Chromatographic Determination of Analgesics

Experiment 1. Chromatographic Determination of Analgesics

Abstract

The components of a capsule of unknown components were studied via thin layer chromatography (TLC). A capsule content solution with unknown components was prepared by combining the contents of capsule #402 and methanol. A drop of the capsule content solution and phenacetin were placed on a TLC silica gel sheet and developed. The difference of Rf values of unknown spot 1 and phenacetin (0.03) and unknown spot 2 and acetylsalicylic acid (0.09) were the lowest in value compared to the other analgesics studied, suggesting that the unknown components of capsule #402 are phenacetin and ASA.

Data and Results

Table 1. Preparation of chromatographic determination of analgesics via thin layer chromatography (TLC)1

Chemical | Amount |

Pharmaceutical drug | 1 capsule #4022 |

Methanol | 5 mL |

Figure 1. Chromatogram of analgesics stained with iron chloride/potassium ferricyanide solvent. A standard phase TLC silica gel plate was used. Spots were visualized and marked via UV light. The two spots on the left side of the chromatogram are that of unknown components of capsule #402, while the single spot on the left is that of phenacetin. 1) Unknown 1. 2) Unknown 2.

3) Phenacetin. 4) Origin line. 5) Solvent front.

Table 2. Rf values of analgesics presented in Figure 1

Analgesic | Distance travelled from origin line to center of spot (cm) | Distance travelled from line of origin to solvent front (cm) | Rf |

Unknown 1 | 2.1 | 5.3 | 0.40 |

Unknown 2 | 3.1 | 5.3 | 0.58 |

Phenacetin | 2.0 | 5.4 | 0.37 |

Table 3. Colleague data of Rf values for known analgesics3

Analgesic | Distance travelled from origin line to center of spot (cm) | Distance travelled from line of origin to solvent front (cm) | Rf |

Caffeine | 0.6 | 5.8 | 0.1 |

Acetylsalicylic acid | 3.8 | 5.7 | 0.67 |

Table 4. Description of chemical hazards

Reagent | Hazards1 |

Acetylsalicylic acid | Toxic, irritant,...