Background & Challenges for the Industry
Anionic surfactants include detergents and some foams and are of interest in many environmental situations in in water. MBAS is an acronym for Methylene Blue Active Substances – a screening test commonly used to determine the presence of anionic surfactants. The colour reaction with methylene blue, which is a cationic dye, is a key component of the analysis and hence the name MBAS.
The challenge for industry practitioners is that MBAS and Surfactants as MBAS are NOT the same thing. Even laboratory accreditations differ however the similarity of the name ‘MBAS’ and ‘Surfactants as MBAS’ can lead practitioners to think they are the same. If using MBAS as a potential screen for PFAS it is important to understand the differences and potential false positives.
ALS has long recognised both the cost of sampling groundwaters and the manual handling risks associated with the use of 500mL amber glass bottles. In addition, an extra bottle (or two) was previously required for dup/MSD determinations meaning up to 1.5L of groundwater a considerable requirement if using low flow sampling.
The latest ALS R&D / method optimisation will make life a lot easier for samplers as follows.
- New bottle requirement is 100mls (down from 500mL)
- As single bottle will suffice for primary plus QC testing (i.e. no extra bottles needed)
- Small sturdier bottles = less breakages and freight costs.
What else is in this article?
- Method and LOR information
- MBAS Methodology and APHA Guidance
- MBAS as a screen for PFAS
- Precision, accuracy and LORS for MBAS analysis
- NATA guidance – 2010
- Sampling considerations