Page 42 - Application Notebook - Solution for Food Safety

LAAN-A-LM-E070

Application Liquid Chromatography Mass Spectrometry

News Quantitative Analysis of Veterinary Drugs Using the

Shimadzu LCMS-8050 Triple Quadrupole Mass
No.C99 Spectrometer

Foods in which chemical residues, like pesticides, feed highly sensitive and rapid analytical technique to
additives, and veterinary drugs found in excess of analyze as many of these compounds as possible in a
maximum residue levels have been banned from sale in single run. This Application News introduces an
many countries around the world. Compounds that are example of the high-sensitivity analysis of 89 veterinary
subject to residue standards vary widely and the list is drugs in a crude extract of livestock and fishery
expected to grow. Because of this, there is a need for a products.

n Sample Preparation
The typical samples used in the analysis of veterinary (1) Homogenize 100 g sample (chicken, pork, salmon, shrimp) in food processor
drugs contain large amounts of lipids because they are
commonly meat and fish samples. Sample preparation (2) Weigh out 10 g homogenized sample, transfer to 50 mL test tube
is extremely important to ensure excellent sensitivity
and repeatability. To avoid the typical time-consuming (3) Add 5 mL water, shake gently by hand
and laborious solid phase extraction sample preparation (4) Add acetonitrile containing 1 % acetic acid and QuEChERS salts*, shake by hand (1 min)
procedure, the QuEChERS method, which is typically
used for the preparation of vegetables, was selected to (5) Centrifuge separation (3 min)
simplify sample preparation.
The QuEChERS method normally consists of two steps, (6) Collect acetonitrile layer and filter
the first is an acetonitrile extraction and the second a (7) LC/MS/MS analysis
cleanup step, but this time only the acetonitrile
extraction step was used.
Fig. 1 Sample Preparation Procedure
TM
* QuEChERS Extraction Salts kit: Restek Q-sep AOAC2007.01
n Improved Peak Shape Using Sample / Water Co-Injection
When conducting reversed phase chromatography, the Diaveridine
peaks of polar compounds may split or collapse 7:261.15>123.10 (+) 7:261.15>123.10 (+)
depending on the relationship between the sample
solvent and mobile phase. In cases where the sample
solvent is rich in organic solvent, the elution strength
must be lowered (by substitution or dilution) with the
addition of water. As the pretreated sample solvent in
this analysis consists of 100 % acetonitrile, injection in
that state into the LC/MS will result in split peaks for 2.0 2.5 3.0 3.5 2.0 2.5 3.0 3.5
some of the substances (Fig. 2 left). Difloxacin
To eliminate as much of the time and effort typically 26:400.10>356.20 (+)
associated with sample preparation, the pretreatment 26:400.10>356.20 (+)
features of the autosampler (SIL-30A) were utilized to
conduct co-injection of sample and water, which
resulted in improved peak shapes.

2.5 3.0 3.5 4.0 2.5 3.0 3.5 4.0
Sample 2 µL S a m 2 e l p µL
Sample + Water 10 µL
Note: Sample solvent: 100 % Acetonitrile
Air
Fig. 2 Comparison of Peak Shape
Draw Sample Draw Air Draw Water Inject