Solid-phase Extraction Liquid Chromatography-tandem Mass Research Articles

Determination of sacubitril and seven sartan drugs in serum samples by online solid phase extraction-liquid chromatography-tandem mass spectrometry

An online solid phase extraction–ultra performance liquid chromatography–tandem mass spectrometry detection method was developed for the simultaneous determination of sacubitril and seven sartan drugs in blood serum in this study. The compounds were separated through a C18 column. Mass spectrometry of the samples was performed using a jet stream electrospray ion source (AJS, ESI+). The samples were detected via a multiple reaction monitoring (MRM) mode and quantified via a stable isotope internal standard method. 900 μL of prepared sample was injected and a run time of 12.5 minutes was obtained in this proposed method. The eight examined target compounds showed good linearity (r2＞0.994) in the corresponding mass concentration range and a lower limit of quantitation (LLOQ) was in the range of 0.05–0.1 μg/L. The recovery of the spiked serum samples ranged from 90.90 % to 106.20 % with relative standard deviations (RSDs) of 4.57 %–9.27 %. Five target compounds were detected in the actual serum samples using this method. The proposed method is simple to use, sensitive, accurate, and suitable for the trace detection of sacubitril and seven sartan drugs present in serum samples. The method can meet the needs for clinical monitoring of blood concentrations of this type of drug, while providing detection technology support for the development of compound preparations of sacubitril and other sartan drugs.

Determination of the urinary concentrations of six bisphenols in public servants by online solid-phase extraction-liquid chromatography tandem mass spectrometry

Bisphenols are widely used as monomers and additives in plastic production. Thus, bisphenol A (BPA) and its most prominent substitutes have been detected in many environmental and human samples. This study proposes an online solid-phase extraction analytical methodology coupled to liquid chromatography with tandem mass spectrometry for the determination of six bisphenols (BPA and bisphenols F (BPF), S (BPS), AF (BPAF), B (BPB), and E (BPE)) in urine samples as an efficient and automated methodology. The method was developed and validated for all bisphenols with good recoveries (92–112%) and repeatability (RSD ≤ 10%) despite the variable matrix effects, except BPAF (which would require a dedicated internal standard), achieving method quantification limits in the 0.05–2.2 ng mL−1 range. The methodology was subsequently applied to 435 urine samples from a non-occupational exposure population (civil servants for the regional government) from Santiago de Compostela (Galicia, Spain). Only BPA, BPF, and BPS were positively detected; the last two presented higher detection frequencies than BPA. When the urinary concentrations are extrapolated to human intake and compared to the European Food Safety Agency (EFSA) tolerable daily intake (TDI) of 2 × 10−4 µg kg−1 day−1 (TDI), all BPA positively identified samples would surpass this threshold. Although no TDI exists currently for the other two identified bisphenols, it is evident that human exposure to bisphenols should be limited. Finally, the results stratification by gender revealed higher levels of exposure to BPF in the women group.

Determination of 21 organophosphate esters and their metabolites in drinking water by automatic solid phase extraction-liquid chromatography-tandem mass spectrometry

To establish a method for simultaneous determination of 21 organophosphate esters(OPEs) and their metabolites in drinking water by automatic solid phase extraction-liquid chromatography-tandem mass spectrometry. The drinking water was purified by automatic solid phase extraction with HLB column, eluted by methanol, determined by liquid chromatography tandem mass spectrometry with ACQUITY UPLC BEH(100 mm×2.1mm, 1.7 μm) column, and quantified by internal standard method. The optimized method could simultaneously detect 21 organophosphate esters and their metabolites in drinking water. The detection limit was 0.01-0.24 ng/L, the quantitation limit was 0.03-0.77 ng/L. The recovery range was 57.6%-121.2% and the relative standard deviation is 1.2%-11.1% when the concentration was 0.8-20 ng/L. Senventeen tap water and 30 packaged drinking water collected by the supermarket were measured. The ΣOPEs range was 16.8-177 ng/L, and the Σdi-OPEs range was 0.328-16.3ng/L, indicating the exposure risk of organophosphates and their metabolites in water. The pretreatment of the method is simple, automatic and sensitive, and is suitable for simultaneous high-throughput determination of organophosphate esters and their metabolites in large quantities of drinking water.

Simultaneous toxicokinetic studies of aristolochic acid I and II and aristolactam I and II using a newly-developed microdialysis liquid chromatography-tandem mass spectrometry.

Aristolochic acids (AAs) are naturally occurring genotoxic carcinogens linked to Balkan endemic nephropathy and aristolochic acid nephropathy. Aristolochic acid I and II (AA-I and AA-II) are the most abundant AAs, and AA-I has been reported to be more genotoxic and nephrotoxic than AA-II. This study aimed to explore metabolic differences underlying the differential toxicity. We developed a novel microdialysis sampling coupled with solid-phase extraction liquid chromatography-tandem mass spectrometry (MD-SPE-LC-MS/MS) to simultaneously study the toxicokinetics (TK) of AA-I and AA-II and their corresponding aristolactams (AL-I and AL-II) in the blood of Sprague Dawley rats co-treated with AA-1 and AA-II. Near real-time monitoring of these analytes in the blood of treated rats revealed that AA-I was absorbed, distributed, and eliminated more rapidly than AA-II. Moreover, the metabolism efficiency of AA-I to AL-I was higher compared to AA-II to AL-II. Only 0.58% of AA-I and 0.084% of AA-II was reduced to AL-I and AL-II, respectively. The findings are consistent with previous studies and support the contention that differences in the in vivo metabolism of AA-I and AA-II may be critical factors for their differential toxicities.

Determination of vancomycin in plasma with a magnetite amino silica adsorbent prepared from rice husks and high-performance liquid chromatography—tandem mass spectrometry (HPLC-MS/MS)

A rapid and simple magnetic solid phase extraction-liquid chromatography-tandem mass spectrometry method is reported to determine vancomycin in human plasma. The Fe3O4@SiO2 nanocomposite was prepared using silica nanoparticles obtained from rice husk waste and its modification using ammonia solution to obtain a Fe3O4@SiO2-NH2 nanohybrid as a new sorbent. The structure and morphology of the sorbent were characterized by X-ray diffraction, field emission scanning electron microscopy, and Fourier transform infrared spectroscopy. The nanosorbent was successfully used in magnetic solid phase extraction without hazardous solvents in 9 min with analysis by high-performance liquid chromatography – tandem mass spectrometry. Under the optimized conditions, the method provided a linear range from 10 to 1000 ng mL−1. The intra-day (n = 3) and inter-day precision (n = 3 working days) were below 10% relative standard deviation. The developed procedure was employed for determining vancomycin in human plasma with recoveries from 84.0 to 109.5% for spiked samples.

Investigation of exposure biomarkers in human plasma following differing levels of tobacco-specific N-nitrosamines and nicotine in cigarette smoke

Tobacco-specific N-nitrosamines (TSNAs) are strong carcinogens widely found in tobacco products, environmental tobacco smoke, lake, and wastewater. The main objective of this study was to investigate the effects of cigarette smoke with different yields of TSNAs (NNK, NNN, NAT, NAB) and nicotine on the levels of biomarkers of exposure in smokers’ plasma. Three hundred healthy volunteers were recruited comprising 60 smokers of each of 3 mg, 8 mg and 10 mg ISO tar yield cigarettes and 60 smokers who smoked 10 mg, 8 mg, and 3 mg for 14 days sequentially and 60 non-smokers. All study participants were male, aged from 21 to 45 years old, and were recruited from a same unit in Hebei, China. We measured the levels of NNAL, NAT, NNN, NAB and cotinine in plasma from 240 smokers and 60 non-smokers using a novel method established by online two-dimensional solid phase extraction-liquid chromatography-tandem mass spectrometry. The results showed that NNAL, NAT, NNN, NAB and cotinine in the plasma of smokers smoking cigarette with low TSNAs and nicotine were lower than that with high TSNAs and nicotine. When smokers switched from higher to lower TSNA yields of cigarettes, their plasma NNAL, NAT, NNN, NAB levels significantly decreased. The plasma concentrations of NNAL were significantly correlated with those of cotinine, NNN, NAT and NAB for smokers (p < 0.001). Similarly, the plasma concentrations of cotinine were significantly correlated with those of NNN, NAT and NAB for smokers (p < 0.001). The plasma NNAL, NAT, NNN, NAB and cotinine levels for smokers were significantly higher than those for non-smokers. These findings suggested that the total NNAL, NNN, NAT, NAB and cotinine in plasma were valid and reliable biomarkers for human exposure to TSNAs and nicotine.

Determination of domoic acid in seawater by solid phase extraction-liquid chromatography-tandem mass spectrometry

软骨藻酸(domoic acid, DA)是一种由海洋硅藻产生的生物毒素,具有强烈的神经毒性,近海水环境中的DA严重威胁海洋渔业生物和人类健康,因此对近海水环境中的DA进行有效监测至关重要。该文基于固相萃取-液相色谱-串联质谱联用技术(SPE-LC-MS/MS),建立了适用于海水中痕量、超痕量DA的检测方法。针对近海水生环境中DA浓度相对较高的情况下,采用在线SPE-LC-MS/MS检测模式,可减少前处理过程,提高样品的分析效率。离线SPE结合在线SPE-LC-MS/MS可实现大洋和极地海水中含量更低的DA的检测。通过对在线固相萃取条件和液相色谱、质谱条件的优化,海水样品经过滤和酸化简单处理后直接进样0.6 mL进行在线SPE-LC-MS/MS检测,DA在10.0~500.0 ng/L范围内线性关系良好(线性相关系数R2=0.9992),检出限(LOD)和定量限(LOQ)分别为4.0和10.0 ng/L,并且具有较好的方法回收率(≥81.0%)和精密度(RSD≤4.2%),表明方法可用于近海海水中痕量DA的检测。通过对离线固相萃取柱的选择和酸化条件的优化,80.0 mL海水样品经离线HLB固相萃取柱富集后,进行在线SPE-LC-MS/MS检测,DA在0.3~50.0 ng/L范围内线性关系良好(R2=0.9990),回收率(≥69.2%)和精密度(RSD≤4.4%)较好,LOD和LOQ分别为0.1和0.3 ng/L,说明方法的灵敏度较直接进样法大幅提升,实现了海水中超痕量DA的准确测定。这两种检测方法操作简单,样品用量小,灵敏度高,可满足近海养殖区及远岸海水中DA监测的要求。

Detection of ultrashort-chain and other per- and polyfluoroalkyl substances (PFAS) in U.S. bottled water

Per- and polyfluoroalkyl substances (PFAS) are compounds of emerging concern due to their persistence in the global water cycle and detection in drinking water sources. However, PFAS have been poorly studied in bottled water, especially in the United States. This study investigated the occurrence of PFAS and related factors in 101 uniquely labelled bottled water products for sale in the U.S. Products were screened for 32 target PFAS by solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC-MS/MS). Fifteen of 32 measured analytes were detected, consisting primarily of C3-C10 perfluorocarboxylic acids (PFCA) and C3-C6 and C8 perfluorosulfonic acids (PFSA). PFAS were detected above method detection limits in 39/101 tested products. The Σ32PFAS concentrations detected were 0.17–18.87 ng/L with a median of 0.98 ng/L; 97% of samples were below 5 ng/L. PFCA (83%) and short-chain perfluoroalkyl acids (PFAA) containing 5 or less CF2 groups (67%) were more prevalent on a mass basis than PFSA and longer-chain PFAA, respectively. Ultrashort-chain PFPrA, measured for the first time in bottled water, accounted for the greatest individual fraction of detected PFAS mass (42%) and was found almost exclusively in products labeled as Spring water. Purified water products contained significantly less PFAS than Spring water products, which was attributed to the use of reverse osmosis (RO) treatment in the majority of Purified waters (25/35) compared to Spring waters (1/45). RO-treated products contained significantly lower Σ32PFAS, long-chain, short-chain, and PFPrA concentrations than products without RO. Although no enforceable PFAS regulations exist for bottled water in the U.S., the finding that some products approach levels of concern justify a framework for monitoring PFAS in bottled water production.

Simultaneous determination of 9 environmental pollutants including bisphenol A in vegetable oil by solid phase extraction-liquid chromatography-tandem mass spectrometry.

In this study, a high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) method with solid phase extraction was established for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil. The sample was extracted with ammonia acetonitrile solution (1 : 9, V/V) by ultrasonication. And the obtained extract was purified by using a PRIME HLB solid phase extraction column. The identification and quantification of the compounds was performed by liquid chromatography-tandem mass spectrometry in multiple reaction monitoring (MRM) mode. The internal standard method was used for quantitative analysis. Under optimal experimental conditions, the limits of quantitation of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol and n-octylphenol in vegetable oil were 1.0 μg kg-1. The limits of quantitation of perfluorooctane sulfonic acid and perfluorooctanoic acid in vegetable oil were 0.1 μg kg-1. The average spiked recoveries of the method were in the range of 89.2-117.1% with the relative standard deviations (RSD) of 2.9-9.8% (n = 6). This method is sensitive, versatile and reproducible, and is suitable for the simultaneous determination of bisphenol A, bisphenol F, bisphenol S, 4-nonylphenol, n-nonylphenol, octylphenol, n-octylphenol, perfluorooctane sulfonate acid and perfluorooctanoic acid in vegetable oil.

Simultaneous determination of fructose, glucose and sucrose by solid phase extraction-liquid chromatography-tandem mass spectrometry and its application to source and adulteration analysis of sucrose in tea

A solid phase extraction-liquid chromatography-tandem mass spectrometry (SPE-LC–MS/MS) method was developed for simultaneous determination of fructose, glucose and sucrose in tea. Tea samples were ultrasonically extracted with ultrapure water and cleaned up by Oasis PRIME HLB SPE cartridge. The separation of the analytes was performed on XBridge BEH Amide column (2.1 × 150 mm, 5 μm) with isocratic elution. Detection of the target compounds were carried out under the multiple reaction monitoring (MRM) mode with negative electrospray ionization (ESI−). The qualitative screening was achieved with retention time and qualitative ion, then confirmation analysis with peak area and quantitative ion. The limits of detection (LODs, S/N ≥ 3) of fructose, glucose and sucrose were 0.02 mg/L, 0.03 mg/L and 0.08 mg/L, respectively. The average recoveries varied from 92.1 %–108.5 % for three levels. Linearity was obtained with the correlation coefficients greater than 0.992 for three target compounds. The established method was rapid, simple and accurate which was suitable for batch determination of fructose, glucose and sucrose in tea. A total of 213 tea samples from 7 countries were analysed and the results statistically analyzed using MATLAB software. Moreover, source and adulteration analysis of sucrose in tea was carried out. Sucrose in tea is mainly derived from photosynthesis during growth, hydrolysis of polysaccharides during the processing and artificial adulteration, once the sucrose content in tea exceeds 24.3 g/kg, it may involve artificial adulteration.

Determination of trace α-amanitin in urine of mushroom poisoning patient by online solid phase extraction-liquid chromatography-tandem mass spectrometry

An analytical method was established for the determination of trace α-amanitin in the urine of patients suffering from mushroom poisoning by online solid phase extraction-liquid chromatography-tandem mass spectrometry (online SPE-LC-MS/MS). The sample was protein precipitated with formic acid acidified acetonitrile-methanol (5:1, v/v). Reversed-phase liquid-liquid microextraction was used to remove the organic solvent from the sample extract. The toxin was purified by online SPE using an ODS micro column (5 mm×2.1 mm, 5 μm), and separated on an XBridgeTM BEH C18 column (150 mm×3.0 mm, 2.5 μm). Finally, the toxin was measured by MS/MS in the negative electrospray ionization (ESI-) mode. Multiple reaction monitoring (MRM) was used, and the conditions were m/z 917.4>205.1 (quantitative ion transition) and m/z 917.4>257.1. Collision energy for both transitions was 55 eV. A fast valve-switching technique with a quantitative loop was used as an interface between the online SPE and LC-MS/MS modules. The two modules were independent, neither the mobile phase nor the pressure would interfere with each other, thus ensuring the stability of the system. Precise purification by the online system could effectively eliminate the matrix effects in the subsequent MS detection. Weak matrix suppression effects were found, with results of 88.7%-96.5%. The linear range of α-amanitin in urine was 0.1-50 μg/L with a correlation coefficient (r2) of 0.9983. The limit of detection (LOD) and limit of quantification (LOQ) in the sample matrix were 0.03 μg/L and 0.1 μg/L, respectively. The average recoveries at three spiked levels (0.1, 2.0 and 20 μg/L) were 84.3%-91.7% with relative standard deviations (RSDs) of 3.8%-7.2%. The accuracy and precision were evaluated using quality control samples with toxin contents of 0.1 μg/L (LOQ), 0.2 μg/L (2-fold LOQ), 2.0 μg/L (medium level), and 20 μg/L (high level). The calculated average intra-day accuracy was 85.1%-96.0% with the precision of 4.1%-7.8%. The inter-day accuracy was 82.9%-94.8% with the precision of 5.0%-9.5%. The specificity of the method was verified by negative samples derived from patients who suffered only gastroenteritis poisoning, without hepatotoxic symptoms. α-Amanitin was found in urine samples from nine mushroom poisoning patients with hepatotoxic symptoms. The sampling time ranged from 19 h to 92 h. The toxin contents were 0.11-53.1 μg/L. For patients with a high intake of poisonous mushrooms, the toxin content was 53.1 μg/L in a patient's urine sampled 19 h after accidental consumption and 0.19 μg/L in another patient's urine sampled 92 h after poisoning. The content of α-amanitin was only 0.53 μg/L in the urine sample obtained 23 h after consumption for a patient with low intake and 0.11 μg/L in the urine sampled from another patient 40 h after poisoning. Amatoxins can metabolize rapidly in vivo. The laboratory identification of amatoxin poisoning requires a method for trace-level analysis in the biological matrix. It is proved that this method is simple, accurate and sensitive by the application to the analysis of actual samples. The protein precipitation and reversed-phase liquid-liquid microextraction steps are fast and simple. Hence, they can be used as a rapid and effective pre-treatment method for online SPE-LC-MS/MS analysis of water-soluble toxins in biomaterial matrix. Highly sensitive analysis of α-amanitin in urine can be obtained using a precise purification technology via online SPE in this study. The problem of qualitative confirmation of the toxin at trace levels (0.03 μg/L) after poisoning can be solved. The laboratory identification time for amatoxin poisoning in some patients exceeds 90 h. The developed analytical method at trace level (0.1 μg/L of LOQ) can provide reliable technical support for establishing the dose-response relationship of α-amanitin in vivo. It can satisfy for the determination of trace α-amanitin in urine samples from patients with hepatotoxic mushroom poisoning.

Online Turbulent Flow Extraction and Column Switching for the Confirmatory Analysis of Stimulants in Urine by Liquid Chromatography-Mass Spectrometry.

Stimulants are often used to treat attention deficit disorders and nasal congestion. As they can be misused and overdosed, the detection of stimulants is relevant in the toxicological field as well as in the doping control field. The effects of stimulants can indeed be beneficial for athletes. Therefore, their in-competition use is prohibited by the World Anti-Doping Agency (WADA). As stimulants represent one of the most detected categories of prohibited substances, automation of methods to detect and confirm their presence is desirable. Previous work has shown the advantages of using turbulent flow online solid-phase extraction liquid chromatography-tandem mass spectrometry (online SPE LC-MS-MS) for the detection and confirmation of diuretics and masking agents. Hence, a turbulent flow online SPE LC-MS-MS method, compliant with the WADA's identification criteria, was developed and validated for the detection and confirmation of 80 stimulants or metabolites with limits of identification varying between 10 (or possibly lower) and 100 ng/mL. As several metabolites are common metabolites for multiple administered stimulants, this means that with this method, misuse of well over 100 compounds can be detected. As the developed method uses the same columns and mobile phases as our turbulent flow online SPE LC-MS-MS method for the confirmation of diuretics and masking agents, there is no need to change the configuration of the instrument when switching between the diuretics method and the developed stimulants method.

Determination of Aromatic Compounds Metabolites in Human Urine by Solid Phase Extraction-liquid Chromatography-Tandem Mass Spectrometry

To establish the method based on high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) with solid phase extraction (SPE) for simultaneous determination of the biological metabolites of aromatic compounds, including N-acetyl-S-phenyl-L-cysteine (SPMA), N-acetyl-S-benzyl-cysteine (SBMA), p-nitrophenol (PNP), methylhippuric acids (MHA), p-Aminophenol (PAP), mandelic acid (MA), phenylglyoxylic acid (PGA) and 1-hydroxypyrene (1-OHP) in urine. After adding 20 μL of β-glucuronidase and 1 mL ammonium acetate buffer solution in 1 mL of urine, the sample was digested in a 37 ℃ incubator for 20 h. After digestion, the enzymatic hydrolysate was purified by PRIME HLB solid phase extraction column. The target compounds were eluted with 4 mL of acetonitrile and blown to dryness with nitrogen, reconstituted with 0.20 mL of methanol. Injected the sample solution into LC-MS/MS system for analysis after filtering with 0.22 μm filter membrane. LC separation was carried out on a reversed-phase C18 column (2.1 mm×150 mm, 3.5 μm); gradient eluting was performed at a flow rate of 0.2 mL/min. The water containing 0.1% formic acid was used as mobile phase A and methanol was used as mobile phase B. The mass spectrometry was performed with multiple reaction monitoring (MRM) mode, using alternating positive and negative ions, and internal standard curves were used for quantification. The eight metabolites showed good linearity within the range of 1-100 ng/mL, with a correlation coefficients greater than 0.995, and the relative precision deviation (RSDs) was 0.050%-9.95%. The method detection limits (MDLs) of the eight target metabolites were 0.041-0.12 ng/mL. The proposed method was used for urine sample analysis and the spiked recoveries were 80.1%-114.0%. The established method is quick, sensitive and accurate; it meets the requirementof the biological monitoring of aromatic compounds for the general population and occupational population.

Development and Validation of an LC–MS-MS Method for the Detection of 40 Benzodiazepines and Three Z-Drugs in Blood and Urine by Solid-Phase Extraction

An analytical method for the detection of 40 benzodiazepines, (±)-zopiclone, zaleplon and zolpidem in blood and urine by solid-phase extraction liquid chromatography-tandem mass spectrometry was developed and validated. Twenty-nine of 43 analytes were quantified in 0.5mL whole blood for investigating postmortem, drug-facilitated sexual assault (DFSA) and driving under the influence of drugs cases (DUID). The four different dynamic ranges of the seven-point, linear, 1/x weighted calibration curves with lower limits of quantification of 2, 5, 10 and 20μg/L across the analytes encompassed the majority of our casework encountered in postmortem, DFSA and DUID samples. Reference materials were available for all analytes except α-hydroxyflualprazolam, a hydroxylated metabolite of flualprazolam. The fragmentation of α-hydroxyflualprazolam was predicted from the fragmentation pattern of α-hydroxyalprazolam, and the appropriate transitions were added to the method to enable monitoring for this analyte. Urine samples were hydrolyzed at 55°C for 30min with a genetically modified β-glucuronidase enzyme, which resulted in >95% efficiency measured by oxazepam glucuronide. Extensive sample preparation included combining osmotic lysing and protein precipitation with methanol/acetonitrile mixture followed by freezing and centrifugation resulted in exceptionally high signal-to-noise ratios. Bias and between-and within-day imprecision for quality controls (QCs) were all within ±15%, except for clonazolam and etizolam that were within ±20%. All 29 of the 43 analytes tested for QC performance met quantitative reporting criteria within the dynamic ranges of the calibration curves, and 14 analytes, present only in the calibrator solution, were qualitatively reported. Twenty-five analytes metall quantitative reporting criteria including dilution integrity. The ability to analyze quantitative blood and qualitative urine samples in the same batch is one of the most useful elements of this procedure. This sensitive, specific and robust analytical method was routinely employed in the analysis of >300 samples in our laboratory over the last 6 months.

Occurrence of Antibiotics in Influent and Effluent from 3 Major Wastewater-Treatment Plants in Finland.

Wastewater-treatment plants (WWTPs) are regarded as one of the main sources of antibiotics in the environment. In the present study, the concentrations of multiple antibiotics and their metabolites belonging to 5 antibiotic classes were determined in 3 major Finnish WWTPs. An online solid phase extraction-liquid chromatography-tandem mass spectrometry method was used for the extraction and analysis of the compounds. The method was fully validated using real and synthetic wastewaters. Seven antibiotics and 3 metabolites were found in the analyzed samples. Sulfonamides were removed most efficiently, whereas macrolides usually showed negative removal efficiency during the treatment, which means that the concentrations for individual antibiotics determined in the effluent samples were higher than in the influent samples. Sulfadiazine was found at concentrations up to 1018 ng/L, which was the highest concentration of any of the detected antibiotics in influent. In the effluent samples, the highest mean concentration was found for trimethoprim (532 ng/L). The measured mass loads of the antibiotics and metabolites to the receiving waters ranged from 2 to 157 mg/d per 1000 population equivalent. The evaluated environmental risk assessment showed that clarithromycin and erythromycin might pose a risk to the environment. The present study further underlines the importance of implementing technology for efficient removal of xenobiotics during wastewater treatment. Environ Toxicol Chem 2020;39:1774-1789. © 2020 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Determination of cylindrospermopsin, nodularin and microcystins in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry

A method was developed for the determination of cylindrospermopsin (CYN), nodularin (NOD), microcystin-RR (MC-RR), microcystin-YR (MC-YR) and microcystin-LR (MC-LR) in freshwater fish by dispersive solid phase extraction-liquid chromatography-tandem mass spectrometry (DSPE-LC-MS/MS). The analytes were extracted from fish tissues with acetonitrile-water-formic acid (89:10:1, v/v/v), and purified by DSPE using C18 as the adsorbent. The separation of analytes was performed on an Agilent ZORBAX Eclipse XDB C18 column with the gradient elution of acetonitrile and water as mobile phases. Qualitative analysis was performed using the multiple reaction monitoring (MRM) mode. The analytes were quantified by matrix-matched external standard curves. The chromatographic and MS parameters were optimized. Major factors affecting the extraction and cleanup efficiencies including the type of extraction solvent and cleanup sorbent were investigated. The linear correlation coefficients (R2) of the five target compounds were no less than 0.9954. The limits of detection (LODs, S/N=3) and limits of quantification (LOQs, S/N=10) of the five target compounds were 5-10 μg/kg and 15-40 μg/kg, respectively. The spiked recoveries of the five target compounds ranged from 62.3% to 101.2%. The developed method is simple, rapid, accurate, sensitive, and is suitable for the determination of cylindrospermopsin, nodularin and microcystins in freshwater fish.

A fully automated approach for the analysis of 37 psychoactive substances in raw wastewater based on on-line solid phase extraction-liquid chromatography-tandem mass spectrometry

This work presents a multi-residue method for the simultaneous determination of 37 legal and illicit psychoactive substances in wastewater, including the most common illicit drugs (cocaine-related compounds, amphetamine-type stimulants, hallucinogens, opiates/opioids, and cannabinoids), new psychoactive substances (two synthetic cathinones, the synthetic opioid AH-7921, and the arylcyclohexylamine methoxetamine), and legal but controlled psychoactive substances (stimulants, benzodiazepines, antidepressants, sedatives, antipsychotics, and hypnotics). To this end a fully automated analytical approach based on solid phase extraction coupled in series to liquid chromatography tandem mass spectrometry detection (on-line SPE- LC–MS/MS) was used. The methodology developed was validated in terms of linearity, recovery, repeatability, and sensitivity in wastewater. Method linearity was between 0.1 ng/L (or the analyte limit of quantification if higher) and 2,000 ng/L (10,250 ng/L in the case of caffeine). Absolute recoveries were variable (between 5% and 132%), depending on the analyte. However, the use of isotopically labeled compounds corrected for analyte losses during the extraction process and matrix effects (relative recoveries within the range of 80–120%). Repeatability of the method was satisfactory for all analytes, with RSD values lower than 13% for most compounds. Limits of detection and quantification in wastewater were below 7 and 23 ng/L, respectively, for all analytes except lormetazepam (10 and 32 ng/L), caffeine (13 and 44 ng/L), and the cannabinoids 11-nor-9-carboxy- Δ9-tetrahydrocannabinol (18 and 61 ng/L) and 11-hydroxy-Δ9- tetrahydrocannabinol (69 and 228 ng/L). The method was applied to the analysis of wastewater samples collected daily in Barcelona for one week. Twenty-five of the 37 analytes were detected in the samples analyzed. Average concentrations ranged from 7 ng/L in the case of zolpidem to 54 μg/L in the case of caffeine.

Per- and polyfluoroalkyl substances and fluorinated alternatives in urine and serum by on-line solid phase extraction–liquid chromatography–tandem mass spectrometry

Per- and polyfluoroalkyl substances (PFAS), man-made chemicals with variable length carbon chains containing the perfluoroalkyl moiety (CnF2n+1–), are used in many commercial applications. Since 1999–2000, several long-chain PFAS, including perfluorooctane sulfonate (PFOS) and perfluorooctanoate (PFOA), have been detected at trace levels in the blood of most participants of the National Health and Nutrition Examination Survey (NHANES)—representative samples of the U.S. general population—while short-chain PFAS have not. Lower detection frequencies and concentration ranges may reflect lower exposure to short-chain PFAS than to PFOS or PFOA or that, in humans, short-chain PFAS efficiently eliminate in urine. We developed on-line solid phase extraction–HPLC–isotope dilution–MS/MS methods for the quantification in 50 μL of urine or serum of 15 C3-C11 PFAS (C3 only in urine), and three fluorinated alternatives used as PFOA or PFOS replacements: GenX (ammonium salt of 2,3,3,3,-tetrafluoro-2-(1,1,2,2,3,3,3-heptafluoropropoxy)-propanoate, also known as HFPO-DA), ADONA (ammonium salt of 4,8-dioxa-3H-perfluorononanoate), and 9Cl-PF3ONS (9-chlorohexadecafluoro-3-oxanonane-1-sulfonate), main component of F53-B. Limit of detection for all analytes was 0.1 ng/mL. To validate the method, we analyzed 50 commercial urine/serum paired samples collected in 2016 from U.S. volunteers with no known exposure to the chemicals. In serum, detection frequency and concentration patterns agreed well with those from NHANES. By contrast, except for perfluorobutanoate, we did not detect long-chain or short-chain PFAS in urine. Also, we did not detect fluorinated alternatives in either urine or serum. Together, these results suggest limited exposure to both short-chain PFAS and select fluorinated alternatives in this convenience population.

Distribution and Treatment of Antibiotics in Typical WWTPs in Small Towns in China

As a new, persistent pollutant in the environment, antibiotics are one of the most important pollutants in sewage treatment plants. The objective of this work was to investigate the concentration distribution and removal efficiency of antibiotics for three typical wastewater treatment technologies applied in small towns (CASS, A2/O, and Orbal oxidation ditch) using solid phase extraction-liquid chromatography-tandem mass spectrometry. Sixteen typical antibiotics, including four tetracyclines, three β-lactams, four macrolides, three quinolones, and two sulfonamides, were analyzed in the influent and effluent. In addition, the relationship between the presence of antibiotics and the basic water quality (NH4+-N, TN, COD, pH, etc.) in the WWTPs was analyzed. The results showed that ofloxacin (OFX) and norfloxacin (NOR) were the main antibiotics in the WWTPs in this study. However, the concentrations of these two antibiotics in the effluent were low, indicating effective antibiotic removal efficiency. The antibiotic removal efficiency was higher than 60% in five of the WWTPs. Compared with the A2/O process, the CASS and Orbal oxidation ditch technologies resulted in higher removals of most of the antibiotics. In addition, the CASS and A2/O processes worked best for the removal of β-lactam [ampicillin (AMP) and penicillin (PCN)], quinolones (ENR, NOR, and OFX), and macrolide (CLR), while the Orbal oxidation ditch worked best for the removal of tetracyclines (TC and OTC) and sulfonamides [sulfadiazine (SD)]. The correlation between antibiotic concentration and the basic parameters of water quality (NH4+-N, TN, COD, pH, etc.) was analyzed, and it was found that the water quality parameters had some effect on the concentration of antibiotics. With higher concentrations of the basic water quality parameters, higher the concentration of erythromycin (EM), roxithromycin (ROX), 4-epi-Tetracycline (E-TC), clarithromycin (CLR), ciprofloxacin (CIP), ofloxacin (OFX), epioxytetracycline (E-OTC), tetracyclines (TC), oxytetracycline (OTC), and norfloxacin (NOR) were observed. In summary, it is important to ensure the stable operation of small town WWTPs to reduce the ecological risk of antibiotics.

On-line solid phase extraction-liquid chromatography-tandem mass spectrometry for insect repellent residue analysis in surface waters using atmospheric pressure photoionization

Insect repellents (IRs) are a group of organic chemicals whose function is to prevent the ability of insects of landing in a surface. These compounds have been found in the environment and may pose a risk to non-target organisms. In this study, an on-line solid phase extraction – high performance liquid chromatography-tandem mass spectrometry multiresidue method was developed using an atmospheric photoionization source (SPE-HPLC-(APPI)-MS/MS). The use of the APPI as an alternative ionization technique to electrospray (ESI) and atmospheric pressure chemical ionization (APCI) allowed expanding the range of analytical techniques suitable for the analysis of IRs, so far relied in gas chromatography. High sensitivity and precision was reached with method limits of quantification between 0.2 and 4.6 ng l−1 and interday and intraday precision equal or below 15%. The validated method was applied to the study of surface water samples from three European river basins with different flow regime (Adige River in Italy, Sava River in the Balkans, and Evrotas River in Greece). The results showed that two IRs (DEET and Bayrepel) were ubiquitous in the Sava and Evrotas basins, reaching concentrations as high as 105 μg l−1 of Bayrepel in the Sava River, and 5 μg l−1 of DEET in the Evrotas River. Densely populated areas and effluent waste waters are pointed out as the responsible for this pollution. In the alpine river Adige, only three samples showed low levels of IRs (6.01–37.8 ng l−1). The concentrations measured were used to perform an environmental risk assessment based on the hazard quotients (HQs) estimation approach by using the chronic and acute eco-toxicity data available. The results revealed that despite the high frequency and eventually high concentrations of these IRs determined in the three basins, only few sites were at risk, with 1 < HQs < 3.3.