The accuracy of the initial drug screen, the immunoassay test, ranges between 92% – 98%. The accuracy of the GC/MS confirmatory test is virtually 100% from a scientific standpoint.
Can a GC MS test be wrong?
GC-MS is a very specific test to identify separate compounds within a sample. However, GS-MS can also lead to a false negative if the GC-MS column is not designed to identify all potential compounds.
How accurate is GCMS?
At concentrations of 75, 100 and 125 ng/mL, GC–MS technology had an average accuracy of 102% with CVs < 5% for all analytes across the three concentrations, while the LC–MS-MS technology average accuracy was a comparable 105% with CVs < 7% (Table II).
Can GCMS detect synthetic urine?
Was the sample even urine? Without the right adulterant screen, a set of tests that determine whether a sample was altered or substituted, even Gas Chromatography/Mass Spectrometry (GC/MS) tests can be fooled by an adulterated sample.
What can GCMS detect?
GC-MS can be used for the bioanalysis of body fluids to detect narcotics, barbiturates, alcohols, and drugs such as anticonvulsants, anesthetics, antihistamines, sedative hypnotics, and anti-epileptic drugs. It is also useful in detecting pollutants and metabolites in serum and in fatty acid profiling in microbes.
Can you fight a false positive drug test?
Some companies will allow strong candidates to retake a drug test. The best way to contest false-positive results is to reach out to your pharmacist and ask if prescription drugs and OTC medications you take on a regular basis can cause a positive drug test result.
What does GC MS confirm test level mean?
Because of this, if a substance shows positive (or above the screen threshold), the specimen is sent on for the GC/MS (Gas Chromatography/Mass Spectrometry) test, or Confirmation Test. The second column of numbers on the NTA, Inc. test under Confirm Threshold are the quantitative cutoff levels for this test.
Which is an advantage of GC MS?
One of the major advantages of GC-MS compared to LC-MS is the high reproducibility of generated mass spectra using EI. The electron impact ionization process, used in GC-MS, is a hard ionization that results in the production of very reproducible mass spectra from one instrument to another.
Why is LC MS better than GCMS?
LC–MS generally requires less sample preparation. For a urine analysis, one can often just dilute with water and inject the sample. With LC–MS, using ESI, an intact molecular ion is generated and enters the mass spectrometer. … GC–MS is generally cheaper because it uses a less sophisticated detector.
How do you analyze GC MS results?
How to Read GC/MS Chromatograms
- The X-Axis: Retention Time. Usually, the x-axis of the gas chromatogram shows the amount of time taken for the analytes to pass through the column and reach the mass spectrometer detector. …
- The Y-Axis: Concentration or Intensity Counts. …
- Differences in Gas Chromatogram Models.
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Can labs tell the difference between real and synthetic urine?
Quick Fix Synthetic urine, along with its competitors, is made from a mix of water, urea, creatinine, pH balance, and/or uric acid. Synthetic urine can have the same density as urine too, as labs also test for this. Urinalysis clinics use a method called gas chromatography-mass spectrometry to test urine.
How long does GC MS take?
Either gaseous or liquid samples, as small as several micro-liters, can be analyzed. And the whole process of GC/MS analysis takes about one hour or less, depending on the complexity of the compound to be analyzed. The two major components of GC/MS are the gas chromatograph and the mass spectrometer.
Can menstrual blood contaminate a urine drug test?
Menstrual blood can contaminate a urine sample. Vitamin C supplements, food coloring in candy, and the natural color in beets can affect the color of your urine. Medicines can also affect your results: Anthraquinone laxatives.
How does the GCMS work?
A mass spectrometer (MS) is commonly used as a GC detector.
The MS will break each separated compound coming from the GC into ionised fragments. To do this, a high energy beam of electrons is passed through the sample molecule to produce electrically charged particles or ions.
How much does a GC MS test cost?
A standard GC/MS laboratory drug test costs about $200 per sample analyzed, so it’s not a very cost effective solution. Also, because it takes time to send the urine sample to the lab, it could take up to 7 days to receive your results.
What does GCMS stand for?
Gas chromatography-mass spectroscopy (GC-MS) is one of the so-called hyphenated analytical techniques. As the name implies, it is actually two techniques that are combined to form a single method of analyzing mixtures of chemicals.