Chemical Analysis Quantitative and Confirmatory Methods

Analytical methods for the detection and/or determination of antibiotic residues in food fall into two categories  

With the development and/or implementation of new LC-MS interfaces, modern column chemistries and advanced mass analyzers, LC-MS has largely superseded 

Chemical Analysis of Antibiotic Residues in Food, First Edition. Edited by Jian Wang, James D. MacNeil, and Jack F. Kay. 2012 John Wiley Sons, Inc. Published 2012 by John Wiley Sons, Inc. 

Matrix Compound Molecular Formula Molecular Weight [M + H]+ [M-H]- [M + NH4]+ [M + Na]+ Column  

Gradient profile mobile QqQ phases A—acetonitrile/ watCT (5 95, v/v) containing 20 mM HFBA B—acetonitrile/ water (50 50, v/v) containing 20 mM HFBA, IPC application 

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The method using GC/MS with selected ion monitoring (SIM) in the electron ionization (El) mode can determine concentrations of alachlor, acetochlor, and metolachlor and other major corn herbicides in raw and finished surface water and groundwater samples. This GC/MS method eliminates interferences and provides similar sensitivity and superior specificity compared with conventional methods such as GC/ECD or GC/NPD, eliminating the need for a confirmatory method by collection of data on numerous ions simultaneously. If there are interferences with the quantitation ion, a confirmation ion is substituted for quantitation purposes. Deuterated analogs of each analyte may be used as internal standards, which compensate for matrix effects and allow for the correction of losses that occur during the analytical procedure. A known amount of the deuterium-labeled compound, which is an ideal internal standard because its chemical and physical properties are essentially identical with those of the unlabeled compound, is carried through the analytical procedure. SPE is required to concentrate the water samples before analysis to determine concentrations reliably at or below 0.05 qg (ppb) and to recover/extract the various analytes from the water samples into a suitable solvent for GC analysis. 

Both infrared and Raman spectroscopy are extremely powerful analytical techniques for both qualitative and quantitative analysis. However, neither technique should be used in isolation, since other analytical methods may yield important complementary and/or confirmatory information regarding the sample. Even simple chemical tests and elemental analysis should not be overlooked and techniques such as chromatography, thermal analysis, nuclear magnetic resonance, atomic absorption spectroscopy, mass spectroscopy, ultraviolet and visible spectroscopy, etc., may all result in useful, corroborative, additional information being obtained. 

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