23. Solving a chemistry problem

The content of phenol in the preparation Rantak (ranitidine, injection solution for intravenous and intramuscular administration) is determined by HPLC using a standard solution of phenol.
To prepare the analyzed solution, 1 ml of the drug is added to a 50 ml volumetric flask, the solution in the flask is brought to the mark with a mixture of methanol and 0.1% acetic acid solution (in a volume ratio of 65:35) and thoroughly mixed. Get the analyzed solution.
To obtain a standard solution, a weighed portion of a standard sample of phenol 100 mg (t) is added to a 100 ml volumetric flask, the volume of the solution in the flask is adjusted to the mark with a mixture of methanol and 0.1% acetic acid solution (in a volume ratio of 65:35) and carefully mixed. Take 1 ml of the resulting solution, add to a 10 ml volumetric flask, bring the solution in the flask to the mark with the same mixture of methanol and acetic acid and mix thoroughly. Get a standard solution.
Equal volumes (20 μl each) of the analyzed and standard solutions are introduced into the HPLC chromatograph, chromatograms are recorded and the peak areas of phenol S and Sct are measured on the chromatograms of the analyzed and standard solutions, respectively.
Calculate the content of phenol in the preparation in mg/ml, if the percentage of phenol in the standard sample is 99.99%, S:Sct = 1.05.