FI on-line chemiluminescence reaction for determination of MCPA in water samples.

This paper reports an economic, simple, and rapid FI-CL method for the determination of MCPA. This method requires simple instrumentation and it is fast enough to be used in routine analyses. A chemiluminescence signal is generated by reaction between photodegraded MCPA and ferricyanide solution in alkaline medium. All physical and chemical parameters in the flow injection chemiluminescence system were optimized in the experimental setting. To eliminate interference, a solid-phase extraction stage with SDB-1 cartridges and ethanol elution is applied. The signal-MCPA concentration relation is linear in concentration intervals between 0.0015 and 0.6 μg·mL(-1). The calibration lines are statistically similar in different working conditions: standards with ethanol without extraction and standards with ethanol and extraction, allowing standards to be excluded from the extraction step, which simplifies the process. The detection limit (DL) is 0.5 ng·mL(-1), which is the same order as the maximum limit established in legislation regarding pesticide limits in water destined for human consumption. A DL of 0.13 ng·mL(-1) can be reached if a sample of 100 mL is preconcentrated. The interday variance coefficient is 3% and the sample throughput is 90 h(-1). The water analysis method is efficient with relative error percentages lower than 5% with respect to the added concentration.