MEPS (Micro Extraction by Packed Syringe) Components
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Questions and Answers

What is a common limitation of sample preparation methods?

  • They can produce ideal results for all samples
  • They are not influenced by the matrix
  • They are applicable to all matrices
  • They can modify the relative composition of the sample (correct)

    • What is the main purpose of SPE?

  • To eliminate analytes from the matrix
  • To isolate and enrich analytes from the matrix (correct)
  • To absorb interferents from the matrix
  • To adsorb analytes from the matrix

    • What is the difference between absorption and adsorption?

  • Absorption is a reversible process, while adsorption is an irreversible process
  • Absorption is a solid phase process, while adsorption is a liquid phase process
  • Adsorption is a reversible process, while absorption is an irreversible process
  • Adsorption is a solid phase process, while absorption is a liquid phase process (correct)

    • What is the Breakthrough volume in SPE?

    <p>The maximum amount of analyte that can be retained by the stationary phase</p> Signup and view all the answers

    What is the main difference between SPE and SPME?

    <p>SPE uses a solid phase, while SPME uses a liquid phase</p> Signup and view all the answers

    What is the purpose of the pH and capacity factor (k’) in SPE?

    <p>To optimize the extraction conditions</p> Signup and view all the answers

    What is the main difference between SPME and SBSE?

    <p>Volume of PDMS used</p> Signup and view all the answers

    What is the general procedure of SPME?

    <p>Extraction, desorption, and injection</p> Signup and view all the answers

    How is the selection of a SPME fiber typically done?

    <p>Based on the analyte polarity and molecular weight</p> Signup and view all the answers

    Who introduced Stir Bar Sorptive Extraction (SBSE) in 1999?

    <p>Erik Baltussen and Pat Sandra</p> Signup and view all the answers

    What is the main difference between non-polar and polar fibers in SPME?

    <p>Non-polar fibers are used for non-polar analytes, while polar fibers are used for polar analytes</p> Signup and view all the answers

    What is the advantage of using SBSE over SPME?

    <p>Higher recoveries</p> Signup and view all the answers

    What is the typical volume of PDMS used in SPME?

    <p>10-50 µL</p> Signup and view all the answers

    What is the mechanism of extraction in SPME?

    <p>Absorption and adsorption</p> Signup and view all the answers

    What is the name of the device used in SBSE?

    <p>Twister</p> Signup and view all the answers

    What is the principle of extraction used in SPME and SBSE?

    <p>Sorption</p> Signup and view all the answers

    What is the purpose of stirring in SPME?

    <p>To improve recoveries</p> Signup and view all the answers

    What is the main advantage of using a stir bar in SBSE?

    <p>It increases the surface area</p> Signup and view all the answers

    What is the main difference between MEPS and SPE?

    <p>MEPS is a miniaturization of SPE with smaller sample volumes</p> Signup and view all the answers

    What is the benefit of using MEPS compared to SPE?

    <p>MEPS reduces the volume of solvents used</p> Signup and view all the answers

    What is the main advantage of using a reusable cartridge in MEPS?

    <p>It eliminates potential carry-overs between extractions</p> Signup and view all the answers

    What is the purpose of the dry step in the MEPS procedure?

    <p>To remove excess solvent</p> Signup and view all the answers

    What type of sample was analyzed in the MEPS procedure for phenols in residual waters?

    <p>Residual water sample</p> Signup and view all the answers

    What is the formula for NCT?

    <p>(0.50 – 0.95) nc1 × nc2</p> Signup and view all the answers

    What is the purpose of the BIN (Barrel Insert and Needle) in MEPS?

    <p>To hold the cartridge in place</p> Signup and view all the answers

    What is the purpose of lowering the slope of the 1D gradient in SCX×RPLC?

    <p>To increase peak capacity</p> Signup and view all the answers

    What is the column temperature in the 1st dimension of Generic RPLC×RPLC, Taxanes?

    <p>30°C</p> Signup and view all the answers

    What is the benefit of using MEPS compared to SPME?

    <p>MEPS can be fully automated</p> Signup and view all the answers

    What is the purpose of the C18 cartridge in the MEPS procedure?

    <p>To retain the analytes</p> Signup and view all the answers

    What is the modulation time in Generic RPLC×RPLC, Taxanes?

    <p>0.40 min</p> Signup and view all the answers

    What is the purpose of the conditioning step in the MEPS procedure?

    <p>To wet the cartridge with solvent</p> Signup and view all the answers

    What is the detection wavelength in LC×LC, Taxanes?

    <p>228 nm</p> Signup and view all the answers

    What is the benefit of using MEPS compared to traditional SPE?

    <p>MEPS reduces the volume of solvents used</p> Signup and view all the answers

    What is the plate height (H) dependent on in chromatography?

    <p>Mobile phase linear velocity</p> Signup and view all the answers

    What is the Van Deemter curve used for?

    <p>To explain the relationship between H and mobile phase linear velocity</p> Signup and view all the answers

    What is the approximate column head pressure (gauge) for optimum flow rate in helium?

    <p>Calculated at 100ºC and with atmospheric pressure detector</p> Signup and view all the answers

    What is the purpose of using 2D chromatography?

    <p>To separate and identify compounds</p> Signup and view all the answers

    What is the name of the detection method used in LC×LC, Taxanes?

    <p>Single Quadrupole</p> Signup and view all the answers

    What is the resolution (RS) in chromatography?

    <p>The ratio between the difference in retention times and the average of the peak widths of two compounds</p> Signup and view all the answers

    What is the plate number (Efficiency N) in chromatography?

    <p>The number of theoretical plates in a column</p> Signup and view all the answers

    What is selectivity (α) in chromatography?

    <p>The ability of a system to differentiate two compounds</p> Signup and view all the answers

    What is the formula for calculating the retention time (tR) in chromatography?

    <p>tR = L/u (k + 1) = xNdp/u (k + 1)</p> Signup and view all the answers

    What is the relationship between the internal diameter of a column and the plate number (N)?

    <p>The internal diameter is inversely proportional to the plate number</p> Signup and view all the answers

    What is the importance of Giddings Statements in chromatography?

    <p>They explain the principles of peak overlap</p> Signup and view all the answers

    What is the typical range of the resolution (RS) in chromatography?

    <p>1.0 - 2.0</p> Signup and view all the answers

    What is the unit of measurement for the concentration of a sample in HPLC?

    <p>ppm</p> Signup and view all the answers

    What is the purpose of the 21st-Century Chromatographic Triangle?

    <p>To describe the relationship between resolution, efficiency, and selectivity</p> Signup and view all the answers

    What is the role of mass spectrometry in chromatography?

    <p>To detect and quantify compounds</p> Signup and view all the answers

    Study Notes

    MEPS (Micro Extraction by Packed Syringe)

    • A miniaturization of SPE (Solid Phase Extraction) with differences:
      • Allows working with smaller sample volumes (10µL vs hundreds/thousands of µL in SPE)
      • Can be fully automated for extraction and injection using a syringe and autosampler for LC or GC
      • Reduces solvent volume and sample handling
      • Allows concentrating larger sample volumes through multiple 100µL or 250µL portions
      • Cartridges are reusable (40-100 samples depending on the matrix)
    • Phase can be efficiently washed out between extractions, eliminating potential carry-overs

    MEPS Cartridge Scheme

    • Cartridge contains SPE phase (C18, C8, C2, SCX e Sil with 45µm diameter particles)
    • Inserted in the syringe needle, prepared for GC or HPLC

    MEPS Applications

    • Phenols in residual waters:
      • Cartridge: BIN - C18 MEPS
      • Conditioning: 30 µL MeOH
      • Re-equilibration: 30 µL H2O
      • Extraction: 10 x 100 µL of the sample at 5 µL/seg
      • Dry step: with air (3 x 80 µL at 50 µL/seg)
      • Elution: 10 µL MeOH
      • Analysis: directly; 2 µL for GC/MS; column BPX5
    • Biological samples:
      • Urine:
        • Sample: 100µL
        • Cartridge: BIN - C18
        • Conditioning: MeOH
        • Re-equilibration: H2O
        • Elution (xanthines): 30µL MeOH
        • Analysis: 2µL; BPX5; GC/MS
      • Plasma:
        • Sample: 50 µL
        • Cartridge: BIN - C2
        • Conditioning: MeOH
        • Re-equilibration: H2O
        • Elution: 30µL 0.1% HCOOH in ACN/H2O (75:25)
        • Analysis: HPLC; C18,100 x 2.1 mm

    Comparison of MEPS, SPME, and SPE

    • MEPS: solid phase extraction in a syringe, with benefits of miniaturization and automation
    • SPME: solid phase microextraction, using a fiber for extraction and desorption
    • SPE: solid phase extraction, using a cartridge or column for extraction and elution

    Chromatographic Parameters

    • Resolution (Rs): ratio of difference in retention times and average peak width
    • Efficiency (N): plate number, a measure of column performance
    • Selectivity (α): ability to separate two compounds
    • Peak capacity: number of peaks that can be separated in a chromatogram
    • Kinetic plots: a graph of peak width vs. retention time
    • Giddings statements: a set of equations describing chromatographic performance

    Liquid Chromatography (LC)

    • Types:
      • Reversed phase (RP)
      • Normal phase (NP)
      • Hydrophilic interaction (HILIC)
    • Parameters:
      • Column: stationary phase and dimensions
      • Mobile phase: solvent composition and flow rate
      • Detection: UV, MS, or other methods

    Mass Spectrometry (MS)

    • Principles:

      • Ionization: converting molecules into ions
      • Separation: based on mass-to-charge ratio
      • Detection: measuring ion intensity

    • Types:

      • Single quadrupole
      • Triple quadrupole
      • Time-of-flight (TOF)
      • Orbitrap### Solid-Phase Microextraction (SPME)

    • SPME fibers have polarity, with options including PDMS and PA

    • PDMS is a type of SPME fiber

    • Analyte molecular weight (MW) is a factor in SPME

    • Supelco is a brand-name related to SPME

    SPME Extraction Time

    • Extraction time is a parameter in SPME
    • Supelco is also relevant to SPME extraction time

    SPME Stirring

    • Stirring is an optional step in SPME
    • Options for stirring include no stirring and stirring

    Stir Bar Sorptive Extraction (SBSE)

    • SBSE was introduced in 1999 by Erik Baltussen and Pat Sandra
    • SBSE is based on the same principles as SPME
    • Instead of a fiber, SBSE uses 10 mm stir bars with a layer of 24 to 500 µL of PDMS for analyte extraction
    • Twister, GERSTEL is a brand-name related to SBSE
    • SBSE has a lower phase ratio (β) compared to SPME, which can lead to higher recoveries
    • The typical volume of PDMS in SPME is greater than in SBSE

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    Description

    This quiz covers the components of Micro Extraction by Packed Syringe (MEPS), including the syringe and cartridge, and their applications in GC and HPLC.

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