What is SIFT-MS?
SIFT-MS stands for selected ion flow tube mass spectrometry. It’s a form of direct mass spectrometry that analyzes volatile organic compounds (VOCs) in air with typical detection limits at parts-per-trillion level (by volume: pptv). Real-time, quantitative analysis is achieved by applying precisely controlled soft chemical ionization and eliminating sample preparation, pre-concentration and chromatography.
SIFT-MS uses ultra-soft, precisely controlled chemical ionization coupled with mass spectrometric detection to rapidly quantify VOCs and permanent gases to low part-per-trillion concentrations by volume (pptv).
Soft chemical ionization is applied very precisely in SIFT-MS, allowing it to provide unparalleled selectivity among direct mass spectrometry techniques.
Eight chemical ionization agents (reagent ions) are applied in SIFT-MS instruments: H3O+, NO+, O2+, O–, O2–, OH–, NO2–, and NO3–. These eight reagent ions react with analyte VOCs and inorganic gases in very well controlled ion-molecule reactions, but they do not react with the major components of air (N2, O2, and Ar). This enables SIFT-MS to analyze air at trace and ultra-trace levels without pre-concentration.
Three Fundamentals of SIFT-MS
- Reagent ion generation and selection. The eight SIFT-MS reagent ions are formed by microwave discharge through moist or dry air at low pressure. One reagent ion is selected at any particular time using the first quadrupole mass filter.
- Analyte ionization. The selected reagent ion is injected into the flow tube and excess energy is removed through collisions with the carrier gas. The sample is then introduced at a known flow rate and the reactive compounds it contains are ionized by the reagent ion to form well-characterized product ions.
- Analyte detection and quantitation. Product ions and unreacted reagent ions are sampled into a second quadrupole mass spectrometer. Utilizing a compound library, the software instantaneously calculates each analyte’s absolute concentration.
Benefits of SIFT-MS
- Instantaneous, quantitative analysis of air and headspace with very high sensitivity and selectivity
- Simultaneous analysis of chemically diverse VOCs (e.g. aldehydes, amines and organosulfurs)
- Direct analysis of high humidity samples
- Simplicity of operation
- Simple integration with existing infrastructure
- Low maintenance and long-term stability.
The above benefits make SIFT-MS an ideal tool for high-throughput and real-time gas analysis applications. The Syft Voice200 ultra SIFT-MS instrument provides non-technical operators with laboratory-grade chemical analysis, presented in a format that they can understand and act on.
Get a better understanding of the principles and operational advantages of SIFT-MS. Download the SIFT-MS Overview Brochure.