Simultaneous determination of seven multiclass veterinary antibiotics in surface water samples in the Republic of Korea using liquid chromatography with tandem mass spectrometry

A simultaneous determination method using solid‐phase extraction and liquid chromatography with tandem mass spectrometry was developed to detect and quantify the presence of seven multiclass veterinary antibiotics (13 compounds in total) in surface water samples, which included the effluents of livestock wastewater and sewage treatment plants, as well as the reservoir drainage areas from dense animal farms. The pH of all water samples was adjusted to 2 or 6 before solid‐phase extraction using Oasis HLB cartridges. The developed method was fully validated in terms of linearity, method detection limit, method quantitation limit, accuracy, and precision. The linearity of all tested drugs was good, with R² determination coefficients ≥ 0.9931. The method detection limits and method quantitation limits were 0.1–74.3 and 0.5–236.6 ng/L, respectively. Accuracy and precision values were 71–120 and 1–17%, respectively. The determination method was successfully applied for monitoring water samples obtained from the Yeongsan River in 2015. The most frequently detected antibiotics were lincomycin (96%), sulfamethazine (90%), sulfamethoxazole (88%), and sulfathiazole (50%); the maximum concentrations of which were 398.9, 1151.3, 533.1, and 307.4 ng/L, respectively. Overall, the greatest numbers and concentrations of detected antibiotics were found in samples from the effluents of livestock wastewater, sewage treatment plants, and reservoir drainage areas. Diverse veterinary antibiotics were present, and their presence was dependent upon the commercial sales and environmental properties of the analytes, the geographical positions of the sampling points, and the origin of the water.     

Determination of aminoglycoside residues by liquid chromatography and tandem mass spectrometry in a variety of matrices

A quantitative LC–MS/MS method was developed for the determination of 13 commonly used aminoglycoside antibiotics in meat (pork muscle, fish, and veal livers and kidneys). The proposed method is sufficiently sensitive and highly selective. Unlike other previously reported methods, it uses a simple clean-up procedure based on a strong cation-exchange solid-phase cartridge that permits high sample extract loading volumes. A unique elution regime based on a volatile buffer at intermediately high pH value in combination with an organic solvent provides quantitative elution of the various aminoglycosides. This methodology ensured that neither a breakthrough of weakly retained aminoglycosides (e.g. spectinomycin) nor the incomplete elution of strongly retained analytes (e.g. neo- and gentamycin) is observed. The single-step clean-up is fast and produces clean extracts that minimize matrix-related signal suppression in the electrospray interface.     

Solid‐phase extraction based on chloromethylated polystyrene magnetic nanospheres followed by gas chromatography with mass spectrometry to determine phthalate esters in beverages

An ultrasound‐assisted magnetic solid‐phase extraction procedure with chloromethylated polystyrene‐coated Fe₃O₄ nanospheres as magnetic adsorbents has been developed to determine eight phthalate esters (bis(4‐methyl‐2‐pentyl) phthalate, dipentyl phthalate, dihexyl phthalate, benzyl butyl phthalate, bis(2‐butoxyethyl) phthalate, dicyclohexyl phthalate, di‐n‐octyl phthalate, and dinonyl phthalate) simultaneously in beverage samples, in combination with gas chromatography coupled to tandem mass spectrometry for the first time. Several factors related to magnetic solid‐phase extraction efficiencies, such as amount of adsorbent, extracting time, ionic strength, and desorption conditions were investigated. The enrichment factors of the method for the eight analytes were over 2482. A good linearity was observed in the range of 10–500 ng/L for bis(2‐butoxyethyl) phthalate and 2–500 ng/L for the other phthalate esters with correlation coefficients ranging from 0.9980 to 0.9998. The limits of detection and quantification for the eight phthalate esters were in the range of 0.20–2.90 and 0.67–9.67 ng/L, respectively. The mean recoveries at three spiked levels were 75.8–117.7%, the coefficients of variations were <11.6%. The proposed method was demonstrated to be a simple and efficient technique for the trace analysis of the phthalate esters in beverage samples.     

Solid‐phase extraction coupled with ultra high performance liquid chromatography and electrospray tandem mass spectrometry for the highly sensitive determination of five iodinated X‐ray contrast media in environmental water samples

A highly sensitive method based on solid‐phase extraction and ultra high performance liquid chromatography with electrospray tandem mass spectrometry has been developed for simultaneous determination of five iodinated X‐ray contrast media in environmental water samples. Various solid‐phase extraction cartridges have been evaluated and a combination of LiChrolute EN and ENVI‐Carb solid phase extraction cartridges was selected for sample enrichment. The method was comprehensively validated on ground water, tap water, surface water, drinking water, and waste water by the conventional procedures: linearity, method detection limits, accuracy and precision, matrix effects. Good linearity (R² > 0.999), low detection limits (0.4–8.1 ng/L), satisfactory recoveries (55.1–109.5%) and precision (0.8–10.0% for intra‐day precisions and 0.6–16.5% for inter‐day precisions) were obtained for all the target compounds. Iopamidol, iohexol, and diatrizoate in some matrices were affected by matrix effects, which were slightly eased by using the isotope‐labeled internal standard. The developed method was successfully applied for real samples collected in Shanghai, China, with detected concentrations up to 2200 ± 200 and 9000 ± 1000 ng/L for iohexol and iopamidol, respectively.     

Multi‐residue analysis of 44 pharmaceutical compounds in environmental water samples by solid‐phase extraction coupled to liquid chromatography‐tandem mass spectrometry

A solid‐phase extraction combined with a liquid chromatography‐tandem mass spectrometry analysis has been developed and validated for the simultaneous determination of 44 pharmaceuticals belonging to different therapeutic classes (i.e., antibiotics, anti‐inflammatories, cardiovascular agents, hormones, neuroleptics, and anxiolytics) in water samples. The sample preparation was optimized by studying target compounds retrieval after the following processes: i) water filtration, ii) solid phase extraction using Waters Oasis HLB cartridges at various pH, and iii) several evaporation techniques. The method was then validated by the analysis of spiked estuarine waters and wastewaters before and after treatment. Analytical performances were evaluated in terms of linearity, accuracy, precision, detection, and quantification limits. Recoveries of the pharmaceuticals were acceptable, instrumental detection limits varied between 0.001 and 25 pg injected and method quantification limits ranged from 0.01 to 30.3 ng/L. The precision of the method, calculated as relative standard deviation, ranged from 0.3 to 49.4%. This procedure has been successfully applied to the determination of the target analytes in estuarine waters and wastewaters. Eight of these 44 pharmaceuticals were detected in estuarine water, while 26 of them were detected in wastewater effluent. As expected, the highest values of occurrence and concentration were found in wastewater influent.     

Multiresidue determination of UV filters in water samples by solid‐phase extraction and liquid chromatography with tandem mass spectrometry analysis

UV filters, contained in sunscreens and other cosmetic products, as well as in some plastics and industrial products, are nowadays considered contaminants of emerging concern because their widespread and increasing use has lead to their presence in the environment. Furthermore, some UV filters are suspected to have endocrine disruption activity. In the present work, we developed an analytical method based on liquid chromatography with tandem mass spectrometry for the determination of UV filters in tap and lake waters. Sixteen UV filters were extracted from water samples by solid‐phase extraction employing graphitized carbon black as adsorbent material. Handling 200 mL of water sample, satisfactory recoveries were obtained for almost all the analytes. The limits of detection and quantification of the method were comparable to those reported in other works, and ranged between 0.7–3.5 and 1.9–11.8 ng/L, respectively; however in our case the number of investigated compounds was larger. The major encountered problem in method development was to identify the background contamination sources and reduce their contribution. UV filters were not detected in tap water samples, whereas the analyses conducted on samples collected from three different lakes showed that the swimming areas are most subject to UV filter contamination.     

超高压液相色谱-串级质谱分析渔业水中7种激素药物

建立了同时测定渔业养殖水中氢化可的松、泼尼松、醋酸可的松、睾酮、甲睾酮、黄体酮及苯丙酸诺龙等7种激素残留药物的超高压液相色谱-电喷雾电离串联质谱(UPLC-ESI-MS/MS)分析方法.水样用HLB固相萃取柱净化、浓缩后,洗脱液经氮气吹干,残渣用乙腈-水(V∶V=1∶1)溶解,以乙腈和0.1％甲酸水溶液为流动相,经ZORBAXSB-C18色谱柱分离后进行LC-MS/MS多反应检测模式作定性定量分析.方法在0.5～40μggL或1～40μg/L范围具有良好的线性,相关系数大于0.997,检出限(S/N=3)为0.03～0.3μg/L,平均回收率为74.8％～113.0％,相对标准偏差为4.0％～16％.方法适用于渔业养殖水中7种激素的检测分析.     

Determination of five sulfonylurea herbicides in environmental waters and soil by ultra high performance liquid chromatography with tandem mass spectrometry after extraction using graphene

A fast and novel analytical method was developed for the determination of trace levels of sulfonylurea herbicides in water and soil samples. Graphene was used as a sorbent for extraction, and ultra high performance liquid chromatography with tandem mass spectrometry was used for quantification. Five sulfonylurea herbicides were preconcentrated from water samples using a graphene‐loaded packed cartridge, while extraction from soil samples was performed in a single step using graphene‐supported matrix solid‐phase dispersion. Under the optimized conditions, the calibration plots were linear in the range between 5 and 1000 ng/L for water samples, and between 1 and 200 ng/g for soil samples. All correlation coefficients (R) were >0.99. The limits of detection for water and soil samples were 0.28–0.53 ng/L and 0.08–0.26 ng/g, respectively. This method was successfully applied to the analysis of spiked samples of environmental water and soil, with recoveries ranging from 84.2–109.3 and 86.12–103.2%, respectively, all with relative standard deviations of <10%.     

Direct analysis of free amino acids by mixed‐mode chromatography with tandem mass spectrometry

We developed a straightforward, robust, and relatively fast method for the analysis of amino acids by mixed‐mode high‐performance liquid chromatography coupled to electrospray ionization tandem mass spectrometry. The method does not involve derivatization and allows the detection of 21 amino acids, representing a wide range of isoelectric points, in less than 40 min. Chromatographic separation was governed by a silica‐based mixed‐mode column providing simultaneous hydrophobic and ion exchange separation mechanisms. The use of tandem mass spectrometry increased selectivity, reducing potential problems associated with poor selectivity in the chromatographic system. For an injection volume of 1 μL, we obtained detection limits <3 μM for the majority of analytes. For all analytes, a linearity of r > 0.99 was obtained, recovery in matrix was >86%, and the retention times were highly reproducible. The method was successfully applied to soil solution and fungal culture samples, demonstrating the advantages in successfully avoiding issues associated with high amounts of substances that may interfere with derivatization‐based methods. This method represents an alternative to derivatization‐based methods and can be applied in areas where sample matrices are highly complex.     

Multiresidue analysis of quinolones in water by ultra‐high perfomance liquid chromatography with tandem mass spectrometry using a simple and effective sample treatment

A rapid and simple analytical method has been developed for the determination of 19 quinolones in environmental water samples using ultra high performance liquid chromatography with tandem mass spectrometry. Chromatographic and detection conditions have been optimized and the separation was achieved in less than 4 min. The separation was carried out using a new‐generation column filled with superficially porous particles, resulting in lower backpressure and better resolution than totally porous particle columns. The quinolones were detected by electrospray ionization in positive mode using multiple‐reaction monitoring mode for acquisition. A sample treatment based on liquid–liquid extraction and phase separation via salting‐out was employed to achieve a fast and simple extraction that enables the multiresidue analysis. The method has been validated for an environmental well water sample from a mountain area. Very low limits of detection (between 10 and 90 ng/L) with relative standard deviations lower than 16.5% and recoveries higher than 73% were achieved. Moreover, well waters from different origins (mountain and coast areas and irrigated land) have been evaluated and similar results were obtained.     

Development of pressurized liquid extraction and solid‐phase microextraction combined with gas chromatography and flame photometric detection for the determination of organophosphate esters in sediments

Organophosphate esters have been extensively used as flame retardants and plasticizers. The analysis of organophosphate esters in the environment is a hot topic because many of them are toxic and persistent. We developed a novel procedure for determining organophosphate esters in sediment. In this work, pressurized liquid extraction and solid‐phase microextraction are used for sample preparation to extract and concentrate the analytes, which are then analyzed by gas chromatography with flame photometric detection. The extraction parameters of pressurized liquid extraction were investigated and optimized by orthogonal design and then evaluated by range analysis and analysis of variance. Under the optimal conditions, the proposed procedure showed wide linear ranges (0.90–100 ng/g) with correlation coefficients ranging from 0.9921 to 0.9990. The detection limits of the method were in the range of 0.009–0.280 ng/g with standard deviations ranging from 2.2 to 9.5%. Recoveries of the proposed method ranged from 82.3 to 108.9% with relative standard deviations <8.4%. The obtained method was applied successfully to the determination of organophosphate esters in real sediments with recoveries varying from 79.8 to 107.3%. The proposed method was proved to be simple, easy, and sensitive for analyzing organophosphate esters in sediment samples.     

Determination of pesticides in water samples by solid phase extraction and gas chromatography tandem mass spectrometry

A multiresidue method for the determination of more than 80 pesticides in water has been developed and validated. The proposed method is based on SPE followed by GC coupled to MS/MS. Different variables affecting SPE procedure, such as cartridges, sample volume and solvents were studied, and mass spectrometric conditions were optimised in order to increase selectivity and sensitivity. Calibration curves were linear over the range of 0.03-0.5 microg/L. Recoveries were in the range of 70-110% and repeatability was below 20% for the lowest calibration point. LODs ranged from 0.001 to 0.025 microg/L and LOQs from 0.003 to 0.076 microg/L. Finally, the method was successfully applied to the analysis of water samples from southeast of Spain.     

Matrix effect in high‐performance liquid chromatography‐tandem mass spectrometry analysis of antibiotics in environmental water samples

This paper describes the matrix effect during the analysis of ten antibiotic compounds in water by SPE followed by HPLC‐ESI‐MS/MS. The target analytes were tetracycline, oxytetracycline (tetracyclines), sulfathiazole, sulfamethazine, sulfadiazine (sulfonamides), erythromycin‐H₂O, roxithromycine, spiramycin (macrolides), ofloxacin, and norfloxacin (quinolones). The matrix effect was examined for internal standards and the target analytes in five different water matrixes, with signal suppression being increased in the order: ultrapure water, tap water, river water, sewage effluent, and sewage influent. A combined application of the internal standards and matrix‐matched extract calibration was shown to be successful in compensating the matrix effect for the analytes. The procedural recovery of the target compounds in sewage effluents and influents was higher than in river water samples, which was further enhanced by sample acidification to pH 2. The validity of the internal standard based matrix‐matched calibration approach was verified by the standard addition method.     

Separation and determination of homogenous fatty alcohol ethoxylates by liquid chromatography with mulitstage mass spectrometry

Alcohol ethoxylates (AEs) are a significant component of a stream of surfactants directed to the aquatic environment. The aim of this work was the investigation of the dependence of the analytical signals of homogeneous AE homologues on liquid chromatography with tandem mass spectrometry conditions, as well as the separation of AEs from the water matrix and, on this basis, the development of an analytical procedure suitable for the determination of AEs in environmental samples. Homogeneous homologues containing dodecyl moiety and 2–9 oxyethylene subunits were investigated. The analytical signals of the investigated homologues were optimized in terms of concentration of ammonium acetate in the mobile phase (optimum 5 mM) and a column temperature (optimum 35°C) of the liquid chromatography with tandem mass spectrometry system. A separation of AEs from the water matrix by liquid–liquid extraction (ethyl acetate, chloroform) or solid‐phase extraction (C₁₈, styrene divinylbenzene, H‐RX) was investigated. In a model investigation, the best recoveries (>90%) were obtained with a styrene divinylbenzene cartridge eluted with a 1:1 mixture of chloroform and methanol. However, much worse recoveries were obtained from the river water sample. Better results were obtained for liquid–liquid extraction with ethyl acetate. Recoveries of 62–80% were obtained for homologues having 4–9 oxyethylene subunits, at the lowest spike.     

Trace determination of organophosphate esters in environmental water samples with an ionogel‐based nanoconfined ionic liquid fiber coating for solid‐phase microextraction with gas chromatography and flame photometric detection

Organophosphate esters, widely used as flame retardants and plasticizers, are regarded as a class of emerging pollutants. In this work, a novel approach was developed for the fabrication of a solid‐phase microextraction fiber by using hybrid silica‐based materials with immobilized ionic liquids with sol–gel technology, and the prepared solid‐phase microextraction fiber was then coupled with gas chromatography and flame photometric detection for the analysis of six organophosphate esters. The high loading of 1‐hexadecyl‐3‐methylimidazolium bis(trifluoromethylsulfonyl)imide was confined within the hybrid network. The developed solid‐phase microextraction fiber possesses a coating thickness of ～35 μm with good thermal stability and long lifetime. The parameters affecting the extraction efficiency such as extraction time, temperature, pH, and ionic strength of the sample solution were optimized. Under the optimized conditions, the limits of detection were in the range of 0.04?0.95 μg L^?1, and the precision of the method assessed with repeatability and reproducibility of (RSD%) ?13 and ?29%, respectively. The proposed method was successfully applied to determine the six organophosphate esters in three real water samples, with recoveries in the range of 64.8?125.4% at two different spiking concentration levels. As a result, the proposed method demonstrated its potential for application in trace determination of organophosphate esters in actual water samples.     

高效液相色谱–串联质谱法检测环境水体中18种全氟化合物

建立了快速检测环境水体中18种全氟化合物的高效液相-串联质谱方法。环境水样经大体积PEP固相萃取柱快速提取、富集和净化后,过0.22μm微孔滤膜,再利用Agilent Zorbax Eclipse XDB-C18反相色谱柱分离,以5 mmol/L乙酸铵溶液和甲醇为流动相梯度洗脱,最终进入电喷雾离子源负离子扫描,在多反应监测模式下定性及定量分析。所有目标化合物的质量浓度在1~20μg/L范围内与色谱峰面积线性良好,相关系数(r2)大于0.999,方法检出限为0.18~0.48 ng/L。18种全氟化合物的加标回收率为90.1%~107.3%,相对标准偏差为0.3%~8.2%(n=6)。该方法操作简单、快速,灵敏度高,可满足环境水体中全氟化合物的检测。     

Determination of phthalate esters from environmental water samples by micro‐solid‐phase extraction using TiO2 nanotube arrays before high‐performance liquid chromatography

We describe a highly sensitive micro‐solid‐phase extraction method for the pre‐concentration of six phthalate esters utilizing a TiO₂ nanotube array coupled to high‐performance liquid chromatography with a variable‐wavelength ultraviolet visible detector. The selected phthalate esters included dimethyl phthalate, diethyl phthalate, dibutyl phthalate, butyl benzyl phthalate, bis(2‐ethylhexyl)phthalate and dioctyl phthalate. The factors that would affect the enrichment, such as desorption solvent, sample pH, salting‐out effect, extraction time and desorption time, were optimized. Under the optimum conditions, the linear range of the proposed method was 0.3–200 μg/L. The limits of detection were 0.04–0.2 μg/L (S/N = 3). The proposed method was successfully applied to the determination of six phthalate esters in water samples and satisfied spiked recoveries were achieved. These results indicated that the proposed method was appropriate for the determination of trace phthalate esters in environmental water samples.     

Chemical constituents of Meconopsis horridula and their simultaneous quantification by high‐performance liquid chromatography coupled with tandem mass spectrometry

Meconopsis horridula Hook.f. Thoms has been used as a traditional Tibetan medicine to clear away heat, relieve pain, and mobilize static blood. In this study, a reliable method based on high‐performance liquid chromatography with diode array detection and electrospray ionization quadrupole time‐of‐flight tandem mass spectrometry was established for the identification of components in this herb. A total of 40 compounds (including 17 flavonoids, 15 alkaloids, and eight phenylpropanoids) were identified or tentatively identified. Among them, 17 components were identified in the herb for the first time. Compound 39 appears to be a novel compound, which is confirmed as 3‐(kaempferol‐8‐yl)‐2,3‐epoxyflavanone by NMR spectroscopy and mass spectrometry. Moreover, seven major constituents were simultaneously quantified by the developed high‐performance liquid chromatography with tandem triple‐quadrupole mass spectrometry method. The quantitative method was validated and quality parameters were established. The study provides a comprehensive approach for understanding this herbal medicine.     

Natural estrogens in dairy products: Determination of free and conjugated forms by ultra high performance liquid chromatography with tandem mass spectrometry

Natural estrogens are synthesized by mammals in different amounts depending on the developmental stage and pregnancy/lactation period, and they may pass into milk, where they are mostly present as glucuronated and sulfated forms. In modern dairy practices, about 75% of milk is produced from pregnant cows; therefore, the amount of hormones that may pass into milk could be of concern. While estrogen determination in milk has been investigated in depth, the individual determination of estrogens and their conjugated forms in dairy products has not been fully addressed. The aim of this work was to develop and assess a sensitive method, using the peculiar retention properties of graphitized carbon black, to extract natural free estrogens and their major conjugated metabolites, without any enzymatic cleavage, from yogurt, cheese, and butter. The free and conjugated estrogens were eluted in two distinct fractions from the solid‐phase extraction cartridge and analyzed separately by ultra high performance liquid chromatography coupled to tandem mass spectrometry. Recoveries were higher than 80% for all the three sample typologies. The highest matrix effects were observed for butter, which was richest in lipid content, but was below 30%. A survey on some commercial dairy products suggests that production processes decreased estrogen content.     

Simultaneous determination of eight alkaloids and oleandrin in herbal cosmetics by dispersive solid‐phase extraction coupled with ultra high performance liquid chromatography and tandem mass spectrometry

We utilized ultra‐high performance liquid chromatography with tandem mass spectrometry and dispersive solid‐phase extraction to develop a new method for the detection of nine analytes (scopolamine, cephaeline, strychnine, hyoscyamine, brucine, hydrastine, ajmalicine, colchicine, and oleandrin) in herbal cosmetics. Acetonitrile/water and 2‐propylaminoethylamine were used to disperse and purify during the dispersive solid‐phase extraction step. The analytes were separated by a Waters UPLC HSS T3 column and detected through electrospray ionization source in the positive mode with multi‐reaction monitoring conditions. Under the optimal conditions, the calibration curves were linear in the range of 0.2–100.0 μg/L with the correlation coefficients higher than 0.995. The method limit of quantitation (S/N = 10) were 5.0 μg/kg for oleandrin and 1.0 μg/kg for the other eight alkaloids. The mean recoveries at three spiked concentration levels of 1.0–10.0 μg/kg were in the range of 86.9–116.5% with the intra‐day relative standard deviations (n  = 6) ranging from 2.4 to 8.8%, and inter‐day relative standard deviations ranging from 2.7 to 5.7%. This method is accurate, simple and rapid, and has been applied to the quality supervision of herbal cosmetics in Guangzhou.