Pretreatment of pyrazolone residue analysis technology-extraction method (1)

(2) Extraction method

Pyrazolone drugs are the most stable under neutral conditions, and their stability decreases under acid and alkaline conditions.
They should be handled as soon as possible to reduce drug hydrolysis
.

The unsaturated bonds on the pyrazolone ring of this kind of drugs are easily oxidized.

1) Liquid liquid extraction (LLE)

Pyrazolone drugs in biological matrices (blood, urine, milk and tissues) are mainly extracted by liquid-liquid extraction (LLE)
.

Reported phenylbutazone and / or oxyphenbutazone extraction solvent include acetonitrile, ethyl acetate , diethyl ether - n-hexane, acetonitrile , and the like acidic solvent; antipyrine solution was extracted with a chloroform , sodium - sulfite solution and the like

A.
Basic drugs

This class of drugs is easy to hydrolyze under acid-base conditions, and should be extracted and purified under neutral conditions as much as possible; if acid-base conditions are selected, the operation should be completed as soon as possible
.

a.
Neutral extraction

Shen Jincan et al.
determined the residues of the three metabolites FAA, AA and MAA of Analgin in the muscle tissues of cattle and pigs
.

In order to maintain the stability of the drug, the 0.

However, there are many reports of direct extraction using organic solvents/mixed solvents
.

Penney et al.

b.
Alkaline extraction

Under alkaline conditions, aminopyrine, analgin, antipyrine and their metabolites are more easily extracted by organic solvents
.

Shen Jincan and others determined the four metabolites of Analgin in milk and milk powder: FAA, AAA, MAA and AA residues
.

The sample was adjusted to alkaline by adding Tris solution, and then extracted with acetonitrile.

Shively et al.
determined antipyrine and aminopyrine in saliva
.

A 1mL saliva sample was alkalized by adding 1mL 1mol/L sodium hydroxide solution, and then added with chloroform for extraction.

Abernethy et al.
extracted antipyrine from plasma, added 1 mL of 1 mol/L sodium hydroxide solution to 1 mL of plasma, and then added 6 mL of ethyl acetate for extraction, centrifuged, and the ethyl acetate layer was evaporated to dryness and reconstituted for GC determination
.

The LOD of the method is 1 μg/mL, the recovery rate is greater than 95%, and the CV is less than 6.

c.
Acidic extraction

There are also reports of extraction with organic solvents under acidic conditions
.

The advantage of acidic extraction is that there is less tissue matrix co-extracted, but the amount of extraction solvent should be increased, and organic solvents with slightly stronger polarity should be used to improve extraction efficiency

Cui Jingbin and others determined the metabolites of Analgin in plasma, took 0.
5mL of plasma, added internal standard isopropylaminoantipyrine, acidified with 0.
1mL 0.
1mol/L HCI, extracted with anhydrous ether, centrifuged and dried the ether layer The residue was dissolved in mobile phase and determined by HPLC
.
The absolute recovery rate of MAA is 82.
5%, the relative recovery rate is 99%, and the CV is less than 3.
66%
.
Jedziniak et al.
determined the residues of four metabolites FAA, AAA, AA and MAA of Analgin in beef
.
The sample was extracted with acetonitrile-0.
33mol/L sodium acetate (8+2, v/v) buffer solution and determined by LC-MS
.
The CV is 7%-30%, and the recovery rate is 45%-95%; the detection limits (CCa) of FAA, AAA, AA and MAA are 11.
6μg/kg, 11.
6μg/kg, 12.
6μg/kg and 113μg/kg, respectively , The detection capacity (CCβ) is 16.
5μg/kg, 15.
8μg/kg, 16.
4μg/kg and 139μg/kg respectively
.