Determination of 5 Cephalosporins Residues in Honey——Selection of Analysis Conditions

5.
2.
5.
7 Selection of analysis conditions

(1) Selection of solid phase extraction column

In the study of this method, OasisHLB solid phase extraction column, BUNDELUT C ₁₈ solid phase extraction column, ENVI-18 solid phase extraction column, Octadecyl C ₁₈ solid phase extraction column, LiChrolutEN solid phase extraction column and Sep-Pak C ₁₈ solid phase extraction column were used.
The extraction efficiency and purification effect of five cephalosporins were compared with six solid phase extraction columns
.

(2) Selection of extraction solution

In the study of this method, according to the characteristics of the honey sample and the nature of the test substance, the sodium dihydrogen phosphate buffer solution was determined as the extracting solution
.

Table 5-37 The effect of extract concentration on the recovery rate (%) of 5 cephalosporins

Table 5-38 The effect of extract pH on the recovery rate (%) of 5 cephalosporins

It can be seen from Table 5-37 and Table 5-38 that when the concentration of sodium dihydrogen phosphate in the extract is 0.
15 mol/L and the pH is 8.
5, the recovery rate of the five cephalosporins is the best.
Therefore, this method uses pH 8 .
5, 0.
15 mol/L sodium dihydrogen phosphate solution as the extract
.

(3) Selection of elution conditions for solid phase extraction column

This method compares the effects of using 1 mL, 2 mL, and 3 mL acetonitrile as the eluent of the solid phase extraction column on the recovery of five cephalosporins.
The results are shown in Table 5-39
.

Table 5-39 The effect of solid phase extraction column eluent dosage on recovery rate (%)

(4) Selection of liquid chromatography analysis column

The chromatographic behaviors of 5 cephalosporins were compared using uBondapak C ₁₈ 300mm×4.
0mm chromatographic column and ZORBAXSB-C ₁₈ 3.
5um 150mm×2.
1mm chromatographic column
.

(5) Determination of mass spectrometry conditions

A syringe pump was used for direct sample injection, and the standard solutions of cefazolin , cefpirin, cephalexin, cefalonine, and cefquinoxime were injected into the ion source at 5 μL/min, and the five cephalosporins were detected by positive ion detection.
The primary mass spectrometry analysis (Q1 scan) shows that the protonated molecular ion peaks are 456, 424, 348, 459, and 529 respectively, and then the molecular ion is subjected to secondary mass spectrometry (product ion scan) to obtain fragment ion information
.