Exam 5 Electrochemistry & Chromatography – Flashcards
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| What are the 3 types of Electrochemistry? |
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| Ion selective electrodes & pH meters Gas Sensing Electrodes Electrophoresis |
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| What are the 4 types of Chromatography? |
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| TLC - thin layer chrom HPLC - high performance liquid chrom GC - gas chromatography MS - mass spec |
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| Define Electrochemistry |
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| Chemical reactions that occur due to the flow or presence of electrons |
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| Define Current |
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| Number of electrons traveling through a substance, measured in amperes |
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| Define Potential |
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| For electrons to flow, force must be applied to the system. Measured in volts |
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| True or False: You can’t measure the potential of one electrode; only the potential difference between two electrodes |
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| True |
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| What does the Ion-Selective Electrodes measure? |
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| Potential |
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| What does ISE stand for? |
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| Ion-Selective Electrodes |
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| What is the potential (V) measured by ISE proportional to? |
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| Level of ion in the patient's sample |
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| Describe a Reference Electrode |
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| known potential and generates a reproducible, constant V |
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| Describe an Indicator Electrode |
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| The V will vary depending on the level of patient ion |
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| What are commonly used Reference Electrodes |
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| Mercury/mercurous chloride (calomel) and Ag/AgCl |
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| What do ISEs selectively allow? |
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| Only 1 Ion to pass through a membrane to the tip of the electrode |
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| When the 1 ion passes through the membrane to the tip of the electrode, what is generated? |
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| V (Potential) |
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| What are 2 Commonly used Glass Sample Membranes |
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| pH meters Sodium |
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| What is the commonly used Liquid membrane? |
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| Calcium |
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| What is the commonly used Liquid membrane antibiotic? |
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| Potassium (uses valinomycin) |
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| What does Direct ISE use? |
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| Whole Blood |
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| What does Indirect ISE use? |
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| Pre-diluted plasma or serum |
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| Indirect ISE - High TP or lipid can cause Sodium to be what? |
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| Falsely Decreased |
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| What is another name for the pCO2 Electrode? |
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| Severinghaus Electrode |
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| What is another name for the Severinghaus Electrode? |
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| pCO2 |
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| pCO2 - CO2 diffuses through and mixes with bicarbonate buffer, causing the release of ________ |
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| H+ ions |
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| pCO2 Electrode - The H+ ions then diffuse thru a H+-permeable membrane, what is this membrane associated with? |
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| ISE |
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| Ammonia Gas Electrode - NH3 mixes with Ammonium Chloride, causing the release of _______ |
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| OH- ions |
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| Ammonia Gas Electrode - The amount of OH- ions is proportional to what? |
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| Level of NH3 in the sample |
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| What is another name for the pO2 Electrode? |
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| Clark Electrode |
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| What is another name for the Clark Electrode? |
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| pO2 Electrode |
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| True or False: Current will not be conducted without O2 in the system |
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| True |
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| pO2 Electrode - The amount of current generated is proportional to what? |
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| Level of pO2 in the sample |
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| What is Chromatrography used for? |
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| Separate mixtures into individual components based on different physical characteristics such as size, solubility, or charge |
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| What are the major applications for Chromatrography? |
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| Drug screens Drug Confirmation |
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| Define the following component of the chromatography system: Mobile Phase |
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| A liquid or gas that carries the patient sample through the system |
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| Define the following component of the chromatography system: Stationary Phase |
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| A solid or liquid through which the mobile phase flows; housed in a column |
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| Define the following component of the chromatography system: Eluate |
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| separated components |
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| True or False: Chromatography - Compounds interacting more strongly with the stationary phase spend a longer time in the column than those with less affinity |
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| True |
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| What are the 4 Chromatography Modes of Separation? |
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| Adsorption Partition Steric Exclusion Ion-Exchange |
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| Describe Adsorption |
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| Competition between the sample and the mobile phase for adsorptive sites on a solid stationary phase |
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| What type of Chromatography is Adsorption? |
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| Liquid-Solid |
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| What type of Chromatography is Partition? |
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| Liquid-Liquid |
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| What type of Chromatography is Steric Exclusion |
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| Liquid-Solid |
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| Partition is based on what? |
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| Solubility patterns in an organic (nonpolar) solvent and an aqueous (polar) solvent |
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| Partition - Polar molecules remain where? |
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| Aqueous Layer |
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| Partition - Nonpolar molecules are what? |
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| Extracted into the organic solvent |
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| What is Steric Exclusion based on? |
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| Size & Shape of molecules |
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| With Steric Exclusion which molecules pass through rapidly: Larger or smaller? |
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| Larger Molecules |
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| With Steric Exclusion which molecules pass through more slowly because they become trapped in the pores: Larger or smaller? |
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| Small molecules |
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| With Ion-Exchange, the Stationary phase (resin) has what on its surface? |
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| Charged functional groups |
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| Ion Exchange - What do Cation-exchange resins remove? |
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| Na+ and other cations |
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| Ion Exchange - What do Anion-exchange resins remove? |
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| Cl- and other anions |
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| Which system is used to deionize water? |
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| Ion-Exchange --Anion & Cation columns combined |
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| How do sample molecules move in Thin Layer Chromatography? |
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| Solvent migrates up by capillary action, dissolving & carrying sample molecules |
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| Define Retention Factor (Rf) |
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| The distance a compound migrates, compared to the distance the solvent front moves |
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| What is the Mathematical formula for the Retention Factor |
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| Distance leading edge unknown component moves / total distance solvent front moves |
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| What is TLC mainly used for? |
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| Drug Screens |
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| What does HPLC use to force a sample through the system? |
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| Pressure |
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| What does HPLC reduce? |
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| Test Time |
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| With HPLC what stage is the mobile phase? |
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| Liquid |
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| What does the following do in the HPLC: Pump |
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| forces the mobile phase through the column |
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| What does the following do in the HPLC: Sample injector or syringe |
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| Shoots the sample into the path of the mobile phase |
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| Describe the following in the HPLC: Column or Stationary Phase |
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| Packed into long stainless steel tubes |
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| What does the following do in the HPLC: Detector |
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| generates an electronic signal as compounds are eluted |
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| What does the following do in the HPLC: Recorder |
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| generates a peak as each compound elutes out |
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| What in the HPLC pump provides constant flow? |
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| Pistons |
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| HPLC Detector - The signal is proportional to what? |
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| Concentration of each separated component |
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| What is the print-out of a HPLC called? |
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| Chromatograph |
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| Define HPLC Retention Time |
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| The time it takes for a compound to elute (after sample injection) |
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| What is retention time used to determine? |
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| Compound identity when compared to standards |
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| True or False: HPLC - Height/Area of the component peak is proportional to quantity |
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| True |
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| What is HPLC most commonly used to screen for & ID? |
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| Drugs of abuse |
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| What does Gas Chromatography do? |
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| Separates mixtures of compounds that are volatile or can be made volatile. |
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| What is the mobile phase of Gas Chromatography? |
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| carrier gas (N, helium, argon) |
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| Gas Chromatography - Which compounds move more slowly? |
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| Higher Boiling Points |
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| Gas Chromatography - Which compounds move most quickly? |
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| Compounds that most easily become gaseous |
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| What do Thermal conductors or flame ionization detectors produce? |
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| Electric signal proportional to the concentration of the volatile components |
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| A chromatogram will ID compounds by what? |
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| Retention Time |
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| Mass Spectrometry - Ions and Fragments are separated according to what? |
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| Mass-to-charge ratio |
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| What is the most specific method for drug confirmation? |
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| GC/Mass Spec |
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| True or False: GC/Mass Spec - Fragmentation is reliable, allowing for published reference library of compounds |
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| True |
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| What is the mobile phase for the following: TLC |
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| Organic Solvent |
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| What is the mobile phase for the following: HPLC |
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| Liquid |
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| What is the mobile phase for the following: GC |
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| Inert Gas |
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| What is the stationary phase for the following: TLC |
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| Silica/cellulose on flat support |
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| What is the stationary phase for the following: HPLC |
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| Solid (silica gel or column) |
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| What is the stationary phase for the following: GC |
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| Polymer or glass filled with inert liquid |
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| What is the stationary phase for the following: Mass Spec |
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| Electron bombardment after leaving HPLC or GC |
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| What is the application for/of the following: TLC |
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| L/S ratios; Drug Screens |
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| What is the application for/of the following: HPLC |
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| Screen & quantitative drugs |
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| What is the application for/of the following: GC |
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| Screen & quantitative drugs |
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| What is the application for/of the following: Mass Spec |
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| Drug confirmation and quantitation |
