Toxicology Flashcards

Question

Methanol

Answer 1

``` Source: some antifreeze windshield washer fluid Effects: not a significant CNS depressant formaldehyde and formic acid metabolites anion-gap metabolic acidosis optic neuropathy blindness ```

Answer 2

``` Treatment block ADH formation of formaldehyde Administer ethanol to serum level of 100-150 mg/dL OR 4-methylpyrazole (Fomepizole) Both act as competitive inhibitors of ADH HCO3- - metabolic acidosis as needed folate – traps formate hemodialysis ```

Answer 3

``` Source: rubbing alcohol is 70% isopropanol ~2-2.5x CNS depressant activity as EtOH Metabolized to acetone (T1/2 = 3.6 hr) No EtOH Rx – IPA is more toxic than acetone Supportive therapy Hemodialysis ```

Answer 4

Source: isopropanol metabolism nail polish remover ketosis (

Answer 5

``` Measure by GLC Use n-propanol as internal standard Direct injection – req. periodic column replacement Headspace – column lasts “forever” sample + int. std. + NaCl in sealed vial heat (45°C) for 10-30 minutes sample the vapor (20-250 µL) and inject Uses low oven temperature (~40°C) Can also measure other solvents with higher oven temperature MeOH by enzymatic assay (non-commercial) ```

Answer 6

``` Some CNS depression Complexes calcium (oxalic acid) CaOx xtals mechanically damage nephron Treatment EtOH to 100-150 mg/dL blocks metabolism 4-methyl pyrazole (Fomepizole) as alternative Hemodialysis if >500 mcg/mL (50 mg/dL) Correct acidosis and hypocalcemia Measurement Blood – GLC, not suitable for average lab Enzymatic assay (non-commercial) Urine – UV lamp, fluorescein in most antifreeze ```

Answer 7

``` TLC – thin layer chromatography GLC – gas-liquid chromatography GC/MS – GLC/mass spectrometry LC-MS (incl. TOF) Require time, capital and experience commitment All require sample preparation steps All require skilled interpretation ```

Answer 8

Specific detector system for GLC or HPLC Compounds exiting chromatograph are excited and ionized by one of several energetic methods Excited compounds break at weaker bonds, yielding characteristic fragment ions as well as neutral fragments Mass filter analyzes charged fragments Increased sensitivity over FID and NPD Increased specificity (structural information)

Answer 9

Total ion chromato. Plot of abundance of all ions detected by mass spectrometer vs retention time (time since injection) Only identifying info is retention time

Answer 10

Histogram of mass:charge ratio (m/z) vs abundance at a single point in time Molecular ion – m/z representing the unfragmented molecule Not necessarily present Base peak – most abundant ion Spectrum is normalized to base peak = 100

Answer 11

Full scan (prev. slide) useful to id unknowns or from large list of potential compounds Comprehensive drug screen If targeting specific compound(s), look for (3) ions “unique” for each compound Ratio two ions to the third Enhanced sensitivity and specificity Confirmation of positive EIA drug screen Specific compound assays

Answer 12

Used to quantitate known compounds: Immunosuppressants Vitamin D (25-OH D2 and D3) Steroids (e.g., testosterone in women and children)

Answer 13

Higher mass resolution and range Gives exact MW of compounds (nnn.nnnn) MALDI-TOF (matrix-assisted laser desorption-ionization) - useful for bacterial id

Answer 14

Lead – no known biological function | Paint – pre-1972, up to 35%. Post

Answer 15

``` Inhibits PBG synthase → ↑ DALA in urine Blocks Fe2+ incorp. into heme → ↑ ZPP ZPP = zinc protoporphyrin Ferrochelatase Binds to many protein sulfhydryls Deposited in bone Permanent effect on developing mental fxn ```

Answer 16

``` CDC, Oct. 1991: test all children below the age of 6 yrs action limit of 10 mcg/dL (now 5 mcg/dL) CA DPH – CHDP testing req. approved lab OSHA – occupational testing req. approval Measure in whole blood only ```

Answer 17

Reinsch – urine As, Hg, Sb, Bi; but NOT Pb Obsolete Atomic absorption Graphite furnace – higher sensitivity for Al, As, Pb Cold vapor – mercury as the hydride (AA or atomic fluorescence) Single element per assay ICP-MS – inductively-coupled plasma mass spectroscopy High sensitivity and universal detector Multiple elements per assay Expensive instrument LeadCare – lead only POC disposable sensor.

Answer 18

``` Amphetamines Barbiturates Benzodiazepines Cannabinoids (THC, marijuana) Cocaine LSD Methadone Opiates PCP (Phencyclidine) Tricyclic antidepressants (TCAs) Measure by homogeneous immunoassay ```

Toxicology Flashcards

(42 cards)