RESUMO
An on-line solid phase extraction using a lab-made restricted access media (RAM) was developed as sample preparation procedure for determination of the pharmaceutical compounds caffeine (CAF), carbamazepine (CBZ), norfloxacin (NOR), ciprofloxacin (CIP), fluoxetine (FLX) and venlafaxine in wastewater treatment plant samples by liquid chromatography-tandem mass spectrometry (LC-MS/MS). This method is suitable for use in routine of analysis, avoiding cross-contamination and requiring only a small sample volume (50 µL), with minimal handling. The method was validated according to international guidelines. The chromatographic efficiency was evaluated using peak resolution and asymmetry parameters. Carryover was also evaluated, in order to ensure reliability of the analysis and the ability to reuse the cartridge. Satisfactory linearity (r2 > 0.99) was obtained for all the compounds. The intra- and inter-day precision values were lower than 5.79 and 14.1%, respectively. The limits of detection ranged from 0.01 to 3 µg L-1 and the limits of quantification were from 0.1 to 5 µg L-1. The method was applied to 20 environmental wastewater samples, with caffeine being the most widely detected compound, at the highest concentration of 392 µg L-1, while other compounds were detected in fewer samples at lower concentrations (up to 9.60 µg L-1). The lab-made modification is a cheaper option for on-line sample preparation, compared to commercially available on-line SPE cartridges and RAM columns. Moreover, a high-throughput procedure was achieved, with an analysis time of 16 min including sample preparation and chromatographic separation. The same RAM column was applied over 200 injections including method optimization, validation and application in wastewater samples without loss of analytical response.
Assuntos
Cromatografia Líquida/métodos , Preparações Farmacêuticas , Extração em Fase Sólida/métodos , Espectrometria de Massas em Tandem/métodos , Poluentes Químicos da Água , Reagentes de Laboratório , Limite de Detecção , Modelos Lineares , Preparações Farmacêuticas/análise , Preparações Farmacêuticas/química , Preparações Farmacêuticas/isolamento & purificação , Reprodutibilidade dos Testes , Águas Residuárias/química , Poluentes Químicos da Água/análise , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificaçãoRESUMO
Colorimetric techniques have been developed and used in routine analyses for over a century and apparently all their potentialities have been exhaustively explored. However, colorimetric techniques have gained high visibility in the last two decades mainly because of the development of the miniaturization concept, for example, paper-based analytical devices that mostly employ colorimetric reactions, and by the advances and popularity of image capture instruments. The impressive increase in the use of these devices was followed by the development and enhancement of different modes of color detection to meet the demands of making qualitative, semi-quantitative, and fully quantitative analyses of multiple analytes. Cameras, scanners, and smartphones are now being used for this purpose and have become suitable alternatives for different approaches to colorimetric analysis; this, in addition to advancements in miniaturized devices. On the other hand, recent developments in optoelectronics technologies have launched more powerful, more stable and cheaper light-emitting diodes (LEDs), which once again have become an interesting tool for the design of portable and miniaturized devices based on colored reactions. Here, we present a critical review of recent developments and challenges of colorimetric detection in modern analytical chemistry in the last five years, and present thoughts and insights towards future perspectives in the area to improve the use of colorimetric detection in different application approaches.
RESUMO
Sulfamethazine (SMZ) is an antibiotic from sulfonamides class widely used in veterinary medicine and reported in wastewater and sewage. Thus, it is essential to study technologies to reduce SMZ present in the aquatic environment. Anaerobic bioreactors are a low-cost technology applied for wastewater treatment. The objective of this paper is to study kinetics parameters related to SMZ removal using a horizontal flow-anaerobic immobilized biomass reactor (HAIB) and to evaluate its transformation products formed during this treatment. The bioreactor was operated at mesophilic condition with a hydraulic retention time of 12 h. The removal of SMZ was evaluated at three different concentrations: 200 ng L-1 (phase I), 400 ng l-1 (phase II) and 600 ng L-1 (phase III). The apparent first-order removal constant obtained for chemical oxygen demand was 0.885 ± 0.094 h-1 while SMZ showed a removal constant of 0.356 h-1. SMZ was removed with an efficiency of 56.0 ± 13.0 % (phase I); 62.0 ± 12.0 % (phase II) and 62.0 ± 6.00 % (phase III). Seven transformation products were detected and one of these with m/z 233 is reported for the first-time. The HAIB bioreactor has a potential to assist in wastewater treatment to remove contaminants at ng L-1 concentration level.
Assuntos
Anti-Infecciosos/metabolismo , Reatores Biológicos , Sulfametazina/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Anaerobiose , Biomassa , Cinética , EsgotosRESUMO
The use of anaerobic biomass attached to a support has been recently presented as a good prospect in the treatment of wastewater containing recalcitrant compounds, such as sulfamethazine (SMZ). SMZ has been found in swine wastewater and sewage treatment plants, which motivates assessing their degradation by new wastewater treatment technologies. Thus, this paper describes the use of a continuous fixed structured bed bioreactor for the purpose of evaluating SMZ removal kinetics present in lab-made wastewater. The analysis of SMZ used online solid-phase extraction coupled to liquid chromatography/tandem mass spectrometry (SPE online-LC-MS/MS). Chemical oxygen demand (COD) was also monitored to evaluate the organic matter removal. The bioreactor was operated under mesophilic conditions (30 ∘ C), with a hydraulic retention time of 24 h. In order to evaluate SMZ removal, four different concentration levels were studied: 200, 400, 600, and 800 ng L-1. COD removal efficiency obtained for filtered effluent kept at 91.01% and there was no interference due to the increase of SMZ concentration. For SMZ, the removal efficiencies were of 52.8±12.1% for 200 ng L-1 concentration level; 55.0±8.15% for 400 ng L-1; 53.0±6.14% for 600 ng L-1, and 48.8±5.44% for 800 ng L-1. COD removal kinetics presented a first-order apparent removal rate constant ( kapp ) of 0.281±0.0295 h-1. SMZ also showed a first-order apparent removal rate constant of 0.158±0.0093 h-1 for the following concentrations levels: 200, 400, 600, and 800 ng L-1.