-
Categories
-
Pharmaceutical Intermediates
-
Active Pharmaceutical Ingredients
-
Food Additives
- Industrial Coatings
- Agrochemicals
- Dyes and Pigments
- Surfactant
- Flavors and Fragrances
- Chemical Reagents
- Catalyst and Auxiliary
- Natural Products
- Inorganic Chemistry
-
Organic Chemistry
-
Biochemical Engineering
- Analytical Chemistry
- Cosmetic Ingredient
-
Pharmaceutical Intermediates
Promotion
ECHEMI Mall
Wholesale
Weekly Price
Exhibition
News
-
Trade Service
5.
2.
7.
6 Determination
(1) Liquid chromatography conditions
Chromatographic column: ZORBAXSB-C 18 , 3.
5μm, 150mm×2.
1mm (inner diameter) or equivalent; see Table 5-35 for mobile phase composition, flow rate and gradient program; column temperature: 30°C; injection volume: 20μL
.
(2) Mass spectrometry conditions
Ion source: electrospray ion source; scanning method: positive ion scan; detection method: multi-reaction monitoring; electrospray voltage: 5500V; atomizing gas pressure: 0.
055MPa; curtain air pressure: 0.
079MPa; auxiliary gas flow rate: 6L/min ; Ion source temperature: 400℃; qualitative ion pair, quantitative ion pair and declustering voltage (DP), collision gas energy (CE) are shown in Table 5-36
.
(3) Qualitative determination
Select one parent ion and two or more product ions of each substance to be tested.
Under the same experimental conditions, the retention time of the substance to be tested in the sample is within ±2.
5% of the retention time of the corresponding substance in the matrix standard solution; Comparing the relative abundance of each qualitative ion in the sample spectrum with the relative abundance of the ion in the matrix standard solution whose concentration is close, the deviation does not exceed the range specified in Table 1-5, it can be determined that there is a corresponding test in the sample Things
.
(4) Quantitative determination
Samples were injected separately with the matrix standard mixed working solution, and the standard working curve was drawn with the concentration of the standard working solution as the abscissa and the peak area as the ordinate
.
Use the standard working curve to quantify the sample.
5.
2.
7.
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 four cephalosporins were compared with six solid phase extraction columns
.
Experiments have found that the Sep-Pak C 18 solid phase extraction column has a low recovery rate (only 50% to 60%) and the purification effect is not ideal.
(2) Selection of extraction solution
In the study of this method, according to the characteristics of the milk sample and the nature of the test substance, the sodium dihydrogen phosphate buffer solution was determined as the extracting solution
.
Through the recovery rate experiment, the effects of the concentration and pH of the sodium dihydrogen phosphate buffer solution in the extract on the recovery rate of four cephalosporins were compared .
Table 5-48 The effect of extract concentration on the recovery rate (%) of four cephalosporins
Table 5-49 The effect of extract pH on the recovery rate (%) of six cephalosporins
It can be seen from Table 5-48 and Table 5-49 that when the concentration of sodium dihydrogen phosphate in the extract is 0.
Related Links: Determination of 4 Cephalosporins in Milk and Milk Powder by Liquid Chromatography-Tandem Mass Spectrometry
