Improved Anions Analysis – Impact of Newer Technologies in Older Contaminants.

Operational Issues Impacting the Environmental Laboratory Industry (Session 2)
Oral Presentation

Prepared by Q. Ho1, R. English1, R. Marfil-Vega1, H. Van2
1 - Shimadzu Scientific Instruments, 7102 Riverwood Drive, Columbia, MD, 21046, United States
2 - ALS Global, 10450 Stancliff Road,, Suite 210, TX, 77099, United States


Contact Information: [email protected]; 410-910-0884

ABSTRACT

Fast and robust analysis of anions in environmental samples is essential for environmental laboratories due to the short turn-around-times required for the analysis of nitrate and nitrite in methods EPA 300 and 300.1. When analyzing samples with diverse and variable composition for nitrate and nitrite together with some of the other targets from these methods (e.g., F-, Cl-, Br-, PO4-, and SO4- from EPA 300), laboratories may run into challenges. For example, high concentrations of chloride in the matrix can mask the presence of nitrite, preventing the detection of the later by suppressed conductivity detector required in the method. Hence, two or more injections may be needed for obtaining the required results, resulting in decreased productivity.
In this work, we first optimized the method conditions to maximize lab productivity and turn-around-time for the analysis of the seven anions targeted in EPA 300 in a run-to-run time of 4.5 minutes (4.0-minute gradient). In an attempt to further increase the efficacy of the method, we evaluated two approaches to eliminate the need for sample-reruns when results from various anions are outside the calibration range or interferences are present: 1) lowering the injection volume (down to 0.2 µL) to avoid the need for sample dilutions (in- or off-line) and 2) using a conductivity and UV detectors in-line to detect nitrite in the presence of high concentration of chloride. In this presentation we will present the results from the method performance evaluation including but not limited to linearity, sensitivity, and reproducibility.