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(3) Derivation method
1) UV detection derivative
The ultraviolet detection wavelength of the β-lactam ring precursor is between 200 and 235 nm, and the ultraviolet absorption lacks characteristic, and the interference component has a greater influence.
Therefore, it is often necessary to derivatize when applying liquid chromatography to make it have characteristic absorption
.
Derivatization is divided into two types: pre-column and post-column
Beconi-Barker et al.
established an HPLC method for the residues of ceftiofur and its metabolites in pork, liver, kidney, and adipose tissue
.
Using erythritol-salt buffer extraction, iodoacetamide precolumn derivatization, 3mL iodoacetamide was added, vortex mixed at room temperature after placing 30min, washed with 5% phosphoric acid solution was adjusted to pH2.
2) Fluorescence detection derivative
There are also reports of derivatization methods to form fluorescent derivatives
.
Luo Daoxu et al.
used trichloroacetic acid solution to precipitate milk proteins and extract ampicillin residues.
The ampicillin and formaldehyde were heated under acidic conditions to generate 2-hydroxy-3-phenyl-6-methylpyrazine, which was then detected by FLD.
.
The fluorescence detection excitation wavelength is 346nm, and the emission wavelength is 422nm
CEPs can also be measured by fluorescence detector after derivatization reaction
.
Meng et al.
3) Gas chromatographic detection and derivatization
β-lactam drugs are highly polar, thermally unstable and difficult to volatile compounds.
When gas chromatography is used for determination, methyl ester derivatization reactions are required to increase their volatility and reduce their polarity
.
Preu et al.
Related links: β-lactam drug residue analysis technology-purification method (2)
