Glacial acetic acid detection: technical sharing of content detection in API by laboratory gas chromatograph
Glacial acetic acid, also known as glacial acetic acid, molecular formula C2H4O2, molecular weight 60.05, CAS No. 64-19-7, colorless clear liquid or colorless crystal block; It is miscible with water, ethanol and glycerin. It can be used to manufacture vinyl chloride plastic, acetic anhydride, organic acetate, acetate (lead, aluminum, copper, etc.) and acetate fiber; It can also be used in dye, pharmaceutical, canned food, food preservation, pigment production and other industrial production.
It is classified as pharmaceutical excipients, pH regulators and solvents in terms of function. It is widely used in pharmaceutical preparations to regulate the pH of prescriptions, and is generally considered to be relatively non-toxic and non irritating. However, when the concentration of glacial acetic acid or acetic acid in water or organic solvent exceeds 50% (W/W), it is corrosive and will cause damage to human skin, nose, etc., so it is necessary to control and determine the content of glacial acetic acid.
To detect the content, take about 2ml of the product, place it in a conical flask with a stopper, accurately weigh it, add 40ml of fresh boiled cold water and 3 drops of phenolphthalein indicator solution, and titrate it with sodium hydroxide titrant (1mol/L). Every 1ml of sodium hydroxide titrant (1mol/L) is equivalent to 60.05mg of C2H4O2. In addition to titration, the microsource detection laboratory consulted literature and shared a method for the determination of glacial acetic acid residues in API by gas chromatography.
A gas chromatograph is required. The chromatographic column is a capillary column, the carrier gas is nitrogen, the flow rate is 1.5ml/min, and the split ratio is 10:1; FID detector; Injection volume 1 μ L； The detector temperature is 250 ℃, and the sample inlet temperature is 160 ℃; Temperature programmed. Accurately weigh 5g of glacial acetic acid and put it into a 100mL measuring bottle, dissolve it in methanol and shake it up to the scale; Accurately measure 1mL, put it into a 100mL measuring flask, dissolve it with methanol and make it to the scale to obtain mixed reference solution. Accurately weigh 1g of sample, put it into a 10mL measuring flask, dissolve it with methanol and make it to the scale to shake it up to obtain the test solution. Take methanol as the diluent, mixed reference solution and test solution, and directly inject sample 1 μ 50. Record the chromatogram.
Accurately measure 3 and 5mL of reference stock solution respectively and place them in 100mL volumetric flasks, then precisely measure 5 and 7.5mL of reference stock solution respectively and place them in 50mL volumetric flasks, add methanol to dilute them to the scale and shake them up, respectively take the limit of quantitation and solution 1 of the above four concentrations μ L test. Take concentration as the abscissa and peak area as the ordinate to determine the linearity and range of the linear regression equation. Results There was no peak interference in the test sample.
The method of using gas chromatography to detect glacial acetic acid is sensitive, accurate, reproducible and simple, which can meet the needs of actual sample detection. Micro source detection laboratories can use high performance liquid chromatography (HPLC), liquid mass spectrometry (LC-MS), gas chromatography mass spectrometry (GC-MS), scanning electron microscopy (SEM), secondary ion mass spectrometry (SIMS) and other detection equipment to detect glacial acetic acid content efficiently and accurately, providing sample freezing point, corrosivity, flash point, concentration Irritation, stability, boiling point, heavy metal content and other detection services. The laboratory is managed according to high standards such as ISO17,025 and GMP, and provides a series of complete solutions such as evaluation report, method development, verification and sample detection for impurities that may be generated during the production of partner products in the biomedical field.
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