Chemical Forums
Chemistry Forums for Students => Analytical Chemistry Forum => Topic started by: JWF239 on January 11, 2018, 11:23:56 AM
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Hello,
Hoping to find someone with extensive experience in FTIR method development to give me an expert opinion on this question:
Can you verify a quantitation limit in FTIR analysis without specifically having a standard at that reporting limit? Or would you only accept a quantitation limit (or reporting limit) if you had specifically analyzed a standard at that concentration?
I don’t want to get too far into it, but I used two methods from ISO 12828-1 “Validation Method for Fire Gas Analysis”. Main method 1 – Determination of LoD and LoQ from matrix data from blank samples, and Main method 2 – Determination of LoD and LoQ from the linearity of calibration data.
There is also a main method 3 – checking a given or prescribed quantification limit, but it is difficult to obtain gas standards at the concentrations that I calculated from main method 1 and 2.
My understanding was that since FTIR measures the entire spectral range during each scan, even “blank” analysis would yield a signal and therefore having a standard specifically at the desired reporting limit was not strictly necessary, or is this incorrect? Would you approve a method where the reporting limit was calculated using the main methods 1 and 2 above, but the limits had not been explicitly tested with a standard at that concentration, or would you not use a method without having tested a reporting limit specifically? Note the reporting limit is well below the specification limits for my desired commodity specifications. Those limits have been verified with a standard at those limits.