Selective extraction of plutonium(IV) over uranium(VI), americium(III), europium(III) and zirconium(IV) with bidentate O-phenoxydiamide ligands: experimental and theoretical study

To rapidly assess the contamination of actinides in emergency water, a method was developed to simultaneously analyze U, Th, Pu and Am. The method consists of two steps: extraction chromatographic separation using UTEVA and DGA resins and isotopic determination of actinides by inductively coupled plasma mass spectrometry (ICPMS). The whole analytical procedure takes only 8 h and high chemical recoveries of actinides were obtained. The cross spectral interferences between actinides in ICPMS measurement were sufficiently removed. The accuracy was validated by analyzing IAEA-443 seawater sample. The low limits of detection of actinides allow this method to distinguish low level contamination.     

Assessment of ultrasound-assisted extraction as sample pre-treatment for the measurement of lead isotope ratios in marine biological tissues by multicollector inductively coupled plasma-mass spectrometry

In this work, ultrasound-assisted extraction (UAE) was evaluated as a sample preparation procedure for lead isotope ratio measurements in marine biological tissues by multicollector inductively coupled plasma-mass spectrometry. 20 mg of marine biological tissue and 1 mL of acid extractant were sonicated for 3 min at 60% ultrasound amplitude. Matrix separation was performed in the supernatant using a chromatographic exchange resin (Sr-Spec™). Total elimination of organic matter was achieved during the separation step. Microwave-assisted digestion and dry-ashing were used for comparative purposes. No significant differences were found in lead isotope ratios at 95% of confidence level. UAE emerges as an advantageous alternative to classical methods for sample preparation owing to its simplicity and rapidity (i.e. operation steps were reduced), low reagent consumption and low contamination risks.     

Nickel species analysis of human colonic tissue using liquid chromatography,gel electrophoresis and mass spectrometry

Studies to specify metal-binding species, such as metalloproteins that are present in trace amounts in colonic cell cytosol, using chromatographic separation methods in combination with inductively coupled plasma mass spectrometry (ICP-MS) as element-specific detection require an optimised sample preparation regarding the solubilisation of the proteins. Focus should be taken to avoid metal contamination, enzymatic digestion by different proteases and oxidation. In this article different sample preparation methods are studied to find a suitable method for the isolation and characterisation of Ni species previously found in cytosols from normal and malignant tissues of the human colon. The total Ni concentrations of the cytosols were determined as well as the total protein content. Thus, a Ni-containing protein could be isolated from cytosols of malignant human colonic tissues using size-exclusion chromatography with ICP-MS for element-specific detection. Ni-containing species in the molecular mass range from 10,000 to 20,000 Da were found and pre-concentrated. The determination of the molecular mass of the species was performed through online coupling of reversed-phase chromatography with electrospray ionisation quadrupole time-of-flight MS. Using identical chromatographic conditions and ICP-MS the detected protein was shown to contain Ni.     

Determination of amphetamine and methadone in human urine by microextraction by packed sorbent coupled directly to mass spectrometry: An alternative for rapid clinical and forensic analysis†

Speed and low cost, together with regulatory approval, are the most important requirements of clinical assays. Therefore, a fast and automated on‐line sample preparation method is essential for the routine analysis of biological samples. Microextraction by packed sorbent is an option for optimal sample preparation due to its easy automation, minimal requirements for the sample and elution solvent volumes, elimination of evaporation and reconstitution steps, and ability to integrate sample preparation and injection into one step. The use of effective sample preparation steps circumvents the need for chromatographic separation and therefore allows more rapid and less expensive sample analysis in clinical and forensic practice. Two biologically active compounds, amphetamine and methadone, were chosen as representative drugs of abuse for the application of microextraction by packed sorbent coupled directly to mass spectrometry. The developed method was validated, with the results confirming the suitability of the combination of these techniques for the analysis of biological samples. The approach was confirmed to be appropriate for use in clinical and forensic practice with regard to cost and time requirements for analysis.     

Increased productivity in quantitative bioanalysis using a monolithic column coupled with high-flow direct-injection liquid chromatography/tandem mass spectrometry

The feasibility of using a monolithic column as the analytical column in conjunction with high-flow direct-injection liquid chromatography/tandem mass spectrometry (LC/MS/MS) to increase productivity for quantitative bioanalysis has been investigated using plasma samples containing a drug and its epimer metabolite. Since the chosen drug and its epimer metabolite have the same selected reaction monitoring (SRM) transitions, chromatographic baseline separation of these two compounds was required. The results obtained from this monolithic column system were directly compared with the results obtained from a previously validated assay using a conventional C18 column as the analytical column. Both systems have the same sample preparation, mobile phases and MS conditions. The eluting flow rate for the monolithic column system was 3.2 mL/min (with 4:1 splitting) and for the C18 column system was 1.2 mL/min (with 3:1 splitting). The monolithic column system had a run time of 5 min and the conventional C18 column system had a run time of 10 min. The methods on the two systems were found to be equivalent in terms of accuracy, precision, sensitivity and chromatographic separation. Without sacrificing the chromatographic separation, sensitivity, accuracy and precision of the method, the reduced run time of the monolithic column method increased the sample throughput by a factor of two.     

Analytical procedures for the determination of emerging organic contaminants in plant material: A review

In this review, recent developments for the determination of emerging organic contaminants (EOCs) in plant tissues are discussed focusing on the homogenization, extraction and determination steps involved. Eleven classes of EOCs, namely antibiotics, analgesics, antiepileptics, antidepressants, antiseptics, plasticizers, fragrances, surfactants, flame retardants, and phenoxy acid herbicides, have been evaluated. Methods are critically reviewed in terms of all the analytical steps involved in the analysis, sampling and sample preparation, separation, and the detection strategies employed. The extraction from tissue samples was performed in most cases by solid–liquid extraction, whereas the clean-up was performed by solid-phase extraction. The identification and quantification of EOCs in crops from the agricultural field (i.e. parts per billion range) is usually performed by using mass spectrometry techniques such as single quadrupole mass spectrometry or tandem mass spectrometry coupled to high resolution chromatographic techniques. Enzyme-linked immunosorbent assays are more rarely used. New developments such as in vivo solid-phase microextraction (SPME) and the assessment of the bioavailability–bioaccesibility of contaminants in crops are shown. The main scope of this review is to critically evaluate the current state of the art of the analytical techniques used and to identify the research needs in the determination of EOCs in crops.     

Enhancing the selectivity of liquid chromatography–mass spectrometry by using trilinear decomposition on LC‐MS data: An application to three‐way calibration of coeluting analytes in human plasma

The high selectivities of liquid chromatography and mass spectrometry make liquid chromatography–mass spectrometry one of the most popular tools for quantitative analysis in complex chemical, biological, and environmental systems, while the potential mathematical selectivity of liquid chromatography–mass spectrometry is rarely investigated. This work discussed the mathematical selectivity of liquid chromatography–mass spectrometry by three‐way calibration based on the trilinear model, with an application to quantitative analysis of coeluting aromatic amino acids in human plasma. By the trilinear decomposition of the constructed liquid chromatography–mass spectrometry‐sample trilinear model and individual regression of the decomposed relative intensity versus concentration, the proposed three‐way calibration method successfully achieved quantitative analysis of coeluting aromatic amino acids in human plasma, even in the presence of uncalibrated interferent(s) and a varying background. This analytical method can ease the requirements for sample preparation and complete chromatographic separation of components, reduce the use of organic solvents, decrease the time of chromatographic separation, and increase the peak capacity of liquid chromatography–mass spectrometry. As a “green analytical method”, the liquid chromatography–mass spectrometry three‐way calibration method can provide a promising tool for direct and fast quantitative analysis in complex systems containing uncalibrated spectral interferents, especially for the situation where the coelution problem is difficult to overcome.     

Moving from fast to ballistic gradient in liquid chromatography/tandem mass spectrometry pharmaceutical bioanalysis: Matrix effect and chromatographic evaluations

The paper describes the steps taken by the authors to move from a fast to a ballistic gradient in routine liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of plasma samples from pharmacokinetic (PK) profiling of new chemical entities. The reduction of column dimensions from 50 x 4.6 mm to 30 x 2.1 mm followed by optimization of chromatographic separation led to a decrease in the typical runtime from 5 (fast) to 2 min (ballistic) using an API4000 tandem mass spectrometer in Turbo Ionspray mode for detection. Three analytical standards representing typical molecular structures from our sample repository were used to spike plasma from four different species (rat, dog, human and mouse). Two different approaches were used to evaluate matrix effect: post-column infusion and comparison of the peak areas of neat standards and standards spiked after extraction into different pools of plasma; the influence of PEG400 as a typical dosing vehicle was also considered. Two different protein precipitation procedures were taken into account for sample extraction prior to injection. Peak shape, width and height, selectivity and sensitivity of the method were taken into account for chromatographic evaluation. The ballistic method was successfully cross-validated with the conventional fast gradient chromatographic assay.     

兴奋剂中利尿剂的检测方法

利尿剂是国际奥委会医学委员会禁止使用的一类兴奋剂。该文对兴奋剂中利尿剂的检测方法进行了综述,重点阐述了样品的处理方法,HPLC－GC－MS的检测方法及各种衍生化方法。     

Extractive liquid-liquid spectrophotometric procedure for the determination of thiocyanate ions employing the ion pair reagent amiloride monohydrochloride

The paper describes analytical methods developed for the production date determination of uranium-based nuclear materials by the measurement of 230Th/234U isotope ratio. An improved sample preparation method for the destructive analysis involving extraction chromatographic separation with TEVA resin was applied prior to the measurement by isotope dilution inductively coupled plasma sector field mass spectrometry (ICP-SFMS). The results obtained were compared with the direct, quasi-non-destructive measurement using laser ablation ICP-SFMS technique for age determination. The advantages and limitations of both methods are discussed.     

Guide to Semi-Quantitative Non-Targeted Screening Using LC/ESI/HRMS

Non-targeted screening (NTS) with reversed phase liquid chromatography electrospray ionization high resolution mass spectrometry (LC/ESI/HRMS) is increasingly employed as an alternative to targeted analysis; however, it is not possible to quantify all compounds found in a sample with analytical standards. As an alternative, semi-quantification strategies are, or at least should be, used to estimate the concentrations of the unknown compounds before final decision making. All steps in the analytical chain, from sample preparation to ionization conditions and data processing can influence the signals obtained, and thus the estimated concentrations. Therefore, each step needs to be considered carefully. Generally, less is more when it comes to choosing sample preparation as well as chromatographic and ionization conditions in NTS. By combining the positive and negative ionization mode, the performance of NTS can be improved, since different compounds ionize better in one or the other mode. Furthermore, NTS gives opportunities for retrospective analysis. In this tutorial, strategies for semi-quantification are described, sources potentially decreasing the signals are identified and possibilities to improve NTS are discussed. Additionally, examples of retrospective analysis are presented. Finally, we present a checklist for carrying out semi-quantitative NTS.     

Congener-specific determination of dioxins and related compounds by gas chromatography coupled to LRMS,HRMS, MS/MS and TOFMS

Their characteristics as persistent organic pollutant and their toxicity (2,3,7,8-TCDD is named as a known human carcinogen) make the dioxins and related compounds a focus of interest in environmental analytical chemistry. In view of the widespread distribution of dioxins in the environment, these compounds must be monitored in several matrices, such as air, effluents, soil, sludge and biological samples. The analytical methodologies are especially difficult owing to the complexity of the mixtures of congeners (210 PCDD/Fs and 209 PCBs) and to the low detection limits required (ppb to ppq). Moreover, time-consuming sample preparation steps are needed owing to the presence of a large number of interfering compounds. The different toxicity of each congener requires the development of congener specific methods. This review of trace dioxin determination by mass spectrometry (MS) includes sample preparation and chromatographic separation. In this Special Feature, the use of different MS techniques such as low-resolution MS (LRMS) and high-resolution MS (HRMS) is discussed in terms of selectivity and sensitivity. The performances of other MS techniques, such as tandem MS (MS/MS) and time-of-flight MS (ToFMS), are compared. Quantification techniques, especially the isotopic dilution method, are also discussed. Conclusions and future perspectives are outlined.     

Sampling hazelnuts for aflatoxin: uncertainty associated with sampling, sample preparation, and analysis

The variability associated with the aflatoxin test procedure used to estimate aflatoxin levels in bulk shipments of hazelnuts was investigated. Sixteen 10 kg samples of shelled hazelnuts were taken from each of 20 lots that were suspected of aflatoxin contamination. The total variance associated with testing shelled hazelnuts was estimated and partitioned into sampling, sample preparation, and analytical variance components. Each variance component increased as aflatoxin concentration (either B1 or total) increased. With the use of regression analysis, mathematical expressions were developed to model the relationship between aflatoxin concentration and the total, sampling, sample preparation, and analytical variances. The expressions for these relationships were used to estimate the variance for any sample size, subsample size, and number of analyses for a specific aflatoxin concentration. The sampling, sample preparation, and analytical variances associated with estimating aflatoxin in a hazelnut lot at a total aflatoxin level of 10 ng/g and using a 10 kg sample, a 50 g subsample, dry comminution with a Robot Coupe mill, and a high-performance liquid chromatographic analytical method are 174.40, 0.74, and 0.27, respectively. The sampling, sample preparation, and analytical steps of the aflatoxin test procedure accounted for 99.4, 0.4, and 0.2% of the total variability, respectively.     

Coupled SFE/SFC/GC for the trace analysis of pesticide residues in fatty food samples

An on-line SFE-chromatographic system, where SFE has been coupled with SFC and GC, was developed and utilized for trace analyses of organochlorine and organophosphorus pesticide residues from gram-sized complex sample matrices, such as chicken fat, ground beef, and lard. The SFE process and chromatographic techniques were instrumentally integrated for efficient and automated on-line analysis, having minimal sample handling between the sample preparation and separation steps. A cleanup step, incorporating packed column SFC, allowed the fractionation of relatively small-sized, non-polar pesticides from the co-extracted fatty materials. This permitted final high-resolution separation of analytes on a capillary GC column. Detection of pesticides was accomplished using selective electron-capture and nitrogen-phosphorus detectors. Pesticide concentrations determined with the on-line system were accurate and reproducible, for fatty samples containing both fortified and incurred pesticides. This method, utilizing supercritical carbon dioxide, was considerably faster and less laborious than the conventional analytical procedures based on liquid extraction.     

Effect of nebulizer/spray chamber interfaces on simultaneous,axial view inductively coupled plasma optical emission spectrometry for the direct determination of As and Se species separated by ion exchange high-performance liquid chromatography

Different nebulizer/expansion chamber combinations were evaluated to assess their performance for sample introduction in the direct coupling with an axial view inductively coupled plasma multielement spectrometer for on-line determination of As and Se species previously separated by ion exchange–high performance liquid chromatography. The column effluents were injected into the plasma without prior derivatization. The instrument operation software was adapted for data acquisition and processing to allow multi-wavelength recording of the transient chromatographic peaks. After optimization of the chromatographic operating conditions, separation of mixtures of inorganic As and Se species, and of inorganic and two organic As species (monomethylarsonic and dimethylarsinic acids), was achieved with excellent resolution. Species discrimination from mixtures of As and Se oxyanions was further improved by the simultaneous element detection at specific analytical wavelengths. Three nebulizers and three spray chambers, employed in seven combinations, were tested as interfaces. Concentric nebulizers associated to a glass cyclonic chamber appear most suitable regarding sensitivity and signal to noise ratio. Measured element detection limits (3 σ) were around 10 ng ml^− 1 for all the species considered, making the method a viable alternative to similar procedures that employ volatile hydride generation previous to sample injection into the plasma. Analytical recoveries both for inorganic and organic species ranged between 92 and 107%. The method was demonstrated to be apt for the analysis of surface waters potentially subjected to natural contamination with arsenic.     

Surface swabbing technique for the rapid screening for pesticides using ambient pressure desorption ionization with high-resolution mass spectrometry

A rapid screening method for pesticides has been developed to promote more efficient processing of produce entering the United States. Foam swabs were used to recover a multiclass mixture of 132 pesticides from the surfaces of grapes, apples, and oranges. The swabs were analyzed using direct analysis in real time (DART) ionization coupled with a high‐resolution Exactive Orbitrap? mass spectrometer. By using a DART helium temperature gradient from 100–350°C over 3 min, a minimal separation of analytes based on volatility differences was achieved. This, combined with the Exactive's mass resolution of 100 000, allowed the chromatographic step, along with the typical compositing and extraction steps associated with gas chromatography/mass spectrometry (GC/MS) or liquid chromatography/mass spectrometry (LC/MS) approaches, to be eliminated. Detection of 86% of the analytes present was consistently achieved at levels of 2 ng/g (per each apple or orange) and 10 ng/g (per grape). A resolution study was conducted with four pairs of isobaric compounds analyzed at a mass resolution of 100 000. Baseline separation was achieved with analyte ions differing in mass by 25 ppm and analyte ions with a mass difference of 10 ppm were partially resolved. In addition, field samples that had undergone traditional sample preparation using QuEChERS (quick, easy, cheap, rugged, and safe) were analyzed using both LC/MS and DART‐MS and the results from the two techniques were found to be comparable in terms of identification of the pesticides present. The use of swabs greatly increased sample throughput by reducing sample preparation and analysis time. Published in 2010 by John Wiley & Sons, Ltd.     

Ion chromatography inductively coupled plasma mass spectrometry (IC-ICP-MS) and radiometric techniques for the determination of actinides in aqueous leachate solutions from uranium oxide

The choice of the analytical method for the determination of actinide isotopes in leachate solutions has to be made considering several parameters: detection limit for each isotope, sample preparation procedure in terms of duration and complexity, counting time and interferences. A leachate solution obtained by keeping a pellet of UO2 doped with 238Pu in contact with distilled water was investigated for the content of U and Pu isotopes by radiometric methods (alpha-, gamma-spectrometry and liquid scintillation counting). The results of the radiometric methods were compared with those obtained from the analysis performed by inductively coupled plasma mass spectrometry on-line to a system for chromatographic separation (IC-ICP-MS). The comparison confirmed that IC-ICP-MS is a powerful method for the detection of long-lived radionuclides. The radiometric methods have a detection limit two orders of magnitude lower than IC-ICP-MS in the case of short-lived radioisotopes mostly due to the low background in the detector. On the other hand, the sample preparation and the analysis duration are more time-consuming compared to IC-ICP-MS; moreover, not all isotopes can be determined by using only one radiometric technique.     

A novel on-line solid-phase extraction approach integrated with a monolithic column and tandem mass spectrometry for direct plasma analysis of multiple drugs and metabolites

An on-line solid-phase extraction liquid chromatography/tandem mass spectrometry (SPE LC/MS/MS) assay using a newly developed SPE column and a monolithic column was developed and validated for direct analysis of plasma samples containing multiple analytes. This assay was developed in an effort to increase bioanalysis throughput and reduce the complexity of on-line SPE LC/MS/MS systems. A simple column-switching configuration that requires only one six-port valve and one HPLC pumping system was employed for on-line plasma sample preparation and subsequent gradient chromatographic separation. The resulting analytical method couples the desired sensitivity with ease of use. The method was found to perform satisfactorily for direct plasma analysis with respect to assay linearity, specificity, sensitivity, precision, accuracy, carryover, and short-term stability of an eight-analyte mixture in plasma. A gradient LC condition was applied to separate the eight analytes that cannot be distinctly differentiated by MS/MS. With a run time for every injection of 2.8 min, a minimum of 300 direct plasma injections were made on one on-line SPE column without noticeable changes in system performance. Due to the ruggedness and simplicity of this system, generic methods can be easily developed and applied to analyze a wide variety of compounds in a high-throughput manner without laborious off-line sample preparation.     

Recent advances in metal‐organic frameworks and covalent organic frameworks for sample preparation and chromatographic analysis

In the field of analytical chemistry, sample preparation and chromatographic separation are two core procedures. The means by which to improve the sensitivity, selectivity and detection limit of a method have become a topic of great interest. Recently, porous organic frameworks, such as metal‐organic frameworks (MOFs) and covalent organic frameworks (COFs), have been widely used in this research area because of their special features, and different methods have been developed. This review summarizes the applications of MOFs and COFs in sample preparation and chromatographic stationary phases. The MOF‐ or COF‐based solid‐phase extraction (SPE), solid‐phase microextraction (SPME), gas chromatography (GC), high‐performance liquid chromatography (HPLC) and capillary electrochromatography (CEC) methods are described. The excellent properties of MOFs and COFs have resulted in intense interest in exploring their performance and mechanisms for sample preparation and chromatographic separation.     

Solid-phase microextraction: a powerful sample preparation tool prior to mass spectrometric analysis

Sample preparation is an essential step in analysis, greatly influencing the reliability and accuracy of resulted the time and cost of analysis. Solid-Phase Microextraction (SPME) is a very simple and efficient, solventless sample preparation method, invented by Pawliszyn in 1989. SPME has been widely used in different fields of analytical chemistry since its first applications to environmental and food analysis and is ideally suited for coupling with mass spectrometry (MS). All steps of the conventional liquid-liquid extraction (LLE) such as extraction, concentration, (derivatization) and transfer to the chromatograph are integrated into one step and one device, considerably simplifying the sample preparation procedure. It uses a fused-silica fibre that is coated on the outside with an appropriate stationary phase. The analytes in the sample are directly extracted to the fibre coating. The SPME technique can be routinely used in combination with gas chromatography, high-performance liquid chromatography and capillary electrophoresis and places no restriction on MS. SPME reduces the time necessary for sample preparation, decreases purchase and disposal costs of solvents and can improve detection limits. The SPME technique is ideally suited for MS applications, combining a simple and efficient sample preparation with versatile and sensitive detection. This review summarizes analytical characteristics and variants of the SPME technique and its applications in combination with MS.