Membrane inlet mass spectrometry (MIMS) is a detection and measurement methodology using a mass spectrometer capable of partitioning analytes based on their physiochemical properties. It is commonly applied for the quantitative analysis of dissolved species in a liquid medium.
MIMS processes use mass spectrometers with an inlet probe featuring a semipermeable partition, or membrane, to separate volatile compounds from a bulk liquid sample before they are channelled into the mass spectrometer. This allows for accurate real-time measurement of these species of interest when dissolved in a solution, with sub-parts per billion detection levels.
MIMS equipment has conventionally been used for industrial and research applications, including: soil core analysis; groundwater studies; environmental monitoring; and more. Most recently, a study has introduced its potential in the complex field of nitric oxide (NO) detection.
The biochemistry of nitric oxide remains a subject of debate. There are multiple conventional and emerging methodologies for both direct and indirect NO detection in liquid samples. However, each of these strategies is severely limited by complicated considerations. NO is intricately involved in a range of physiological processes including oxidative stress, cellular signalling, and vascular dilation. As such, accurate quantification of NO is crucial for ongoing research into health and disease.
This study explored the potential of MIMS-enabled mass spectrometers to detect NO in various fluidic solutions, using a Hiden Analytical HPR-40 DSA membrane inlet mass spectrometer with a quartz probe assembly for the comprehensive filtration of NO particles generated chemically from solutions such as sodium nitrite and MAHMA NONOate. It is also capable of monitoring NO which is generated enzymatically by nitric oxide synthase.
The mass spectrometer array allowed for direct and continuous measurement of nitric oxide in liquid solutions with a lower detection limit of 10 nM and a linear response to 50 μM. This allowed the researchers to continuously measure dissolved nitric acid in a range of concentrated solutions with response times of 3 – 4 seconds. This promising research is ongoing. (1)
MIMS Mass Spectrometers from Hiden Analytical
Hiden Analytical are experts in the design, development, and supply of dedicated quadrupole mass spectrometers for a range of applications. We have developed a reputation for providing bespoke instrumentation for studies and industrial purposes, tailoring our intuitive machinery to customers’ unique requirements.
The HPR-40 DSA MIMS system is a pre-configured mass spectrometer capable of performing accurate dissolved species analysis for gaseous particles in varying solutions. It features a mass range of up to 300 amu and an interchangeable membrane inlet probe suitable for variable specifications.
(1) Goodwin, JM.; Chrestensen, CA.; Moomaw, EW.; Detection of Nitric Oxide by Membrane Inlet Mass Spectrometry, in Nitric Oxide: Methods and Protocols, 1st ed.; Mengel, A.; Lindermayr, C.; Eds.; Humana Press: USA, 2018.