page_title: Direct analysis in real time
section_title: Mass spectra
hierarchical_section_title: Direct analysis in real time / Mass spectra
caption_attribution_description: Time-of-flight mass spectrum of red ink analyzed by using DART ion source
context_page_description: In mass spectrometry, direct analysis in real time is an ion source that produces electronically or vibronically excited-state species from gases such as helium, argon, or nitrogen that ionize atmospheric molecules or dopant molecules. The ions generated from atmospheric or dopant molecules undergo ion-molecule reactions with the sample molecules to produce analyte ions. Analytes with low ionization energy may be ionized directly. The DART ionization process can produce positive or negative ions depending on the potential applied to the exit electrode.
  This ionization can occur for species desorbed directly from surfaces such as currency, tablets, bodily fluids, polymers, glass, plant leaves, fruits & vegetables, clothing, and living organisms. DART is applied for rapid analysis of a wide variety of samples at atmospheric pressure and in the open laboratory environment. It does not need a specific sample preparation, so it can be used for the analysis of solid, liquid and gaseous samples in their native state.
  With the aid of DART, exact mass measurements can be done rapidly with high-resolution mass spectrometers.
context_section_description: In positive ion mode, DART produces predominantly protonated molecules [M+H]⁺  and in negative-ion mode deprotonated molecules [M-H]⁻. Both negative and positive modes of DART provides relatively simple mass spectra. Depending on the type of analyte, other species may be formed, such as multiple charged adducts .DART categorized under soft ionization technique.Fragmentation can be rarely observed for some molecules.
  Use of DART compared to traditional methods minimizes sample amount, sample preparation, eliminates extraction steps, decreases limit of detection and analysis time. Also it provides a broad range sensitivity, simultaneous determination of multi-drug analytes and sufficient mass accuracy for formulation determination.
  The DART ion source is a kind of gas-phase ionization, and it requires some sort of volatility of the analyte to support thermally assisted desorption of analyte ions. This limits the size range of the molecules that can be analyzed by DART i.e. m/z 50 to 1200. DART-MS is capable of semi-quantitative and quantitative analysis. To accelerate sample release from the surface, the DART gas stream is usually heated to temperature in the range 100-500 °C and this operation can be employed for temperature-dependent analysis.
caption: DART source red ink spectrum
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