Page 9 - 毕业论文

prepared, according to traditional preparation methods reported by literatures. And

then, the standard decoctions were evaluated by measuring percentage yield,
extraction rate, content of major component, thin-layer chromatography and
4
characteristic spectrum. Secondly, an orthogonal experiments using L9(3 ) orthogonal
array was applied to determine the appropriate amount of water, the number of
decoctions, and the time of each decoction. The most appropriate parameters of

extraction process were decided only when the results of one orthogonal experiment
were most similar to the standard decoction. Finally, the optimized extraction process

was verified with scale-up experiments.
To obtain the optimal parameters for concentration process, decoctions prepared by

means of the optimized extraction process were concentrated under vacuum at
different temperatures and the contents of major component and characteristic
spectrums were compared before and after concentration.

3 Results
3.1 Analytical method development for simultaneous determination of AFB1, AFB2,

AFG1, AFG2 and ZEA
（1）Analytical method development and validation

The sample was extracted with 84% acetonitrile/water and directly injected into a
HPLC-MS/MS system without further purification procedure. The HPLC separation

was performed on a C18 column with a linear gradient elution program of 4mM
NH4Ac-0.1% formic acid solution and menthol as the mobile phase. Selected reaction
monitoring (SRM) was used for selective determination of these five mycotoxins on a

triple quadruple mass spectrometer (TSQ Quantum Access), which was operated both
in positive and in negative ionization modes in one chromatographic run.

LOD of AFB1、AFB2、AFG1、AFG2 and ZEA at a signal-to-noise ratio of 3︰1
was determined as 0.003ng/ml, 0.003 ng/ml, 0.005ng/ml, 0.008ng/ml, and 0.063ng/ml,

respectively. LOQ at a signal-to-noise ratio of 10︰1 was 0.005ng/ml, 0.008ng/ml,
0.010ng/ml, 0.030ng/ml and 0.125ng/ml, respectively. All five kinds of mycotoxins

showed a good linearity with the linear equation of AFB1、AFB2、AFG1、AFG2 and
ZEA was Y=1.124e5+1.225e6*X（R=0.995）; Y=-2.526e5+6.391e6*X（R=0.997）;
Y=-1.200e5+7.254e6*X（R=0.996）; Y=-7033+2.292e6*X（R=0.995）; Y=-9315

+8884 *X（R=0.999）, respectively. The average recoveries were between 65%~110%.
The intra-day RSD was between 0.64% and 4.6% and the inter-day RSD was between

3.4% and 8.9%.
（2） Sample analysis

V