Direct injection ultra-performance liquid chromatography-tandem mass spectrometry for the high-throughput determination of etomidate and etomidate acid in wastewater.

Etomidate (ET), a hypnotic agent used for the induction of anesthesia, is rapidly metabolized to etomidate acid (ETA) in the liver. Recently, ET has become one of the most serious alternative drugs of abuse in China. Therefore, an urgent need exists to develop a fast and convenient analysis method for monitoring ET. The current work presents a simple, fast, and sensitive direct injection method for the determination of ET and ETA in wastewater. After the optimization of the ultra-performance liquid chromatography-tandem mass spectrometry and sample filtration conditions, the method exhibited satisfactory limits of detection (1 ng/L) and good filtration loss. The validated method was successfully applied to determine the concentrations of ET and ETA in wastewater samples (n = 245) from several wastewater treatment plants in China. The concentrations of the targets in positive samples ranged from less than the lower limits of quantitation to 47.71 ng/L. The method can meet ET monitoring and high-throughput analysis requirements.

Direct injection ultra-performance liquid chromatography-tandem mass spectrometry for the high-throughput determination of 11 illicit drugs and metabolites in wastewater.

The measurement of illicit drugs in wastewater is increasingly being adopted as a method for objective monitoring of population-level illicit drug use. This work describes the first small-volume direct-injection ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) method for the simultaneous determination of 11 illicit drugs and metabolites in wastewater. The method required an injection volume of only 30 µL of wastewater sample, the limits of detection (LOD) ranged from 0.4 ng/L to 2 ng/L and the lower limits of quantitation (LLOQ) ranged from 1 ng/L to 5 ng/L. Application of the method to real wastewater samples collected from wastewater treatment plants revealed morphine in all samples, together with other illicit drugs (methamphetamine, codeine, ketamine, and nor-ketamine) in some samples. Small-volume direct injection showed great potential as an efficient method for the high-throughput determination of illicit drugs in wastewater.

Estimation of the Frequency and Time of Human Exposure to Arsenic by Single Hair Analysis.

Arsenic (As) and its compounds are widely used in many applications. Long-term exposure to As can cause acute and chronic poisoning. In severe cases, it can lead to adverse effects, such as gene mutation, cell cancer and fetal malformation. The objective of this study was to accurately estimate As exposure frequency and time. Quantitative analysis of As in single hairs obtained from APL (acute promyelocytic leukemia) patients treated with As2O3 was performed by LA-ICP-MS. An informative As concentration distribution profile of single hair was applied to estimate the As exposure frequency and time. As exposure frequency was estimated according to the number of As concentration peaks. As exposure time was estimated according to the hair growth length in combination with the hair growth rate. The validation results demonstrate that this method was more efficient than the traditional method; compared with the traditional method, which provides estimates in months, our model shortened the As exposure time estimate to the range of a few days, which considerably improved the inference accuracy. Therefore, these results can be used for forensic toxicology studies, environmental exposure monitoring, etc.

Excessive hydrogen sulfide causes lung and brain tissue damage by promoting PARP1/Bax and C9 and inhibiting LAMB1.

Excessive hydrogen sulfide (H2S) causes serious damage to human organs and tissues. In this study, we aimed to explore the role and underlying mechanism of excessive H2S in brain and lung tissues. A H2S concentration of 100-800 pm promotes apoptosis and inflammation of brain and lung cells in ICR mice. Mechanistically, a H2S concentration of 100-800 pm upregulates PARP1 and Bax expression in a dose-dependent manner in vivo and in vitro, and functional gain-and-loss experiments verified that an excessive amount of H2S plays a pro-apoptotic role in HT22 and MML1 cells via regulation of PARP1 and Bax in vitro. By combining animal and cell experiments, we clarified that excess H2S promotes the inflammatory response of mouse brain and lung cells by promoting the expression of C9. In addition, the downregulation of LAMB1 by an excessive H2S concentration was confirmed using mass spectrometry and western blotting in vivo and in vitro. Combined with in vitro experiments, we found that an excessive H2S concentration promotes the expression of STAT1 and EGFR in HT22 and MML1 cells by inhibiting the expression of LAMB1. In summary, 100-800 pm H2S causes the brain and lung tissue damage in ICR mice, the underlying mechanisms include H2S induced apoptosis and inflammation of mouse brain and lung cells by upregulation of PARP1/Bax and C9, respectively, and H2S might induce fibrosis of mouse brain and lung cells by downregulation of LAMB1.

A rGO-DNAzyme assisted fluorescence method for sensitive RNase A activity assay and natural compound screening.

As a key regulator of human physiology and metabolic processes, ribonuclease (RNase) A can be used as an important biomarker for predicting human disease occurrence. Hence, establishing sensitive methods for tracking RNase A activity in vitro and in living cells is of great importance. Herein, we present a convenient fluorescence method assisted by reduced graphene oxide (rGO) and DNAzyme mediated fluorescence signal release for RNase A assay. The fluorescence change of the new method showed a positive linear relation with RNase A concentration in the range from 0.5 pg µL-1 to 1 ng µL-1 with a detection limit of 0.089 pg µL-1. By using this method to screen the effector of RNase A from natural compounds, the natural compound of B6 was found to stimulate RNase A activity in vitro and in vivo, the result of which was supported by the real-time imaging of RNase A in living cells. In summary, this fluorescence method with high sensitivity and specificity provides an alternative for RNase A activity assay and effector screening.

Determination of twenty herbicides in blood by ultrapressure liquid chromatography-tandem mass spectrometry.

A sensitive and rapid method for the simultaneous determination of twenty herbicides (aclonifen, lactofen, terbutryn, butylate, carbetamide, fluazifop-P-butyl, propanil, prometryn, isoproturon, terbumeton, pretilachlor, pendimethalin, cycloxydim, tri-allate, metolachlor, diuron, alloxydim, prosulfuron, triflusulfuron-methyl, and acetochlor) in human blood is reported herein. Liquid-liquid extraction coupled with ultra-pressure liquid chromatography-tandem mass spectrometry was employed for the simultaneous analysis of all compounds in 15 min. Validation parameters were studied through the estimation of the limits of detection and quantification, calibration curves, sensitivity, spiked recovery and precision. The limits of detection ranged from 0.1 to 1.0 ng/mL. The limits of quantification ranged from 0.5 to 2.0 ng/mL. Good linearity was obtained for all compounds with R2> 0.99 in all cases. Furthermore, interday precision (< 15%) and intraday precision (< 15%) were shown to be satisfactory. Recoveries in spiked blood samples were evaluated, and acceptable values (88.0%~108.8%) were found. Finally, this method was successfully applied to the determination of fluazifop-P-butyl, isoproturon and acetochlor in blood samples from real forensic cases. These results suggest that this method is reliable for rapid forensic and clinical diagnosis.

A graphene-based fluorescent nanoprobe for simultaneous imaging of dual miRNAs in living cells.

MicroRNAs (miRNAs) are regarded as important biomarkers for disease diagnostics and therapeutics due to their significant regulatory roles in physiologic and pathologic processes. Herein, a versatile nanoprobe based on reduced graphene oxide (rGO) and nucleic acid (DNA) probe was prepared for simultaneously visualize miR-451a and miR-214-3p in living cells. In vitro experiments demonstrated that the nanoprobe exhibits excellent selectivity and outstanding sensitivity as low as 1 nM towards miR-451a and miR-214-3p. Moreover, the detection signals of miRNAs have good linearity in their respective concentration ranges (miR-451a: 1-100 nM, Y1 = 9.3062X1+114.85 (R2 = 0.9965). miR-214-3p: 1-200 nM, Y2 = 1.4424X2+91.312 (R2 = 0.9961)). Finally, simultaneous dual-color imaging of miR-451a and miR-214-3p in human breast cancer cells (MDA-MB-231) was realized by exploiting the P1&P2@rGO nanoprobe. In summary, this simple and effective strategy provides a general sensing platform for highly sensitive detection and simultaneous imaging of dual miRNAs in living cells.

Simultaneous determination of 11 illicit drugs and metabolites in wastewater by UPLC-MS/MS.

Assessing collective drug consumption based on the concentrations of illicit drugs and their metabolites in wastewater is a new technology. Currently, this technology is receiving attention in China, and methods for multiple illicit drug detection in wastewater are urgently needed. In our study, a method with a short runtime (7 min), a small solid-phase extraction (SPE) loading volume (50 mL) and high sensitivity (lower limits of quantitation (LLOQs) ranged from 0.2 to 5 ng/L) was developed for the simultaneous determination of amphetamines, ketamine, opiates, cocaine and their metabolites in wastewater. Samples were enriched by SPE on a mixed-mode sorbent (Oasis MCX) and analyzed by ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The limits of detection (LODs) ranged from 0.1 to 2 ng/L, and the LLOQs varied between 0.2 and 5 ng/L. Moreover, the method developed was applied to real wastewater samples collected from 15 different wastewater treatment plants (WWTPs). In the results, the most abundant compounds were morphine (1.8-46.6 ng/L) and codeine (3.7-24.9 ng/L), which were detected in 13 WWTPs. After successful optimization of the UPLC-MS/MS conditions and sample loading pH, the method developed is able to meet the needs of common illicit drug monitoring and high-throughput analysis requirements.

RNase A activity analysis and imaging using label-free DNA-templated silver nanoclusters.

A label-free, ultra-sensitive and turn-on method for detecting RNase A has been developed using enhanced DNA-templated silver nanoclusters (DNA-AgNCs) as the fluorescence probe. In this system, an RNA strand, which can perfectly hybridize with DNA template of nanocluster synthesis, was applied to lock the fluorescent signal of DNA-AgNCs by forming an RNA/DNA duplex. Meanwhile, the hybridized RNA/DNA duplex was used as the substrate of RNase A. The fluorescence signal of AgNCs was restored due to the degradation of RNA by RNase A. From the fluorescence signal change of this system caused by RNase A, it was found that the fluorescence signal showed a positive linear relation with RNase A concentration in the range from 0.2 pg/µL to 10 pg/µL with a detection limit of 0.098 pg/µL. Except for potential inhibitor screening and the kinetic study of this enzyme, this strategy was further used for monitoring dynamic change of RNase A in living cells successfully. In summary, the simple and sensitive method for RNase A assay can be hopefully used for drug screening in vitro and in vivo.

Determination of arsenic and lead in single hair strands by laser ablation inductively coupled plasma mass spectrometry.

The purpose of this study was to develop matrix-matched hair standards and a LA-ICP-MS technique for determination of the As and Pb in a single human hair using single spot scan mode. These results could subsequently be used to infer when the element entered the body. This study was conducted in two parts. First, a method was developed and validated for the elemental analysis of hair by LA-ICP-MS. A calibration strategy in LA-ICP-MS was developed using prepared matrix-matched laboratory hair standards doped with analytes of interest at a defined concentration. The use of hair strand standards enables calibration curves to be obtained by plotting the analyte ion (M+) intensity normalized to34S+(the ratio M+/34S+) as a function of the concentration determined by ICP-MS of the acidic digests. The linear correlation coefficients (R2) of the calibration curves for the analytes As and Pb were typically between 0.9970 and 0.9998, respectively. Second, an actual hair was measured using the developed method. The spatial distribution of As along the hair was observed in a hair sample from a leukaemia patient treated with arsenic trioxide (As2O3). The actual and estimated times over which the drug entered the body were compared and discussed.

Biomonitoring of 33 Elements in Blood and Urine Samples from Coastal Populations in Sanmen County of Zhejiang Province.

OBJECTIVE: To determine the normal reference values of 33 elements, Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hg, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Th, Ti, Tl, U, V, Zn and Zr, in the blood and urine samples from the general population in Sanmen County of Zhejiang province, a typical coastal area of eastern China. METHODS: The 33 elements in 272 blood and 300 urine samples were determined by inductively coupled plasma-mass spectrometry (ICP-MS). The normality test of data was conducted using SPSS 17.0 Statistics. The data was compared with other reports. RESULTS: The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County were obtained, which of some elements were found to be similar with other reports, such as Co, Cu, Mn and Sr, while As, Cd, Hg and Pb were generally found to be higher than those previously reported. There was a wide variation between the reports from different countries in blood Ba. CONCLUSION: The normal reference values of the 33 elements in the blood and urine samples from the general population in Sanmen County are established, and successfully applied to two poisoning cases.

Elements concentrations in the scalp hair of methamphetamine abusers.

The concentrations of 16 elements (As, Au, Ca, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Mo, Ni, Se, Sr and Zn) in the hair of 40 methamphetamine (METH) abusers and control subjects were determined by inductively coupled plasma mass spectrometry (ICP-MS). Comparisons of the element levels in the hair of properly matched METH abuser and control groups revealed significant imbalances in the concentrations of 6 elements (As, Au, Ca, Cu, Mg and Sr) between the abuser and control groups. Ca (p<0.01), Cu (p<0.05), Mg (p<0.01) and Sr (p<0.01) levels are significantly lower in the hair samples of METH abusers compared to control subjects, whereas the As (p<0.01) and Au (p<0.01) concentrations are higher. The concentration of the remaining elements in the hair of METH abusers was similar to the concentration in the control subjects. The geometric means for each element in hair of METH abuser and control subjects are presented. The cause of these alterations is also discussed.

Determination of 33 elements in scalp hair samples from inhabitants of a mountain village of Tonglu city, China.

Hair samples from 190 relatively healthy 20- to 98-year-old volunteers from a mountain village of Tonglu city (Zhejiang province, China) were analyzed to determine the contents of 33 chemical elements (Ag, Al, As, Au, B, Ba, Be, Ca, Cd, Co, Cr, Cs, Cu, Fe, Ga, Hg, Li, Mg, Mn, Mo, Ni, Pb, Rb, Sb, Se, Sr, Th, Ti, Tl, U, V, Zn, and Zr) with the aim of assessing preliminary reference values. Mean values, median values, ranges and selected percentiles of all element concentrations in scalp hair are presented. By comparing data from different countries, it was determined that the mean concentrations of the majority of elements in our study clearly differed from the mean levels reported in the literature. The effects of gender and age on element concentrations were also investigated. Significant differences that were correlated with age and gender were determined for certain elements. For example, Fe exhibited a mean value of 11.26mg/kg for males and 4.37mg/kg for females. An age-dependent pattern for Fe was also apparent when the two age subgroups of 20-59 and 60-98 years were compared.

[Determination of 33 inorganic elements in human hair by electricity plate digestion and inductively coupled plasma-mass spectrometry].

OBJECTIVE: To establish the electricity plate digestion and inductively coupled plasma-mass spectrometry (ICP-MS) method for determination of 33 inorganic elements in human hair. METHODS: Lithium (6Li), Germanium (72Ge), Yttrium (89Y), Indium (115In), and Terbium (159Tb) were used as internal standards. The electric heating board digestion in a mixture of nitric acid and hydrogen peroxide was used as the pre-treatment of the hair. Thirty-three inorganic elements in human hair were analyzed by ICP-MS method. RESULTS: The detection limit of ICP-MS was 0.0001 microg/g(Th)-10.9 microg/g (Ca) and the limit of quantitation was 0.0005 microg/g (Th)-25 microg/g (Ca). The recovery rate of this method was 86%-113%. The RSD for the intra-day and inter-day were less than 9.2%. The method was not statistically different from microwave digestion method. CONCLUSION: This method is highly efficient and accurate. It can be used for analysis of 33 inorganic elements in human hair.

[Measurement of acetonitrile in blood and urine by head-space gas chromatography].

OBJECTIVE: To establish the method for measurement of acetonitrile in blood and urine by head-space gas chromatography. METHODS: DB-ALC1 (30 m x 320 microm x 1.8 microm) and DB-ALC2 (30 m x 320 microm x 1.2 microm) capillary column were used to measure the acetonitrile in blood and urine with the isopropanol as internal standard reference. RESULTS: The limits of detection of acetonitrile in both blood and urine were 0.5 microg/mL, with a linear range of 5-1000 microg/mL (r = 0.999).The accuracy of this method was 93.2%-98.0%. The RSD for the intra-day and inter-day were less than 3.7%. CONCLUSION: The method is capable for measurement analysis of acetonitrile in blood and urine.