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Toxicology & TDM
Instrumentation
| Question | Answer |
|---|---|
| Analysis of Toxic Agents: 2-step procedure 1. Screening Tests | Rapid, simple, qualitative procedure Intended to detect specific substances or classes of toxicants has good analytic sensitivity but lacks specificity |
| Analysis of Toxic Agents: 2-step procedure 2. ConfirmatoryTests | Confirms [+] results from screening test i.e Gas Chromatography |
| Two reasons for testing for Drugs of Abuse | 1. Identify drug in overdose for appropriate treatment 2. Identify drug abuse in non-overdose cases to provide a rationale for treatment |
| Analytic Methods used for Drug Testing -Screening, Confirmatory & both | Screening: Thin-layer chromatography Confirmatory: Liquid & Gas Chromatography Both: Immunoassays |
| Gas Chromatography (GC) -the basic design of a GC consists of the following 5 components | 1. Carrier gas supply 2. Sample injection device & GC inlet 3. Column 4. Detector 5. Data system/recorder |
| Paper Chromatography separates materials according to.... --Examples of materials separated include [x3] | their differing solubilities in a give solvent ie: sugars, amino acids, drugs |
| Paper Chromatography -solvents are varied by | pH & polarity |
| Paper Chromatography -Rf value (4:10) | calculated ratio of the distance of the unknown compound moves to the distance moved by the solvent front |
| Paper Chromatography -staining is also used to aid in identification w/ 5 basic steps | 1. extraction 2. concentration 3. inoculate 4. development 5. detect |
| Gas-Liquid Chromatography: Definition "distribution of samples b/t two phases.." | One is a stationary bed (liquid) of large surface area and the other phase is a gas which percolates through the stationary bed. Liquid is spread as a thin film over an inert solid The sample is partitioned by going in and out of the liquid film |
| GC Technique: 1-Components to be separated are carried through the column by... | an inert gas (carrier gas) |
| GC Technique: 2- the sample mixture is... | partitioned by the carrier gas & non-volatile solvent [stationary phase] supported on an inert size graded solid [solid support] |
| GC Technique: 3- the solvent selectively... | retards the sample components until they form separate bands in the carrier gas. |
| GC Technique: 4- these component bands leave the column in the.... | gas stream & are recorded as a function of time by a recorder. |
| Examples of Inert or Carrier Gases you can use... (x4) | Helium, Nitrogen, Hydrogen, Argon |
| Injecting a sample into the GC: --type of syringe --rubber septum f[x] | Hamilton syringe; rubber septum used to seal the end of injection port |
| GC Column: what shape is used & why? | Straight is most efficient but space is a problem; use Coiled instead (has more surface area) |
| GC Considerations: -Solid Support: purpose | Purpose is to provide a large uniform, inert surface area for distributing the liquid phase |
| GC Considerations: -what is the most important parameter in GC? | Stationary (liquid) Phase |
| GC Considerations: -Stationary (liquid) Phase: samples must exhibit, have reasonable, & have a negligible.... | must exhibit different distribution coefficient and have reasonable solubility in the solvent Should have negligible vapor pressure at operating temp (2-300C) |
| GC Considerations: -Thermostats for Temp Monitoring [x3] | Injection Port Column Detector |
| Detectors indicate & measure... example of detector is | the amount of components in the column effluent ie: Mass spectrometry |
| Desirable characteristics of Detectors [x6] | High sensitivity low noise (no interference) Wide range of linear response Rugged & inexpensive Response to all types of compounds Insensitive to flow & temp changes |
| Recorder -peaks appear on recording device as... | each band (component) is eluted from the column. Successive peaks will be recorded |
| Recorder -Retention Time | the length of time for each of the peaks to appear on the recorder from the injection time; usually characteristic of the substance of interest |
| Qualitative vs Quantitative -Retention Time vs Peak Area | RT: qualitates the substance of interested PA: quantitates the amount |
| Mass Spectroscopy -3 components | 1. ion source 2. mass analyzer 3. ion detector |
| Mass Spectroscopy determines the....which allows....thus, the ability to determine.... | mass to charge ratio of a molecule that has been ionized--which allows sorting and thus, the ability to determine what unknown is based on the parent molecule & their fragment ions |
| Ion Source Requirements for GC-MS -Temp | High temp & vacuum [200-300C] |
| Ion Source Requirements for GC-MS -Heated Filament is a source of the.... ***constant ?? electron volts allows for.... | -Heated filament is a source of the electrons that bombarded the sample molecules --> **Constant 70 electron volts allow for reproducibility |