你如果是要做仪器空白,就可以用载流空白来做,如果你想做这种方法对于某种介质的空白,一定要用样品空白来做.
对于LoD和LoQ的计算,有好几种不同的方法,每个方法都有自己的优缺点,下面给你一些方法可以参考,但是计算出LoD和LoQ后,最好是将这个浓度验证一下,一般来说RSD达到17.7%就可以了.
LoD and LoQ could be assessed by different approaches. From the following procedures, choose the one which is the most appropriate to the method to be validated:
1) LoD and LoQ estimation by signal/noise ratio procedure (chromatographic and spectroscopic methods):
Parameter Minimum requirement
Samples: Spike one blank sample at 3 low concentration levels close to the expected LoD and LoQ (at least 3 concentration levels)
Number of replicates: Analyze each spiked sample 3 times
2) LoD and LoQ by standard deviation of the blank (gravimetric, photometric, enzymatic, titrimetric methods):
Parameter Minimum requirement
Samples: 1 blank sample (or 1 sample with a low amount of analyte)
Number of replicates: At least 6 replicates
3) LoQ by target performance characteristics (precision and/or recovery):
Parameter Minimum requirement
Samples: Spike one blank sample at low concentration levels close to the expected LoQ (at least 3 concentration levels)
Number of replicates: Analyze each spiked sample at least 3 times.
4) LoQ corresponding to the lowest calibration point (lowest validated level)
一个完整的Method Validaiton除了LoD和LoQ之外,还需要很多的步骤.