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PERFORMANCE OF POLYVINYL ALCOHOL GEL COLUMNS ON THE ION CHROMATOGRAPHIC DETERMINATION OF PERCHLORATE IN FERTILIZERS
Citation:
De Borba, B. M. AND E T. Urbansky*. PERFORMANCE OF POLYVINYL ALCOHOL GEL COLUMNS ON THE ION CHROMATOGRAPHIC DETERMINATION OF PERCHLORATE IN FERTILIZERS. JOURNAL OF ENVIRONMENTAL MONITORING 4(1):149-155, (2002).
Description:
Interest in possible sources of perchlorate (ClO4-) that could lead to environmental release has been heightened since the EPA placed this anion on its Contaminant Candidate List (CCL) for drinking water. Besides its association with defense and aerospace activities, perchlorate is a known contaminant in some fertilizers, in particular, saltpeters derived from naturally occurring caliche, in which perchlorate is present as a native impurity. Although recent investigations have suggested that fertilizers are minor contributors to environmental perchlorate contamination overall, there is still interest in screening commercial products for possible contamination and quantitating perchlorate when it is found. Ion chromatography (IC) has been used for this application owing to its speed, low detection limits, widespread availability, and moderate ruggedness relative to other techniques. However, fertilizer matrixes complicate the IC analysis relative to potable water matrixes. In this study, performance of polyvinyl alcohol gel resin IC columns (100 mm and 150 mm) was evaluated for fertilizer matrixes using method EPA/600/R-01/026. The NaOH eluent included an organic salt, sodium 4-cyanophenoxide. Detection was by suppredded conductivity. A set of 55 different field samples representing 48 products and previously used by the EPA to assess occurrence of perchlorate in fertilizers (EPA/600/R-01/049) was reanalyzed on the 150-mm column. The 100-mm column was used to further investigate the positive hits. Both columns gave satisfactory performance in fertilizer matrixes, with spike recoveries (+/- 15%), assured reporting levels (0.5-225 ug g-1 except for one at 1000 ug g-1), accuracy relative error<30% always and most <15%), and precision (injection-to-injection reproducibility <3% RSD) comparable to those reported in other studies. performance did not vary substantially between column lengths. Lastly, the results of this investigation provided further evidence in support of the conclusions that had been reached previously by the EPA on the occurrence of perchlorate in fertilizers.