What kind of substances interfere with mass spectrometry analysis?

There are many substances that cause interference with mass spectrometry analysis. They are as follows; substances specific to patient treatment (drugs, parental nutrition), metabolites created by various diseases and disorders, substances ingested by patients (alcohol, non-clinical drugs, nutritional supplements, food), substances added during sample preparation(anticoagulants, preservatives), contamination during handling samples(hand cream, serum separators, collection tube stoppers), and lastly there is interference from the physical sample matrix, like hemolysis, icterus, and lipemia. 

Labs must consider the amount and type of interference when analyzing their data as a source of error. Moreover, labs need to set error limits based on the interference, because in every experiment in science there are always errors to consider. In an assay for example, interference appears as partially or total co-eluting peaks in the chromatogram. So, a lab may decide that a certain value on their peak is considered too much error and use that as their error limit. To technologists, the interference might even be invisible.