Anion-exchange Cartridge Research Articles

Determination of Methamphetamine and Amphetamine in Hair by Mixed-Mode Anion Exchange Solid Phase Extraction and Liquid Chromatography–Tandem Mass Spectrometry

Methamphetamine is one of the most widely used sympathomimetic amines in Asia. To identify cases of methamphetamine abuse and to estimate its abuse, hair segmental analysis is used extensively. However, existing hair analysis has several limitations due to matrix interferences. In an attempt to resolve these issues, a simple, rapid, and sensitive liquid chromatography–tandem mass spectrometry method is reported for the determination of methamphetamine and amphetamine in human hair with anion exchange solid phase extraction. Hair dissolved in sodium hydroxide was loaded on a mixed-mode anion exchange cartridge and amphetamine and methamphetamine were eluted with methanol in less than ten minutes followed by liquid chromatography–tandem mass spectrometry. The recovery of this method was between 93.9 and 102.0 percent. The limits of detection and quantitation were 0.01 and 0.05 nanograms per milligram for both analytes. The accuracy and precision were satisfactory for quantitative analysis. The suitability of the method for practical analysis was investigated using hair from methamphetamine users.

501. Radioiodinated Adeno-Associated Virus: A Promising New Approach for Monitoring Gene Therapy

Late infantile neuronal ceroid lipofuscinosis (LINCL) is a form of Batten disease that is caused by mutations in the CLN2 gene. These defects cause widespread neurodegeneration resulting in death by the age of 10-12 years. One treatment for LINCL that has shown promise in animal and clinical studies is gene therapy using adeno-associated virus (AAV) as a vehicle to deliver the CLN2 gene throughout the brain. This is currently accomplished by direct infusion, but there is no way to measure the spatial distribution of administered vector. Iodine-124 labeling of the viral capsid may offer a means for non-invasive determination of spatial distribution using MicroPET imaging. The production of AAVrh.10CLN2 under GMP conditions met endotoxin, mycoplasma, sterility and transgene expression release criteria. Purified AAVrh.10CLN2 was concentrated to 1013 gene copies/ml. Labeling with Na124I was carried out at 2-5 0C under mild oxidizing conditions in pH 7.5 buffer. Following radiolabeling, the product mixture was purified using an anion exchange cartridge and centrifugal filtration. Purified I124-AAVrh.10CLN2 was formulated in a pH 7.4 PBS buffer. The sterile formulation was injected (2 ml at 2.5 μCi/ml) intraparenchymally to the striatum in the murine brain and imaged on a Siemens Inveon MicroPET scanner. Thirty minute PET scans were acquired for each mouse (n=3). For the control group, we performed the same procedure using free Na 124I alone (n=3). The radiolabeling efficiency of AAV was in the range of 12-14%. PET/CT imaging clearly demonstrated the spatial distribution of vector over a ten day period, with minimal 124I uptake in the unblocked thyroid. In contrast, free iodide was rapidly cleared from the brain within 2 days (Figure 1). In conclusion, adeno-associated virus was successfully labeled with 124I and its distribution in the mouse brain was observed. This radiolabeling approach has the potential for wide application in gene therapy trials. View Large Image | Download PowerPoint Slide

Challenges in optimizing sample preparation and LC-MS/MS conditions for the analysis of carglumic acid, an N-acetyl glutamate derivative in human plasma.

This paper describes a systematic approach to overcoming challenges in developing a robust and selective liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for reliable and precise determination of carglumic acid in human plasma. Sample extraction was tested on several reversed-phase solid-phase extraction (SPE) sorbents with different chemistries, such as hydrophobic C18, hydrophilic-lipophilic balance, and mixed-mode cation and anion exchange. The best recovery under the optimized extraction conditions was obtained with Oasis MAX (30 mg, 1cc) mixed-mode anion exchange (~ 50%) cartridge, compared to other sorbents from 100 μL plasma sample. Complete analytical separation of carglumic acid and carglumic acid-13C5 15N as an internal standard (IS) from endogenous plasma components was achieved on ACE 5CN (150 × 4.6 mm, 5 µm) column under isocratic conditions using acetonitrile:methanol (50:50, v/v) - 0.1% acetic acid in water [80:20, v/v] as the mobile phase. The deprotonated precursor → product ion transitions for carglumic acid (189/146) and IS (195/152) were monitored in the negative ionization mode on a triple quadrupole mass spectrometer. The regression curves were linear over a concentration range of 6.00-6000 ng/mL (r(2) ≥ 0.9987). Matrix effect was evaluated in terms of IS-normalized matrix factors, which ranged from 0.95 to 1.01 across four quality control levels. Intra- and inter-batch accuracy and precision, and the stability of carglumic acid in spiked plasma samples were assessed under different conditions. The method was applied to assess the pharmacokinetics of 100 mg/kg body weight carglumic acid in a healthy Indian subject.

Comparative evaluation of seven different sample treatment approaches for large-scale multiclass sport drug testing in urine by liquid chromatography–mass spectrometry

Sample preparation is a critical step in large-scale multiclass analysis such as sport drug testing. Due to the wide heterogeneity of the analytes and the complexity of the matrix, the selection of a correct sample preparation method is essential, looking for a compromise between good recoveries for most of the analytes and cleanliness of the extract. In the present work, seven sample preparation procedures based on solid-phase extraction (SPE) (with 5 different cartridges), liquid–liquid extraction (LLE) and sorbent-supported liquid extraction (SLE) were evaluated for multiclass sport drug testing in urine. The selected SPE sorbents were polymeric cartridges Agilent PLEXA™ and Oasis HLB™, mixed mode cation and anion exchange cartridges Oasis MAX™ and MCX™, and C18 cartridges. LLE was performed using tert-butyl methyl ether and SLE was carried out using Agilent Chem Elut™ cartridges. To evaluate the proposed extraction procedures, a list of 189 compounds were selected as representative from different groups of doping agents, including 34 steroids, 14 glucocorticosteroids, 24 diuretics and masking agents, 11 stimulants, 9 beta-agonist, 16 beta-blockers, 6 Selective Estrogen Receptors Modulators (SERMs), 24 narcotics and 22 other drugs of abuse/sport drugs. Blank urine samples were spiked at two levels of concentration, 2.5 and 25μgL−1 and extracted with the different extraction protocols (n=6). The analysis of the extracts was carried out by liquid chromatography electrospray time-of-flight mass spectrometry. The use of solid-phase extraction with polymer cartridges provided high recoveries for most of the analytes tested and was found the more suitable method for this type of application given the additional advantages such as low sample and solvent consumption along with increased automation and throughput.

Hydrophilic interaction liquid chromatography as second dimension in multidimensional chromatography with an anionic trapping strategy: Application to prostate-specific antigen quantification

Liquid chromatography (LC) coupled with tandem mass spectrometry (MS–MS) in selected reaction monitoring mode (SRM) has become a widely used technique for the quantification of protein biomarkers in plasma and has already proven to give similar results compared to the conventional immunoassays. To improve the lack of insufficient sensitivity for quantification of low abundance protein, we propose a new two dimensional liquid chromatography (2D-LC-SRM) method for the quantitation of prostate specific antigen (PSA) in human plasma. The method centers on anion exchange cartridge between reversed-phase chromatography and hydrophilic interaction liquid chromatography (HILIC) in an on-line arrangement. The use of the anionic cartridge allows an easier online transfer of the analytes between both dimensions. Moreover, it provides an additional selectivity since the more basic peptides are not retained on this support. This setup has been applied to the quantification of prostate specific antigen (PSA) protein in plasma on a previous generation of mass spectrometer, which enabled a limit of quantification (LOQ) of 1ng/mL without any upfront immuno-depletion or intense off-line fractionation before the SRM analysis. The obtained LOQ is compatible with the required sensitivity for the clinically relevant plasma-based PSA tests.

Simultaneous determination of 18 tetrahydrocorticosteroid sulfates in human urine by liquid chromatography/electrospray ionization-tandem mass spectrometry

A liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometry (MS) method for the direct determination of eighteen tetrahydrocorticosteroid sulfates in human urine has been developed. The analytes were 3- and 21-monosulfates and 3,21-disulfates of tetrahydrocortisol (THF), tetrahydrocortisone (THE), tetrahydro-11-deoxycortisol (THS), and their corresponding 5α-H stereoisomers. The mass spectrometric behavior of these sulfates in negative-ion ESI-MS/MS revealed the production of intense structure specific product ions within the same group of sulfates and permitted distinction between regioisomeric sulfates by collision-induced fragmentation with the MS/MS technique using a linear ion-trap instrument. For the quantitative analysis, selected reaction monitoring analysis in the negative-ion detection mode using triple-stage quadrupole mass spectrometer was performed by monitoring transitions from [M−H]− to the most abundant product ion of each tetrahydrocorticosteroid sulfate. After addition of 3- and 21-monosulfates of [2,2,3β,4,4-d5]-THF, -THE, and -THS as internal standards, urine sample was applied to a solid phase extraction using a lipophilic-weak anion exchange cartridge column, and then analyzed by LC/ESI-MS/MS. The method had satisfactory performance in terms of intra- and inter-assay precision (less than 9.7% and 9.6%, respectively), and accuracy (91.2–108.2%). The limit of quantification was lower than 2.5ng/mL for all sulfates examined. We applied this method to determine the concentration of eighteen tetrahydrocorticosteroid sulfates in the urine of healthy subjects. Thus, we have developed a sensitive, precise and accurate assay for urinary tetrahydrocorticosteroid sulfates that should be useful for clinical and biological studies.

Comparison of different solid-phase extraction materials for the determination of fluoroquinolones in chicken plasma by LC-MS/MS

Fluoroquinolones are synthetic antibiotics which are frequently used in veterinary medicine e.g. for the treatment of poultry. Their specific importance is based on the fact that they are regarded as antibiotics of last resort because of their broad spectrum of action against Gram-negative and -positive bacteria. Here, a new and sensitive method for the simultaneous determination of four fluoroquinolones (marbofloxacin, ciprofloxacin, enrofloxacin and difloxacin) in chicken plasma by LC-MS/MS was developed. Solid-phase extraction was chosen for sample preparation because a selective sample clean-up is combined with an effective extraction. Various solid-phase extraction materials including polymer-based reversed-phase, silica-based reversed-phase and mixed-mode sorbents were compared. Selection criteria were analyte recovery, sample extract purity and economical aspects (analysis time and elution solvent volume). Best recoveries and minimized elution solvent volumes were achieved using polymeric reversed-phase cartridges. However, post-column infusion experiments revealed that the analysis is influenced by co-eluting matrix components. Hence, a combination of a mixed-mode anion-exchange cartridge and a mixed-mode cation-exchange cartridge was used as final extraction method. This method yield slightly lower analyte recoveries compared to polymeric-reversed-phase cartridges but exhibit no matrix effects. Recoveries of spiked chicken plasma ranged from 61.9% to 84.8% with an inter-day precision of generally less than 12%. LODs are between 0.03 and 0.05μg/L; LOQs are between 0.08 and 0.16μg/L. Maximum plasma concentrations of chickens medicated with an enrofloxacin dosage of 3mg/kg bodyweight were 38.9μg/L for enrofloxacin and 3.3μg/L for its main metabolite ciprofloxacin.

Using 5-deoxy-5-[18F]fluororibose to glycosylate peptides for positron emission tomography

So far seven peptide-based (18)F-radiopharmaceuticals for diagnostic applications with positron emission tomography (PET) have entered into clinical trials. Three candidates out of these seven are glycosylated peptides, which may be explained by the beneficial influence of glycosylation on in vivo pharmacokinetics of peptide tracers. This protocol describes the method for labeling peptides with 5-deoxy-5-[(18)F]fluororibose ([(18)F]FDR) as a prosthetic group. The synthesis of [(18)F]FDR is effected by a nucleophilic fluorination step by using dried Kryptofix 2.2.2-K2CO3-K(18)F complex and a subsequent HCl-catalyzed hydrolysis. The conjugation of [(18)F]FDR to the N-terminus aminooxy (-ONH2)-functionalized peptides is carried out in anilinium buffer at pH 4.6 and at room temperature (RT, 21-23 °C), with the concentration of peptide precursors being 0.3 mM. The procedure takes about 120 min and includes two cartridge isolation steps and two reversed-phase (RP) HPLC purification steps. The quaternary methyl amine (QMA) anion exchange cartridge and the hydrophilic-lipophilic balanced (HLB) cartridge are used for the isolation of (18)F-fluoride and [(18)F]FDR-conjugated peptides, respectively. The first HPLC purification provides the (18)F-fluorinated precursor of [(18)F]FDR and the second HPLC purification is to separate labeled peptides from their unlabeled precursors. The final product is formulated in PBS ready for injection, with a radiochemical purity of >98% and a radiochemical yield (RCY) of 27-37% starting from the end of bombardment (EOB). The carbohydrate nature of [(18)F]FDR and the operational convenience of this protocol should facilitate its general use.

SPE speciation of inorganic arsenic in rice followed by hydride-generation atomic fluorescence spectrometric quantification

Due to high toxicity, inorganic arsenic (iAs) species are the focus of monitoring effort worldwide. In this work arsenic was first extracted from rice by microwave-assisted digestion in HNO3-H2O2, during which As(III) was oxidized to As(V). Silica-based strong anion exchange cartridges were used to separate As(V) from organic forms. After prereduction by iodide, iAs was quantified by hydride-generation atomic fluorescence spectrometry (HG-AFS). This method achieved 1.3 ng g(-1) limit of detection (LOD), and 94 ± 3% and 93 ± 5% recoveries, respectively, for As(III) and As(V) at 100 ng g(-1). Validation was performed using standard reference material NIST 1568a (102 ng g(-1)) and ERM BC211 (124 ng g(-1)) rice flour. By eliminating chromatography, SPE speciation gained throughput and cost advantages. HG-AFS, at 10% budget and operation cost of a typical inductively-couple plasma mass spectrometer (ICPMS), proved highly sensitive and specific for iAs quantification.

Comparative lipidomics of mouse brain exposed to enriched environment

Several studies have shown that housing conditions and environmental exposure to a series of stimuli lead to behavior improvement in several species. While more works have been focused on illustrating changes of the proteome and transcriptome following enriched environment exposure in mice, little has been done to understand changes in the brain metabolome in this paradigm due to the complexity of this type of analysis. In this paper, lipidomics focused on phospholipids and gangliosides were conducted for brain tissues of mice exposed to enriched or impoverished conditions. We optimized previously reported method and established a reliable relative comparison method for phospholipids and gangliosides in brain tissue using prefractionation with weak anion exchange cartridge. We used liquid chromatography mass spectrometry to explore metabolic signatures of the cerebral cortex and hippocampus after confirming the animals had significant memory differences using the fear conditioning paradigm and brain immunohistochemistry. Although both cerebral cortex and hippocampus regions did not show major alterations in ganglioside composition, we found significant differences in a series of phospholipids containing 22:6 fatty acid in the prefrontal cortex, indicating that environmental enrichment and impoverished housing conditions might be a relevant paradigm to study aberrant lipid metabolism of docosahexaenoic acid consumption. Our study highlights the hypothesis-generating potential of lipidomics and identifies novel region-specific lipid changes possibly linked not only to change of memory function in these models, but also to help us better understand how lipid changes may contribute to memory disorders.

Inter-Laboratory Study of an LC-MS/MS Method for Simultaneous Determination of Fumonisin B<sub>1</sub>, B<sub>2</sub> and B<sub>3</sub> in Corn

To validate an LC-MS/MS method using a strong anion exchange cartridge for simultaneous determination of fumonisin B1, B2 and B3 in corn, an inter-laboratory study was performed in 9 laboratories using one fumonisin-negative corn sample, three spiked corn samples (FB1: 100-1,000 μg/kg, FB2 and FB3: 10-100 μg/kg) and two naturally contaminated corn samples. The recoveries were in the ranges of 79.7-87.2% for FB1, 78.6-103.2% for FB2 and 80.1-92.8% for FB3. The relative standard deviations for repeatability (RSDr) ranged from 3.7 to 8.0% for FB1, from 2.6 to 15.3% for FB2 and from 4.3 to 9.7% for FB3. The relative standard deviations for reproducibility (RSDR) for FB1, FB2 and FB3 were in the ranges of 6.3-10.1%, 5.9-18.7% and 9.3-16.0%, respectively. The HorRat values for all analytes ranged from 0.2 to 0.9. The difference of the trueness between the two kinds of commercially available anion exchange cartridges used in this study was not significant (p>0.05). Surveillance for fumonisins in corn grits was performed using the validated method. All of the samples were contaminated with fumonisins and the mean concentrations for FB1, FB2 and FB3 were 118.1, 37.3 and 17.9 μg/kg, respectively. These results indicated that the method for simultaneous determination of FB1, FB2 and FB3 in corn was successfully developed and validated.

Biodistribution of99mTc Labeled Integrin Antagonist

The selective targeting of an integrin αvβ3 receptor using radioligands may enable the assessment of angiogenesis and integrin αvβ3 receptor status in tumors. The aim of this research was to label a peptidomimetic integrin αvβ3 antagonist (PIA) with 99mTc(CO)3 and to test its receptor targeting properties in nude mice bearing receptor-positive tumors. PIA was reacted with tris-succinimidyl aminotriacetate (TSAT) (20 mM) as a PIA per TSAT. The product, PIA-aminodiacetic acid (ADA), was radiolabeled with [99mTc(CO)3(H2O)3]+1, and purified sequentially on a Sep-Pak C-18 cartridge followed by a Sep-Pak QMA anion exchange cartridge. Using gradient C-18 reverse-phase HPLC, the radiochemical purity of 99mTc(CO)3-ADA-PIA (retention time, 10.5 min) was confirmed to be > 95%. Biodistribution analysis was performed in nude mice (n = 5 per time point) bearing receptor-positive M21 human melanoma xenografts. The mice were administered 99mTc(CO)3-ADA-PIA intravenously. The animals were euthanized at 0.33, 1, and 2 hr after injection for the biodistribution study. A separate group of mice were also co-injected with 200 μg of PIA and euthanized at 1 hr to quantify tumor uptake. 99mTc(CO)3-ADA-PIA was stable in phosphate buffer for 21 hr, but at 3 and 6 hr, 7.9 and 11.5% of the radioactivity was lost as histidine, respectively. In tumor bearing mice, 99mTc(CO)3-ADA-PIA accumulated rapidly in a receptor-positive tumor with a peak uptake at 20 min, and rapid clearance from blood occurring primarily through the hepatobiliary system. At 20 min, the tumor-toblood ratio was 1.8. At 1 hr, the tumor uptake was 0.47% injected dose (ID)/g, but decreased to 0.12% ID/g when co-injected with an excess amount of PIA, indicating that accumulation was receptor mediated. These results demonstrate successful 99mTc labeling of a peptidomimetic integrin antagonist that accumulated in a tumor via receptor-specific binding. However, tumor uptake was very low because of low blood concentrations that likely resulted from rapid uptake of the agent into the hepatobiliary system. This study suggests that for 99mTc(CO)3-ADA-PIA to be useful as a tumor detection agent, it will be necessary to improve receptor binding affinity and increase the hydrophilicity of the product to minimize rapid hepatobiliary uptake.

Rapid high‐yield N‐acylation of aminothiols: N‐acetylglutathione and N‐acetylhomocysteine and their thiol pKa values

Methodology for the rapid N-acylation of aminothiols in aqueous solution using procedures commonly employed in biochemical studies is described here. Glutathione disulfide (GSSG) and homocystine were diN-acetylated in ~100% yield in 0.1 M aqueous NaHCO3 (pH 8.5) at room temperature by 2.5 equiv of the activated ester, N-hydroxysulfosuccinimidyl acetate, an efficient water-soluble acetylating reagent. Following acetone precipitation, diN-acetylGSSG was further purified and desalted on a strong anion-exchange (SAX) cartridge. DiN-acetylhomocystine was simultaneously purified and desalted on a C18 cartridge. The N-acetylated aminothiols were generated using gel-immobilized tris(2-carboxyethyl)phosphine as a reductant, which obviated the need for further purification. Alternatively, disulfide exchange with dissolved dithiothreitol yielded N-acetylglutathione, which was purified on the SAX cartridge. pH titrations of N-acetylglutathione (8.99) and N-acetylhomocysteine (9.66) as well as those of commercially available N-acetylcysteine (9.53) and N-acetylpenicillamine (10.21) yielded pK(a) (SH) values of importance for biological studies.

Trace analysis of mono-, di-, tri-substituted polyfluoroalkyl phosphates and perfluorinated phosphonic acids in sewage sludge by high performance liquid chromatography tandem mass spectrometry

A new method using ultrasonic extraction and solid phase extraction (SPE) clean-up pretreatments was developed for the analysis of mono-, di- and tri-substituted polyfluoroalkyl phosphates (abbreviated as mono-PAPs, di-PAPs and tri-PAPs) and perfluorinated phosphonic acids (PFPAs) in sludge from wastewater treatment plants (WWTPs). For the ultrasonic extraction of three mono-PAPs, three di-PAPs and three PFPAs in sludge samples, a mixture of tetrahydrofuran/acetic acid (1:1, v/v) was found to be the most suitable extraction solvent. The subsequently optimized clean-up and enrichment procedures were carried out with weak anion exchange (WAX) cartridges in-line coupled with graphitized carbon black (ENVI-Carb) tubes. Two tri-PAPs were ultrasonically extracted by acetonitrile/tetrahydrofuran (1:1, v/v) and cleaned by mixed-mode anion exchange (MAX) in-line coupled with ENVI-Carb cartridges. The analytes were analyzed by optimized high performance liquid chromatography tandem mass spectrometry (HPLC–MS/MS) method either in negative or positive ionization mode. The method quantification limits (MQLs) of the 11 analytes in sludge ranged from 0.6 to 5.1ng/g, meanwhile the total recoveries of the pretreatment varied from 24% (6:2 mono-PAP) to 107% (PFDPA). The method was successfully applied to analyze 16 sewage sludge samples collected from seven provinces in China, and two mono-PAPs were identified with concentrations ranging from <MQLs to 10.7ng/g.

Development of a chiral micellar electrokinetic chromatography–tandem mass spectrometry assay for simultaneous analysis of warfarin and hydroxywarfarin metabolites: Application to the analysis of patients serum samples

The enantioseparation of warfarin (WAR) along with the five positional and optical isomers is challenging because of the difficulty to simultaneously separate and quantitate these chiral compounds. Currently, no effective chiral CE–MS methods exist for the simultaneous enantioseparation of WAR and all its hydroxylated metabolites in a single run. Polymeric surfactants (aka. molecular micelles) are particularly compatible with micellar electrokinetic chromatography–mass spectrometry (MEKC–MS) because they have a wider elution window for enantioseparation and do not interfere with the MS detection of chiral drugs. Using polysodium N-undecenoyl-l,l-leucylvalinate (poly-l,l-SULV) as a chiral pseudophase in MEKC–MS baseline separation of WAR, its five metabolites along with the internal standard was obtained in 45min. This is in comparison to 100min required for separation of the same mixture with packed column CEC–MS using a vancomycin chiral stationary phase. Serum samples were extracted with mixed-mode anion-exchange (MAX) cartridge with recoveries of greater than 85.2% for all WAR and hydroxywarfarin (OH-WAR) metabolites. Utilizing the tandem MS and multiple reaction monitoring mode, the MEKC–MS/MS method was used to simultaneously generate calibration curves over a concentration range from 2 to 5000ng/mL for R- and S-warfarin, 5 to 1000ng/mL for R- and S-6-, 7-, 8- and 10-OH-WAR and 10 to 1000ng/mL for R and S-4′-OH-WAR. For the first time, the limits of detection and quantitation for most WAR metabolites by MEKC–MS/MS were found to be at levels of 2 and 5ng/mL, respectively. The method was successfully applied for the first time to analyze WAR and its metabolites in plasma samples of 55 patients undergoing WAR therapy, demonstrating the potential of chiral MEKC–MS/MS method to accurately quantitate with high sensitivity.

Determination of fumonisins B1 and B2 in Chinese rice wine by HPLC using AQC precolumn derivatisation

Fumonisins are a group of naturally occurring mycotoxins produced by various Fusarium species that commonly infect maize and other cereals, including sorghum and rice. In this study a sensitive and selective method was developed for the determination of fumonisins B₁ and B₂ (FB₁ and FB₂) in Chinese rice wine. The method is based on high-performance liquid chromatography and fluorescence detection following precolumn derivatisation with 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate (AQC). FB₁ and FB₂ in Chinese rice wine were extracted and purified using strong anion exchange cartridges and derivatised with AQC at room temperature. The AQC derivatives were stable for 5 days. Optimal fluorescence was obtained at an excitation wavelength of 246 nm and an emission wavelength of 390 nm. Chromatography was performed using a C18 column and gradient elution at 1 mL min⁻¹ with methanol and 0.05 mol L⁻¹ phosphate buffer at pH 4. The limit of detection was 6 µg L⁻¹ for both FB₁ and FB₂. The method was successfully applied to the determination of FB₁ and FB₂ in Chinese rice wine, with recoveries of 87.5-94.5% being obtained. The established method was stable and sensitive for the determination of FB₁ and FB₂ in Chinese rice wine.

Field separation‐based speciation analysis of inorganic arsenic in public well water in Hungary

Twenty‐three water samples were collected from public wells from 3 different counties, having a history of high natural arsenic occurrence in Hungary, as well as in the resort area close to the capital city for speciation analysis of arsenic As(III) and As(V). In order to prevent interconversion of arsenic species in the samples, a simple field separation method was applied by using solid phase extraction anion exchange cartridges prior to the inductively coupled plasma sector field mass spectrometric analyses. Total arsenic level in the samples was confirmed to be higher than the health limit value established by the European Union (10μg×L−1) for drinking water in 22 samples. Thus, the total As concentration of the samples ranged between 7.2 and 210.3μg×L−1. According to the speciation study, two thirds of the samples contained As(V) in more than 60%. Beside the calculation of As(V)/As(III) ratios in the samples, the oxidative character of the geochemical environment could be suggested by determining the concentration of oxyanion‐forming elements (Mo, Se, U, V and W).

Simultaneous extraction and determination of fluoroquinolones, tetracyclines and sulfonamides antibiotics in soils using optimised solid phase extraction chromatography-tandem mass spectrometry

An analytical method was developed for the simultaneous extraction and determination of 18 fluoroquinolones (FQs), tetracyclines (TCs) and sulfonamides (SAs) antibiotics from soils using solid phase extraction and liquid chromatography-tandem mass spectrometry. The soils were extracted by different solvents with the help of mechanical shaking and ultrasonic treatment at 59 kHz, followed by a strong anion exchange (SAX) cartridge to clean up soil samples and a hydrophilic lipophilic balance (HLB) cartridge as enrichment. The method was evaluated by testing the following variables: extraction solvents, the type of SPE cartridges, solvent volumes, initial spiking levels and soil types (silty clay loam and clay loam soils). The soil extraction method was validated using these two types of soils, representing two typical agricultural soils in northern China. For 2 g soil, the extraction steps with the mixture of potassium phosphate buffer and acetonitrile (ACN) (1/1, v/v, pH 3.2) provided satisfactory recoveries. In the clay loam soil, the recoveries of all the compounds were from 56% to 89% at the spiking level of 50 µg kg−1 soil, and from 69% to 97% at the spiking level of 200 µg kg−1 soil, respectively. Recoveries in silty clay loam soil were similar to that in clay loam. The method was successfully employed using soil samples collected from a farmland and afforestion area irrigated with sewage in northern China. The result indicates that trace antibiotics in sewage may accumulate in soil irrigated by river water containing sewage.

Development of a multi-residue method using acetonitrile-based extraction followed by liquid chromatography–tandem mass spectrometry for the analysis of steroids and veterinary and human drugs at trace levels in soil

The aim of this study was to develop an analytical method for the analysis of traces of hormonal steroids and veterinary and human drugs in soil. Thus, 31 substances were selected, including 14 veterinary products, 11 hormonal steroids and 6 other well-known human contaminant compounds. The procedure inspired by the quick, easy, cheap, effective, rugged and safe (QuEChERS) extraction method was developed. First the acetonitrile-based extraction was optimized. This step was followed by a solid-phase extraction (SPE) clean-up using both a strong anion-exchange cartridge and a polymeric cartridge. The analysis was then performed using liquid chromatography coupled to a triple quadrupole analyser operated with tandem mass spectrometry. This analytical procedure was validated using the ICH/2005 standard by evaluating the linearity (from 0.01ng/g to 1000ng/g –R2>0.99), the intra-day precision (relative standard deviation (RSD)<20%), the inter-day precision (RSD<30%), recoveries (40–110% for most of the compounds) and limits of detection and quantification. This method allowed for the determination of the target analytes in the lower ng/g concentration range. The methodology was then applied to real soil samples collected in several areas of France that received different manure or sludge treatments. Some target compounds were detected at very low level (inferior to the ng/g). Veterinary antibiotics, mainly from the sulfonamide family, were found in soils treated by manure (0.02–0.12ng/g). On the other hand, pharmaceuticals usually used by humans (carbamazepine, ibuprofen) were detected in soils treated by domestic sludge.

Simultaneous determination of human and veterinary antibiotics in various environmental matrices by rapid resolution liquid chromatography–electrospray ionization tandem mass spectrometry

A robust and sensitive analytical method is presented in which 11 classes of antibiotics are simultaneously extracted and determined in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge. Water samples with different volumes were adjusted to pH 3, added with 0.2g Na2EDTA and then extracted using Oasis hydrophilic–lipophilic balance (HLB) cartridges. Extraction of solid samples was carried out by a combination of ultrasonic and vortex mixing using a mixture of acetonitrile and citric buffer at pH 3 as the extraction solution. The extracts of the solid samples were then cleaned-up by a tandem solid phase extraction (SPE) method using a strong anion exchange cartridge (SAX) and a HLB cartridge, followed by analysis using rapid resolution liquid chromatography–tandem mass spectrometry (RRLC–MS/MS) equipped with electrospray ionization source. Among the 50 target compounds, the recoveries in the range of 50–150% were obtained for 39, 40, 36, 40, 38, 33 and 36 antibiotics in the spiked samples of surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge with three concentrations, respectively. Method quantification limits (MQLs) for the target compounds (except sulfaguanidine and sulfanilamide) were in the range of 0.52–5.88ng/L, 2.36–65.8ng/L, 1.73–20ng/L, 1.42–9.52ng/L, 0.64–6.67ng/g (except bacitracin and cloxacillin), 1.33–17.4ng/g (except salinomycin, narasin, monensin, cloxacillin and novobiocin) and 1.50–28.6ng/g (except salinomycin, narasin, monensin and cloxacillin) in surface water, lagoon wastewater, influent, effluent, sediment, manure and sludge, respectively. The developed analytical method was successfully applied in the determination of target compounds in wastewater and sludge samples from Huiyang wastewater treatment plants, and in ground water, lagoon wastewater, manure and sediment collected from a pig farm, in South China.