Direct injection high efficiency nebulizers DIHEN

The second type of direct injection nebulizer, called the direct injection high-efficiency nebulizer (DIHEN), is a specific type of the Meinhard HEN [38] that is inserted into the ICP torch in place of the center, injector tube. The main advantage of the DIHEN compared to the Cetac DEN is that a high-pressure pump is not needed to deliver sample to the nebulizer. An unusually low nebulizer gas flow rate (0.25 L/min) and high ICP power (1.5 kW) were found to provide optimal ICP-MS sensitivity when DIHEN is used [38]. 

They were initially developed over 15 years ago and found some success in certain niche applications that could not be adequately addressed by other nebulization systans, such as introducing samples from a chromatography separation device into an ICP-MS or the determination of mercury by ICP-MS, which is prone to severe memory effects. Unfortunately, they were not considered particularly user-friendly, and as a result became less popular when other sample introduction devices were developed to handle microUter sample volumes. More recently, a refinement of the direct injection nebulizer has been developed, called the direct inject high-efficiency nebulizer (DIHEN), which appears to have overcome many of the limitations of the original design. The advantage of the DIHEN is its ability to introduce microliter volumes into the plasma at extremely low sample flow rates (1-100 pL/min), with an aerosol droplet size similar to a concentric nebnlizer fitted with a spray chamber. 

To overcome these problems, many kinds of micronebulizers, such as a total consumption micronebulizers with a low-volume spray chamber and direct-injection high-efficiency nebulizer (DIHEN),have been developed for interfaces of HPLC to ICP-MS. In comparison with the traditional interface, these devices can minimize the dead volume, improve the nebulization efficiency, and allow efficient coupling of HPLC to ICP-MS. Another method in HPLC/ICP-MS is to use post-column sheath flow, which ensures the eonstant sensitivity of ICP-MS during HPLC gradient elution. ... 

Todoli, J. L. and Mermet, J. M. (2001) Evaluation of a direct injection high-efficiency nebulizer (DIHEN) by comparison with a high-efficiency nebulizer (HEN) coupled to a cyclonic spray chamber as a liquid sample introduction system for ICP-AES. J. Anal. At. Spectrom., 16, 514-20. 

USN Ultrasonic Nebulizer DIHEN Direct Injection High Efficiency Nebulizer. 

DIHEN An abbreviation for direct injection high-efficiency nebulizer. 

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