To achieve peak performance from your ICP-OES and ICP-MS, it is essential that you first choose the proper nebulizer based on your sample types. Once your ICP laboratory has standardized on a particular nebulizer model, it is crucial that you follow a regular and proper maintenance procedure. This will enable your ICP laboratory to continuously maintain expected levels of performance, in addition to extending the lifetime of your nebulizer. It is also important that your ICP analysts learn how to properly identify performance issues specific to the nebulizer. This will minimize the wasted analysis time spent troubleshooting other sample introduction components.
In this article we detail a complete guide to nebulizer care, listing a step-by-step nebulizer maintenance procedure, featuring Glass Expansion’s easy-to-use Eluo™ nebulizer cleaning tool. We also point out nebulizer maintenance practices that should be avoided to prevent damage to the nebulizer and provide methods of identifying an issue specific to nebulizer performance.
Introduction
Glass Expansion is an international supplier with over 30 years of experience in manufacturing ICP-OES and ICP-MS sample introduction components. Our products are made in-house, in our world-class manufacturing facilities to our exacting standards. These designs are often supplied as standard equipment on many ICPs because of their reproducibility, longer lifetime, and dependability. Glass Expansion’s most popular product designs include our extensive line of concentric nebulizers, including trademark models such as the MicroMist, SeaSpray, Conikal, and DuraMist.
The nebulizer maintenance procedures that follow are specific to Glass Expansion nebulizer designs; however, many of these guidelines apply to other nebulizer manufacturers. We suggest you contact your nebulizer manufacturer for their recommended maintenance procedure, as all nebulizer models are not the same and, as we have noted, improper care can lead to shortened lifetime and damage.
Maintenance Practices to Avoid
First, let’s cover how your ICP laboratory can prevent damage:
- Do not insert anything through the orifice of the nebulizer, including wires and probes. This is most likely to damage the nebulizer beyond repair.
- Never touch the nebulizer tip. Any deposit of body oils can have a detrimental effect on the performance of the nebulizer.
- Do not use any concentration of HF to clean a glass or quartz nebulizer. Even dilute HF can alter the orifice of the internal capillary and deteriorate the performance of the nebulizer.
- Do not place a glass nebulizer in an ultrasonic bath as it may dislodge the internal capillary.
- Do not use hot liquid to flush the sample capillary of an inert nebulizer. The temperature can potentially deform the capillary and affect nebulizer performance.
If a high nebulizer back pressure is observed, you likely have a partially blocked or clogged nebulizer. A blocked nebulizer can also be identified by a decrease in your sample uptake rate. Glass Expansion’s TruFlo sample monitor (Figure 2) provides a real-time digital display of the sample uptake rate. The actual sample flow is shown on the TruFlo’s inbuilt digital display, and a graph of flow vs. time can also be displayed on your computer. This enables the analyst to take immediate corrective action if there is a nebulizer blockage in the middle of an analysis, peristaltic pump tubing is worn, or the tension on the pump tubing clamps is incorrect. In addition to monitoring your nebulizer back-pressure, your laboratory can also record your normal sample uptake rate, to ensure you are using the same uptake rate from day to day. The TruFlo sample monitor is an essential tool for any ICP laboratory attempting to improve the day-to-day performance of their nebulizer.
Particulates
The most common nebulizer blockages are due to salting or particulates. Particulates are small undissolved solids that remain in your samples, either due to incomplete digestion, errant fibers from pre-filtering steps, or contamination from the laboratory environment. Some particulates are impossible to remove from the nebulizer, requiring your laboratory to ultimately replace the blocked nebulizer. To eliminate the risk of particulates getting trapped in your nebulizer, Glass Expansion developed the Guardian inline particle filter, which is a reusable filter (P/N 70-803-1108).
The Guardian features a 120-micron PEEK filter within its housing, which can be installed on your sample uptake line between the autosampler probe and nebulizer. The filter is easily cleaned by back flushing, using an adaptor (P/N 70-803-1160) connected to the Eluo Nebulizer Cleaning Tool. This allows your laboratory to quickly clean the filter each day without production interruption and greatly extends the lifetime of your nebulizer by preventing blockages.
The best cleaning procedure for the inline filter is to do a quick soak (~5min) in a 25% Fluka RBS-25 solution, sonicate the assembly for ~5min, then backflush 3 times with warm DI water using the Eluo tool and backflushing adapter. If you do not wish to use the Fluka RBS- 25, a similar glassware cleaner or even dilute acid will help. The TruFlo can be used to alert the analyst when the inline filter needs to be backflushed in addition to optimizing nebulizer conditions.
Conclusion
Proper care combined with regularly scheduled maintenance of your nebulizer will help to maintain optimum performance and increase the lifetime, reducing your laboratory’s nebulizer replacement costs. Establishing daily nebulizer performance checks and being able to quickly identify ICP performance issues related to the nebulizer will greatly reduce instrument downtime. Accessories, such as the Eluo, Guardian inline filter and TruFlo, monitor greatly improve and simplify the task of daily nebulizer maintenance, while also protecting one of the most critical sample introduction components of your ICP.
Glass Expansion’s Quality Assurance Kit (P/N KT-1136) combines all the nebulizer maintenance tools discussed in this article: Guardian inline filter, backflushing adapter, Eluo nebulizer cleaner, and TruFlo sample monitor. This complete kit provides your ICP laboratory with all the tools necessary to protect and maintain your ICP nebulizer.
Glass Expansion’s intimate understanding of the relationship between the various sample introduction components, together with our expertise in manufacturing high-quality nebulizers, spray chambers, torches, ICP-MS cones and ICP accessories, means that we can offer you a complete solution regardless of your sample matrix. Visit us at www.geicp.com or contact us at enquiries@geicp.com to find the best solution for your ICP laboratory.
References
1. Glass Expansion Newsletter, February 2016 Issue, “The Elegra Argon Humidifier: Uninterrupted and Maintenance-Free ICP Operation.”'
2. Glass Expansion Newsletter, June 2017 Issue, “Considerations when Analyzing Real-World Samples by ICP Spectrometry.”
