Development of a Methodology to Detect Pharmaceutical Compounds in Water using Solid Phase Extraction (SPE) and Gas Chromatography-Mass Spectrometry (GC/MS)

The interest in the analysis of pharmaceutically active compounds or PhACs in the water supply has increased in the last decade. Today they are considered a new class of water pollutants. PhACs, their precursors, and degradation products are released into the environment as a result of their manufacture, use and disposal. The detection and quantification of these products in the environment are of great importance. Today, many environmental scientists and government agencies are giving increased attention to this new class of pollutants. The main concern is not only the presence of these compounds but their effects on humans and animals. Some of the potential concerns from the environmental presence of these compounds include abnormal physiological processes and reproductive impairment, increased incident of cancer, the development of antibiotic-resistant bacteria and the potential increased toxicity. In Puerto Rico the detection of pharmaceuticals in water has not been amply studied and the water treatments employed lack the technology necessary to completely remove these compounds. Additionally, due to the high consumption of pharmaceutical and the poor management of sewage water in Puerto Rico, it is suspected that this could be a serious problem on the island. Our aim is to develop a rapid and reliable GC/MS method to detect the most common pharmaceuticals and metabolites present in the water supply of Puerto Rico at low concentrations.;An analytical procedure to determine pharmaceutical compounds at low concentrations in water samples by solid phase extraction (SPE) and gas chromatography/ mass spectrometry (GC/MS) was developed. The methodology consists of extracting the compounds from water using SPE-Envi Chrom P (styrene/ divinylbenzene), eluting the compounds with ethyl acetate and concentrating the sample to 1 mL. Analytes were derivatized with silylating agents BSTFA + TMCS at 45 ºC for 45 min and analyzed by GC/MS. For most of the pharmaceuticals, recoveries were in the range of 67 to 96% in water, and the reproducibility was within 6% for the complete method. Detection limits (LOD) and quantization limits (LOQ) ranged between low ppb to high ppt for the full scan mode and selective ion monitoring mode (SIM). The method was applied to surface water (Guajataca, Carraizo and La Plata Lakes), ground water (Water Authority aquifers in Salinas and Arroyo) and tap water (Rio Piedras, Bayamon and Trujillo Alto) samples. Caffeine, Acetaminophen, Niacin (vitamin B3), Nadolol (beta-blocker) were detected in water samples in the 100 ng/L to 10 microg/l range.;The original suspicion that PhACs could be found at significant levels in the naturals waters in Puerto Rico was not the case. A possible reason could be due to the abnormally high amounts of rainfall during the periods when samples were taken.