A new approach for the estimation of expanded uncertainty of results of an analytical method developed for determining antibiotics in seawater using solid-phase extraction disks and liquid chromatography coupled with tandem mass spectrometry technique

Occurrence and spatial distribution of 158 pharmaceuticals, drugs of abuse and related metabolites in offshore seawater

The occurrence and spatial distribution of 158 pharmaceuticals and drugs of abuse were studied in seawater of the Eastern Mediterranean Sea (Saronikos Gulf and Elefsis Bay in central Aegean Sea). This area is affected by various anthropogenic pressures as it receives the treated wastewater of the greatest Athens area and off-shore input fluxes. This study constitutes the largest one in terms of number of analytes in this environmental compartment. It provides the first evidence on the occurrence of several pharmaceuticals in marine environment including amoxicillin, lidocaine, citalopram or tramadol, among others. 22 samples were collected at three different depths in 9 sampling stations in order to assess the presence and the spatial distribution of the target compounds. A multi-residue method based on solid phase extraction and liquid chromatography coupled to tandem mass spectrometry was developed for the determination of the 158 target substances and validated for seawater sample analysis. 38 out of the 158 target compounds were detected, 15 of them with frequencies of detection equal to or higher than 50%. The highest detected values corresponded to amoxicillin, caffeine and salicylic acid, with concentrations in the range of < 5.0-127.8 ng L(-1); 5.2-78.2 ng L(-1) and < 0.4-53.3 ng L(-1), respectively. Inputs from the wastewater treatment plant (WWTP) of Athens revealed to be the main source of pollution in the Inner Saronikos Gulf, whereas, other anthropogenic pressures such as contamination from shipping activity, industrial effluents, dredging and/or inputs from land proved to be also relevant. Τhe concentrations of some compounds varied significantly with depth suggesting that currents play an important role in the dilution of the target compounds.

A series of strategies for solving the shortage of reference standards for multi-components determination of traditional Chinese medicine, Mahoniae Caulis as a case

In order to solve the bottleneck of reference standards shortage for comprehensive quality control of traditional Chinese medicines (TCMs), a series of strategies, including one single reference standard to determine multi-compounds (SSDMC), quantitative analysis by standardized reference extract (QASRE), and quantitative nuclear magnetic resonance spectroscopy (qNMR) were proposed, and Mahoniae Caulis was selected as an example to develop and validate these methods for simultaneous determination of four alkaloids, columbamine, jatrorrhizine, palmatine, and berberine. Comprehensive comparisons among these methods and with the conventional external standard method (ESM) were carried out. The relative expanded uncertainty of measurement was firstly used to compare their credibility. The results showed that all these three new developed methods can accurately accomplish the quantification by using only one purified reference standard, but each of them has its own advantages and disadvantages as well as the specific application scope, which were also discussed in detail in this paper.

Contamination of the southern Baltic Sea waters by the residues of selected pharmaceuticals: Method development and field studies

In this study the occurrence of thirteen pharmaceuticals in seawaters collected from southern Baltic Sea was evaluated for the first time. It was performed by applying newly developed analytical procedure. The method was characterized in terms of its basic validation parameters as well as matrix effects, extraction efficiency and absolute recovery. The results were expressed as result ± expanded uncertainty, which was estimated according to the Guide to the Expression of Uncertainty in Measurement. Additionally, in order to verify the influence of variable parameters of the analyzed samples on method performance parameters, chemometric analysis was carried out. The obtained results revealed that residues of pharmaceuticals were present in seawaters at a concentration level of ng L(-1). Trimethoprim, sulfamethoxazole and enrofloxacin were most frequently detected compounds. The highest concentration was determined for ketoprofen (135.0 ± 10.9 ng L(-1)). Marine pollution potential hotspots were found in enclosed or semi-enclosed bodies of water.

Effectively designed molecularly imprinted polymers for selective isolation of the antidiabetic drug metformin and its transformation product guanylurea from aqueous media

In the present study, two novel molecularly imprinted polymers (MIPs) with remarkable recognition properties for metformin and its transformation product, guanylurea, have been prepared for their selective, enrichment, isolation and removal from aqueous media. The prepared adsorbents were characterized by Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and swelling experiments. The performance of the prepared MIPs was evaluated by various parameters including the influence of pH, contact time, temperature and initial compound concentration. The effects on the adsorption behavior of the removal process parameters were studied and the equilibrium data were fitted by the Langmuir and Freundlich models. Due to the imprinting effect, adsorption performance of MIPs was always superior to its corresponding NIP (non-imprinted polymer), with maximum adsorption capacity ∼80 mg g(-1) for both MIPs. Stability and reusability of the MIPs up to the 5th cycle meant that they could be applied repeatedly without losing substantial removal ability. In the next step, the prepared MIP nanoparticles were evaluated as sorbents in a dispersive solid phase extraction (D-SPE) configuration for selective enrichment and determination of metformin and guanylurea in different aqueous matrices. Under the working extraction conditions, the D-SPE method showed good linearity in the range of 50-1000 ng L(-1), repeatability of the extractions (RSD 2.1-5.1%, n=3), and low limits of detection (1.5-3.4 ng L(-1)). The expanded uncertainty of the data obtained was estimated following a bottom-up approach. The proposed method combined the advantages of MIPs and D-SPE, and it could become an alternative tool for analyzing the residues of METF and its transformation product GUA in complex water matrices, such as wastewaters.

Liquid chromatography-tandem mass spectrometry multiclass method for the determination of antibiotics residues in water samples from water supply systems in food-producing animal farms

A sensitive liquid-chromatography-electrospray tandem mass spectrometry multiclass method for determination of 45 veterinary compounds belonging to 9 different antibiotic groups, including aminoglicosides (4), β-lactams (13), diaminopyrimidines (1), fluoroquinolones (10), lincosamides (1), macrolides (5), pleuromutilins (1), sulfonamides (6) and tetracyclines (4), in water from breeding animal watering supply system has been developed. Isolation of the analytes was carried out by solid phase extraction with heptafluorobutyric acid as an ion-pair agent on the Strata-X reversed phase cartridges. All analytes were determined simultaneously in one single run on a C18 column with gradient elution and short analysis time (13 min). Method was validated, average relative recoveries were in the range of 84.3-109.3% with satisfactory precision are repeatability for all compounds are in the range of 4.7-12.2%, within-laboratory reproducibility are in the range of 4.4-13.5% for. The limit of quantitation (LOQ) of the method was in the range of 0.02-10 μg L(-1), depending of analyte. The applicability of the method was tested by determining antimicrobial compounds in real water samples collected from water supply systems in breeding animal farms. The average antibiotics concentration in real water samples were, respectively, in the range of 0.14-1670 μg L(-1).

Critical points in the evaluation of analytical methods based on liquid chromatography separation for the determination of doramectin in different environmental samples

In recent years, the number of analytical methods of target compound residues (such as pharmaceuticals) has grown rapidly. Most of them are based on high performance liquid chromatography (HPLC). From the economic point of view, it is usual to apply the conditions of available HPLC methods or to design extraction and chromatographic separation conditions using HPLC and transfer them subsequently to a more sensitive technique like liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS). However, if such a transfer is planned, it is important to assess the quality of the newly-designed LC-MS/MS method. The determination of parameters like matrix effects (ME), extraction efficiency (EE) and absolute recovery (AR) is mandatory. These parameters can visualise the weakest step in the analytical method and enable methods based on different techniques to be compared. The aim of this work was to show how quality assessment should be carried out in order to transfer an optimised method from one technique to another. The representative compound used in our investigation was doramectin (DOR), an anthelmintic drug used in veterinary medicine. The quality of the suggested methods for determining this drug in three environmental matrices (water, sediment and fish tissue) using HPLC-UV and LC-MS/MS was evaluated on the basis of known values of absolute recovery (HPLC-UV) and matrix effect, extraction efficiency and absolute recovery (all LC-MS/MS). Finally, the suggested methods for determining DOR in water, sediment and fish tissue based on LC-MS/MS measurements were validated and applied to the analysis of real environmental samples.

Development of sensitive and reliable LC-MS/MS methods for the determination of three fluoroquinolones in water and fish tissue samples and preliminary environmental risk assessment of their presence in two rivers in northern Poland

Antibiotic consumption (e.g. fluoroquinolones (FQs)) and, as a consequence, their presence in the environment, have received a lot of attention in the last several years due to increasing numbers of diseases and infections that are becoming resistant to traditional treatments for both humans and animals. In addition, even though antibiotics are safe for human and veterinary usage, ecosystems may be exposed to these substances. In this study, analytical methods for determining enrofloxacin (ENR), norfloxacin (NOR) and ciprofloxacin (CIP) in water samples and fish tissue based on the LC-MS/MS technique were developed and validated. As there is no data available concerning the risks posed by antibiotics in Poland, the proposed methods were applied for monitoring drug presence in environmental samples collected from two rivers in northern Poland. Evaluations of the ecotoxicity of ENR, NOR and CIP towards four different species of aquatic organisms: marine bacteria (Vibrio fischeri), green algae (Scenedesmus vacuolatus), duckweed (Lemna minor) and crustacean (Daphnia magna), were also carried out. All the investigated compounds were detected at least once in the survey. NOR was found to be the most ubiquitous drug with concentrations of up to 442.8 ng L(-1). Moreover, it was established that L. minor is the most sensitive species to the investigated drugs (EC50NOR = 0.13 mg L(-1), EC50ENR = 0.22 mg L(-1) and EC50CIP = 0.34 mg L(-1)). The calculated risk quotient (RQ) values confirmed that the concentrations of the investigated FQs in the environmental samples were at a level of moderate environmental risk (1<RO ≤ 10), however, for CIP they were found to be closer to a level of high environmental risk (RQCIP = 8.1).