Forensic Drug Testing Lab

PEth Testing

Dried Blood Spots
Dried blood spot collection is the fastest, most convenient way to test for phosphatidylethanol (PEth)Phosphatidylethanol (PEth)PEth is created in red blood cells where it exists as part of the cell membrane. Research suggests a PEth test can differentiate between incidental exposure (hand sanitizer use, etc.) and the intentional use of ethanol. A PEth test in blood gives a 2-3 week history of alcohol (ab)use. We offer PEth testing in both dried blood spots and whole blood. The sample amount is 5 dried blood spots from a finger puncture or 5 ml of blood from a standard blood draw using anticoagulation tube collection.. Standard collection supplies provided include 2 lancets, 2 alcohol prep pads, gauze, a collection card, and the dried blood spot drying box. We also provide the requisition form for the collection, which includes all necessary bar code stickers to maintain a proper chain-of-custody. Unlike venipuncture, dried blood spot collection is performed by the individual being tested (the donor) and can be observed by any staff member, after a short training session. The dried blood spot drying box makes collection even easier by eliminating wait time. PEth is an abnormal phospholipid formed in red blood cells following alcohol exposure. PEth in blood exists as a component of the red cell membrane. PEth is a mid to long-term alcohol biomarker, and a positive result (measuring phosphatidylethanol species 16:0/18:1) is an indication of alcohol exposure during the 2-3 weeks prior to sample collection.

Click here to view dried blood spot collection instructions.

Click here to view dried blood spot collection slides.

Whole Blood Specimens
For those interested in whole blood testing, we test for THC, EtOH, and PEth.

Click here to view whole blood collection instructions.

Click here to view the PEth Resources page.

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Collection

Collection Instructions
Collection Steps
Wash hands
Collector and donor should wash their hands with soap and water.
CAUTION: Do not use an ethanol-based sanitizer.
Use powder-free latex gloves
Collector should use powder-free latex gloves when handling the specimen and for donor assistance throughout the collection.
Verify the donor
Verify the donor with a government-issued photo ID (driver’s license, state ID, or a
passport) and record the donor information in Step 1 of the requisition form.
Position Finger below the heart
The donor’s finger should be positioned below the heart to increase venous pressure. Massaging the hand and finger lightly before puncturing may also help circulation.
Wipe the finger with an isopropyl alcohol pad
Wipe the finger with an isopropyl alcohol pad. CAUTION: Do not use an ethanol-based alcohol pad.
Air dry finger
Allow the finger to air dry.
Twist off protective cap
Twist off the small end of the protective cap (clockwise) on the sterile safety lancet.
Puncture the finger with the lancet
Place the open end of the sterile safety lancet against the sterilized finger, making sure that placement is slightly off-center. Puncture the finger by pressing the button on top of the lancet to release the spring-loaded system. CAUTION: Do not puncture the center of the fingertip. Blood flow is best accomplished with an off-center puncture.
Wipe away first drop of blood
Wipe away the first drop of blood with a tissue or gauze. NOTE: Wiping away the first drop improves blood flow.
Wait for formation of a large drop of blood
Wait for the formation of a large drop of blood before attempting to fill the collection circle. There should be a big enough blood drop to reasonably assume that it will fill the collection circle in a single attempt. Allow the drop of blood to come in contact with the center of the collection circle. NOTE: Allow the collection paper to wick blood out of the puncture. Do not press the finger against the collection paper and do not layer successive drops.
Continue this process until all collection circles are filled
Continue this process until all collection circles are filled by single applications. Be sure to wait for a large drop of blood to form between each attempt at filling the collection circles. Avoid “milking” the finger as this will cause more interstitial fluid to surround the puncture and will speed clotting (will slow / stop the bleeding). Do not layer successive drops.
Record donor's name and date on card
Record donor’s name and date on the collection card. Caution: Do not touch the filled collection circles.
Donor initials and dates the collection card
Donor initials and dates the collection card. Caution: Do not touch the filled collection circles.
Add barcode sticker
Affix one of the small barcode stickers from the bottom of the requisition form above the donor name on the collection card. Caution: Do not tuck the cover or let the cover touch the collection circles.
Place specimen card in the blood spot drying box
Place specimen card in the blood spot drying box. Seal the box with the long specimen seal from the bottom of the requisition form. If you don’t have a requisition form there is a tamper-evident seal provided in the collection kit. The seal should reach around both ends of the box and effectively fasten both ends shut.
Donor initials and dates the seal
Donor initials and dates the seal. This serves as the tamper-evident seal.
Collector signs and dates Step 4 of the requisition form
Collector signs and dates Step 4 of the requisition form.
Donor signs Step 5 of the USDTL requisition form (optional)
Donor signs Step 5 of the USDTL requisition form (optional).
Place the sealed blood spot drying box and the requisition form in a non-plasticized envelope
Place the sealed blood spot drying box and the requisition form in a non-plasticized envelope or other form of USDTL approved package. If sending more than one collection card, be sure to use separate blood spot drying boxes for each collection card. Caution: Do not place inside an airtight plastic specimen transport bag.
Dispose of used and leftover materials according to local protocol
Dispose of used and leftover materials according to local protocol.
Client Services

By Phone: 1.800.235.2367

Business Hours (CST)

Monday 6am - 8pm
Tuesday 6am - 8pm
Wednesday 6am - 8pm
Thursday 6am - 8pm
Friday 6am - 8pm

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Testing Details

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Can we use any tube for whole blood collection?

Please use only purple, gray, and green top tubes.

Do we need to spin (centrifuge) whole blood samples?

No.

How do PEth results differ from Urine EtG/EtS results?

Recent studies have indicated that low-level positive EtG results can be produced by certain agents like hand sanitizers and mouth wash. The PEth blood assay is an ideal tool to define low-level positive EtG results. The volume of alcohol required to trigger a positive PEth result is far above the level available from incidental exposure.

How much blood is required for a PEth testing sample?

5 individual large drops on a collection card.

How much blood is required for whole blood testing?

Requested sample volume is 5 milliliters.

What is the window of detection for PEth?

PEth is a mid- to long-term biomarker measurable after consumption of approximately 200 grams of alcohol. An individual consuming 1 drink per day for 6-7 days will produce a positive result. PEth can be measured for 2-3 weeks following the most recent alcohol consumption.

What is the window of detection for whole blood testing?

Whole blood testing for substances of abuse identifies usage over a 2-3 day period.

When will I receive whole blood testing results?

Results are available four to seven days after the sample is received in the laboratory.

Which phosphatidylethanol species do you measure during PEth testing?

Our PEth testing in dried blood spots measures the 16:0/18:1 PEth species.

Why was one matrix positive and another negative on the same donor?

Different sample matrices have different detection time frames. The result of any second collected specimen has no bearing on the validity of a first collected specimen. For example, a hair sample with a three month window of detection might test positive for a particular substance, while a urine sample from the same donor, with a 2-3 day window of detection, might test negative. In this case, the donor has used that substance within the past three months, but may not have used it within the most recent three days.




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