Full Description

There are numerous cases where groundwaters have been found to be high in nitrate andattributed to either septic influence or agricultural practices. In many cases the nitrate dataalone have been insufficient to differentiate between these causes for contamination. Correctivemeasures in response to high nitrates vary depending upon the cause. With the advent of ultrasensitivemethods for trace analysis for pharmaceuticals and personal care products (PPCPs) asdemonstrated by the USGS (Kolpin et al, 2002), other analytical results could be used to shedlight on such situations. The Kolpin methods detect numerous compounds at the 1-50 part pertrillion level. However, they rely on LC-MS, expensive instrumentation that is not found inmost environmental labs. In contrast, HPLC systems are widely available in manycommercial and utility labs. Therefore, the lab developed a sensitive HPLC/UV method for theanalysis of 3 representative surrogate human tracers, caffeine, cotinine, and acetaminophen.This HPLC method was targeted to achieve a reporting limit of 30 ppt (with a 10 ppt detectionlimit), sensitive enough to be useful in natural systems impacted by human activities.A 1000 milliliter (mL) sample aliquot is passed through a methanol and water conditionedWaters Oasis-HLB polymeric cartridge. After a sorbent wash step, the compounds are elutedfrom the cartridge with a small quantity of methanol followed by acidified methanol, andconcentrated further by evaporation of some of the solvent. A 10 mM Formate buffer is used tobring the extract to volume. The extract is then analyzed by HPLC at two wavelengths (254and 280 nm) with conditions optimized to separate the compounds in a 15 minute run time.This run time is short enough to allow analysis of large numbers of samples to establishpatterns of groundwater occurrence. The method was validated using a variety of standardprotocols to assess precision and accuracy (analysis of LFB, LFM, MRL checks). Asconfirmation of accuracy, selected samples are also analyzed for caffeine by a separate GCMSSPEmethod that has a reporting limit of 5 ppt (MDL of 1 ppt). Includes 4 references, table, figures.

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Edition: Vol. - No. Published: 11/15/2004 Number of Pages: 8File Size: 1 file , 5.2 MB