检出限大家是怎么做的？PAHs的检出限一般是多少？

应助达人

我们实验室是测定方法空白7次，来计算SD,MDL=3.14SD.

应助达人

MATTEL7420对应的GC-MS IDL与MDL，有附件，请参考
2.6.6.5 Note: Instrument Detection Limit (IDL) – 3 times the standard deviation of 1
replicate measurements of reagent blank.
Method Detection Limit (MDL) – Reagent blank fortified with 2-3 times of th
IDL. Seven replicate measurements are made. Calculate the MDL as follow
MDL = (t) x (S), where t=3.14(99% confidence level for 7 replicates) and s
standard deviation.
ƒ Since the MDL is statistically based, the MDL value obtained must
verified to ensure the instrument can accurately detect at this level.
ƒ Prepare a standard at a concentration equivalent to the MDL of eac
phthalate.
ƒ Analyze this standard with the number of replicates set to 10.
ƒ The average result shall be within ±10% of the MDL value.
ƒ If the average result is not within ±10% of the MDL value, prepare a new
standard at a higher concentration and repeat steps until an acceptable
value is obtained. This value is the MDL that shall be used
tive Identification

您的意思是测定空白7次，但空白中有PAHs吗？在那个位置有峰吗？若没峰怎么办

应助达人

没峰，就加低浓度的标液。

我们和1楼的做法一样

请问SD怎么计算？

应助达人

SD就是求标准偏差。

哦！明白了！

你好，请问这个方法有文献可以参考吗？有什么资料吗？我们实验室用的是安捷伦的6850-5975GC-MS，用信噪比计算检出限太麻烦了，我也想用你说的那个方法做，但是最好能有参考文献或者资料，这样可行度更大一点！