Extraction-high Performance Liquid Chromatography-tandem Mass Research Articles

Occurrence and Risk of Organophosphate Flame Retardants in Multiple Urban Water of Beijing, China

Investigating the organophosphate flame retardants (OPFRs) concentration and attenuation in multiple water of Beijing would provide valuable insight into OPFR management and reduction; thus, 6 OPFRs were determined by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry to explore the pollution characteristics, and ecological risk of OPFRs. The results showed that 5 OPFRs were detected with a concentration ranging from ND to 394.77 ng/L except for tris(2,3-dibromopropyl) phosphate (TDBP). The chloroalkyl phosphate was the main compound and tris(chloropropyl) phosphate (TCPP) was the most abundant OPFRs with the highest concentration. The concentration of aryl-OPFRs in surface water and groundwater was much lower than that of chlorinated ones, and the concentration of chlorinated OPFRs in surface water was higher than that in groundwater. The treatment effect of chlorinated OPFRs including TCPP, TCEP, and TDCPP in STPs was negative. Ecological risk assessment showed that low risk of OPFRs for the organisms (algae, crustacean, and fish).

Determination of trace perfluorinated compounds in environmental water samples by dispersive solid- phase extraction-high performance liquid chromatography-tandem mass spectrometry using carbon nanotube composite materials

In this work, carbon nanotubes (CNTs) on silica rod (SiO2) composite materials were prepared to extract six perfluorinated compounds (PFCs) in real environmental water samples by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The as-synthesized sorbents, hereafter referred to as CNT@SiO2, were employed for dispersive solid-phase extraction (d-SPE). Perfluoroheptanoic acid (PFHpA), perfluorohexane sulfonate (PFHxS), perfluorooctanoic acid (PFOA), perfluorononanoic acid (PFNA), perfluorooctane sulfonate (PFOS), and perfluorodecanoic acid (PFDA) were selected as target analytes. The main extraction parameters were systematically optimized using the single-factor optimization method. The optimum adsorption parameters were as follows: adsorption time of 30 min, sorbent amount of 10 mg, pH 6 and NaCl concentration of 1.7 mol/L for sample solution, and 4 mL acetone as desorption solvent, desorption for 4 min. LC-triple quadrupole MS was conducted to quantify the selected PFCs in water samples. The mobile phase was 5 mmol/L ammonium acetate and methanol, the flow rate was set to 0.4 mL/min, the column temperature was set to 40 ℃, and the injection volume was 5.0 μL. The chromatographic separation system was equipped with a Kinetex C18 column (100 mm×2.1 mm, 1.7 μm). The mass spectrometer was operated with negative electrospray ionization in multi-reaction monitoring mode. CNT@SiO2 was prepared in five batches and used as the d-SPE sorbent, and the relative standard deviations (RSDs) of the PFC recoveries among these five batches ranged from 4.9% to 9.3%. The reusability of the CNT@SiO2 sorbent was assessed. After eight d-SPE cycles using the same sorbent, the RSDs of the PFC recoveries were 3.7%-8.2%. These results indicated that the sorbent had good stability and reusability for d-SPE. Excellent results were achieved under optimal extraction conditions. The method validation results indicated that the linear ranges were 0.4-1000 ng/L for PFNA, PFOS, and PFDA, 0.9-1000 ng/L for PFHpA, 0.7-1000 ng/L for PFHxS, and 0.6-1000 ng/L for PFOA. The correlation coefficients were 0.973-0.997. The limit of detection (LOD) and limit of quantification of the method were 0.10-0.26 ng/L and 0.33-0.87 ng/L, respectively. At 20 ng/L, the RSDs of the intra- and inter-day precisions were 2.73%-7.75% and 3.38%-8.21%, respectively. At 100 ng/L, the RSDs of the intra- and inter-day precisions were 2.95%-8.46% and 4.16%-9.14%, respectively. Finally, at 500 ng/L, the RSDs of the intra- and inter-day precisions were 2.51%-7.48% and 3.59%-9.63%, respectively. The developed method was applied to analyze six PFCs in tap water, barreled drinking water, and river water samples. PFOA and PFOS were determined in tap water at mass concentrations of 5.6 and 8.7 ng/L, respectively. No PFCs were found in barreled drinking water and river water. Satisfactory recoveries of 72.1%-109.6% at low, middle, and high spiking levels were also obtained. In conclusion, the d-SPE-LC-MS/MS method based on CNT@SiO2 composite sorbents is accurate and sensitive. The results of this study demonstrate that CNT@SiO2 is a good choice for the rapid and effective determination of PFCs from water samples. Further exploration of the use of CNT@SiO2 sorbents for the extraction and determination of trace organic pollutions in environmental samples is in progress.

Simultaneous determination of 22 antibiotics in environmental water samples by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry

The widespread and frequent use of antibiotics to treat diseases or encourage animal growth has resulted in their persistence and accumulation in water, soil, and sediments. As a typical emerging pollutant in the environment, antibiotics have become an important research focus in recent years. Antibiotics are commonly found at trace levels in water environments. Unfortunately, the determination of various types of antibiotics, all of which exhibit different physicochemical properties, remains a challenging endeavor. Thus, developing pretreatment and analytical techniques to achieve the rapid, sensitive, and accurate analysis of these emerging contaminants in various water samples is an essential undertaking.In this paper, a solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for the simultaneous determination of 22 antibiotics including 4 penicillins, 12 quinolones and 6 macrolides in environmental water samples was developed. Based on the characteristics of the screened antibiotics and sample matrix, the pretreatment method was optimized, focusing on the SPE column, pH of the water sample, and amount of ethylene diamine tetra-acetic acid disodium (Na2EDTA) added to the water sample. Prior to extraction, a 200 mL water sample was added with 0.5 g of Na2EDTA and pH-adjusted to 3 using sulfuric acid or sodium hydroxide solution. Water sample enrichment and purification were achieved using an HLB column. HPLC separation was carried out on a C18 column (100 mm×2.1 mm, 3.5 μm) via gradient elution with a mobile phase composed of acetonitrile and 0.15% (v/v) formic acid aqueous solution. Qualitative and quantitative analyses were performed on a triple quadrupole mass spectrometer in multiple reaction monitoring mode using an electrospray ionization source. The results showed correlation coefficients greater than 0.995, indicating good linear relationships. The method detection limits (MDLs) and limits of quantification (LOQs) were in the ranges of 2.3-10.7 ng/L and 9.2-42.8 ng/L, respectively. The recoveries of target compounds in surface water at three spiked levels ranged from 61.2% to 157%, with relative standard deviations (RSDs) of 1.0%-21.9%. The recoveries of target compounds in wastewater at three spiked levels were 50.1%-129%, with RSDs of 1.2%-16.9%. The method was successfully applied to the simultaneous determination of antibiotics in reservoir water, surface water, sewage treatment plant outfall, and livestock wastewater. Most of the antibiotics were detected in watershed and livestock wastewater. Lincomycin was detected in 10 surface water samples, with a detection frequency of 90%, and ofloxacin showed the highest contents (127 ng/L) in livestock wastewater. Therefore, the present method exhibits excellent performance in terms of MDLs and recoveries compared with previously reported methods. The developed method presents the advantages of small water sample volumes, wide applicability, and fast analysis times; thus, it can be considered a rapid, efficient, and sensitive analytical method with excellent potential for monitoring emergency environmental pollution. The method could also provide a reliable reference for formulating antibiotic residue standards. The results provide strong support for and an improved understanding of the environmental occurrence, treatment, and control of emerging pollutants.

Effect of Bisphenol A-Mediated RBP-4 on Pregnancy Outcomes in Nonobese Pregnant Female with Subclinical Hypothyroidism.

Hypothyroidism is a systemic hypometabolic syndrome caused by the thyroxine resistance or a reduction in its extent. It is an endocrinopathy secondary to gestational diabetes and occurs usually without significant symptoms. This study explored the effect of bisphenol A (BPA)-mediated retinol-binding protein 4 (RBP-4) on pregnancy outcomes in a nonobese pregnant female with subclinical hypothyroidism. Three hundred nonobese pregnant females who had that established pregnancy files and had regular obstetric examinations from January 2021 to March 2022 were enrolled and classified with 100 cases in each group as early pregnancy (6–12 weeks of gestation), second-trimester (13–24 weeks of gestation), and third-trimester groups (25–36 weeks of gestation). Thirty pregnant women with subclinical hypothyroidism were selected as subjects, and another thirty pregnant women with normal thyroid function were selected as the normal control group. Thyroid function (thyroid-stimulating hormone (TSH), free triiodothyronine (FT3), free T4 (FT4), and thyroid peroxidase antibody (TPO-Ab)) was measured by immunoelectrochemiluminescence. The level of BPA in urine was determined by solid-phase extraction high-performance liquid chromatography-tandem mass spectrometry. Serum RBP4 levels were determined by enzyme-linked immunosorbent assay. The level of TSH in the third-trimester group was higher than that in the first- and second-trimester groups, while the levels of FT3, FT4, and TPO-Ab were lower than those in the other two groups (P < 0.05). TSH in the second-trimester group was higher than that in the first-trimester group, while FT3, FT4, and TPO-Ab levels were lower than those in the first-trimester group (P < 0.05). The levels of BPA and RBP4 in gestational diabetes mellitus and hypertension were higher than those in the nongestational period, and the levels of BPA and RBP4 in gestational intrahepatic cholestasis and anemia were higher than those in the nongestational period, and the levels of BPA and RBP4 in preterm delivery were higher than those in nongestational period (P < 0.05). Also, the level of urinary BPA in the hypothyroidism group was higher than that in the normal control group (P < 0.05) and the level of serum RBP4 in the hypothyroidism group was higher than that in the normal control group (P < 0.05). According to multivariate logistic regression analysis, age ≥30 years and the ascending BPA and RBP4 were risk factors for subclinical hypothyroidism during pregnancy in the nonobese female. BPA and RBP-4 are closely related to the pregnancy outcome of nonobese subclinical hypothyroidism in the pregnant female. The degree of BPA and RBP-4 in adverse pregnancy outcomes is increased, which is the risk factor for nonobese subclinical hypothyroidism.

Distribution and Ecological Risk Assessment of Pharmaceuticals and Personal Care Products in Sediments of North Canal, China

The pollution of water bodies by pharmaceuticals and personal care products (PPCPs) has attracted widespread concern due to their widespread use and pseudo-persistence, but their effects on sediments are less known. In this study, solid-phase extraction-high performance liquid chromatography–tandem mass spectrometry (SPE-LC/MSMS) was used to investigate the occurrence and ecological risks of five typical pharmaceuticals and personal care products (PPCPs) in thirteen key reservoirs, sluices, dams, and estuaries in the Haihe River Basin. At the same time, the PPCP exchanges of surface water, groundwater, and sediments in three typical sections were studied. Finally, the PPCP’s environmental risk is evaluated through the environmental risk quotient. The results showed that the five PPCPs were tri-methoprazine (TMP), sinolamine (SMX), ibuprofen (IBU), triclosan (TCS), and caffeine (CAF). The average concentration of these PPCPs ranged from 0 to 481.19 μg/kg, with relatively high concentrations of TCS and CAF. The relationship between PPCPs in the surface sediments was analyzed to reveal correlations between SMX and TMP, CAF and IBU, CAF and TCS. The risk quotients (RQ) method was used to evaluate the ecological risk of the five detected PPCPs. The major contributors of potential environmental risks were IBU, TCS and CAF, among which all the potential environmental risks at the TCS samples were high risk. This study supplemented the research on the ecological risk of PPCPs in sediments of important reaches of the North Canal to reveal the importance of PPCP control in the North Canal and provided a scientific basis for pollution control and risk prevention of PPCPs.

Exposure assessment of polycyclic aromatic hydrocarbons in refined coal tar sealant applications.

Refined coal tar sealant (RCTS) emulsions are used to seal the surface of asphalt pavement. Nine of the 22 polycyclic aromatic hydrocarbons (PAHs) evaluated in this study are classified as known, probable, or possible human carcinogens. Exposure assessment research for RCTS workers has not been published previously. The overall objective of this study was to develop a representative occupational exposure assessment of PAH exposure for RCTS workers based on worksite surveys. The specific aims were to: 1) quantify full-shift airborne occupational exposures to PAHs among RCTS workers; 2) quantify workers' dermal exposures to PAHs; 3) quantify biomarkers of PAH exposure in workers' urine; 4) identify specific job titles associated with RCTS exposure; and 5) apply these results to a biological exposure index to assess risk of potential genotoxicity from occupational exposures. A total of twenty-one RCTS workers were recruited from three companies. Personal and area air samples were collected using a modification of NIOSH Method 5515. Dermal exposure was assessed by hand and neck wipes before and after shifts. Twenty-two PAHs were quantified via gas chromatography-mass spectrometry selected ion monitoring. Internal dose was estimated by quantifying select PAH metabolites in pre- and post-shift urine samples using on-line solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. PAH levels in the worker breathing zones were highest for naphthalene, acenaphthene, and phenanthrene, with geometric means of 52.1, 11.4, and 9.8μg/m3, respectively. Hand wipe levels of phenanthrene, fluoranthene and pyrene were the highest among the 22 PAHs with geometric means of 7.9, 7.7, and 5.5μg/cm2, respectively. Urinary PAH biomarkers for naphthalene, fluorene, phenanthrene, and pyrene were detected in all workers and were higher for post-shift samples than those collected pre-shift. Urinary concentrations of the metabolite 1-hydroxypyrene were greater than the American Conference of Governmental Industrial Hygienists (ACGIH) Biological Exposure Index (BEI) for this metabolite in 89 percent of post-shift samples collected on the final day of the work week or field survey. Statistically significances were found between concentrations of fluorene, naphthalene, and phenanthrene in the breathing zone of workers and their corresponding urinary PAH biomarkers. Workers were placed in two work place exposure groups: applicators and non-applicators. Applicators had higher total PAH concentrations in personal breathing zone (PBZ) air samples than non-applicators and were more likely to have post-shift hand wipe concentrations significantly higher than pre-shift concentrations. Concentrations of post-shift urinary biomarkers were higher, albeit not significantly, for applicators than non-applicators. The exposure results from RCTS worker samples cannot be explained by proximal factors such as nearby restaurants or construction. Air and skin concentration levels were substantially higher for RCTS workers than previously published levels among asphalt workers for all PAHs. PAH profiles on skin wipes were more consistent with RCTS sealant product than air samples. Last day post-shift urinary concentrations of 1-hydroxypyrene greatly exceeded the ACGIH BEI benchmark of 2.5μg/L in 25 of 26 samples, which suggests occupational exposure and risk of genotoxicity. When pyrene and benzo[a]pyrene were both detected, concentration ratios from personal exposure samples were used to calculate the adjusted BEI. Concentrations of 1-hydroxypyrene exceeded the adjusted BEIs for air, hand wipes, and neck wipes in most cases. These results indicate the need to increase safety controls and exposure mitigation for RCTS workers.

Determination and level investigation of 45 hormones in edible bird's nest by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry

建立了固相萃取-高效液相色谱-串联质谱(SPE-HPLC-MS/MS)同时测定食用燕窝中皮质激素、雌激素、雄激素及孕激素等5类45种激素的多残留分析方法。采用乙腈-乙酸乙酯(1∶1, v/v)超声辅助提取、亲水亲脂平衡固相萃取柱净化,甲醇洗脱。分别在正、负电喷雾电离源、多反应监测模式下检测45种激素。正离子模式下的流动相为乙腈-0.1%甲酸水溶液,负离子模式下的流动相为乙腈-水,色谱柱为Phenomenex Kinetex C18柱(100 mm×2.1 mm, 2.6 μm)。在优化条件下,45种激素在0.20~20.0 μg/L范围内线性关系良好,相关系数(R2)≥0.9990,方法的检出限(LOD)为0.04~0.70 μg/kg,定量限(LOQ)为0.16~2.00 μg/kg。按三水平(2.0、4.0、20.0 μg/kg)进行加标回收试验,氟米龙、布地奈德、醛固酮、醋酸氟轻松、炔雌醇的回收率为40.2%~63.6%,可对这5种激素进行定性分析,其余40种激素的平均加标回收率为72.2%~112.3%,相对标准偏差(RSD)为2.5%~11.6%,该方法可对40种激素进行准确定性定量,精密度好,灵敏度高,简便、快速。从2017~2021年,通过研究建立的方法对来自马来西亚、印度尼西亚、泰国和越南等国家的1021个燕窝样品进行监测,仅勃地酮、雄烯二酮、孕酮有检出(大于检出限),其他激素均小于检出限。孕酮检出率为100%,勃地酮、雄烯二酮检出率分别为79%和89%, 3种激素含量范围分别为0.097~3.58、0~0.096和0~1.77 μg/kg。与同为动物源性食品的鸡蛋、纯牛奶、乳制品相比,所有测定的鸡蛋样品中均检出雄烯二酮,含量比其他3类产品略高;勃地酮在4类产品中的含量差别不大,均为微量;孕酮含量在鸡蛋中最高,其次是纯牛奶,燕窝中含量最低。研究结果表明,食用燕窝带入的激素种类少,含量低,对健康影响小。

Simultaneous determination of 76 pesticide residues in the traditional Chinese medicine by magnetic hydrophilic-lipophilic-balanced materials assisted matrix solid phase dispersion extraction-high performance liquid chromatography-tandem mass spectrometry

建立灵敏、可靠的中药材中农药多残留的检测方法对保证中药材的质量和安全十分重要。制备了磁性亲水亲脂平衡萃取材料Fe3O4@PLS,将其应用于农药多残留的磁性基质固相分散萃取中,并结合高效液相色谱-串联质谱法(HPLC-MS/MS)检测了金银花、菊花和三七块根(干)3种中药材中76种农药残留量。研究通过扫描电子显微镜(SEM)、傅里叶变换红外光谱(FT-IR)和X-射线衍射仪(XRD)对磁性萃取材料Fe3O4@PLS进行表面形貌和结构的表征。同时考察了影响磁性基质固相分散萃取效率的主要因素,结果表明,磁性萃取材料Fe3O4@PLS的用量为10 mg、研磨分散吸附时间为5 min、淋洗液为10 mL 20%(v/v)甲醇水溶液、涡旋振荡清洗1 min、以0.5 mL 0.1%(v/v)甲酸乙腈为洗脱剂、涡旋振荡洗脱1 min, 76种农药的萃取效果最佳。在实际应用中,76种农药在金银花、菊花、三七块根(干)3种中药材中的萃取回收率别为69.1%~112.2%、67.1%~102.8%和70.1%~105.1%,相对标准偏差分别为2.0%~12.4%、2.1%~13.2%和2.0%~13.5%。该方法利用Fe3O4@PLS良好的磁响应性和亲水亲脂通用吸附特性,可以同时萃取极性农药(如多菌灵等)和非极性农药(如敌瘟磷等),建立了测定中药材中76种农药残留的磁性基质固相分散萃取-高效液相色谱-串联质谱联用的分析方法,具有低消耗、操作简便、灵敏度高等优点,适用于非液态中药材基质中多种类农药残留的检测。

Analytical characterization of nucleotides and their concentration variation in drinking water treatment process

Nucleotides, as the basic building blocks of nucleic acids, widely exist in aqueous environment. In this study, we developed a solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-UPLC-MS/MS) method for the analysis of 5′-adenosine monophosphate (AMP), 5′-uridine monophosphate (UMP), 5′-cytidine monophosphate (CMP) and 5′-guanosine monophosphate (GMP). The method achieved limits of detection (LODs) of 0.1–1.0 ng/L, and recoveries of 85–95% for the four tested nucleotides. The occurrence and concentrations of the four nucleotides in water from eight representative drinking water treatment and distribution systems in China were determined using this method. All four nucleotides were detectable in water treatment plant (WTP) influent and effluent, at concentrations of up to 30 ng/L and with occurrence frequency of around 90%. The concentrations of identified nucleotides increased 3–10 times after 10 km of water age in the water distribution system. Biological filters and coagulation increased the concentrations of nucleotides, conversely, active carbon, ozonation, and ultrafiltration membrane removed nucleotides in water. The effects of active carbon and coagulation were further confirmed using laboratory-controlled experiment. In addition, monochlorinated nucleotides were identified as the chlorination products of nucleotides.

Simultaneous Quantification of 17 Cannabinoids by LC-MS-MS in Human Plasma.

In recent years, the surge in use of tetrahydrocannabinol (THC) and cannabidiol (CBD) has increased the need for sensitive and specific analytical assays to measure the said compounds in patients, to establish dose-effect relationships and to gain knowledge of their pharmacokinetics and metabolism. We developed and validated an online extraction high-performance liquid chromatography-tandem mass spectrometry (HPLC-MS-MS) method for simultaneous quantification of 17 cannabinoids and metabolites including THC and its metabolites, CBD and its metabolites and other minor cannabinoids in human plasma. CBD-glucuronide (CBD-gluc) standard was produced in-house by isolation of CBD-gluc from urine of patients using pure CBD oil. For calibration standards and quality control samples, human plasma was spiked with cannabinoids at varying concentrations within the working range of the respective compound and 200 µL of the plasma was extracted using a simple one-step protein precipitation procedure. The extracts were analyzed using online trapping LC/LC-atmospheric pressure chemical ionization-MS-MS running in the positive multiple reaction monitoring mode. The lower limit of quantification ranged from 0.78 to 7.8 ng/mL, and the upper limits of quantification were between 100 and 2,000 ng/mL. Inter-day analytical accuracy and imprecision ranged from 90.4% to 111% and from 3.1% to 17.4%, respectively. The analysis of plasma samples collected during clinical studies showed that (3R-trans)-cannabidiol-7-oic acid (7-CBD-COOH) was the major human metabolite with 5960% (59.6-fold) of CBD followed by 7-hydroxy-CBD (177%), CBD-gluc (157%) and 6α-hydroxy-CBD (39.8%); 6β-hydroxy-CBD was not detected in any of the samples. In the present study, we developed and validated a robust LC-MS-MS assay for the simultaneous quantification of cannabinoids and their metabolites, which has been used to measure >5,000 samples in clinical studies. Moreover, we were able to quantify CBD-gluc and showed that 7-CBD-COOH, 7-hydroxy-CBD and CBD-gluc are the major CBD metabolites in human plasma.

Direct Flavonoid-Focused Chemical Comparison among Three Epimedium Plants by Online Liquid Extraction-High Performance Liquid Chromatography-Tandem Mass Spectrometry.

It is usually a tedious task to profile the chemical composition of a given herbal medicine (HM) using high performance liquid chromatography–tandem mass spectrometry (LC–MS/MS) due to the time-consuming sample preparation and laborious post-acquisition data processing procedures. Even worse, some labile compounds may face degradation risks when exposed to organic solvents for a relatively long period. As one of the most popular HMs, the promising therapeutic benefits of Epimedii Herba (Chinese name: Yinyanghuo) are well defined; however, the chemical profile, and in particular those flavonoids that have been claimed to be responsible for the efficacy, remains largely unknown. Attempts are devoted here to achieve direct LC–MS measurement and efficient post-acquisition data processing, and chemome comparison among three original sources of Epimedii Herba, such as Epimedium sagittatum (Esa), E. pubescens (Epu), and E. koreanum (Eko) was employed to illustrate the strategy utility. A home-made online liquid extraction (OLE) module was introduced at the front of the analytical column to comprehensively transfer the compounds from raw materials onto the LC–MS instrument. A mass defect filtering approach was programmed to efficiently mine the massive LC–MS dataset after which a miniature database was built involving all chemical information of flavonoids from the genus Epimedium to draw a pentagonal frame to rapidly capture potential quasi-molecular ions (mainly [M–H]−). A total of 99 flavonoids (66 in Esa, 84 in Eko, and 66 in Epu) were captured, and structurally annotated by summarizing the mass fragmentation pathways from the mass spectrometric data of authentic compounds and an in-house data library as well. Noteworthily, neutral loss of 144 Da was firstly assigned to the neutral cleavage of rhamnosyl residues. Significant species-differences didn’t occur among their chemical patterns. The current study proposed a robust strategy enabling rapid chemical profiling of, but not limited to, HMs.

Rapid determination of trace ciprofloxacin residue in milk samples using molecularly imprinted membrane extraction-high performance liquid chromatography-tandem mass spectrometry

An enrofloxacin (ENR) molecularly imprinted membrane (MIM) was prepared with a polyvinylidenedifluoride (PVDF) membrane as the carrier, ENR as the dummy template molecule, α-methacrylic acid (MAA) as the functional monomer, ethylene glycol dimethacrylate (EGDMA) as the cross-linker, and a chloroform-methanol mixture solvent as the porogen. The MIM showed excellent selectivity, high adsorption capacity, and high adsorption rate for ciprofloxacin. Additionally, a method combining molecularly imprinted membrane extraction (MIME) and high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS) was developed and validated for the selective analysis of trace ciprofloxacin residue in milk samples. The sample pretreatment involved only a single step of protein precipitation. Ciprofloxacin showed good linearity in mass concentration range of 0.1-200 μg/L with a high correlation coefficient (r2>0.9996). The limit of detection (LOD, S/N=3) and limit of quantification (LOQ, S/N=10) were 0.02 μg/L and 0.1 μg/L, respectively. The relative standard deviations (RSDs) of interday and intraday precisions ranged from 3.3% to 7.9%. The ciprofloxacin recovery was in the range of 92.6%-119.1%. The results showed that the proposed method is simple and fast, with high accuracy and sensitivity, thus being suitable for the rapid detection of trace ciprofloxacin residue in milk samples.

Simultaneous determination of five baicaleins in healthy product tablets by dispersive solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry

A method based on dispersive solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (DSPE-HPLC-MS/MS) was developed for the simultaneous determination of five analytes scutellarein, 4'-hydroxywogonin, norwogonin, baicalein, and wogonin in healthy product tablets. The samples were extracted with 10 mL acetone and purified on 75 mg C18. The types and dosages of the extracted solvents and adsorbents were optimized. The results showed that these five analytes exhibited good linear relationships in their respective linear ranges. The correlation coefficients (r) were more than 0.99. The detection limits and quantitative limits were 0.5-40 μg/kg and 2.0-120 μg/kg, respectively. Recovery tests were carried out using three kinds of health product tablet matrices. The concentrations were one, five, and ten times the quantitative limit. The average recovery of these five targets was 83.1% to 106.5%, with relative standard deviations (RSDs) ranging from 0.97% to 4.52%. This method is easy to operate, and it shows high sensitivity and good reproducibility. Thus, it is suitable for the simultaneous determination of the target compounds in health tablets.

Occurrence and Risk Assessment of Organophosphate Esters in Source Water of the Nanjing Section of the Yangtze River

We explored the pollution characteristics, spatial and temporal distribution, ecological risk, and human health risk of organophosphate esters (OPEs) in the source water of the Nanjing section of the Yangtze River. Thirteen OPEs were determined by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. The results showed that twelve OPEs were detected to different extents with total concentrations ranging from 85.21 to 1557.96 ng·L-1[excluding tris (2,3-dibromopropyl) phosphate]. Chloroalkyl phosphate was the main compound and tris(2-chloroethyl) phosphate (TCEP) was the most abundant of the thirteen OPEs, which reached up to 447.08 ng·L-1. Seasonal variation of OPEs showed that the concentrations of OPEs in summer ranged from 220-1557.96 ng·L-1, with the average concentration of 493.78 ng·L-1 being 1.7-2.6 times higher than of that in spring and autumn. An ecological risk assessment showed that tricresyl phosphate and 2-ethylhexyl diphenyl phosphate were associated with moderate or high risks to organisms (algae, crustaceans, and fish). At a high exposure concentration, the total non-carcinogenic risk of OPEs in source water ranged from 4.41×10-3-2.91×10-2, with the highest risk being associated with children aged 0-3 months. The total cancer risk value was 5.88×10-7-3.89×10-6, among which TCEP and Tris(1,3-dichloro-2-propyl) phosphate was associated with a potential risk for children. We conclude that the long-term exposure risk for children of OPEs in the source water of the Nanjing section of the Yangtze River deserve more attention.

Simultaneous Determination of Selected Trace Contaminants in Drinking Water Using Solid-Phase Extraction-High Performance Liquid Chromatography-Tandem Mass Spectrometry

Accurate determination of emerging contaminants in drinking water constitutes a major environmental challenge for which highly sensitive analytical methods are needed. This work details the development of a novel highly sensitive solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS) method for simultaneous determination of a diverse panel of widely used trace contaminants, including two pharmaceuticals (fluoxetine and gemfibrozil), three pesticides (3-hydroxycarbofuran, azinphos-methyl, and chlorpyrifos), and two hormones (testosterone and progesterone) in water. The method is highly reproducible and sensitive with detection limits at subnanogram per liter level (0.05–0.5 ng/L). It was used to monitor the occurrence of these contaminants in source and drinking water across 18 drinking water treatment facilities in Missouri, USA in 1 year including cold winter and hot summer seasons. The experiment results indicated that all of the monitored contaminant concentrations are very low, lower than or close to the method detection limits, in the selected water treatment facilities. Pesticide concentrations were slightly elevated in some source waters during hot season, whereas slightly higher pharmaceuticals were observed during cold season. The concentrations of two hormones were lower than the limits of detection in all the water samples. These contaminants were present, if any, at below detection limits in all treated drinking water samples analyzed, suggesting that treatment processes effectively removed the contaminants studied herein.

Simultaneous determination of five types of 40 antibiotics in surface water using high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of five categories of 40 antibiotics in surface water by using solid-phase extraction-high performance liquid chromatography-tandem mass spectrometry (SPE-HPLC-MS/MS). The water samples were enriched and cleaned-up by filtration and with SPE cartridges. All antibiotics were separated by gradient elution with the mobile phase of 0.2% (v/v) formic acid aqueous solution and acetonitrile, and then analyzed with an electrospray ionization source in the positive ion and multiple reaction monitoring (MRM) modes. The results showed that the 40 antibiotics achieved great linearity in the range of 1-200 μg/L, and the average recoveries ranged from 41.3% to 112.6%. Using the developed method, thirteen antibiotics were identified in surface water from Nanjing section of the Yangtze River. The total antibiotic contents in the real samples ranged from 13.4 ng/L to 780.5 ng/L. The established method is efficient, sensitive and reliable, and is suitable for the determination of different antibiotics in real water samples.

Quantification of DEET and neonicotinoid pesticide biomarkers in human urine by online solid-phase extraction high-performance liquid chromatography-tandem mass spectrometry.

Neonicotinoid insecticides are widely used replacements for organophosphate and carbamate insecticides, but the extent of human exposure is largely unknown. On the other hand, based on urinary concentrations of DEET metabolites, human exposure to N,N-diethyl-m-toluamide (DEET) appears to be widespread. We developed a fast online solid-phase extraction high-performance liquid chromatography-isotope dilution tandem mass spectrometry (HPLC-MS/MS) method to measure in 200μL of human urine the concentrations of six neonicotinoid biomarkers (acetamiprid, N-desmethyl-acetamiprid, clothianidin, imidacloprid, 5-hydroxy-imidacloprid, thiacloprid), and two DEET biomarkers (3-diethyl-carbamoyl benzoic acid, 3-ethyl-carbamoyl benzoic acid). Limits of detection ranged from 0.01 to 0.1μg/L, depending on the biomarker. Accuracy ranged from 91 to 116% and precision ranged from 3.7 to 10 %RSD. The presented method can be used to increase our understanding of exposure to neonicotinoid insecticides and DEET, and to evaluate the potential health effects from such exposures.

Determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-ultra high performance liquid chromatography-tandem mass spectrometry

A method was developed for the determination of 42 glucocorticoids in infant eczema products by auto-solid phase extraction-high performance liquid chromatography-tandem mass spectrometry (ASPE-UHPLC-MS/MS).The analytes were extracted by acetonitrile after dispersing in saturated sodium chloride solution.Macromolecules matrix were precipitated by adding potassium and zinc acetate, and then purified by HLB SPE column.The chromatographic separations were performed on a DIKMA EndeavorsilTM C18 column (100 mm×2.1 mm, 1.7 μm).Acetonitrile and 0.1%(v/v) formic acid aqueous solution were used as the mobile phases.Electrospray ionization (ESI) source was operated in the positive mode using multiple reaction monitoring (MRM) scanning mode.The results were quantified by external standard method.The correlation coefficients of linear calibration curves were greater than 0.998 in the corresponding mass concentration ranges.The average recoveries at three spiked levels ranged from 78.7% to 101.5%, and the relative standard deviations (RSDs) were 2.0%-8.8%(n=6).The LODs (S/N ≥ 3) and LOQs were 0.002-0.031 mg/kg and 0.0007-0.103 mg/kg, respectively.The method is simple, rapid, sensitive, and reliable, and can be used for the detection of glucocorticoids in infant eczema products.

Simultaneous determination of monepantel and its metabolite residues in cow and sheep milk by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry

A method for the rapid and simultaneous determination of monepantel and its metabolite residues in cow and sheep milk has been developed using high performance liquid chromatography-tandem mass spectrometry. The samples were extracted with acetonitrile to precipitate the proteins and passed through a neutral alumina solid phase extraction (SPE) cartridge. The extracts were separated on an Inertsil C8-3 column (150 mm×4.6 mm, 5 μm) with a gradient elution program consisting of methanol and ammonium acetate. A triple stage quadrupole mass spectrometer equipped with an electrospray ionization source in negative ion mode was used to detect monepantel and its metabolite residues. The quantification of the analytes was performed by the external standard method. Good linear relationships between the peak areas and mass concentrations of the analytes were obtained in the range of 0.1-5.0 μg/L with correlation coefficients greater than 0.99 (n=6). The limits of quantification were 2.0 μg/kg. The recoveries of the analytes in cow and sheep milk at three spiked levels (2.0, 50, and 100 μg/kg) were in the range of 90.1%-103.3% with relative standard deviations between 2.0% and 6.2% (n=6). This method is fast, accurate, and highly sensitive, exhibits strong anti-interference capability with good recovery and repeatability, and can thus be used to simultaneously determine monepantel and its metabolite residues in cow and sheep milk.

Perfluoroalkyl acids in surface waters and tapwater in the Qiantang River watershed—Influences from paper, textile, and leather industries

Perfluoroalkyl acids (PFAAs) are widely used as multi-purpose surfactants or water/oil repellents. In order to understand the contamination level and compositional profiles of PFAAs in aqueous environment in textile, leather, and paper making industrial areas, surface waters and tap waters were collected along the watershed of the Qiantang River where China's largest textile, leather, and paper making industrial bases are located. For comparison, surface water and tapwater samples were also collected in Hangzhou and its adjacent areas. 17 PFAAs were analyzed by solid phase extraction-high performance liquid chromatography-tandem mass spectrometry. The results show that the total concentrations of PFAAs (ΣPFAAs) in the Qiantang River waters ranged from 106.1 to 322.9 ng/L, averaging 164.2 ng/L. The contamination levels have been found to be extremely high, comparable to the levels of the most serious PFAA contamination in surface waters of China. The PFAA composition profiles were characterized by the dominant PFOA (average 58.1% of the total PFAAs), and PFHxA (average 18.8%). The ΣPFAAs in tap water ranged from 9.5 to 174.8 ng/L, showing PFAA compositional pattern similar to the surface waters. Good correlations between PFAA composition profiles in tap waters and the surface waters were observed.