Ultra-Violet Assay Method for Erythromycin Tablets

Each Film Coated Tablet Contains:

Erythromycin Stearate equivalent to Erythromycin 250mg

Preparation of 0.2 M KH₂PO₄: 

Dissolve 13.61g of potassium dihydrogen orthophosphate in 500ml of distilled water. 

Preparation of 0.2 M NaOH: 

 Dissolve 4g of NaOH in 500ml of distilled water. 

Preparation of buffer solution: 

 Mix uniformly 250ml of 0.2M potassium dihydrogen orthophosphate and 250ml of 0.2M NaOH and adjust the pH 8 with sodium hydroxide or potassium dihydrogen orthophosphate. 

Preparation of Diluent: 

Buffer Solution pH 8 : Methanol (25:25, v/v) 

Preparation of Standard Solution: 

Weigh & transfer 138.8mg of Erythromycin Stearate SRS in 50mL volumetric flasks, add 10mL of diluent to dissolve & dilute with buffer solution to volume. Dilute 1mL of this solution to 25mL with buffer solution. 

Preparation of Sample Solution: 

Weigh & powder 20 tablets. Transfer accurately weigh tablet powder equivalent to 138.8mg of Erythromycin Stearate in 50mL volumetric flasks, add 10mL of diluent to dissolve & dilute with buffer solution to volume. Dilute 1mL of this solution to 25mL with buffer solution. 

Filter the standard and sample solution and measure the absorbance at 280 nm. 

Calculation: 

Calculate the % Assay of Erythromycin by using the following formula: 

    Where, 

      At = Average Absorbance of Sample 

      As = Average Absorbance of Standard 

      Ws = Weight standard 

      Wt = Weight of Sample 

      L = Label claim 

      P = Potency of standard

NOTE: Analyst have to perform Method Validation as per Regulatory Guidelines. Also needs to established comparative study with microbiological assay of antibiotics.