Q3 M2.6 TOXI LAB FINALS

Activated charcoal's adsorptive capacity is primarily influenced by which characteristic of its internal structure?

• External surface area exclusively

• Pore size distribution ranging from 10 to 20 angstroms that aligns with the molecular size of xenobiotics

• Chemical reactivity of the surface groups

• The color and odor of the charcoal powder

Which van der Waals and hydrogen bonding forces contribute to activated charcoal’s preferential adsorption of xenobiotics in which molecular form?

• Ionized state in acidic pH only

• Dissolved, nonionized molecular form depending on ambient pH as per the Henderson-Hasselbalch relationship

• Covalently bonded polymers in solid state

• Ionized salts in strongly dissociated states

What effect does increasing AC surface area have on its adsorptive capacity and affinity according to in vitro and in vivo studies?

• Both capacity and affinity increase proportionally

• Adsorptive capacity increases but affinity decreases due to diminished hydrophobic and van der Waals forces

• Affinity increases but adsorptive capacity decreases

• Neither capacity nor affinity changes significantly

Which property of an inorganic molecule like mercuric chloride favors its adsorption by activated charcoal?

• Strongly ionized and highly dissociated ionic salts

• Weakly dissociated or nonionized form that predominates at higher pH levels

• Presence of an alkyl chain increasing lipid solubility

• High molecular weight polymeric complexes

Why are nonpolar, poorly water-soluble organic substances adsorbed better by activated charcoal compared to polar water-soluble substances?

• Due to their higher ionic charge density

• Because hydrophobic interactions dominate over aqueous solubility leading to stronger binding to carbon surface

• They degrade slower, making adsorption easier

• They form covalent bonds with charcoal

Which chemical groups on organic molecules increase adsorption affinity by activated charcoal?

• Hydroxyl and amino groups

• Sulfonic and carboxyl groups

• Nitro groups and branched chain structures

• Saturated aliphatic straight chains only

How does environmental pH influence the adsorption of weak bases such as cocaine by activated charcoal?

• Adsorption capacity is independent of pH

• Adsorption is greater at acidic pH because more molecules are ionized

• Adsorption is reduced at acidic pH due to ionization decreasing lipophilicity and interaction with AC

• Adsorption is increased at very high pH due to precipitation

What major limitation does activated charcoal have concerning adsorbing strongly ionized salts such as sodium chloride and potassium chloride?

• Their molecular weight is too high

• They dissociate fully in aqueous media, reducing interaction with AC’s hydrophobic surface

• They form irreversible covalent bonds only

• AC selectively binds only metals, not salts

Describe the relationship between pore size of activated charcoal and the molecular weight of xenobiotics it most effectively adsorbs.

• Larger pore sizes (1000+ angstroms) adsorb low molecular weight compounds best

• Optimal adsorption occurs with pore sizes 10-20 angstroms matching most xenobiotics molecular sizes (100-800 daltons)

• Micropores < 5 angstroms provide maximal adsorption for all molecules

• Pore size has negligible impact on adsorption kinetics

What is a critical consideration in determining the dose of activated charcoal for effective adsorption in a poisoned patient?

• Patient’s BMI exclusively

• Unknown quantity of ingested xenobiotic and ensuring at least a 10:1 charcoal to xenobiotic mass ratio when possible

• Fixed dose of 25g for all adults regardless of toxin

• Visual estimation of gastric contents