Specimen Collection & Handling Flashcards

When placing rock core into a standard core box, how should the core be oriented?

Answer: Shallowest core at the top-left, read left to right like a book

Convention places the top of the hole at the upper-left and the core is read left to right, row by row, like text on a page.

What is the primary purpose of a trip blank in a groundwater VOC sampling program?

Answer: To detect VOC contamination introduced during shipping and storage

Trip blanks are prepared in the lab with analyte-free water, travel unopened with the samples, and reveal contamination from transport and storage.

Which sampler is designed to obtain relatively undisturbed samples of soft, cohesive clay for consolidation testing?

Answer: Thin-walled (Shelby) tube

Thin-walled Shelby tubes (ASTM D1587) have a low area ratio that minimizes disturbance in soft cohesive soils.

Groundwater samples collected for dissolved metals analysis should typically be handled how in the field?

Answer: Filtered through a 0.45-micron filter and preserved with nitric acid to pH below 2

Dissolved metals are operationally defined by 0.45-µm filtration, followed by HNO3 preservation to keep metals in solution.

Why should VOC soil samples be collected with a coring device such as an EnCore or Terra Core sampler rather than spooned into a jar?

Answer: To keep volatile loss to a minimum by limiting disturbance and headspace

EPA Method 5035 calls for low-disturbance coring and sealed containers or methanol preservation to prevent volatilization.

What is the standard temperature for cooler storage of most environmental water and soil samples during shipment?

Answer: At or below 6°C without freezing

Most EPA methods require samples to be cooled to 6°C or below but not frozen, often stated as 4 ± 2°C.

On a chain-of-custody form, what must happen each time samples change hands?

Answer: Both the relinquishing and receiving parties sign, date, and record the time

Every transfer of custody needs signatures, dates, and times from both parties so possession is documented without gaps.