Mass Spectrometer
Assessment

























4 - 6. Please read the following abstract and then answer the questions associated with the reading.

Baron JM, Griggs DA, Nixon AL, Long WH, Flood JG. The trazodone metabolite meta-chlorophenylpiperazine can cause false-positive urine amphetamine immunoassay results. Journal of Analytical Toxicology. 35(6):364-8, 2011.

Abstract: Amphetamines and methamphetamines are part of an important class of drugs included in most urine drugs of abuse screening panels, and a common assay to detect these drugs is the Amphetamines II immunoassay (Roche Diagnostics). To demonstrate that meta-chlorophenylpiperazine (m-CPP), a trazodone metabolite, cross-reacts in the Amphetamines II assay, we tested reference standards of m-CPP at various concentrations (200 to 20,000 g/L). We also tested real patient urine samples containing m-CPP (detected and quantified by HPLC) with no detectable amphetamine, methamphetamine, or MDMA (demonstrated by GC MS). In both the m-CPP standards and the patient urine samples, we found a strong association between m-CPP concentration and Amphetamines II immunoreactivity (r = 0.990 for the urine samples). Further, we found that patients taking trazodone can produce urine with sufficient m-CPP to result in false-positive Amphetamines II results. At our institution, false-positive amphetamine results occur not infrequently in patients taking trazodone with at least 8 trazodone-associated false-positive results during a single 26-day period. Laboratories should remain cognizant of this interference when interpreting results of this assay.


















7 - 8. Please read the following abstract and then answer the questions associated with the reading.

Vorce SP, Holler JM, Cawrse BM, Magluilo J. Dimethylamylamine: a drug causing positive immunoassay results for amphetamines. Journal of Analytical Toxicology. 35(3):183-7, 2011.

Abstract: The Department of Defense (DoD) operates six forensic urine drug-testing laboratories that screen close to 5 million urine samples for amphetamines yearly. Recently, the DoD laboratories have observed a significant decrease in the confirmation rates for amphetamine (mass = 135.20622 Da) and methamphetamine (mass = 149.237 Da) because of specimens screening positive by two separate immunoassays and confirming negative by gas chromatography-mass spectrometry (GC-MS). Previous studies conducted by the Division of Forensic Toxicology, Armed Force Institute of Pathology (AFIP) utilizing a GC-MS basic drug screen and a designer drug screen revealed no common compound or compound classes as to the cause of the immunoassay-positive results. Additional information obtained from an immunoassay vendor suggested the anorectic compound dimethylamylamine (DMAA, mass = 115.22 Da) may be the cause of the false-positive screens. An additional 134 false-positive samples were received and analyzed using liquid chromatography-tandem mass spectrometry (LC-MS-MS) for DMAA. LC-MS-MS analysis revealed the presence of DMAA in 92.3% of the false-positive samples at a concentration of approximately 6.0 mg/L DMAA, causing a positive screen on both immunoassay kits.





















































15 – 17. Using HPLC initial separation followed by MALDI-TOF mass spectrometry, Vitamin D2 (mass = 396.6484 Da) has a retention time of 6.05 minutes, while vitamin D3 (mass = 384.6377 Da) has a retention time of 5.74 minutes. The patient’s mass spectrum analysis is shown below.

























































© Copyright 2012, The Athena Group, Inc. Legal Disclaimer