Hi there can be many reasons for the extra peak, it can come from impure compounds, contamination during sample prep, impure reagents, degradation of compounds.

Hi
False positive rises from wrong interpretation of MS spectra when relying only on matching the spectra with authentic libraries. However such analysis must be confirmed by convolution as all positive falsies happened when both compounds eluted together and sum of fragmentations pattern match a third compound.
It is very easy to clear out the results and match the ion ratios must be identical to those in the library without any additional ion.
Other solution just extract the parent ion with 4 confirming ions if all appear in your sample this is positive result otherwise negative

I am a business man that fell into the business. Not a scientist. However it seems that the majority of scientists and clinicians are not aware of this frequent occurrence of false positives specifically for methamphetamine. However, I deal with around 20 people a month that test positive and swear they have never even used the drug. They can’t all be calling my company lying since I don’t have anything to do with how they were originally tested. Several lawyers have contacted me and believe that a number of these people are probably telling the truth. This means that countless people are having their kids taken away and/or are being falsely imprisoned due to false allegations.

Can someone with more knowledge of this topic give me some ideas of what could be or is likely happening?

Much appreciation.

Blake Brewer
Founder and President
Drug Testing Solutions Dallas
Recovery Solution
North Texas and Southern California

Most software give you the option to do this. If not you will have to add all of them up and calculate manually ore in excel.