High-Resolution mass spectrometry method for detection, characterization and quantitation of pharmaceuticals in water.

Introduction

-Pharmaceuticals end up in water via being flushed, unused prescribed drugs, excreta of patients, and agricultural run off.

-Common pharmaceutical found in trace amounts are acetaminophen, fluoexine, gemfibrozil, caffeine, metformin, erythromycin, codeine. (just to name a few)

- Currently pharmaceutical s and their derivatives are not fully removed from water by current wastewater treatment methods.

A recent geological studied found pharmaceuticals in 850,000 Northern New Jersey’s drinking water supply

While another study found pharmaceuticals, antibiotics, and deodorants in 30 of New Jersey’s rivers, lakes and streams

-Although pharmaceutical quantities found are unlikely to account for any harmful affects to humans, the aquatic ecosystems are affected.

A study by bender and macCrehan showed that fluoretine and metoprolol are transformed into toxicants during the disinfection treatment processes for drinking water.

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Instrumentation

-Normally environmental scientists use GC-MS to detect and quantify organic compounds in water, however do to the extensive preparation of the sample and lack of sensitivity.

-LC MSMS on the other requires less sample preparation and can detect highly polar and nonvolatile compounds down to the nanogram/liter level.

-One drawback to most of the analytical methods used is that metabolites are not readily seen like the precursor pharmaceuticals

Pharmaceutical metabolites are capable of posing a higher degree of toxicological effects then precursor pharmaceuticals.

-Currently most labs use LC-triple quad- for selective reaction monitoring; this process requires one to know the precursor and product m/z ion values, thus the metabolites and degradants are normally lost .
Flexibility of HLC-HRMS over LC-SRM allows for detection of metabolites and degradants without direct targeting (thus you can run a sample and it look for the metabolites and degradants later.)

***In this paper a LC-MS /MS consisting of a linear ion trap and orbital trap is used to acquire parent drug and its metabolites and degradants. (shown in figure one)

-By using ultra high-pressure liquid chromatography, polarity switching, High resolution mass spec, a five minute method of detection ,characterization and quantification of eight common pharmaceuticals and a metabolite of caffeine in tap water and bottle water.

Sample preparation

All water samples were stored at 4 degrees Celsius
-bottled water
-water containing pharmaceuticals
-water samples collected from New Jersey

Used four C-18 based disposable solid-phase extraction cartridges
-these were connected to individual disposable liners in the solid phase extraction manifold which were connected to vacuum supply by tubing

Each cartridge was conditioned with equal volumes of methanol, acidified water, and water.
-one liter of enriched/spiked or new jersey water was loaded on to the cartridge and effluent was collected

UHPLC-LTQ-Orbitrap method

- All samples were analyzed using an Accela UHPLC system

-Mobile phase solvents used were water (% formic acid) and acetonitrile (0.005% formic acid)

-Analytes were chromagraphically resolved using programmed stepwise A/B ratios over the course of five minutes.

The entire UHPLC eluent was introduced into ESI source interfaced with to a hybrid LTQ-orbitrap mass spectrometer. ---------------------------------------------------------------------------------------------------------

Results and Discussion

-Most HRMS system used today have been for structural elucidation of small molecules, metabolites, degradants, peptides and proteins. -These systems are not suited for routine quantitative bioanalysis because of nonoptimum full scan MS scan speed, limited dynamic range and suboptimum