Analysis of Illicit Compounds by Gas Chromatography-Mass Spectrometry in Wastewater

Abstract

The occurrence in wastewater of pharmaceuticals, drugs of abuse, and the metabolites produced through the use of such compounds, is becoming a question of concern. The recreational abuse of illicit compounds in South Africa has increased tremendously over the past years and is currently a serious problem among the youth. Data on the use of illicit drugs and the amounts consumed is limited to information coming from law enforcement agencies, rehabilitation centres, and self-reported cases. Thus, an objective means of measuring the actual drug use of a specific geographical area needs to be developed. In this study, a method was developed to measure trace amounts of drug metabolites, including 11-nor-9-carboxy-Δ9-THC, benzoylecgonine, codeine, morphine, and 6 monoacetyl morphine in wastewater. The Daspoort treatment plant—a facility serving the Pretoria West and the Hatfield areas—was selected. An appropriate sampling procedure and sample pretreatment was employed to yield the best resolution and separation possible for the selected analytes. Sample pre-treatment involved the derivatization of analytes with methyl-N-tert-butyldimethylsilyltrifluoroacetamide (MTBSTFA), pentafluoropropanol (PFPOH) and propionic anhydride (PA), respectively. The samples were prepared in accordance with the method of standard addition. A GCxGC/TOF-MS analysis was performed and a weekly concentration profile for each analyte was produced. The measured concentration obtained for each analyte was corrected for flow to ensure accurate estimation of the total weight of parent compound per day. The total parent compound weight measured confirms that the abuse of illegal substances is occurring in the population. The results obtained in the study provide further evidence for the fact that drug abuse in the Daspoort area must be urgently addressed.Die voorkoms van medisyne, dwelms en hul metaboliete in afvalwater is steeds kommerwekkend. Die misbruik van onwettige middels in Suid-Afrika het geweldig toegeneem oor die afgelope paar jaar en is 'n ernstige probleem onder die jeug in 'n sosiale omgewing. Inligting oor die gebruik van onwettige dwelms is sterk afhanklik van wetstoepassingsagentskappe, inligting van rehabilitasiesentrums en self-gerapporteerde gevalle. Metodes word benodig om ‘n objektiewe opname van die werklike dwelmgebruik van ‘n geografiese area te kan doen. Tydens hierdie studie is 'n metode ontwikkel om spoorvlakke van dwelm-metaboliete in afvalwater te meet. Hierdie metaboliete sluit in: 11- nor-9-karboksie-Δ9-THC, bensoïelecgonine, kodeïen, morfien en 6 monoasetielmorfien. Die Daspoort Waterwerke Fasiliteit was gekies en bedien die Pretoria-Wes en die Hatfield metropolitaanse areas. Die mees toepaslike monsterneming asook monster-behandeling vir die geselekteerde analiete, is uitgevoer om die beste instrumentele analise moontlik te lewer. Monster behandeling behels die derivatisering van analiete met Metiel-N-tertbutieldimetielsilieltrifluoroasetamied (MTBSTFA), Pentafluoropropanol (PFPOH) en propionsuuranhidried (PA). Die monsters is geanaliseer in ooreenstemming met die metode van standaard addissie. 'n GCxGC / TOF-MS analise is uitgevoer en 'n weeklikse konsentrasie-profiel vir elke analiet is gevind. Die konsentrasie vir elke analiet is aangepas vir vloei om sodoende ‘n akkurate skatting van die totale massa van elke dwelm per dag te bekom. As daar na die resultate gekyk word, is die misbruik van onwettige middels kommerwekkend. Hierdie studie bevestig die erns waarmee die misbruik van dwelms in die Daspoort-area aangespreek moet word.