Determination Method of Sulfur Dioxide Residues in Chinese Medicinal Materials (2)

2.

The 2015 edition of "Chinese Pharmacopoeia" included ion chromatography

(1) General requirements for instruments

All ion chromatography instrument in contact with the test sample or eluant supply pipe, the device should employ inert materials, such as polyether ether ketone (PEEK) and the like

1.

(1) Organic polymer carrier filler: the most commonly used, the carrier of the filler is generally styrene-divinylbenzene copolymer, ethylvinylbenzene-divinylbenzene copolymer, polymethacrylate or polyethylene Organic polymers such as polymers

(2) Inorganic carrier filler: generally silica gel is used as the carrier

2.

3.

(1) Conductivity detector: mainly used to determine inorganic anions, inorganic cations and some polar organics, such as carboxylic acids

(2) Amperometric detector: used to analyze compounds with low dissociation degree but with oxidation or reduction properties

(3) UV detector: suitable for trace amounts of bromide ions (Br-), nitrite ions (NO ₂ -), nitrate ions (NO ₃ -) and others with strong UV in the presence of high concentrations of chloride ions, etc.

Atomic absorption spectroscopy, atomic emission spectroscopy (including inductively coupled plasma atomic emission spectrometry), and mass spectrometry (including inductively coupled plasma mass spectrometry) can also be used as ion chromatography detectors

(2) Sample processing

For simple matrix, clear aqueous solution is usually diluted and filtered with 0.

(3) Chromatographic conditions and system suitability test

Use ion chromatography, anion suppressor, conductivity detector to detect

Chromatographic column: AS-11-HC (250mm×4mm), guard column is AG-11-HC (50mm×4mm), eluent is 20mmol/L potassium hydroxide solution, flow rate is 1ml/min, column temperature is 30 ℃

Eluent: 3.

Flow rate: 0.
7ml/min
.

Injection volume: 20ul
.

The preparation of the reference solution: take the sulfate standard solution (Chinese Academy of Metrology, the concentration is 1000ug/ml), add water to make each 1ml containing sulfate 0.
5, 1, 2, 5, 10, 20, 50, 100, For solutions of 150 and 200ug/ml, 10ul each was injected, and a standard curve was drawn
.

Preparation of test solution: Take the test powder 10g (through sieve III), pinsetter A (two-necked flask), add water 50ml, shake, steam distillation flask ON C
.
Add 20ml of 3% hydrogen peroxide solution to absorption bottle B (100ml graduated tube) as the absorption liquid, and insert the lower end of the absorption tube below the liquid level of the absorption liquid
.
Add 5ml of hydrochloric acid to bottle A along the wall of the bottle and quickly close it tightly
.
Start the distillation, collect about 100ml of distillate, add water to dilute to the mark, shake well, and let it stand for 3 hours (centrifuge or filter with a microporous membrane if necessary) to get it
.
Determination method: accurately draw 10ul each of the reference solution and the test solution, inject the sample, determine, use the standard curve method to calculate the sulfate content in the sample, and convert it into sulfur dioxide in the sample according to (SO ₂ /SO ₄ ^2- =0.
6669) Content .

Related Links: Determination of Sulfur Dioxide Residues in Chinese Medicinal Materials (1)