Lidocaine Hydrochloride Testing Procedure

To test the purity and potency of lidocaine hydrochloride in a pharmaceutical setting, Lidocaine Hydrochloride Testing Procedures several analytical methods. Lidocaine hydrochloride is a local anesthetic commonly used for numbing a specific area of the skin or mucous membranes. To test its purity and potency, the following procedure.


To ensure the quality of incoming raw material of Lidocaine Hydrochloride.


It is applicable for the analysis of Lidocaine Hydrochloride in the quality control department.


  • Quality Control Manager
  • Assist. Q.C. Manager
  • Q.C Analyst


  • SAP: Standard Analytical Procedure
  • QC: Quality control


Lidocaine Hydrochloride Testing Procedure

High-performance liquid chromatography (HPLC): This method separates and quantifies the components of a sample using a liquid chromatography column. The sample is injected into the column, and the lidocaine hydrochloride is separated and quantified based on its properties.

Ultraviolet-visible spectrophotometry (UV-Vis): This method measures the absorbance of light by a sample at specific wavelengths. Lidocaine hydrochloride has a characteristic absorption spectrum, which can be used to confirm its presence in a sample and determine its concentration.

Infrared spectroscopy (IR): This method involves measuring the absorption of infrared light by a sample. The resulting spectrum can be used to identify and confirm the presence of specific chemical functional groups in the sample.

Thin-layer chromatography (TLC): This method separates and identifies components of a sample based on their physical and chemical properties. A sample is applied to a stationary phase (a thin layer of silica gel or other material) and then separated based on its properties as it moves up the layer with a solvent.

Dissolution testing: This method assesses the rate at which a drug dissolves in a solvent. The sample is placed in a dissolution vessel, and the dissolution rate is monitored over time.


  • Glassware
  • Analytical balance
  • pH meter
  • Oven
  • Desiccator
  • Burette
  • Melting point apparatus
  • Karl Fischer Titrator
  • Water bath


  • Distilled water
  • Carbon Dioxide free water
  • Ethanol (96%)
  • Glacial acetic acid
  • Fuming nitric acid
  • Chloroform
  • Acetone


  • Sulphuric acid 1M
  • Ammonium carbonate 15.8 %
  • Alcoholic potassium hydroxide solution
  • Mercury (II) acetate solution R
  • Crystal violet
  • Perchloric acid VS 0.1N
  • Nitric acid 2M
  • Silver Nitrate solution R1
  • Ammonia 10M

Physical Analysis

Test of Physical Form:

Check the sample and confirm its physical form; it should be crystalline powder.

Test of Colour:

Confirm the colour of the material by comparing with reference sample; it should be white or almost white.

Test of Solubility:

Water: Very soluble. (1g should dissolve in less than 1ml)
Ethanol: Freely soluble. (1g should dissolve in 10ml)

Appearance of solution:

Solution S:

Dissolve 2.5 g of substance in water and dilute to 50 ml with distilled water.

Fill Nessler cylinder of 15 – 20 mm in internal diameter to the depth of 40 mm with solution S.

Take the same type of Nessler cylinder and fill with distilled water upto 40 mm depth this cylinder is taken as blank. Observe both cylinders against black background by viewing in diffused daylight down the vertical axis of cylinders.
It should be clear and colourless


Dilute 2.5 ml of solution S to 25 ml with distilled water. Note its pH using pH meter.
It should be 4.0 – 5.5.

Test of water:

Find out the water contents of the sample (using 0.25g) by Karl Fischer Titrator.
It should not be 5.5 – 7.0%.

Chemical Analysis:

Identification Test of Lidocaine Hydrochloride:

Melting point:

  1. Dry the finely powdered substance at the temperature below 74oC.
  2.  Transfer a sufficient portion to a dry capillary tube to from a compact column of 4 – 6 mm in height.
  3. Note the melting point by observing the temperature at which last solve particle passes into liquid phase. It should be 74o – 79o
  4. To about 5 mg add 0.5 ml of fuming nitric acid. Evaporate to dryness on a water bath, cool and dissolve the residue in 5 ml of acetone and add 0.2 ml alcoholic potassium hydroxide solution a green colour should produce.
  5. Dissolve a quantity of the substance being examined containing about 2 mg of chloride ion in 2 ml of water or use 2 ml of the prescribed solution. Acidify with 2M nitric acid, add 0.4 ml of silver nitrate solution R1, shake and allow to stand; a curdy, white precipitate is produced. Centrifuge and wash the precipitate with three 1 ml quantities of water. Carry out this operation rapidly in subdued light, disregarding the fact that the supernatant solution may not become perfectly clear. Suspend the precipitate in 2 ml of water and add 1.5 ml of 10 M ammonia; the precipitate dissolves easily with the possible exception of a few large particles which dissolve slowly.

Contents of Lignocaine Hydrochloride:

Standard preparation:

Dissolve 0.25 g of substance in 30 ml of anhydrous acetic acid. Add 6 ml mercury (II) acetate solution. Mix and titrate with 0.1N perchloric acid, using crystal violet TS as indictor, till amaranth green colour is developed.


Volume of perchloric acid used against sample = P ml
Volume consumed = Q ml
Exact Normality of HClO4 after stdzn = N
Note the readings


Calculate the contents of Lignocaine Hydrochloride as follow:

Factor: Each ml of 0.1N HClO4 is equivalent to 27.08 mg of lignocaine Hydrochloride.
Q x Factor
= ——————- x 100

P x N
Q = ————–

Limit: It should be 99.0% to 101.0% calculated with reference to dried substance.

Quality Record(s)/Form(s):

The following Quality Records shall be generated and managed in accordance with the Procedure for Control of Company Quality Records.


It’s important to follow all relevant safety guidelines and regulations when handling and testing lidocaine hydrochloride, and to ensure that the analytical methods used are validated and appropriate for the specific product and application. Additionally, it’s recommended to use properly calibrated and maintained equipment, and to follow good laboratory practices (GLP) to ensure the accuracy and reliability of the test results.

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