Selective determination of acidic pharmaceuticals in wastewater using molecularly imprinted solid-phase extraction

Area of Science:

• Environmental Chemistry
• Analytical Chemistry

Background:

• Acidic pharmaceuticals, including non-steroidal anti-inflammatory drugs (NSAIDs) and clofibric acid, are frequently detected in wastewater.
• Low ng/L levels necessitate highly selective and sensitive analytical methods for accurate determination.
• Matrix components in wastewater can interfere with analytical procedures, particularly during LC-MS analysis.

Purpose of the Study:

• To develop and validate a simple method for the enrichment and cleanup of NSAIDs and clofibric acid from sewage water.
• To reduce matrix effects in liquid chromatography-tandem mass spectrometry (LC-MS) analysis.
• To quantify acidic pharmaceuticals in raw sewage and treated wastewater.

Main Methods:

• Molecularly imprinted solid-phase extraction (MISPE) was employed for sample preparation to enrich and clean up target analytes.
• Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used for the final analysis.
• Method performance was evaluated using fortified tap and sewage water, assessing recovery, precision, linearity, and method quantification limits.

Main Results:

• The MISPE method demonstrated high recovery rates (84-116%) for all tested compounds across different matrices.
• Intra-day relative standard deviation (R.S.D.) values were consistently below 11.5%.
• Significant matrix effects were not observed even in complex samples like pond and sewage water compared to tap water.
• Acidic pharmaceuticals were detected in raw sewage and treated water at concentrations ranging from 5.1 to 5153.0 ng/L.

Conclusions:

• MISPE is a simple, effective technique for sample preparation in the analysis of acidic pharmaceuticals in wastewater.
• The developed method allows for sensitive and selective determination of NSAIDs and clofibric acid, minimizing matrix effects.
• The presence of these pharmaceuticals in raw and treated wastewater highlights the need for effective monitoring and removal strategies.