High Temperature and Pressure Automated Sequential Microwave Digestion of Bunker Oil

September 1, 2015
Tina Restivo , CEM Corporation , Matthew Nigro

Application Notebook

Issue 0

CEM's Discover SP-D Gold microwave digestion system with high temperature and pressure chamber enables safe, fast, and automated preparation of previously difficult sample types

CEM's Discover SP-D Gold microwave digestion system with high temperature and pressure chamber enables safe, fast, and automated preparation of previously difficult sample types. The world's first and smallest automated high pressure microwave system, allows you to analyze sample sizes up to 2 g with individual temperature and pressure programs in a load and walk away automated platform. The SP-D Gold eliminates the challenge of batching similar matrices, while improving throughout and maximizing method parameters for the best possible digestion in half the time of any system on the market.

Summary

Bunker fuel oil quality testing supports the world's shipping industry, helping reduce the risk of engine problems and failures. Bunker fuel laboratories test to international industry and regulatory standards. Many of these test require state of-the-art trace metal analysis instrumentation includes inductively coupled plasma spectroscopy (ICP), ICP-mass spectrometry (ICP-MS), GC–ICP-MS, HPLC–ICP-MS, scanning electron microscopy (SEM-EDX), and other proven analytical techniques for finding and characterizing trace metals and metallic molecular species in materials and products. In most cases, these samples need to be processed before trace metal analysis can be performed. This includes digesting the sample in order to get a clear solution suitable for analysis. This is most effectively completed using a proven technique called microwave digestion, but when it comes to bunker oils and other tough-to-digest samples, there are more extreme methods of digestion employed such as high pressure microwave digestion.

In this application note, two bunker oil customer samples were completely digested in triplicate.

Instrumentation

CEM's Discover SP-D Gold microwave digestion system with automated 24-sample rack using 80 ml HPQ vessels. VWR Hotplate/Stirrer.

Method Details

Samples were heated on a hotplate for a few minutes in order to decrease viscosity for manageable sample handling. A 0.25 g sample was weighed into each of 6 vessels and combined with 10 mL nitric acid and capped. The vessels were loaded into the auto sampler and programmed to run according to Table I. The samples were then diluted to volume with DI water in preparation for analysis.


Table I: Discover SP-D Gold Method

Results

All of the samples were completely digested, yielding clear solutions without any remaining particulate or undigested material. Total digestion time was 20 min per sample. Figure 1 shows bunker oil before and after digestion.


Figure 1: Bunker oil pre and post digestion.

Conclusion

Bunker oil poses significant sample prep challenges, which can be overcome with the use of high pressure microwave digestion. Traditional microwaves have fallen short when trying to create a clear matrix for accurate and precise detection. The Discover SP-D Gold provides laboratories with the necessary flexibility to successfully digest even the most difficult sample types using a batch or individual sample method. The SP-D Gold will increase throughput, reduces labor, and save space making CEM the clear solution.

CEM Corporation
P.O. Box 200, Matthews, NC 28106
tel. (704) 821-7015, fax (704) 821-7894
Website: www.cem.com