1.首先声明此方法里面涉及的任何仪器和耗材都是推荐使用,并不代表必须使用此仪器和耗材。使用相同类型的仪器和耗材能得到相同的分析结果。
2.其次,由于双氰胺同位素内标会在二周后才能得到,所以推荐用两点或者三点标准加入法对阳性样品进行定量。
3.由于时间有限,此方法难免有不当之处,请大家根据自己实验室条件更新。
DCD Method Setup (Modified FDA Method)Instrument ConditionMobile Phase B | 10 mM Ammonium Acetate (pH=4.0) |
Mobile Phase A | Acetonitrile (LC-MS Grade) |
Column | Waters Acquity HIILIC,2.1*100 mm, 1.7um |
Column Temperature | 35 |
Flow ratio | 0.3 mL/min |
Gradient | Time | B (%) | 0.00 | 10 | 2.00 | 10 | 4.00 | 50 | 5.00 | 50 | 5.01 | 10 | 10.00 | 10 |
|
MS/MS Parameters (Agilent 6410B+1200 RRLC)Transition | Fragmentor | CE | Dwell Time (ms) |
85.0-68.0 (Quantitative) | 50 | 20 | 400 |
85.0-43.0 (Qualitative) | 50 | 10 | 400 |
ESI Ion Source ParametersESI Model | Positive |
Gas Flow | 13 mL/min |
Pressure | 50 Psi |
Gas Temperature | 350 |
Capillary Voltage | 2000 V |
Resolution | Unit (both) |
EMV | 200 |
Divert Valve | From 0.5 min to 3 min to MS |
Sample Preparation1. Weigh exactly 1.00±0.01 g sample into 50 mL centrifuge tube2. Add 7.5 mL formic acid solution (2 %, v/v) to dissolve the sample by shaking 5 min, then ultrasonic 30 min, and make sure there is no lump produced during mixing.3. Add 12.5 mL acetonitrile and shake under 500 rpm for 5 min.4. Centrifuge at 8500 g for 10 min, and transfer the supernatant into sample vial for injection. Chromatograms1. 1 ppb DCD Standard