Frequently Asked Questions

We have compiled a list of the most common questions that our clients ask

Got Questions? We’ve Got Answers!

The information found on this webpage can help answer many common questions, and assist you in managing a substance abuse testing program. The questions listed here are constantly updated, expanded, and refined to ensure that you have access to the very latest information. Begin by browsing the list of questions below. Click the question to reveal the answer.

What is specimen adulteration?

Methods to adulterate urine samples for substance abuse testing generally fall into three categories:
Urine substitution, ingestion of fluids or compounds for flushing out the system, diluting the sample, or interfering with the testing process or direct addition of adulterants to the urine specimen itself. The substitution of one’s own urine sample with one which is clean is a common practice.

Can passive exposure cause a positive drug screen for THC?

In general, routine passive exposure to marijuana smoke will not result in a positive result for cannabinoids in excess of a 50 ng/mL screening cutoff and the THC-COOH (by LC/MS/MS or GC/MS) is in excess of 15 ng/mL.

Why are screening and confirmation cutoff levels different?

Screening and confirmation testing are performed using different methodologies that necessitate different cutoff levels. The cutoff levels of an immunoassay screen are typically higher than those of a more sensitive GC/MS or LC/MS/MS confirm test, because they screen for a larger group of parent compounds, metabolites and other structurally similar compounds.

If an immunoassay test detects a drug (above the screening cutoff level) the presumptive positive specimen may be sent to GC/MS or LC/MS/MS confirmation testing. Many times, these individual compounds are present in concentrations much lower than the total immunoassay response, thus resulting for the cutoff levels being lower for the GC/MS or LC/MS/MS test.

What laboratory technology and equipment does CBS Labs utilize?

Our leading-edge equipment and proven methodologies help us “find out”. You can depend on CBS Labs to utilize the most sensitive equipment, proven processes and highly skilled personnel to deliver timely, accurate and reliable results. We’ll find out—using the optimal combination of gas chromatography/mass spectrometry (GC/MS), liquid chromatography/tandem mass spectrometry (LC/MS/MS) and enzyme immunoassay (EIA).

How do I collect a specimen for laboratory confirmation?

Laboratory drug and alcohol test results are often used in legal proceedings. The manner in which specimens are collected and handled is very important. Specimens must be handled and controlled by collection site personnel throughout the collection process. Redwood Toxicology Laboratory provides suggested specimen collection and labeling guidelines. It is the responsibility of individual collection agencies to adopt their own policies and procedures according to their needs in compliance with individual state and federal regulations.

How do I ship a specimen to the laboratory?

You can send a rapid on-site collection device (presumptive positives only), or you can send specimens collected using an appropriate urine or oral fluid container.

When can I expect to see the drug test report?

Urine screening results are typically available within 24 hours1 of receipt of the specimen, while oral fluid screen results take 24-48 hours1. Presumptive positive specimens are usually confirmed (unless they are “Screen Only”) within 24-72 hours depending on the method. Confirmation of specimens that are presumptive positive by rapid/on-site devices take a minimum of 48 hours.

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 GC/MS or LC/MS/MS result is commonly expressed in ng/mL.

How long does CBS Labs store the specimen?

CBS Labs stores positive urine specimens for six (6) months (2 months for methadone accounts). All positive oral fluid specimens are stored 6 months in frozen storage. Negative specimens are kept for 48 hours.

What are the urine screening cutoffs and methodologies?

CBS Labs screens urine specimens by enzyme immunoassay (EIA). 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.

What are the urine confirmation cutoffs and methodologies?

Confirmations are available by thin layer chromatography (TLC), radioimmunoassay (RIA), gas chromatography (GC), gas chromatography/mass spectrometry (GC/MS) and liquid chromatography/mass spectrometry/mass spectrometry (LC/MS/MS). Based on your agency’s account settings, specimens may be confirmed by one or more of the aforementioned methods. GC/MS and LC/MS/MS provides identification of the molecule(s) based on characteristic fragmentation patterns at specific retention times.

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.

What is the importance of checking urine creatinine levels?

Creatinine is a metabolic by-product of muscle metabolism, and 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) or as a marker identifying a specimen as urine. Greater than normal intake of water will increase the urine water content (lowering the creatinine level) consequently diluting any drug which may be present in urine. Conversely, a limited intake of water can lead to an abnormally concentrated urine specimen (as occurs with dehydration) resulting in elevated creatinine levels.

Need an urgent test?

Need to perform a test and have it analyzed as soon as possible to make an urgent patient care decision? Our STAT 24 service is available 24 hours a day, Monday thru Saturday, and provides results within 4 hours of notification or 2 hours of receipt by our lab. As soon as the testing is complete, one of our representatives will contact you with the results.

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Have other questions?

Over the thousands of tests that we perform, our experts in toxicology have resolved the questions and concerns for thousands of customers. If you have a question about testing, our services, or any specific concern contact us today!

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