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15 Cards in this Set
- Front
- Back
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Immunoassays are commonly used in
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Screening tests
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Confirmatory Tests commonly use
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GC/MS
But also AA, HPLC |
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Immunoassays
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Use antibody against analyte
Little or no sample preparation Low specificity Primarily spectrophotometric |
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Thin Layer Chromatography
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Polar silica medium
Fast, easy, cheap Sensitivity is low Specificity is low |
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Atomic Absorption Spectroscopy
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Usually method of choice for metals (Fe, Hg)
Detects metal atom, not compound or valence state |
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Gas Chromatogaphy
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Expensive
Well-trained technologist High specificity and sensitivity Molecules partition between gas and liquid phase as they traverse column |
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Mass Spectrometry
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Usually coupled with GC- GC separates, MS detects
Expensive Well-trained technologist Specificity excellent Unparalleled detection of organic molecules Shoots electrons at molecules, fragments ions |
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Mass Spectrometry Limitations
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Cannot separate enantiomers
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High Performance Liquid Chromatography
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Expensive
Good for quantitiation Separates a substance between a stationary and mobile liquid phase under pressure |
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Ethanol Testing
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2 techniques
GC Enzymatic |
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Enzymatic Ethanol Testing
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Alc DH to convert EtOH to acetaldehyde
Accompanied by reduction of NAD to NADH NADH Increases, so does absorption at 340nm High serum lactate, LDH will convert lactate to pyruvate, generating NADH |
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Adulteration of Drug testing
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Dilution (sp gravity solves)
Substitution Ingestion of Weak acids, bases Use of interfering substances Benzalkonium Goldenseal Strong chemicals Glutaraldehyde, interferes with enzymes used in immunoassays |
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Opioid Interpretive Challenges
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Enantiomers not differentiated by MS
Dextrorphan and levorphanol (opioid) Poppy seed contain morphine and codeine (drug testing pgm uses 2000ug/L to prevent false +) |
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TCA interpretive Challenges
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Other 3-ringed structures
CBZ Phenothiazine Diphenhydramine |
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Plasma cholinesterase challenges
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Non specific (cocaine and succ will effect)
Decreased in deficiency of enzyme Hepatic disease Fe deficiency Chronic disease Malnutrition |
