Ultra-fast Liquid Chromatography-tandem Mass Spectrometry Research Articles

Contamination level of aflatoxin B1 in lotus seeds rapid screening by indirect competitive ELISA method

A simple and cost-effective indirect competitive enzyme-linked immune sorbent assay (ic-ELISA) was developed to rapidly screen the content of aflatoxin B1 (AFB1) in lotus seeds, and the results were confirmed by ultra-fast liquid chromatography-tandem mass spectrometry( UFLC-MS/MS). Matrix-matched calibration expressed a good linearity ranging from 0. 171 to 7. 25 µg · L(-1) for AFB, with R2 > 0.978. The medium inhibitory concentration( IC50 ) for AFB1 was 1.29 µg · L(-1), the recovery for AFB1 was 74.73% to 126.9% with RSD < 5%, and the limit of detection (IC10) was 0.128 µg · L(-1). The developed ic-ELSIA method was applied to rapid analysis of AFB, in 20 lotus seeds samples and the results indicated that the contents of AFB, in samples 1-15 were in the range of 1. 19- 115. 3 µg · kg(-1) and in 40% of the samples exceeded the legal limit(5 µg · kg(-1)), while the contamination rate of AFB, in samples 16-20 was 40%. Pearson correlation coefficient(r) reached 0.997 for AFB1 content in the samples detected by ic-ELSIA and UFLC-MS/MS methods. The results proved that the developed ic-ELISA method is simple, sensitive and reliable, and can be used for rapid and high-throughput screening of AFB1 in lotus seeds

Rapid determination of memantine in human plasma by using nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer d-μ-SPE and UFLC-MS/MS.

A novel, simple, and sensitive method based on the use of dispersive micro-solid-phase extraction (d-μ-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) for the determination of memantine (ME) was developed and validated over the linearity range 0.05-10.0 µg/L with 100 μL of human plasma using memantine-D6 (ME-D6) as the internal standard. The novel nanoring carboxyl-functionalized paramagnetic molecularly imprinted polymer (NR-CF-Mag-MIP) was synthesized by ultrasound-assisted suspension polymerization, using ME as a template molecule, methacrylic acid as a functional monomer, and divinylbenzene as a cross-linking agent. The NR-CF-Mag-MIP was used as the d-μ-SPE sorbent to extract ME from human plasma samples. The obtained results demonstrated the higher extraction capacity of NR-CF-Mag-MIP with recoveries between 97.6 and 101%. The limits of quantification (LOQs) for ME was 0.015 µg/L. Validation results on linearity, specificity, accuracy, precision, and stability, as well as on application to the analysis of samples taken up to 480 h after oral administration of 20 mg (two 10 mg capsules) of ME in healthy volunteers demonstrated the applicability to bioequivalence studies.

Determination of secondary and tertiary amines as N-nitrosamine precursors in drinking water system using ultra-fast liquid chromatography–tandem mass spectrometry

N-Nitrosamines are potent mutagenic and carcinogenic emerging water disinfection by-products (DBPs). The most effective strategy to control the formation of these DBPs is minimizing their precursors from source water. Secondary and tertiary amines are dominating precursors of N-nitrosamines formation during drinking water disinfection process. Therefore, the screening and removal of these amines in source water are very essential for preventing the formation of N-nitrosamines. A rapid, simple, and sensitive ultrafast liquid chromatography–tandem mass spectrometry (UFLC-MS/MS) method has been developed in this study to determine seven amines, including dimethylamine, ethylmethylamine, diethylamine, dipropylamine, trimethylamine, 3-(dimethylaminomethyl)indole, and 4-dimethylaminoantipyrine, as major precursors of N-nitrosamines in drinking water system. No sample preparation process is needed except a simple filtration. Separation and detection can be achieved in 11min per sample. The method detection limits of selected amines are ranging from 0.02μg/L to 1μg/L except EMA (5μg/L), and good calibration linearity was achieved. The developed method was applied to determine the selected precursors in source water and drinking water samples collected from Midwest area of the United States. In most of water samples, the concentrations of selected precursors of N-nitrosamines were below their method detection limits. Dimethylamine was detected in some of water samples at the concentration up to 25.4μg/L.

Rapid determination of trace dicyandiamide in mussels from Zhejiang coast by ultra-fast liquid chromatography-tandem mass spectrometry with isotope internal standard dilution technique.

In this study, a rapid and accurate ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS) method coupled with the isotope internal standard dilution technique was established and validated to determine trace dicyandiamide (DCD) in mussels. The sample was extracted by acetonitrile, and chromatographic separations were performed on an Acquity UPLC BEH Amide column by using water-acetonitrile (9:91, v/v) as the mobile phase within 3 min. DCD was determined by using DCD-(15)N4 as an internal standard. The results showed that the recoveries were between 96.2 and 103 % with relative standard deviations (RSDs) in the range of 0.6-6.0 %. The limit of quantification (LOQ) was 0.05 μg/kg. This method can be applied to the routine analysis for the rapid and sensitive determination of trace DCD in mussels. Overall, the data reiterate the importance of investigating the presence of DCD in marine biological samples, which can act as food quality controls for human health.

Rapid determination of corticosterone in mouse plasma by ultra fast liquid chromatography-tandem mass spectrometry.

Major depressive disorder is a severe, life-threatening and highly prevalent psychiatric disorder. A high percentage of people suffering from depression are characterized by hyperactivity of the hypothalamic-pituitary-adrenal axis, resulting in plasma glucocorticoid (cortisol in human and corticosterone in rodent) elevations. Glucocorticoid is a critical molecule in the onset of pathology of depression. A simple, highly sensitive and specific method based on ultra-fast liquid chromatography-tandem mass spectrometry method has been developed for the quantitation of corticosterone in mouse plasma for the first time, which provides technical support for the high-throughput measurement for clinical determination of corticosterone in biological samples. Samples were spiked with methanol to precipitate the protein, and then chromatographed on an Agilent Zorbax Eclipse Plus C18 (100 × 2.1 mm,1.8 µm) column by linear gradient elution with methanol and 0.1% formic acid as the mobile phase within 5 min. The detection of corticosterone was performed on ultra-fast liquid chromatography-triple quadrupole tandem mass spectrometry in the positive ion. The ions [M + H](+) m/z 347.2 → m/z 311.1 for corticosterone and [M + H](+) m/z 363.2 → m/z 327.2 for hydrocortisone (internal standard) were used for quantitative determination. The lower quantification limit for corticosterone was 1 ng/mL. The validated method was successfully applied to the quantitation of corticosterone in mouse plasma.

A rapid and sensitive UFLC-MS/MS method for the simultaneous determination of gentiopicroside and swertiamarin in rat plasma and its application in pharmacokinetics.

Radix Gentianae is a traditional Chinese medicine derived from medicinal plants of the family Gentianaceae. Its pharmacological effects have been primarily attributed to the presence of a number of secoiridoid glycosides, in particular gentiopicroside and swertiamarin. In this study, a rapid and sensitive method based on ultrafast liquid chromatography-tandem mass spectrometry has been developed for the simultaneous determination of gentiopicroside and swertiamarin in rat plasma using paeoniflorin as internal standard (IS). After liquid-liquid extraction with ethyl acetate-isopropanol (95 : 5, v/v), separation was achieved on a Shim-pack XR-ODS C18 column (75 mm × 3.0 mm, 2.2 μm) with a mobile phase consisting of methanol : 0.1% formic acid (30 : 70, v/v) at a flow rate of 0.4 ml/min. Detection on an API 3200 QTRAP mass spectrometer equipped with an electrospray ionization source operated in the negative ionization mode was performed by multiple reaction monitoring of the precursor-to-product ion transitions of gentiopicroside, swertiamarin and IS at m/z 401.0 → 179.0, 419.0 → 179.1 and 525.1 → 121.0 respectively. The calibration curves were linear over the concentration range of 20-10 000 and 2-1000 ng/ml for gentiopicroside and swertiamarin with corresponding lower limits of quantification of 20 and 2 ng/ml. The limits of detection were 4 and 0.5 ng/ml for gentiopicroside and swertiamarin, respectively. The intraday and interday precisions were below 11.9% for gentiopicroside and below 9.5% for swertiamarin in terms of relative standard deviation, and the accuracy was within ±8.3% for gentiopicroside and within ±10.2% for swertiamarin in terms of relative error. Extraction recovery, matrix effect and stability were satisfactory in rat plasma. The method was fully validated and applied to a pharmacokinetic study involving oral administration of a Radix Gentianae extract to groups of male and female rats. Results showed that in female rats, both compounds were absorbed to a greater extent and eliminated more slowly than in male rats, although the rate of absorption was similar in the two groups. There were remarkable differences in pharmacokinetic properties of gentiopicroside and swertiamarin between male and female rats. The results will provide helpful information for the development of suitable dosage forms and clinical references on rational administration.

Fast determination of seven synthetic pigments from wine and soft drinks using magnetic dispersive solid-phase extraction followed by liquid chromatography–tandem mass spectrometry

A novel, simple and sensitive method based on the use of magnetic dispersive solid-phase extraction (M-dSPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC–MS/MS) was developed to determine seven synthetic pigments (tartrazine, amaranth, carmine, sunset yellow, allura red, brilliant blue and erythrosine) in wines and soft drinks. An amino-functionalized low degrees of cross-linking magnetic polymer (NH2-LDC-MP) was synthesized via suspension polymerization, and characterized by transmission electron microscopy (TEM). The NH2-LDC-MP was used as the M-dSPE sorbent to remove the matrix from the solution, and the main factors affecting the extraction were investigated in detail. The obtained results demonstrated the higher extraction capacity of NH2-LDC-MP with recoveries between 84.0 and 116.2%. The limits of quantification (LOQs) for the seven synthetic pigments were between 1.51 and 5.0μg/L in wines and soft drinks. The developed M-dSPE UFLC–MS/MS method had been successfully applied to the real wines and soft drinks for food-safety risk monitoring in Zhejiang Province, China. The results showed that sunset yellow was in three out of thirty soft drink samples (2.95–42.6μg/L), and erythrosine in one out of fifteen dry red wine samples (3.22μg/L), respectively. It was confirmed that the NH2-LDC-MP was a kind of highly effective M-dSPE materials for the pigments analyses.

Fast determination of 22 sulfonamides from chicken breast muscle using core–shell nanoring amino-functionalized superparamagnetic molecularly imprinted polymer followed by liquid chromatography-tandem mass spectrometry

A novel, simple and sensitive method was developed for the simultaneous determination of 22 sulfonamides (SAs) in chicken breast muscle by using the dispersive micro-solid-phase extraction (d-μ-SPE) procedure combined with ultra-fast liquid chromatography-tandem quadrupole mass spectrometry (UFLC-MS/MS). The excellent core–shell nanoring amino-functionalized superparamagnetic molecularly imprinted polymer (CS-NR-Mag-MIP) was used as sorbent, and the main factors affecting the extraction efficiency were investigated in detail. All target compounds showed good linearities in the tested range with correlation coefficients (r) higher than 0.9980. The mean recoveries were in the range of 85.0–112.2% at low, medium and high concentration levels (0.1, 1.0 and 5.0ng/g). The intra-day and inter-day relative standard deviations (RSDs) were lower than 6.0% and 8.9%, respectively. The limits of quantification for the 22 SAs were between 0.013 and 0.099ng/g. The developed d-μ-SPE-UFLC-MS/MS method had been successfully applied to the chicken breast muscle samples for food-safety risk monitoring in Zhejiang Province, China. The results showed sulfamethazine, sulfamethoxazole and sulfaquinoxaline in five out of three hundred collected samples were detected with concentrations of 0.418–2.28, 16.4 and 2.93ng/g, respectively. It was confirmed that the CS-NR-Mag-MIP was a kind of highly effective d-μ-SPE materials used for the SAs analyses.

Determination of cefuroxime lysine in rat brain microdialysates by ultra‐fast liquid chromatography with UV and tandem mass spectrometry: application to an acute toxicokinetic study

Cefuroxime lysine is a new second-generation cephalosporins, which can penetrate the blood-brain barrier to cure the meningitis. In order to investigate its acute toxicokinetic study after intraperitoneal injection of 675 mg/kg cefuroxime lysine, a sensitive and clean ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method for the determination of cefuroxime lysine in microdialysate samples was developed and validated, which was compared with UFLC-UV as a reference method. Chromatographic separation was performed on a Shim-pack XR-ODS C18 column (75 × 3.0 mm, 2.2 µm), with an isocratic elution of 0.1% formic acid in acetonitrile-0.1% formic acid in water (45:55, v/v) for LC-MS and acetonitrile-20 mm potassium dihydrogen phosphate (pH 3.0,20:80, v/v) for LC-UV. The lower limit of detection was 0.01 µg/mL for LC-MS and 0.1 µg/mL for LC-UV method, with the same corresponding linearity range of 0.1-50 µg/mL. The intra- and inter-day precisions (relative standard deviation) for both methods were from 1.1 to 8.9%, while the accuracy was all within ±10.9%. The results of both methods were finally compared using paired t-test; the results indicated that the concentrations measured by the two methods correlated significantly (p < 0.05), which suggested that the two methods based on LC-MS and LC-UV were suitable for the acute toxicokinetic study.

Simultaneous determination of four Sudan dyes in blood by solid-phase extraction combined with ultra-fast liquid chromatography-tandem mass spectrometry

A method for the simultaneous determination of Sudan I, II, III, and IV in blood samples by solid-phase extraction (SPE) combined with ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) has been established. The samples were extracted with acetonitrile by vortex and vibrate technique, and then the supernatant was diluted with equal volume of water and cleaned up by a C18 SPE column. The separation was performed on an Agilent Eclipse Plus C18 column (100 mm x 2.1 mm, 1.8 microm) by gradient elution with acetonitrile containing 0.1% (v/v) formic acid and 0.1% (v/v) formic acid aqueous solution as the mobile phases. The electrospray ionization (ESI) source in the positive mode and multiple reaction monitoring (MRM) mode were used for the quantitative analysis. In addition, the phenomenon of E-Z optical isomer occurred by the azo group from Sudan III and IV was found, and the influencing factors were discussed. The results showed that the calibration curves were in good linearity for the four Sudan dyes ranged from 0.1 to 20.0 microg/L with the correlation coefficients of more than 0.999. The average recoveries were from 93.0% to 108.2% with the relative standard deviations (RSDs) from 4.8% to 9.5%. The limits of detection (LODs) and the limits of quantification (LOQs) were 0.06 microg/L and 0.2 microg/L for the four analytes, respectively. The developed method is simple, rapid, and highly sensitive. It can be used for the determination of trace Sudan dyes in blood samples.

Analysis of six phenolic environmental estrogens in bullfrog blood by using dispersive solid-phase extraction and ultrafast liquid chromatography-tandem mass spectrometry

A rapid, sensitive and accurate method for the simultaneous determination of six phenolic environmental estrogens, i. e., bisphenol A (BPA), diethylstilbestrol (DES), dienestrol( DE), hexestrol (HEX), 4-( tert-octyl)-phenol (4-tOP) and 4-nonylphenol (4-NP) in bullfrog blood by dispersive solid-phase extraction-ultrafast liquid chromatography-tandem mass spectrometry (dSPE-UFLC-MS/MS) was established. After protein precipitation, bullfrog blood samples were cleaned-up by dSPE method with ethylenediamine-functionalized Fe3O4, magnetic polymers (EDA-MPs) as adsorbent. The effects of precipitation solvents, adsorption time and the amount of EDA-MPs used on the recoveries of six phenolic environmental estrogens were investigated in detail. Chromatographic separation was performed on a Shim-pack XR-ODS II analytical column (100 mm x 2.0 mm, 2.2 microm). The mass spectrometer was operated by using electrospray ion (ESI) source in the multiple reaction monitoring (MRM) mode. The results showed that the linearities were in the range of 0.5-100.0 microg/L with correlation coefficients (r2) not less than 0.999 6 for all the six phenolic environmental estrogens. The lim- its of quantification (LOQs) (S/N > 10) in bullfrog blood samples were between 0. 075 microg/L and 0.40 microg/L. The recoveries were between 95.0% and 110.0% at three spiked levels. The precision values expressed as relative standard deviations (RSDs) were in the range of 0.6%-6.3%. The developed method can be applied to the routine analysis of the six phenolic environmental estrogens in bullfrog blood samples.

Analysis of six phenolic environmental estrogens in bullfrog blood by using dispersive solid-phase extraction and ultrafast liquid chromatography-tandem mass spectrometry

Analysis of six phenolic environmental estrogens in bullfrog blood by using dispersive solid-phase extraction and ultrafast liquid chromatography-tandem mass spectrometry

An UFLC-MS/MS Method for Quantification of Panaxadiol in Rat Plasma and Its Application to a Pharmacokinetic Study

Panaxadiol is a novel antitumor agent extracted from the Chinese medical herb Panax ginseng. This agent is being developed for the treatment of tumor diseases. A rapid, selective, and simple method based on ultrafast liquid chromatography-tandem mass spectrometry was established and validated to determine panaxadiol in rat plasma following oral and sublingual intravenous administration of panaxadiol. The plasma samples were pretreated with acetic ether, and chromatographic separation was achieved on a Shim-pack XR-ODS III column using isocratic elution with the mobile phase of 0.1 % formic acid and acetonitrile. Analytes and protopanaxadiol (internal standard) were analyzed and identified using electrospray positive ionization mass spectrometry in the multiple reaction-monitoring mode. The MS/MS detection was carried out by monitoring the fragmentation of m/z 461.45 → m/z 127.1 for panaxadiol and m/z 425.4 → m/z 95.1 for protopanaxadiol (internal standard) on a triple-quadrupole mass spectrometer. The result showed good linearity over a wide concentration range (0.1-20 ng/mL) (R2 > 0.999) and its lower limit of detection and quantification were 0.03 and 0.1 ng/mL, respectively. The intra- and interday precision (RSD %) was within 15 % and the accuracy ranged from 94.9 % to 112.0 %. The absolute bioavailability was 12.5 %. The method was fully validated and successfully applied to the pharmacokinetic study of a single dose of panaxadiol.

UFLC–MS/MS method for simultaneous determination of luteolin-7-O-gentiobioside, luteolin-7-O-β-d-glucoside and luteolin-7-O-β-d-glucuronide in beagle dog plasma and its application to a pharmacokinetic study after administration of traditional Chinese medicinal preparation: Kudiezi injection

A rapid, sensitive and selective ultra-fast liquid chromatography–tandem mass spectrometry (UFLC–MS/MS) method for the simultaneous determination of three active flavonoid glycosides: luteolin-7-O-gentiobioside, luteolin-7-O-β-d-glucoside and luteolin-7-O-β-d-glucuronide in beagle dog plasma was developed and validated. Puerarin was used as internal standard (IS). After protein precipitation with acidified acetonitrile, the analytes were separated on a Venusil MP C18 column with a gradient elution system composed of 0.05% formic acid and acetonitrile at a flow rate of 0.4ml/min. Detection was performed using multiple reaction monitoring (MRM) mode with a turbo ion spray source under a negative ionization condition. The calibration curves of the three analytes showed good linearity (r>0.995) within the tested concentration ranges. The lower limits of quantification for luteolin-7-O-gentiobioside, luteolin-7-O-β-d-glucoside and luteolin-7-O-β-d-glucuronide were 1.0ng/ml, 1.0ng/ml and 4.0ng/ml, respectively. The intra-day and inter-day precision and accuracy deviations were less than 15%, and the extraction recoveries of the three analytes from beagle dog plasma were more than 75%. The validated method was successfully applied to a pharmacokinetic study of the three flavonoid glycosides in beagle dog plasma after intravenous administration of the traditional Chinese medicinal preparation: Kudiezi injection.

QUANTITATIVE DETERMINATION OF BIVALIRUDIN IN HUMAN PLASMA BY ULTRA-FAST LIQUID CHROMATOGRAPHY-TANDEM MASS SPECTROMETRY AND ITS APPLICATION IN A PHARMACOKINETIC STUDY

A rapid, sensitive, and selective ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) method was developed for the quantitative determination of bivalirudin in human plasma and its application in a pharmacokinetic study. With nafarelin as internal standard, the sample pretreatment involved one-step protein precipitation with methanol of 0.2 mL plasma. The analysis was conducted on Shim-pack XR-ODS II (75 mm × 2.0 mm, i.d., 2.2 µm) column. The mobile phase consisted of acetonitrile and 0.2% formic acid (20:80,v/v) at a flow rate of 0.35 mL min−1. The detection was performed on a triple-quadruple tandem mass spectrometer by multiple reaction monitoring mode via electrospray ionization. The linear calibration curves for bivalirudin were obtained in the concentration range of 1.006–2011 ng mL−1, with a lower limit of quantification of 1.006 ng mL−1. The intra-day and inter-day precision were high, with relative standard deviations lower than 15%. The accuracy in terms of relative error ranged from 2.7% to 7.8% at all quality control levels. The method was successfully applied to a clinical pharmacokinetic study of bivalirudin in healthy volunteers following intravenous administration of bivalirudin.

Dermoscopy of black-spot poison ivy

Black-spot poison ivy is an uncommon presentation of poison ivy (Toxicodendron) allergic contact dermatitis. A 78-year-old sought evaluation of a black spot present on her right hand amid pruritic vesicles. The presentation of a black spot on the skin in a clinical context suggesting poison ivy is indicative of black-spot poison ivy. Dermoscopy revealed a jagged, centrally homogeneous, dark brown lesion with a red rim. A skin sample was obtained and compared against a poison ivy standard using ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS). This finding confirmed the presence of multiple urushiol congeners in the skin sample. Black-spot poison ivy may be added to the list of diagnoses that show a specific dermoscopic pattern.

High-throughput determination of barbiturates in human plasma using on-line column-switching ultra-fast liquid chromatography–tandem mass spectrometry

A high-throughput method was developed for determinations of eight barbiturates (barbital, allobarbital, phenobarbital, cyclobarbital, amobarbital, secobarbital, thiopental, and thiamylal) in human plasma by on-line column-switching ultra-fast liquid chromatography–tandem mass spectrometry (MS–MS). Plasma samples (100 μl) spiked with the eight barbiturates and 5-(4-methylphenyl)-5-phenylhydantoin (internal standard) were diluted with 300 μl of 13.3 mM ammonium acetate/acetonitrile (33:67, v/v). After centrifugation and filtration, the clear supernatant was injected directly onto the extraction column (Oasis HLB cartridge column). The following procedure was fully automated. The analytes retained on the extraction column were eluted by backflushing of the extraction column and introduced onto the analytical column (Phenomenex Onyx monolithic C18 column, 100 mm × 4.6 mm i.d.) by column switching. Quantification was performed by multiple reaction monitoring with negative-ion atmospheric pressure chemical ionization. Good peak separation and peak shapes of the eight drugs were achieved within an analysis time of 3 min, including the extraction time. All drugs spiked into plasma showed recoveries of 80–93 %. The regression equations for the eight drugs showed excellent linearities in the range of 10–5000 ng/ml of plasma, and the limits of detection ranged from 1.0 to 10 ng/ml. The lower and upper limits of quantitation were 10–50 ng/ml and 5000 ng/ml, respectively. Intraday and interday coefficients of variation for all the drugs were not >9.1 %. The accuracies of quantitation were 92.0–108 %. The method was successfully applied to determination of the level of amobarbital in human plasma after its oral administration to a volunteer.

Determination of 135 pesticides and their metabolites in Angelica sinensis by ultra-fast liquid chromatography-tandem mass spectrometry coupled with solid-phase extraction

A method using solid-phase extraction (SPE) followed by ultra-fast liquid chromatography-tandem mass spectrometry (UFLC-MS/MS) has been established for simultaneously quantitative determination of 135 pesticides and their metabolites (organophosphorus pesticides, pyrethroid pesticides and carbamate pesticides, etc.) in Angelica sinensis. The pesticide residues were extracted from the samples by acetonitrile, cleaned-up with a primary secondary amine (PSA) column and then analyzed using UFLC-MS/MS in multiple reaction monitoring (MRM) mode with positive electrospray ionization. The pesticide residues were quantified by matrix matched standard solution-internal standard method. All of the pesticides had good linear responses with r > 0.99. The average recoveries of the pesticides at the spiked levels of 10, 50, 100 μg/kg ranged from 71.3% - 119.7% with the RSDs of 1.0% - 19.9%, except for clethodim (62.0% - 68.2%). The limits of quantification of the 135 pesticides and their metabolites were 1.0-10.0 μg/kg. The results demonstrated that the method is simple, fast, sensitive and can be used for the analysis of the multiclass of pesticide residues in Angelica sinensis.

Fast Separation and Quantification Method for Nitroguanidine and 2,4-Dinitroanisole by Ultrafast Liquid Chromatography–Tandem Mass Spectrometry

Explosives are now persistent environmental pollutants that are targets of remediation and monitoring in a wide array of environmental media. Nitroguanidine (NG) and 2,4-dinitroanisole (DNAN) are two insensitive energetic compounds recently used as munitions explosives. To protect our environment and human health, the levels of these compounds in soils and waters need to be monitored. However, no sensitive analytical methods, such as liquid chromatography-tandem mass spectrometry (LC-MS/MS), have been developed for detecting these new compounds at trace levels and to be concurrently applied to monitor the common explosives. In general, the concentrations of explosives in either soil or water samples are very low and widely distributed. Therefore, a fast and sensitive method is required to monitor those compounds and increase our ability to find and address the threats they pose to human health and ecological receptors. In this study, a fast and sensitive analytical method has been developed to quantitatively determine NG and DNAN in soil, tap water, and river water by using ultrafast LC-MS/MS. To make this method a comprehensive analytical technique for other explosives as well, it has included other commonly used explosives in the method development, such as octahydro-1,3,5,7-tetranitro-1,3,5,7-tetrazocine (HMX), 1,3,5-trinitroper-hydro-1,3,5-triazine (RDX), 2,4,6-trinitrotoluene (TNT), 2-amino-4,6-dinitrotoluene (ADNT), and pentaerythritol tetranitrate (PETN). The method detection limits (MDLs) of these compounds in soil ranged from 0.2 to 5 ppb, and a good linearity was obtained over a concentration range of 0.5-200 ppb. The recoveries of some compounds are equal to or better than the current EPA methods but with much higher sensitivities.

Contamination and bioaccumulation of benzotriazole ultraviolet stabilizers in fish from Manila Bay, the Philippines using an ultra-fast liquid chromatography–tandem mass spectrometry

Benzotriazole ultraviolet stabilizers (BUVSs) used in plastic products, building materials and personal hygiene products were analyzed in fishes collected from Manila Bay, the Philippines. BUVSs were detected at ng g −1 level in all the fish samples, indicating their ubiquitous contamination in coastal waters. Among the targeted eight BUVSs, UV-328 was predominantly found with a mean concentration of 34.2 ng g −1 lipid weight, implying large scale production and use of this compound in the Philippines. High concentrations of ∑BUVSs were found in bumpnose trevally ( Carangoides hedlandensis), bluetail mullet (adult) ( Valamugil buchanani), common ponyfish ( Leiognathus equulus) and coral grouper (adult) ( Epinephelus corallicola) indicating their active uptake and/or lower metabolic capacity to eliminate BUVSs. Among BUVSs, UV-P showed significant positive relationship ( p < 0.05) between concentration and fish length ( r = 0.29) and fish weight ( r = 0.31). Levels of UV-P in demersal species had positive correlation with δ 15N, indicating that possibile sink of UV-P is bottom sediment in the bay, and ultimately accumulate through benthic food web rather than pelagic food web. To our knowledge, this is the first study on BUVSs distribution in fish from developing countries.