Quantitative Determination of Methanol in Iranian Herbaceous Distillates

Introduction: Methanol, as a colorless liquid, is freely miscible with water and easily cross the blood-brain barrier. Along with lethal dose of 1–2 mL/kg, methanol poisoning is common in clinical practice. Death and blindness have been shown with as low as 0.1 mL/kg. Methanol poisoning can result in optic nerve lesion, hypotension, and CNS damage and anion gap metabolic acidosisMaterials and Methods: Sixty-five herbal distillates which commonly used in Iran were provided. Methanol content were determined by gas chromatography with flame ionization detector.Results: The calibration curve was obtained in a concentration range from 25 to 500 mg/L for methanol. LOD and LOQ were 10 and 25 mg/L, respectively. Accuracy and precision of the method were 97% and 96%, respectively. In 15 herbal distillates, the methanol concentration was below the limit of quantitation. The methanol concentrations in all samples ranged from 43 to 277 mg/ L. Forty-five samples contained methanol in excess of the Iranian standard. The maximum concentration was found in an herbal distillate of Mentha piperita (factory E) (277 ± 12), and the minimum in a distillate of Carum carvi (factory B) (42.6 ± 0.5).Discussion: Herbal distillate or herbal water refers to a liquid obtained from the cooled steam of medicinal plants. They contain a biologically active portion of the plant without its cellular residue. Methanol is present in vegetable and fruit juice and related product. Pectin, a heteropolysaccharide component in the cell wall, composed of linear chains of α-1, 4-galacturonic acids. In nature, usually carboxyl groups of galacturonic acid are esterified with methanol. During fruit and vegetable process, enzymatic activities (i.e. Pectinesterase) are resulted in methanol and pectin release. Hence, methanol is found in those product bonded and freely. On the other hand, fermentation of cellulose may lead to methanol production. Different factors including type of yeast strain, fruit varieties and species and oenological practices can influence methanol level. In addition, various process of food production in different factories is another key factor influence methanol concentration in final product. Methanol is poisonous volatile liquid which potentially can produce symptoms such as optic nerve damage, diarrhea, abdominal pain, hypotension, and anion gap. Metabolic acidosis, seizures, and coma are associated with blood methanol concentration above 500 mg/L Concentration above 1500–2000 mg/L will result in death. Owing to its major toxicity, quality control of Ma-al-shaeer products is greatly recommended.

کلیدواژه ها:

gas chromatography ، herbal distillates ، methanol