What chain of custody is

Chain of custody is the documented, unbroken record of specimen possession from the moment of collection to the moment of analysis — and, if needed, to the courtroom. It exists so that a drug screen result can be defended against a legal challenge to its authenticity.

A regular drug screen ordered by a clinician does not require chain of custody. It is a clinical test for medical decision-making, not a legal test for evidence. The PBT exam tests the chain-of-custody procedure specifically for forensic or employment-related drug screens.

When chain of custody is required

• Federal workplace drug testing programs (DOT-regulated truck drivers, pilots, transit workers, etc.) — SAMHSA-mandated procedures.
• Court-ordered drug testing — probation, child custody, criminal cases.
• Employment pre-employment screening — many employers use chain-of-custody collection to protect against legal challenges.
• Athletic testing — NCAA, professional sports, Olympic-level testing.
• Insurance testing — life insurance applications sometimes require chain-of-custody collection.

The exam distinguishes clinical drug testing (no chain of custody) from forensic drug testing (chain of custody required). A candidate who cannot make this distinction will miss at least one question.

The chain-of-custody form (CCF)

The SAMHSA standard chain-of-custody form is the federally mandated document for federal workplace drug testing. It includes:

• Donor identification — name, SSN or employee ID, date of birth.
• Collection site information — facility, address, collection date and time.
• Collector identification — name and signature.
• Specimen information — bottle seal numbers, specimen temperature, specific gravity, pH.
• Donor signature — acknowledging the collection procedure.
• Chain of possession signatures and dates — each person who handles the specimen signs and dates the form, recording the transfer.

The form accompanies the specimen bottles to the lab. The lab completes its section when the specimen is received, analyzed, and reported.

The collection procedure

The chain-of-custody collection has specific requirements:

1. Donor identification — verify identity with photo ID.
2. Donor privacy — collection in a private restroom or partitioned area, with water and soap available (but disabled to prevent dilution).
3. Specimen collection — typically a 30 to 45 mL urine sample, divided into two bottles (30 mL primary, 15 mL split).
4. Specimen temperature — measured within 4 minutes of collection; acceptable range is 90 to 100 °F (32 to 38 °C). Out-of-range temperature suggests tampering or substitution.
5. Specimen integrity tests — specific gravity (1.0010 to 1.0200) and pH (4.5 to 9.0). Out-of-range values are sent for additional testing.
6. Donor signature on the CCF acknowledging the collection.
7. Collector seals the bottles with tamper-evident seals bearing unique numbers.
8. Collector signature on the CCF.
9. Specimen packaging — bottles and CCF in a shipping container, transferred to a SAMHSA-certified lab or courier.

The temperature and integrity tests are the most commonly missed questions. The exam tests whether the candidate knows the temperature range (90 to 100 °F) and the specific gravity / pH limits.

The collector's role

The collector is a neutral party whose job is to verify the specimen's authenticity and maintain the chain of custody. The collector:

• Verifies donor identity.
• Witnesses the collection (or at minimum verifies that the specimen came from the donor).
• Measures temperature and integrity.
• Seals and labels the bottles.
• Documents every step on the CCF.

The collector is not the analyst. The lab performs the analysis; the collector's role is integrity and documentation.

Why split bottles exist

The split specimen design allows the donor to request a re-test of the split (B bottle) if the primary (A bottle) result is positive. This protects against false-positive results and gives the donor due process. The lab analyzes the A bottle first; the B bottle is stored for re-test if needed.

The exam sometimes asks what the B bottle is for. The answer: it is the donor's re-test sample. If the donor requests re-test within 72 hours of receiving the result, the lab analyzes the B bottle at a different SAMHSA-certified lab.

Common exam traps

1. Confusing clinical and forensic drug testing. A clinical urine drug screen ordered by a physician does not require chain of custody. A forensic drug screen required by an employer or court does. The exam distinguishes these clearly.

2. Believing the donor is responsible for chain of custody. The collector is responsible. The donor's only obligation is to provide the specimen and sign the form.

3. Confusing temperature ranges. The 90 to 100 °F range is for urine drug screens. Other specimens have different rules.

4. Believing chain-of-custody collection can be done by any phlebotomist. Many facilities require specific training for collectors. The federal program has a specific collector certification (Certified Professional Collector, or equivalent).

The exam's favorite chain-of-custody questions

Question type 1: "When is chain of custody required for a drug screen?" — Answer: federal workplace testing, court-ordered testing, employment pre-employment in many cases, and athletic or insurance testing.

Question type 2: "What is the acceptable temperature range for a urine drug screen specimen?" — Answer: 90 to 100 °F (32 to 38 °C), measured within 4 minutes of collection.

Question type 3: "A specimen has a specific gravity of 1.0005. What action should the collector take?" — Answer: flag the specimen as dilute. The acceptable range is 1.0010 to 1.0200; the result is below the limit.

A practical closing note

Chain of custody is one of the most procedure-heavy tasks a phlebotomist can be assigned. The form is detailed, the steps are specific, and the legal implications are real. Take a SAMHSA-approved collector training before performing these collections, and the procedure becomes routine. The PBT exam rewards the candidate who knows when chain of custody applies and what the temperature/integrity limits are.