Bubble Trouble Solution

Operational Issues Impacting the Environmental Laboratory Industry
Oral Presentation

Prepared by M. Bruce
Eurofins Environment Testing America, 4101 Shuffel St NW, North Canton, OH, 44720, United States


Contact Information: [email protected]; 330-966-7267

ABSTRACT

In 2017 and 2018 many environmental labs saw an increase in the occurrence of headspace bubbles in water sample vials intended for volatile organic analysis. Historically, less than 0.5 % of VOA water samples were narrated to have headspace bubbles > 6 mm, whereas nearly 4% of samples were narrated for this non-compliance at the peak of the problem. As such, Eurofins began investigating a variety of potential contributing factors of this phenomenon and compiled a list of factors that might contribute to bubble formation. It became clear that more than one factor was influencing the formation of headspace bubbles since it was occurring in only a small minority of samples and was not affecting all clients and sites equally. These potential factors were grouped into four areas: sample composition, collection technique, transport and storage conditions, and container. In total, about 20 different potential factors were evaluated. Detailed experiments focusing on the cap, septum, sampling conditions and sample collection techniques were conducted as part of the investigative process.

Two primary conclusions were made: First, that proper sampling techniques for filling the vials and securing the caps are vital factors in reducing the formation of air bubbles. Second, that the vial and cap configurations are critical components in minimizing air bubble formation. Eurofins has collaborated with container suppliers to design and obtain cap and septum supplies which minimize air bubble formation. With these changes to sampling technique and sample container, the frequency of bubble formation is reducing to historical rates of < 0.5%.