Determination of fluoroquinolones in cattle manure-based biogas residue by ultrasonic-enhanced microwave-assisted extraction followed by online solid phase extraction-ultra-high performance liquid chromatography-tandem mass spectrometry

Development of a new synchronous fluorescence spectrometry combined with Al3+ sensitized for simultaneous and rapid determination of trace flumequine, ciprofloxacin and doxycycline hydrochloride residues in wastewater

Antibiotics are a new type of environmental pollutants. Due to its wide application in many fields, antibiotic residues are ubiquitous in the wastewater environments. Given their potential threat on water ecosystem functioning and public health, the detection of antibiotic residues in wastewater environments has become very necessary. Based on the complexation of Al3+ with flumequine (FLU), ciprofloxacin (CIP) and doxycycline hydrochloride (DOX), their molecular conjugated area were increased and fluorescence intensity were enhanced, combined with synchronous fluorescence spectrometry (SFS) had good selectivity and high sensitivity, a novel method of Al3+ sensitized synchronous fluorescence spectrometry for the determination of FLU, CIP and DOX residues in wastewater was established. When the wavelength difference (Δλ) was selected 115.0 nm, synchronous fluorescence spectra of the three antibiotics could be well separated and the interference of wastewater matrix were eliminated primely. The new SFS made good use of spectral separation instead of conventional chemical separation, and the actual wastewater sample could be directly determined after simple filtration. The experiment results showed that the concentrations of FLU, CIP and DOX in the range of 0.5000-800.0 ng·mL-1, 0.5000-640.0 ng·mL-1 and 10.00-3500 ng·mL-1 had a good linear relationship with fluorescence intensity. The detection limits of three antibiotics were 0.02054 ng·mL-1, 0.03956 ng·mL-1 and 0.8524 ng·mL-1, respectively. Recovery rates of three antibiotics in wastewater samples were 90.72%-98.23%, 88.68%-95.08% and 85.94%-96.70%. The new SFS established in this experiment had the advantages of simple, rapid, sensitive, accurate and good selectivity. Simultaneous and rapid detection of FLU, CIP and DOX residues in wastewater was successfully realized. It had good application prospects in real-time water quality monitoring.

A novel synchronous fluorescence spectrometry combined with fluorescence sensitization for the highly sensitive and simultaneous detection of enoxacin, ofloxacin and tetracycline hydrochloride residues in wastewater

The synergistic effect of sodium dodecyl sulfate (SDS) and Mg2+ could significantly enhance the fluorescence intensity of enoxacin (ENO) at λex/λem = 269.2 nm/385.6 nm, ofloxacin (OFL) at λex/λem = 290.8 nm/466.2 nm and tetracycline hydrochloride (TCH) at λex/λem = 372.6 nm/514.8 nm. Moreover, when the wavelength difference (Δλ) was chosen 135 nm, the synchronous fluorescence spectra of the three antibiotic complexes could be well separated and the interference of the samples matrix were eliminated primely. Therefore, only one synchronous fluorescence scan was needed to simultaneously determine the three antibiotics. Based on these facts, a synchronous fluorescence spectrometry combining fluorescence sensitization for highly sensitive and selective determination of ENO, OFL and TCH residues in wastewater was developed for the first time. The experimental results showed that the concentrations of ENO, OFL and TCH in the range of 0.5-550 ng mL-1, 1-1500 ng mL-1 and 10-5500 ng mL-1 showed a good linear relationship with fluorescence intensity. The limits of detection were 0.0599 ng mL-1, 0.115 ng mL-1 and 0.151 ng mL-1, respectively. The recoveries of the actual sample were 87.50%-99.99 %, 93.00%-98.50 % and 85.70%-98.42 %, respectively. Overall, the novel synchronous fluorescence spectrometry established in the experiment has the advantages of high sensitivity, good selectivity, fast detection speed and high accuracy. It has been successfully applied to the detection of residual amounts of ENO, OFL and TCH in wastewater with satisfactory results.

Determination of contaminants of emerging concern in raw pig manure as a whole: difference with the analysis of solid and liquid phases separately

The content of veterinary drugs in manure is usually estimated by the amount of residues determined in its solid or liquid phase, individually, which previously required a separation step. As an alternative, a multiresidue method for the analysis of 48 veterinary drugs and other contaminants of emerging concern (CECs) in swine raw manure as a whole has been developed and in-house validated in this work. The impact of several experimental factors during ultrasound assisted extraction was assessed. Hence, the use of alumina seemed to especially decrease the matrix effect and improve the overall recovery of drugs, mainly those with a high octanol-water partition coefficient. CECs in the extracts were analyzed by ultra-high performance liquid chromatography coupled to mass spectrometry in tandem. A standard addition-matrix matched calibration was used for quantification. Application of the method to two related samples (raw manure and farm centrifuged raw manure) from a facility revealed that the concentrations of CECs determined in the raw manure by the comprehensive methodology were higher than those calculated by adding the concentrations measured in the solid and liquid phases, separately. This was attributed to the loss of CECs adsorbed on fine particles in the suspension during the sample preparation procedure of the liquid-phase. Furthermore, the decrease of residues in the raw manure when this is centrifuged in the farm to yield compost is shown.

Sample pretreatment and analytical methodology for the determination of antibiotics in swine wastewater and activated sludge

An analytical method for the simultaneous extraction and determination of eight veterinary antibiotics in swine wastewater and activated sludge was developed and validated based on the instrumental determination by liquid chromatography tandem quadrupole mass spectrometry. Ultrasound-assisted extraction and solid-phase extraction were introduced into the pretreatment procedure of the two complex environmental matrices. The critical steps involved in the sample pretreatment procedure and the instrumental analysis conditions were optimized progressively. Recoveries of the optimized method were good with 75.3-118.2% in wastewater and 82.8-130.1% in sludge. The absolute deviations of methods were lower than 11.7%, presenting a high reproducibility and precision. The limits of quantification for the eight pharmaceuticals in wastewater and sludge were 5-15 ng·L^-1 and 2-6 ng·g^-1, showing high sensitivity of the methods. The developed method has been successfully applied to evaluate the actual concentration levels of tetracyclines, quinolones, and sulfonamides in actual swine wastewater (maximum detected concentration of 87.377 μg·L^-1) and activated sludge (maximum detected concentration of 51242.3 ng·g^-1).

Simultaneous extraction and determination of 45 veterinary antibiotics in swine manure by liquid chromatography-tandem mass spectrometry

A multiresidue method for identification and quantification of 45 veterinary antibiotics (VAs) belonging to 5 different drug classes has been developed, which is the first comprehensive method for pig manure. The proposed method used mixed liquor with methanol: acetonitrile: citrate buffer ratio of 1:1:2 to extract the target VAs from freeze-dried manure. The extracting solution passed through solid-phase extraction (SPE) procedure with Oasis HLB cartridges, which could isolate the target VAs and clean the samples in a single step. After blow-drying and concentrating, the samples were analyzed by ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) in one single injection with a run time of 12 min. The average recovery rates for most of the VAs were in the range of 50-120% with relative standard deviations below 15%. Linearity was studied in the range between 2 and 1000 μg/kg using matrix-matched calibration and pure solvent calibration, to evaluate the matrix effects (MEs). The limits of detection (LDs) and quantification (LQs) were in the range of 0.01-1.54 μg/kg and 0.03-5.13 μg/kg respectively, except for penicillin G. Finally, the proposed method was used to quantify VA residues in real swine manure from three farms with different scales; tetracyclines, sulfonamides, quinolones and macrolides were the most frequently detected compounds.

The simultaneous quantification of phytosterols and tocopherols in liposomal formulations using validated atmospheric pressure chemical ionization- liquid chromatography -tandem mass spectrometry

A novel liquid chromatography tandem mass spectrometry (LC-MS/MS) method was developed and validated to simultaneously quantify phytosterols (brassicasterol, campesterol, stigmasterol and β-sitosterol) and tocopherols (alpha, beta, gamma and delta) entrapped in the lipid bilayer of a liposomal formulation. Apart from liposomes (a pharmaceutical product), the developed method was able to quantify target analytes in agricultural products, thus showing wide applications. Atmospheric pressure chemical ionization (APCI) was employed due to the enhanced ionization of phytosterols and tocopherols in comparison to electrospray ionization. Unlike published work, the chromatographic conditions were modified to simplify the analytical approach. For the first time, a simple isocratic elution (acetonitrile:methanol 99:1 v/v) was utilized for the separation of four phytosterols and four tocopherols in a single run. A substantially better baseline separation of phytosterols were obtained in comparison to reported methods by using poroshell C18 column. The method has a total run time of 7 min, which is the shortest run time among all reported quantitative methods for the simultaneous determination of four phytosterols and four tocopherols. Calibration curves for all phytosterols were linear in the range of 0.05-10 μg/mL. In the case of tocopherols, alpha tocopherol showed linear response in the range of 0.25-10 μg/mL. However, gamma and delta tocopherols exhibited quadratic relationship in the same concentration range (0.25-10 μg/mL). Validation parameters met the International Conference on Harmonization (ICH) guidelines in terms of selectivity, accuracy, precision, repeatability, sensitivity, matrix effects, dilution integrity and stability. The method was, for the first time, successfully applied for the quantifying phytosterols and tocopherols entrapped inside liposomes. An interesting chromatographic phenomenon was observed during sample analysis. Alpha tocopherol (entrapped in the liposomal lipid bilayer) was found to elute at two retention times, 2.53 min and 3.60 min. Such dual separation was not observed in calibration standards and quality controls. It was concluded that the chiral recognition ability of liposomes made up of phosphatidylcholine separated the enantiomers of alpha tocopherol, giving rise to two peaks at two different retention time. To sum, the reported novel LC-MS/MS method addresses three major analytical shortcomings, namely i)longer run time, ii)complex gradient elution and iii)poor baseline separation of phytosterols and tocopherols.

Innovative Configurations of Sample Preparation Techniques Applied in Bioanalytical Chemistry: A Review

Background:

Recently, in all fields of analytical chemistry, increased attention has been paid to extraction procedures and instrumental methods, which are easily scalable and are able to automate in order to improve the “high-throughput” capability.

Introduction:

The main goal of these applications relates to an improvement of the precision in the quantitative analysis, reduction of different sources of errors, decrease the analysis time and, in general, improve the analytical performances. Often these points can be in contrast to each other, not allowing to achieve the expected result but forcing a compromise between the objectives of the method and the analytical performance.

Methods:

In this review, following the evolution of the (micro)extraction procedures and instrument configurations, the recent procedures used in bioanalytical chemistry are critically evaluated. The aim of this paper is providing an overview of the approaches available in order to perform on-line coupling of various extraction techniques with chromatographic methods for the analysis of different compounds in various samples. Furthermore, a comparison between off-line and on-line systems, advantages of on-line systems applied on major extractive techniques and future perspectives are described.

Result:

The extraction methods suitable for on-line coupling covered in this review are: liquid-liquid extraction (LLE), solid phase extraction (SPE), solid phase microextraction (SPME), dispersive liquid- liquid microextraction (DLLME), microextraction by packed sorbent (MEPS), supercritical fluid extraction (SFE) and fabric phase sorptive extraction (FPSE).

Conclusion:

An overview of the micro-extraction techniques mentioned above was provided, making a comparison between them and focusing attention on future perspectives.

Evaluation of the tubing material and physical dimensions on the performance of extraction columns for on-line sample preparation-LC-MS/MS

Nowadays, high analytical throughputs are required considering an increasing demand for faster, simple and improved methods to analyze contaminants in a considerable number of samples. Generally, these compounds are present in complex matrices in contact with a high number of interferents becoming their determination difficult at low concentration. In this context, on-line extraction techniques arose to improve the extraction as well as separation power, while minimizing errors related to human sample manipulation. This paper describes a study regarding the development and optimization of columns used as an extraction device in multidimensional liquid chromatography. The main goals were the evaluation of the material used as column body as well as the investigation of the tube dimensions (internal diameter and length) in the extraction performance. Firstly, several tube materials were tested (steel, fused silica, PEEK, among others) being steel whose reported the best performance and was consequently chose for further studies. The investigation about the effects of the columns physical dimensions revealed a linear relationship between performance and the amount of sorbent utilized as extractive phase. However, when different columns with same amount of sorbent were tested results suggests that both i.d. and lengths play an important role in extraction efficiency. The longest columns with lower internal diameter showed the best results favoring the radial as well as axial analytes diffusion into the extraction column. After evaluation of these column variables, applications were carried out employing several different analytes belonging to various chemical classes and practical utilization, in order to reinforce the versatility as well as the robustness of this proposed study.

Recent advances of online coupling of sample preparation techniques with ultra high performance liquid chromatography and supercritical fluid chromatography

Ultra high performance liquid chromatography and supercritical fluid chromatography techniques are favored because of their high efficiency and fast analysis speed. Although many sample preparation techniques have been coupled with common liquid chromatography online, the online coupling of sample preparation with the two popular chromatography techniques have gained increasing attention owing to the increasing requirements of efficiency and sensitivity. In this review, we have discussed and summarized the recent advances of the online coupling of sample preparation with ultra high performance liquid chromatography and supercritical fluid chromatography techniques. The main sample preparation techniques that have been coupled with ultra high performance liquid chromatography online are solid-phase extraction and in-tube solid-phase microextraction, while solid-phase extraction and supercritical fluid extraction are the main techniques that have been coupled with supercritical fluid chromatography online. Especially, the strategies for online coupling of sample preparation with chromatography techniques were summarized. Typical applications and growing trends of the online coupling techniques were also discussed in detail. With the increasing demands of improving the efficiency, throughput, and analytical capability toward complex samples of the analysis methods, online coupling of sample preparation with chromatography techniques will acquire further development.