If you asked Canadian petroleum chemist J.S. Charlesworth in 1947 what the most important characteristic of lubricating oil was, he would have said, Viscosity1. After all, he said, “it’s a measure of the oil’s resistance to flow, or of its internal friction…[i]t indicates…the ability of an oil to support loads.” At just about the mid-20th century, the American Society of Testing and Materials (ASTM) published a set of standards for the measurement of viscosity of petroleum products2. Of course, the importance of viscosity is well known today, and there are standard methods worldwide to ensure uniformity of testing.
- Is your instrument optimized?
In a recent blog we explored the importance of instrument optimization for ICP-OES and ICP-MS, but all instruments should be frequently checked to confirm they are operating as expected. Preventive maintenance and appropriate start up and shut down SOPs are key to the integrity of analysis.
An ICP-MS system will operate and deliver numerical data even if not set up correctly or operating at expected levels. As discussed in a previous blog, , internal standards can be used to compensate for a variety of factors that degrade analytical performance, however, proper instrument set-up is core to data integrity. As a result, tuning of ICP-MS instruments is considered by most users to be a daily, if not more frequent, activity, and a prerequisite for achieving accurate results. Best practices dictate, and many standard methods require, that a sample sequence begin with an optimization block, during which a tuning solution is used to set-up the instrument.
ICP-OES is the go-to-technique across a number of industries, and when configured correctly, today’s instruments yield detection limits of 1 to 10 ppb for the majority of elements. Although a powerful elemental analysis technique, it is in fact a simple comparator, incapable of making absolute measurements.