Toxicologic Internship: Overview of Analytical Methods

Toxicologic Internship: Overview of Analytical Methods

This article summarizes knowledge about toxicologic analytical methods, focusing on qualitative and quantitative methods for commonly encountered toxins in poisoning cases.

1. Qualitative and Quantitative Determination of Phenol:

• Form of Bromine used in the quantitative determination of phenol in urine: Bromide-bromate solution is used because free bromine solution is unstable and prone to volatilization.

• Phenol isolation method: Steam distillation.

• Method of quantifying phenol in urine: Iodometry.

• Mechanism of quantifying phenol: The iodometry method determines the amount of excess bromine after the reaction to form tribromophenol precipitate with phenol.

• Role of chloroform: Dissolves the tribromophenol precipitate.

• Role of Bromide-bromate: Generates free bromine in the presence of acid, which reacts with phenol to form tribromophenol precipitate.

• Why not directly quantify with bromine? Bromine is more volatile than iodine, leading to reduced accuracy and reproducibility of the results.

• Phenol qualitative determination phenomenon: Unstable blue-violet solution (FeCl3), yellow color (picric acid), dirty blue (indophenol formation).

2. Qualitative and Quantitative Determination of Ethanol:

• Method of quantifying ethanol: Nicloux.

• Oxidizing agent in the Nicloux method: Potassium dichromate/concentrated sulfuric acid.

• Role of picric acid: Precipitates proteins.

• Phenomenon of ethanol oxidation reaction: Color change from yellow (Cr6+) to green (Cr3+).

• Phenomenon of iodoform formation reaction: Formation of yellow precipitate.

• Methods for qualitative determination of ethanol: Iodoform reaction, ethyl acetate formation.

• Sensitivity of the iodoform reaction: 0.04mg/mL.

3. Qualitative and Quantitative Determination of Methanol:

• Methods for qualitative determination of methanol: Schiff, resorcin.

• Schiff reagent: Fuchsin sulfite acid.

• Resorcin reagent: 1% resorcin.

• Phenomenon of reaction with Schiff: Blue or blue-violet solution.

• Phenomenon of reaction with resorcin: Pink or deep red solution.

4. Qualitative and Quantitative Determination of Arsenic:

• Methods for qualitative determination of arsenic: Bougault.

• Bougault reagent: H3PO2/HCl (hypophosphorous acid).

• Phenomenon of the Bougault reaction: Brown precipitate – As metal.

• Method of quantifying arsenic: Cribier.

• Reducing agent in the Cribier method: Nascent hydrogen.

• Phenomenon of reaction with HgCl2-impregnated paper: Yellow => Orange => Brown.

5. Qualitative and Quantitative Determination of Lead:

• Methods for qualitative determination of lead: Reaction with dithizone, KI, potassium chromate.

• Phenomenon of reaction with dithizone: Pink-purple solution.

• Phenomenon of reaction with KI: Yellow precipitate (PbI2).

• Phenomenon of reaction with K2Cr2O7: Yellow precipitate (PbCrO4).

6. Qualitative and Quantitative Determination of Manganese:

• Method of quantifying manganese: Spectrophotometry.

• Phenomenon of the Marshall reaction: Pink-purple solution.

• Method for qualitative determination of manganese: Marshall reaction.

7. Qualitative and Quantitative Determination of Hydrogen Cyanide:

• HCN isolation method: Steam distillation.

• Methods for qualitative determination of HCN: Grignard, Prussian blue.

• Grignard reagent: Picric acid/alkali.

• Prussian blue reagent: Fe II and Fe III sulfate/alkali.

• Phenomenon of the Grignard reaction: Picric acid-impregnated paper: yellow => orange-yellow => brown.

• Phenomenon of the Prussian blue reaction: Blue precipitate upon acidification.

8. Quantifying Mercury:

• Method of isolating Hg: Inorganification with sulfo-nitric acid.

• Method of quantifying Hg: Formation of Cu2I2 complex.

Note: This article only provides a general overview of toxicologic analytical methods. Performing these methods requires technical expertise and in-depth knowledge of chemistry.

Additionally, note:

• Toxicologic analytical methods can vary depending on the sample type, toxicant, and research purpose.

• Sample processing and analytical steps must adhere to standard protocols to ensure accuracy and reliability of the results.

• When handling hazardous chemicals, safety regulations regarding workplace safety and the environment must be followed.