[av0930]

 I have a question about mass spectometry as it relates to the cocaine metabolite benzoylecgonine.  Will the target ions and the qualifying ions differ from test to test (or lab to lab) depending on what methods are used for extraction, derivatization, etc.?  Are there any other factors that will affect said ions?  Allow me to explain. 
        I have searched the internet and found several Mass Spectrum (MS) of the metabolite benzoylecgonine.  They all seem to have the same abundant ions.  Well, that being said, I have in my possesion three drug screen MS results.  Two are from the same urine sample (DOT Mandated) and one is from a hair sample (all three from the same person).  One of the urine sample results and the hair results show the target ions and qualifying ions as being identical to the abundant ions shown on every one of the benzoylecgonine MS I've found online.  Yet the other urine sample MS result shows different target and qualifying ions that were monitored.  Is this because they just used different methods for GC/MS testing?  Two of the ions, on the different MS results, that were monitored (ion 300 and 303) I've found on cocaine MS (also acquired online).  The other qualifying ions used don't match ions on the benzoylecgonine or the cocaine MS I've found online.  Did they test for cocaine only and not the metabolite?  The test results stated it was positive for "cocaine metabolite". 

This is some of the information that was on the first urinalysis (the negative standard control sample):

                                                              CONCENTRATION
                                                           ON-COL           FINAL
 RT        MASS        RESPONSE        (ng/ml)        (ng/ml)
   1 D3-BENZOYLECGONINE
4.177        303            69155               300.0
4.180        424            15077   

   2  BENZOYLECGONINE
4.183        300            24336               150.0               150.0
4.186        421            5549                 
4.183        316            3358

There are also "Target Range" and "Ratio" columns which I didn't include.  Is the "RESPONSE" the same as abundance?  I know what D3-BENZOYLECGONINE is and why the mass is 303 instead of 300 (like the benzoylecgonine), but should the amount under the "RESPONSE" column have been the same for every control sample tested (low control, high control, negative control, etc.)?   Is the D3-BENZOYLECGONINE response what is being compared to the benzoylecgonine response to determine concentration?  How do they come up with the concentration figure under "ON-COL" and "FINAL"?  I also noticed, that on all control samples, when the response for benzoylecgonine (mass 300) was lower than that of D3-BENZOYLECGONINE; then the concentration was lower than the 300.00 listed for the D3-BENZOYLECGONINE.  Should this always be the case?  Or is it possible that the concentration can be greater even though the response is lower?  Thanks in advance.