern teaching curriculum that is attractive to students and can also be customised for institutes’ individual requirements. This saves teachers a substantial amount of time in developing experimental practicals for a range of different courses.

The latest FT-IR microscopy and imaging systems can also significantly reduce the time it takes to view a complete chemical picture of samples. In some cases, a full day of work is reduced to a mere half an hour. Researchers and students can therefore view information they have never seen before while enjoying significant speed advantages.

Advancements in IR engineering have also resulted in a number of compact instruments being launched lately. Their smaller size helps organisations make use of smaller benches or fume cupboard space, while features such as WiFi connectivity and cable-free operation increase flexibility of use and maximise teaching and research capabilities.

In contrast to academic laboratories, those performing IR analyses in the polymer manufacturing sectors may not have a scientific or technical background and it is often not possible to use an experienced analyst on site. Therefore, polymer analysis systems that are easy for untrained personnel to use are in demand. Polymer QC increasingly takes places in-house, even with smaller manufacturers, where a laboratory environment is not a viable option. Instruments that ensure low maintenance costs make on-site analysis possible for small or mid-size manufacturers. For example, Spectrum Two features a unique humidity shield to protect the instrument from degradation in harsh environments, as well as an interferometer mechanism that does not require specific maintenance or alignment.

In any kind of manufacturing plant, reduced downtime and process efficiency are vital. The competitive polymer market is no exception. There is also often a requirement to perform measurements closer to production and receiving lines. In these cases, IR spectroscopy provides an option for rapid, accurate polymer analysis. With a variety of sampling accessories available, IR analysis can be used in a range of QA/QC procedures and for characterising polymer additives. For example, ATR can be used to identify contaminants, which is essential when using PET recyclate. Confirming the quality of the material and the correct grade is also important with recyclate, where the material can degrade over time.

A further step in QC is to ensure that the raw material you received is exactly what you ordered. It is far more cost-effective to analyse material pre-production, rather than discover a problem in the finished product. Microscope imaging systems can also help operators visualise the chemical composition of a diverse range of end products and intermediates. This greater understanding accelerates product development and quality trouble shooting, providing information to aid process improvements, reducing costs and increasing competitiveness.

IR is an analytical technique that addresses a diverse range of applications and end industries. Thanks to the latest generation of instruments, even inexperienced users can obtain answers faster, easier and in more locations than ever before. By enabling more users to generate accurate, reliable results, IR helps companies maximise time and resources and provides a welcome boost to productivity.

Author: Dr Jerry Sellors, IR business manager, PerkinElmer Analytical Sciences and Laboratory Services

Contact t: +44 (0) 1494 679 248 f: +44 (0) 1494 679 331 e: jerry.sellors@perkinelmer.com w: www.perkinelmer.com