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Evaporative Light Scattering Detector

Evaporative Light Scattering Detector. ANALATYCAL CHEMISTRY 427 PHC Done by: Madawi AlUbied Areej Alsuwayyid. (ELSD). Objectives. What is Evaporative Light Scattering Detector ? Capabilities how does it work ? Characteristic properties Advantages Sensitivity Problems.

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Evaporative Light Scattering Detector

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  1. Evaporative Light Scattering Detector ANALATYCAL CHEMISTRY427 PHCDone by:Madawi AlUbied • AreejAlsuwayyid (ELSD)

  2. Objectives • What is Evaporative Light Scattering Detector ? • Capabilities • how does it work? • Characteristic properties • Advantages • Sensitivity • Problems

  3. 1. What is Evaporative Light Scattering Detector ? • Evaporative Light Scattering Detectors (ELS Detectors) are essentially universal detectors. • primarily used in High Performance Liquid Chromatography (HPLC). • ELS detectors are an ideal substitute, or supplement to, traditional HPLC detectors for liquid chromatography concentration detection.

  4. 2. Capabilities • The detector responds to all compounds that are, relative to their mobile phase, sufficiently nonvolatile at the conditions of analysis. • ELSD is suitable for all LC separated analyses that does not have light absorbing chromophores. So it dose not rely on optical properties . Ex: phospholipids, carbohydrates, amino acids , fatty acids and synthetic polymers.

  5. 3. how does it work? 3 key stages: 2 3 1

  6. Stage 2: Evaporation

  7. 4. Characteristic properties • Low background noise (no solvent peaks) • Reproducibility (in the 1μg range, STD ~ 1%) • Low band broadening (short transit time) • “Near” linear response (instrument and concentration dependent, smart choice of stand)

  8. 5. Advantages • No sample preparation • No drivatisation • Universal - responds to all compounds in the mobile phase • Not dependent on spectroscopic properties of analyte • Not susceptible to baseline drift during gradient elution, temperature or solvent pump fluctuations • ELSD compatible with a much wider range of solvents compared to Refractive Index detector • No interference from solvent front peaks (enables fast analysis) • Flow rates up to up to 5ml/min can be achieved with no affect on baseline stability • Ideal for High Throughput Screening and quantification

  9. The ELSD Improves Baseline Stability and Detection Sensitivity Compared to RI 10278 1. Fructose 2. Glucose 3. Sucrose 10277 Column: Prevail™ Carbohydrate ES, 5µm, 53 x 7mm (Part No. 35104) Mobile Phase: Acetonitrile:Water (75:25) Flowrate: 2.0mL/min RI ELSD

  10. 6. Sensitivity Sensitivity with ELSD is limited to 1–50 ng on-column in the best instances. the followings factors are considered to be affect ELSD sensitivity : • Gas quality • Solvent quality • Column contributions • Solvent modifiers

  11. 7. Problems: • arising with an ELSD are usually manifest in a noisy baseline. This can have several causes: • Evaporation Temperature too low: the solvent is not completely evaporated. • Evaporation Temperature too high: the solvent is boiling in the nebuliser. • Air or nitrogen not clean:remove traces of water or oil with a filter. • Gas flow too low:poor nebulisation of the eluent. • Involatilematerial in the eluent: replace any buffer salt with a volatile one (such as ammonium acetate) and ensure that the eluent is particle free.

  12. References • http://www.usedhplc.co.uk/UsedHPLC-IntroductiontoEvaporativeLightScatteringDetectorsELSD.htm • http://www.separationsnow.com/details/ezine/sepspec10174ezine/Exploring-the-alluring-charms-of-a-charged-aerosol-detector-for-HPLC.html?tzcheck=1 • http://www.laserchrom.com/LaserchromHPLC-TechnicalSupportCentre-TechnicalTips-IntrotoELSD.htm • http://fxg-ent.com/downloads/SoftaELSDBrochure.pdf

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