Chromatography Forum

The ICH defines a Reporting Threshold as "A limit above which (ie greater than) the impurity should be reported" so in Empower 3 Impurity tab if I put 0.05 in the reporting threshold then Empower will flag any value GREATER THAN 0.05.
But my impurity method states that "disregard any impurities less than 0.05%" so in order to include values of 0.05 upwards do I have to adjust the reporting threshold value to 0.04 to reflect this, similar to how RANGE in Empower treats the lower value as Greater than ie a RANGE of 10-20 will only include 11-20.

Hi ,,

that is my understanding of threshold values in Empower .. though watch decimal places

Less than or equal ? 0.05 = 0.044,, anything more reported as => 0.05 though depends on your internal SOP for rounding or truncation here

the actual value (amount/% area) is rounded according to the decimal places defined for the threshold so I am to believe

For RANGE are you meaning as custom field ?
Not use it much but try using it along with LG and GT perhaps

There are also GTE, LTE terms available among CF operators that may be helpful in checking the work of the impurities tab in your proc. methods...

Thanks for the replies but im still confused as to what to put in. ynda, if I put in 0.044 then surely Empower reads that as 0.04400000000000 at its full precision of 14 decimal places and a number like 0.04446788998701 is STILL not 0.05 when rounded to 2 decimal places and would not be flagged as above the reporting threshold? If it were a custom field I could just round it to 2 decimal places example GTE(ROUND(Impurity,-2),0.05) but because these thresholds are defined as only greater than how do you calculate down to still include values of 0.05?!

Hi

Check out tech note for reference :

https://us.v-cdn.net/6030142/uploads/ed ... rch0zt.pdf

Depends on your internal SOP on rounding and /or truncation at the end of the day and additional decimal place recommended

Thanks for that, the article is helpful. ill have to play around with precisions to see what exactly Empower considers included when setting a threshold. Thanks.