Our expert team has resolved a list of frequently asked questions, and concerns regarding services and processes completed in our lab.  The questions listed are constantly updated, expanded, and refined to ensure you have access to the most up to date information. Do not hesitate to contact us with any additional questions or concerns that were not covered. 


Q: Who do I contact about a specific question?

Please contact LJP Lab with any questions or concerns.
New and existing customers: 336-992-3901

Q: How long can drugs be detected in the system?

Please reference this table.

Q: What is specimen adulteration?

Methods to adulterate urine samples for substance abuse testing generally fall into three categories:

  1. Urine substitution
  2. Flushing out the system by ingesting liquids or compounds. Diluting the sample. Interfering with the testing process
  3. Addition of adulterants to the urine specimen itself or substitution of one’s own urine sample with urine.


Q: What does ng/mL mean?

Drug testing cutoff levels are usually expressed in the units of measure ng/mL (nanograms per milliliter). A quantitative positive LC-MS/MS result is commonly expressed in ng/mL.


Q: What are the urine screening cutoffs and methodologies?

An immunoassay is a test that uses antibodies to detect the presence of drugs and other substances in urine. The initial screening process does not measure the specific amount of drug present in urine samples. It provides either a positive or negative result, indicating the presence or absence of detectable drug metabolites above a specific cutoff level.

Q: What are the urine confirmation cutoffs and methodologies?

Confirmations are available by liquid chromatography/mass spectrometry/mass spectrometry (LC-MS/MS). LC-MS/MS provides identification of the molecule(s) based on characteristic fragmentation patterns at specific retention times.

Q: What is the importance of checking the urine temperature strip on the collection cup?

Under normal situations fresh urine will display a temperature between 90 and 100 degrees Fahrenheit on the temperature strip, if read within 4 minutes of the collection. Should the temperature strip not register, the specimen should be immediately re-checked using a new cup (or strip) and the results recorded on the requisition. Specimens with a temperature out of range may indicate a substituted or adulterated sample.

Q: What is the importance of checking urine creatinine and pH levels?

Creatinine normally appears in urine in relatively constant quantities over a 24 hour period with “normal” liquid intake. Therefore, urine creatinine can be used as an indicator of urine water content (dilution). pH: Reference Range = 3–11. Urine specimens with a pH outside of this range strongly suggests the specimen has been adulterated.

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