Automated method to determine pharmaceutical compounds in wastewater using on-line solid-phase extraction coupled to LC-MS/MS.

An automated method was developed using on-line solid-phase extraction (SPE) as a sample preparation step, coupled to liquid chromatography-tandem mass spectrometry (LC-MS/MS), for determination of pharmaceutical compounds in wastewater samples at nanograms per liter to micrograms per liter concentration levels. This method is suitable for use in routine analysis, especially in environmental applications, avoiding cross-contamination and requiring minimal sample handling. Results can be obtained rapidly, with a chromatographic run time of only 24 min (including sample preparation and chromatographic analysis). Using a 50 µL injection volume, the method was validated according to international guidelines, considering parameters included in terms of method detection (MDL) and quantification limit (MQL), linearity, inter-day and intra-day precisions, and matrix effects. Assessment of chromatographic efficiency considered peak resolution and asymmetry, and carryover was evaluated to ensure analytical reliability and the ability to reuse the SPE cartridge. The intra- and inter-day precisions were lower than 10 and 17%, respectively. The MDL values ranged from 1×10-6 to 1 µg L-1, while the MQL values were from 0.001 to 3 µg L-1. Matrix effects were minimized by isotope dilution calibration. Application of the method to 20 wastewater samples showed that caffeine was the most frequently detected compound, with the highest concentration of 715 µg L-1, while other pharmaceutical compounds were detected in fewer samples and at lower concentrations (up to 8.51 µg L-1).

Label-Free Ultrasensitive and Environment-Friendly Immunosensor Based on a Silica Optical Fiber for the Determination of Ciprofloxacin in Wastewater Samples.

Emerging contaminants, including pharmaceutical compounds, are receiving research attention as a result of their widespread presence in effluents and wastewater treatment plants (WWTPs). The antibiotic ciprofloxacin (CIP) is extensively employed to treat infections in animal and human medicine. Both CIP and its metabolites are common contaminants found in WWTPs. In this study, a label-free ultrasensitive U-bent optical fiber-based immunosensor for the determination of CIP in wastewater samples was developed using the properties of the conducting polymer polyaniline (PANI). The anti-CIP immunoglobulin G (IgG) was deposited on a silica optical fiber surface previously functionalized with PANI. Scanning electron microscopy and micro-Raman spectroscopy were used to investigate the surface of the immunosensor. The analysis of CIP in wastewater was performed without the use of an organic solvent or sample preparation steps, with only the sample dilution in saline buffer (pH = 7.4). The linear range for CIP was from 0.01 to 10,000 ng L-1. The detection limit was 3.30 × 10-3 ng L-1 and the quantification limit was 0.01 ng L-1. The immunosensor provided a high average recovery of 91% after spiking wastewater samples with CIP at a concentration of 9,100 ng L-1. The method was applied in triplicate to wastewater samples from Quebec (Canada), obtaining concentrations of 549 and 267 ng L-1. A comparison with a reference method showed no significant difference (t-test at 95% confidence). The new technique developed is selective, allowing a quantitative analysis of CIP in wastewater.

Continuous removal of caffeine in a horizontal-flow anaerobic immobilized biomass bioreactor: identification of transformation products.

Anaerobic bioreactors are an efficient technology for the biodegradation of emerging contaminants in environmental matrices. In this work, a horizontal-flow anaerobic immobilized biomass (HAIB) bioreactor was used to remove caffeine (CAF), which is frequently found in various aqueous matrices. The acrylic bench top bioreactor, with dimensions of 100 × 5.00 cm, was operated with a hydraulic retention time (HRT) of 12 h, during 45 weeks, under mesophilic conditions. The operation was performed in 4 phases: without CAF addition (phase I); CAF spiked at 300 µg L-1 (phase II); CAF at 600 µg L-1 (phase III); and CAF at 900 µg L-1 (phase IV). Samples of bioreactor influent and effluent were analyzed by liquid chromatography/tandem mass spectrometry (LC-MS/MS). The bioreactor removed organic matter (OM) and CAF with efficiencies of 88 and 93%, respectively. The first-order apparent removal constant (Kapp) values for OM and CAF were 0.419 and 0.304 h-1, respectively. Five transformation products (TPs) were identified, with m/z 243, 227, 211, and 181 (two products). The HAIB bioreactor is a suitable system for the removal of CAF present in wastewater, even at a concentration level of µg L-1.

Modular 3D-printed fluorometer/photometer for determination of iron(ii), caffeine, and ciprofloxacin in pharmaceutical samples.

The demand for the development of portable and low-cost analytical devices has encouraged studies employing additive manufacturing techniques, such as 3D-printing. This method can be used to produce components such as printed electrodes, photometers, and fluorometers for low-cost systems that provide advantages including low sample volume, reduced chemical waste, and easy coupling with LED-based optics and other instrumental devices. In the present work, a modular 3D-printed fluorometer/photometer was designed and applied for the determination of caffeine (CAF), ciprofloxacin (CIP), and Fe(ii) in pharmaceutical samples. All the plastic parts were printed separately by a 3D printer, using Tritan as the plastic material (black color). The final size of the modular 3D-printed device was 12 × 8 cm. The radiation sources were light-emitting diodes (LEDs), while a light dependent resistor (LDR) was used as a photodetector. The analytical curves obtained for the device were: y = 3.00 × 10-4 [CAF] + 1.00 and R 2 = 0.987 for caffeine; y = 6.90 × 10-3 [CIP] - 3.39 × 10-2 and R 2 = 0.991 for ciprofloxacin; and y = 1.12 × 10-1 [Fe(ii)] + 1.26 × 10-2 and R 2 = 0.998 for iron(ii). The results obtained using the developed device were compared with reference methods, with no statistically significant differences observed. The 3D-printed device was composed of moveable parts, providing flexibility for adaptation and application as a photometer or fluorometer, by only switching the photodetector position. The LED could also be easily switched, permitting application of the device for different purposes. The cost of the device, including the printing and electronic components, was lower than US$10. The use of 3D-printing enables the development of portable instruments for use in remote locations with a lack of research resources.

Optimization of in situ derivatization SPME by experimental design for GC-MS multi-residue analysis of pharmaceutical drugs in wastewater.

This paper presents the development of a procedure, which enables the analysis of nine pharmaceutical drugs in wastewater using gas chromatography-mass spectrometry (GC-MS) associated with solid-phase microextraction (SPME) for the sample preparation. Experimental design was applied to optimize the in situ derivatization and the SPME extraction conditions. Ethyl chloroformate (ECF) was employed as derivatizing agent and polydimethylsiloxane-divinylbenzene (PDMS-DVB) as the SPME fiber coating. A fractional factorial design was used to evaluate the main factors for the in situ derivatization and SPME extraction. Thereafter, a Doehlert matrix design was applied to find out the best experimental conditions. The method presented a linear range from 0.5 to 10 µg/L, and the intraday and interday precision were lower than 16%. Applicability of the method was verified from real influent and effluent samples of a wastewater treatment plant, as well as from samples of an industry wastewater and a river.

Simple, fast and environmentally friendly method to determine ciprofloxacin in wastewater samples based on an impedimetric immunosensor.

In this study an impedimetric immunosensor was developed in order to determine ciprofloxacin (CIP) in wastewater samples, an emergent contaminant widely found in wastewater. To achieve this, an anti-ciprofloxacin antibody was immobilized on the surface of a printed carbon electrode. Then, the developed immunosensor was applied in wastewater samples from Université Laval residences (Québec, Canada) through the load transfer resistance (R ct) using [Fe(CN)6]3-/4- as a redox probe, and the average CIP concentration was found to be 2.90 × 10-4 µg mL-1. The observed R ct changes presented a linear relationship from CIP concentrations of 10-5 to 1.0 µg mL-1, with detection and quantification limits of 2.50 × 10-6 and 7.90 × 10-6 µg mL-1, respectively. The immunosensor presented high selectivity and repeatability, as well as a good recovery rate in wastewater samples (97%). Significant interference with other compounds was not observed. The proposed method requires only 30 µL of sample without the use of organic solvents or preceding sample preparation and/or extraction techniques. Moreover, the method is fast: only 20 min of incubation followed by 2 min of analysis time was sufficient to obtain the CIP concentration. The method's estimated cost is U$ 2.00 per sample.

Development of miniaturized fluorimetric device for caffeine determination using a smartphone.

Caffeine is an element that is consumed worldwide. It is present in many products such as beverages, chocolate, coffee, tea, energy drinks and medicines. Portable 3D devices working together with colorimetric and fluorimetric reactions have been able to determine the presence of caffeine in different kinds of samples. Also, digital image-based methods using smartphones have conferred portability and accessibility to miniaturized devices that are innovative and promising options for quick and low cost analyses. This study proposes a miniaturized fluorimetric device to determine caffeine by digital image using a smartphone. The OpenCamera app was used to capture images that were processed using ImageJ software to obtain RGB channels values. The red (R) channel signal intensity was selected as the analytical response. The device developed was applied to determine caffeine in an energy drink and medicines. The method developed presented a linear range from 100 to 600 mg L-1 of caffeine, and quantification (LOQ) and detection (LOD) limits of 100 mg L-1 and 30.0 mg L-1, respectively. The caffeine concentration found in the products analyzed was 328 mg L-1 (±2.5%) for the energy drink, 345 mg L-1 (±15%) for medicine A and 322 mg L-1 (±7.3%) for medicine B. The proposed device presented important characteristics such as low cost, required small volumes of reagents and samples, quick analysis, portability and suitable to be applied in complex matrices.