Abstract: The aim of this research was to develop method to identify the pharmaceuticals in waste water. Water samples from pharmaceutical company, food factory and municipal drainage water were monitored for Tylosin, Sotalol, Diclofenac and Erythromycin . An analytical method using capillary electrophoresis has been developed for the determination and confirmation of traces of these compounds in the water samples. The method uses solid phase extraction, liquid chromatography -mass spectrometry with positive electro spray ionization. The analysis of pharmaceuticals was carried out using bare silica capillary with a length of 56.4cm with a buffer solution containing 0.02molar citric acid and 15%methanol in water. The applied voltage was 20kV with +polarity. Detection was achieved by UV absorption. liquid chromatography -mass spectrometry with positive mode electro spray ionization method screening was based on monitoring of one specific MS-MS ions and on the exact masses of MS-MS product ions obtained for a molecular ion by use of Q-TOF, MS.The results indicate traces of tylosin in the pharmaceutical waste water, diclofenac sodium salt and sotalol hydrochloride in none of the samples.
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Key words: liquid chromatography, MS-MS, Q-TOF, Capillary electrophoresis, Tylosin, Erythromycin, Diclofenac, Sotalol.
INTRODUCTION: Recent research has been focused on the analysis of pharmaceutical compounds in wastewaters, the broad application of pharmaceuticals in human and veterinary drug formulations and their residues can reach the environment via urinary or faecal excretion. In addition agricultural and industrial discharge of chemicals must also to be considered [1, 2] . A high percentage of the antibiotics consumed by human and animals are excreted as the unmetabolised drug. Pharmaceuticals may not be completely eliminated in sewage treatment plant (STP) .consequently they contaminate reaching the surface and ground water. There has been growing interest in developing methods to monitor the presence of pharmaceuticals in water . Pharmaceuticals were detected in water in many countries (Canada, Germany, Netherland, and U.K) Sacher et al used six different analytical methods for the screening and identification of sixty pharmaceuticals. All methods were based on automated solid phase extraction followed by GC-MS or LC-ESI-MSMS. The methods were used in a programme of monitoring of pharmaceuticals in ground water in Baden Wurttem-berg.Several compounds e.g: sotalol, phenazone, diclofenac, iopamidol, carbamazepine, anhydroerythromycin, sulfamethoxazole, and amidotrizoic acid were detected. This paper describes methods to identify the residues of 4 pharmaceuticals in waste water samples collected from a pharmaceutical company, municipal waste water and food factory using capillary electrophoresis and MS-MS. LC-MS is very commonly used method in pharmaceuticals for separation and identification of drugs and is thus the most frequently used technique in the field of bioanalysis. MS is used due to high sensitivity and exceptional specificity compared to UV (as long as the analyte can be suitably ionised), and short analysis time.
Capillary electrophoresis (CE) is a powerful separation technique that has found numerous analytical applications for a wide range of compounds. This method has many advantages, such as a high efficiency, rapid method development, simple instrumentation and low solvent and sample consumption. UV-vis spectrophotometry is the most widely used detector in CE because of its on-line configuration particularly in the pharmaceutical field. However, its sensitivity, which directly relates to the optical path length afforded by the capillary internal diameter (in the μm range), remains the major disadvantage of this technique.
In this study three specific categories of wastewater samples namely wastewater from a pharmaceutical company, food factory and municipal waste water are screened for the presence of any higher level of concentrations of pharmaceutical compounds. The main hypothesis of my project is to screen the pharmaceuticals compounds from waste water specifically Tylosin,(figure1a) erythromycin (figure1b), Sotalol (figure1c) and diclofenac (figure1d) using capillary electrophoresis and mass spectrometry tools.
Chemicals and Samples: Tylosin, diclofenac Sodium salt, Sotalol Hydrochloride, Erythromycin are the pharmaceuticals compoundsof maximum purity obtained from Sigma Aldrich United Kingdom. Structures of these compounds are provided in figure1.
Selected pharmaceutical compounds and their molecular weight and molecular formula (Table 1).
Sample collection: Waste water effluent streams were obtained from three different origins and were supplied by Northern Ireland water (Londonderry, UK).the waste water samples were sourced from a Pharmaceutical Company, Food factory and municipal drainage water.
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Solid Phase Extraction Analysis: Waste water samples obtained from different origins of waste water treatment plants was filtered using Whatman filter paper, the pH of pharmaceutical waste water is 9 using conical flask and funnel.
The solid phase extraction cartridges are preconditioned with sufficient amount of methanol and washed with water and the filtered waste water sample is loaded onto cartridges for solid phase extraction (SPE). A suction pump was used to pull the water into the chamber where a beaker is placed for collecting the elluents. Strata C18-E 20g/60ml Giga tubes Phenomenex. Reversed phase cartridges were used. Solid phase extraction procedure is used to eliminate compounds from the mixture using their chemical and physical properties. Sample (40 ml) has been loaded on to a SPE cartridge (Strata C18-E 20g/60ml Giga tubes Phenomenex, Torrance, CA, USA). Methanol (15ml) with 1% acetic acid was poured in the above cartridge and the resultant extract was collected.
Quadrupole Time of Flight (QTOF):
ESI-QTOF-MS analysis was performed using water Q-TOF Ultima API mass spectrometer (water UK Ltd, Manchester, UK). The pharmaceutical compounds at a concentration of 1.0x10-3 M dissolved in methanol, 1% formic acid, were directly infused at 1µl/min into ESI probe. The collision induced dissociation (CID) of Glu-Fibrinopeptide B (Sigma Gillingham, UK) [M+2H] 2+ ion was used for the calibration of mass spectrometer. To the standard solution adenosine was added being infused as internal locked mass standard with an m/z signal of 268.1040. The source temperature at 100OC the spray voltage 3.4kV and the desolvation temperature at 150OC. Nitrogen set at 100 psi was delivered from a Peak Scientific nitrogen generator (Inchinnan, UK) and resulted in a desolation gas flow of 300 Lh-1. and nebulising gas flow of solution. A collision gas argon (99.999%) with 20eV energy was used for both MS and MS/MS mode with collision energy of 20-40eV. The ESI-Q-TOF-MS experiment was 5ppm or less. LC Grade water and methanol and formic acid were obtained from (Sigma Aldrich, Pool, UK). 1.0X10-3 M. concentrations of pharmaceutical drugs Tylosin, Diclofenac, sodium salt, Sotalol hydrochloride, Erythromycin,1.0X10-4 adenosine mol.wt=268, are injected in Q-TOF one after the other to determine the fragmentation pattern of the each compound.
The fragmentation pattern of pharmaceutical compounds is done in Q-TOF,the compounds elemental composition is noted for its exact mass so that specific compound can be confirmed.
This method was performed for the confirmation of pharmaceuticals in the waste water samples.
A method was developed to analyse the samples. Capillary tube was conditioned firstly with 1M NaOH at 600C, 0.1M NaOH at 600C and 0.1M of NaOH in 300C and flush with water at 300C. Capillary electrophoresis was performed using 56.4 capillary lengths with an internal diameter of 50 µm in electro kinetic mode with citric acid buffer using positive polarity and voltage 20kV. The buffer was changed to borate buffer the migration time was decreased to approximately seven times (e.g.: methanol shown a peak at 35mins with citric acid buffer (pH=4) and borax buffer (pH=9.3) showed peak at 5mins and is changed to Hydrodynamic method using pressure 50mbar.First a method was developed to run the sample at specific wavelengths where the drugs absorb to UV spectra in specific conditions. Methanol blank sample was run to keep it as locked migration peak and consider rest of the peaks. The selective pharmaceutical compounds at 1.0X10-3M concentrations were run in Capillary electrophoresis at their respective UV absorption wavelengths, the migration times off specific compounds is noted and further analysis is done on SPE.
Filtered waste water samples and the specific migration times were compared to see any migration times matches so that to confirm the specific compound. (Table 2).The UV absorption wavelengths were obtained from British pharmacopoeia.
Results and Discussion:
Q-Tof MS ES and Q-Tof MS/MS of drugs as standards were performed and the masses were found to be as shown in Table3, [fig2a,b,c,d,e,f,g, and h] Capillary electrophoresis of drugs as standards was performed. Using Citric acid buffer in capillary electrophoresis was not successful in showing migration peaks. Capillary electrophoresis of drugs as standards was performed and the migration times were found as shown in Table2, [fig3a, b, c and d]. Confirmation of pharmaceuticals was done by spiking using increased concentrations of interested pharmaceuticals. Increase in respective peak with increase in concentration indicates the presence of that particular pharmaceutical. None of the selective pharmaceuticals were found in food factory waste water, pharmaceutical waste water, and municipal waster water using capillary electrophoresis. LC-MS was performed on pharmaceutical waste water none of the selective pharmaceuticals were found.
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Conclusion: The origin of wastewater samples came from does not have any higher concentrations of specific four pharmaceutical compounds. It is proposed in future worth to interface CE using Citric acid buffer with Q-TOF MS/MS.