Analysis of hydroponic fertilizer matrixes for perchlorate: comparison of analytical techniques

Abstract

Seven retail hydroponic nitrate fertilizer products, two liquid and five solid, were comparatively analyzed for the perchlorate anion (ClO4-) by ion chromatography (IC) with suppressed conductivity detection, complexation electrospray ionization mass spectrometry (cESI-MS), normal Raman spectroscopy, and infrared spectroscopy using an attenuated total reflectance crystal (ATR-FTIR) coated with a thin film of an organometallic ion-exchange compound. Three of the five solid products were found by all techniques to contain perchlorate at the level of approximately 100-350 mg kg(-1). The remaining products did not contain perchlorate above the detection level of any of the techniques. Comparative analysis using several analytical techniques that depend on different properties of perchlorate allow for a high degree of certainty in both the qualitative and quantitative determinations. This proved particularly useful for these samples, due to the complexity of the matrix. Analyses of this type, including multiple spectroscopic confirmations, may also be useful for other complicated matrixes (e.g., biological samples) or in forensic/regulatory frameworks where data are likely to be challenged. While the source of perchlorate in these hydroponic products is not known, the perchlorate-to-nitrate concentration ratio (w/w) in the aqueous extracts is generally consistent with the historical weight percent of water soluble components in caliche, a nitrate-bearing ore found predominantly in Chile. This ore, which is the only well-established natural source of perchlorate, is mined and used, albeit minimally, as a nitrogen source in some fertilizer products.

Unexpected Diversity of Chlorite Dismutases: a Catalytically Efficient Dimeric Enzyme from Nitrobacter winogradskyi

“…While significant natural sources of perchlorate are restricted to mineral deposits in Chile, environmental contamination with this compound results from its extensive use as an oxidizer in pyrotechnics and rocket fuel and its presence in certain fertilizers (9). Intake of perchlorate by humans occurs mainly via drinking water, milk, and certain consumed plants and should be minimized since this chemical affects hormone production by the thyroid gland (39).…”

Heterotrophic–autotrophic sequential system for reductive nitrate and perchlorate removal

“…In many parts of the world, extensive perchlorate contamination of the surface and groundwater detected in 1997 with the development of instrumental techniques that uses highly sensitive chromatography which allowed the detection level less than 4 µg/L. These techniques demonstrated that the real extend of perchlorate contamination was underestimated [1,3]. In many parts of the world, extensive presence of perchlorate has been detected in measurable quantities in rice, fish and dairy products, vegetables and even breast milk [4,5].…”

Forensic Identification of Anthropogenic and Naturally Occurring Sources of Perchlorate

“…Seven retail hydroponic nitrate fertilizer products, two liquid and five solid, were also tested for perchlorate. The test results indicated that three of the five solid products contained perchlorate ranging from about 100 to 350 mg/kg (Collette et al, 2003). Other investigators have reported perchlorate in fertilizers not derived from Chilean nitrate deposits (Susarla et al, 1999(Susarla et al, , 2000Urbansky et al, 2000).…”

“…Lithium carbonate and boric acid are extracted from these ponds and remaining salts are processed for potassium chloride, potassium sulfate, and fertilizers. Deposits mined for this fertilizer contains 6.3% nitrate, and from 0.1 to 0.03% perchlorate (Collette et al, 2003;Grossling and Erickson, 1971;Tian et al, 2005;Urbansky, Brown, et al, 2001;Urbansky, Collectte, et al, 2001). Presence of perchlorate in groundwater originating from perchlorate enriched deposits in the Atacama Desert is well known (Crump et al, 2000).…”