Introduction
The Trident CT mixing tee is based on the industry-proven design of the Trident, but with the addition of Glass Expansion’s ConstantTorque™ (CT) technology to provide a simple-to-use, leak-free connection for both the internal standard and sample, every time.
The heart of the Trident CT In-Line Reagent Additions Kit is the new CT mixing chamber (Figure 1). It is designed with zero dead volume CT ratchet style ¼-28 fittings on the sample and IS inlets, in addition to the outlet to the nebulizer. The use of inert, metal-free, ratchet fittings provides simple-to-use, leak-free, zero-dead volume connections for the internal standard and sample, every time.
With other mixing chambers, worn or incorrectly fitted connections can leak, injecting a stream of air bubbles into the nebulizer flow, which can degrade short-term analytical precision (%RSD). By using CT ratchet style fittings, the Trident CT eliminates air leaks, optimizing analytical performance.
Like the previous design, the Trident CT provides a complete solution for a simple, easy and error-free way to continuously add IS or ionization buffers in ICP spectrometry. The Trident CT In-Line Reagent Additions Kit is completely modular so that damaged or lost components can easily be replaced. A schematic of the Trident CT is shown in Figure 2 (peristaltic pump shown for reference only, not included).
Results
A comparison of the IS stability and precision achieved with and without the Trident is shown in Figure 3. The stability of IS signal with the Trident closely matches the sample set that was manually spiked with IS. Over a period of 85 minutes, an IS signal precision of 0.4% RSD is achieved with the Trident compared to 0.7% where the IS was manually added. These results show that the performance of in-line addition with the Trident is at least as precise as a manual addition.
A comparison of the relative signal intensity and IS precision (%RSD) achieved with the new Trident CT and original Trident is shown in Figures 4a and 4b, respectively. Both sensitivity and precision results indicate no significant differences. The 14-line average sensitivity advantage for the new Trident CT compared to the original Trident was 1 %, whereas the average IS precision obtained with both the Trident CT and original Trident was 0.7 %. These test results were important to confirm the new Trident CT design matched the performance of the industry standard, the original Trident design. With identical analytical performance, the new Trident CT simply offers a design to improve the reliability of proper installation and eliminate air leaks due to worn or incorrectly installed fittings.
Since in-line addition with the Trident relies, in part, on the stability of the IS uptake rate via the peristaltic pump, it is important to check the condition of the peristaltic pump tubing and the tension of the clamp. The TruFlo™ real-time sample monitor2 is a very useful tool to diagnose any problems associated with sample tubing or the nebulizer. Pump tubing wear can be slowed by lubricating the pump rollers with the EzyGlide cloth (P/N 70-EZG-CLOTH). This improves precision, reduces drift, and extends the period between recalibrations.
Glass Expansion also offers a complete range of contour flared-end pump tubing, making it easy to connect capillary tubing to small-ID pump tubing. Our contour flared-end pump tubing is available in a range of sizes and materials to suit all applications.
Self-aspiration is an alternative delivery method to the more common peristaltic pump. In some cases, ICP-MS laboratories choose self-aspiration for improved precision by eliminating the pulsations from the peristaltic pump that are more pronounced at very low uptake rates. The Trident CT, when paired with a Glass Expansion concentric nebulizer, can self-aspirate both the sample and IS, providing a means of in-line addition of an IS via self-aspiration. Glass Expansion also offers a complete line of high-quality PTFE encapsulated carbon fiber autosampler probes that can be directly connected to the Trident CT mixing chamber via a zero dead volume connection providing a stable and consistent sample uptake. The previous results showed that the IS stability obtained using the Trident and manual addition is indistinguishable when using self-aspiration.
