USE OF REFLECTOMETRY FOR DETERMINATION OF NITRATE-NITROGEN IN WELL WATER

Recurrent monitoring of water wells is necessary to ensure that nitrat e-nitrogen (NO3-N) concentrations in groundwater do not exceed 10 mg/L , the maximum contaminant level set by the U.S. Environmental Protecti on Agency. Continuous chemical analysis is often a time consuming and expensive process. A recently developed 'Reflectoquant Analysis System ', which employs reflectometry techniques, may offer a simple and accu rate method for NO3-N analysis. The objective of this study was to eva luate the 'Reflectoquant Analysis System' as an alternative method for determination of NO3-N in well water. Water samples were collected fr om 42 wells in Oklahoma. The samples were analyzed using the 'Reflecto quant Analysis System', automated cadmium reduction (Griess-Ilosvay), ion chromatography, and phenoldisulfonic acid procedures. The linear r ange of the 'Reflectoquant Analysis System' is 1.1 to 50.6 mg/L NO3-N. Samples exceeding this range must be diluted before analysis is perfo rmed. Excluding two wells where NO3-N was >50.6 mg/L, simple correlati on was high (r > 0.91) among the four procedures evaluated. In additio n, slopes and intercepts from linear regression of NO3-N among procedu res were not significantly different. Population means obtained using the four methods were very similar. For this sample of wells, the 'Ref lectoquant Analysis System' was precise and provided NO3-N analysis of water samples equivalent to standard methods. Other advantages of the 'Reflectoquant Analysis System' are short analytical times, reduced o perator training period, and competitive costs compared to standard me thods.