Multi-element analysis of urine by inductively coupled plasma orthogonal acceleration time-of-flight mass spectrometry

This work shows the analytical potential of inductively coupled plasma orthogonal-acceleration time-of-flight mass spectrometry (ICP-OA-TOF-MS) for rapid, simultaneous, and reliable determination of more than 50 elements at ultra-trace levels in urine. Under optimum instrumental conditions, after a 10-fold sample dilution step, and by using Rh as an internal standard, ICP-OA-TOF-MS also enables the determination of elements whose assay is more diffcult when using conventional quadrupole instruments. This is confirmed by the analysis of commercially available reference urine samples and/or by analytical recoveries study and isotope ratio based determination of accuracies. On the other side, the interference resulting from polyatomic carbon, chlorine, or various sulfur species does not allow the determination of elements such as Cr, Fe, V, Se and As without a mathematical correction.

Identification and quantification of glutathione adducts of clozapine using ultra-high-performance liquid chromatography with orthogonal acceleration time-of-flight mass spectrometry and inductively coupled plasma mass spectrometry

The application of sulphur-specific detection via ultra-performance liquid chromatography coupled to inductively coupled plasma mass spectrometry (UPLC/ICPMS) to detect and quantify the glutathione (GSH)-adducts produced via the in vitro formation of reactive metabolites is demonstrated. The adducts were formed in human liver microsomes supplemented with unlabelled GSH for clozapine. The calculation of adduct concentration was performed via comparison of the peak areas to calibration curves constructed from omeprazole, a sulphur-containing compound over the range of 0.156 to 15.62 μM of sulphur with a detection limit of 1.02 ng of sulphur on-column. Identification of the adducts was performed using conventional UPLC/time-of-flight (TOF)-MS with the calculation of clozapine intrinsic clearance carried out by high-performance liquid chromatography/tandem mass spectrometry (HPLC/MS/MS). The use of ICPMS in this way appears to offer a novel, rapid and sensitive means of determining the quantity of GSH conjugates with the combined adducts producing 0.9 μM of reactive metabolite out of a total of 3.5 μM of metabolites. The GSH adduct therefore represents 26% of this total produced as a result of the metabolism of drug to reactive species.     

Directly coupled liquid chromatography with inductively coupled plasma mass spectrometry and orthogonal acceleration time-of-flight mass spectrometry for the identification of drug metabolites in urine: application to diclofenac using chlorine and sulfur detection

We report the application of high-performance liquid chromatography (HPLC) linked to inductively coupled plasma mass spectrometry (ICPMS) and orthogonal acceleration time-of-flight mass spectrometry (oa-TOFMS) for the identification of phase I and II urinary metabolites of diclofenac. The metabolites were separated by reversed-phase HPLC monitored with a UV diode array detector (UV-DAD) after which 90% of the eluent was directed to an ICPMS source, with the remainder going to an oa-TOF mass spectrometer. Compounds containing (35)Cl, (37)Cl and (32)S were detected specifically using ICPMS and identified by oa-TOFMS. The metabolites detected and identified in this way included glucuronic acid and sulfate conjugates, mono- and dihydroxylated and free diclofenac. In addition a previously unreported in vivo metabolite, an N-acetylcysteinyl conjugate of diclofenac, was also characterised. This is the first application of the combination of HPLC/UV-DAD/ICPMS/oa-TOFMS for the investigation of the metabolic fate of chlorinated xenobiotics by direct biofluid analysis.     

Arsenic speciation by coupling high-performance liquid chromatography with inductively coupled plasma mass spectrometry

Summary An ICP-MS detector in combination with HPLC has been evaluated for the analysis of six arsenic compounds. The influence of the presence of an organic modifier in the mobile phase on arsenic response and the quality parameters of the analysis are discussed. Detection limits for arsenic species under study range from 10 to 30 pg. The determination of arsenic compounds in solutions simulating fish or sediment extracts has been used to demonstrate the applicability of this technique.     

Quantification of trace elements in human serum fractions by liquid chromatography and inductively coupled plasma mass spectrometry

On‐line coupling of LC and ICP‐MS has been used for fractionation and detection of species of Cu, Fe, I, Se and Zn in human serum. It has been shown that anion exchange chromatography provided better separation capability (both intra‐ and inter‐element) than size‐exclusion chromatography. The mobile phases for ion exchange chromatography consisted of Tris–HNO₃ buffer and ammonium salt (nitrate, acetate or formate). Formate was found to be the best mobile phase counter ion, enabling good chromatographic separation, and is acceptable for mass spectrometry too. The quantitative evaluation of element concentrations adhering to individual fractions was performed by the peak area normalization method. The repeatability of results ranged from 3 to 15% (depending on the element concentration level) and represented the main part of the result uncertainty. The accuracy of Cu and Zn fraction determinations was confirmed by comparison with the isotope dilution technique. Copyright © 2006 John Wiley & Sons, Ltd.     

Speciation of arsenic compounds by coupling high-performance liquid chromatography with inductively coupled plasma mass spectrometry

There is considerable evidence that toxicity and physiological behavior of arsenic depends on its chemical forms. Arsenic speciation became therefore the subject of increasing interest in recent years. A sensitive method for the determination of arsenic species has been developed. The proposed procedure involves the use of high-performance liquid chromatography and inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Six arsenic compounds were separated by anion-exchange chromatography with isocratic elution using tartaric acid as mobile phase with an elution order: arsenocholine, arsenobetaine, dimethylarsinic acid, methylarsonic acid, arsenous acid and arsenic acid. The chromatographic parameters affecting the separation of the arsenic species were optimized. Analytical characterization of the method has been realized with standard solutions. The detection limits for six arsenic compounds were from 0.04 to 0.6 g/L as As element. The repeatability (expressed by R.S.D) was better than 7% for all investigated compounds. The HPLC-ICP-MS system was successfully applied to the determination of arsenic compounds in environmental and biological samples in g/L level.     

Determination of selenium species in human urine by high performance liquid chromatography and inductively coupled plasma mass spectrometry

A method developed to determine organic and inorganic selenium species in human urine samples is presented in detail. After a simple sample treatment based on elimination of non-charged organic compounds, selenium species were separated by high performance liquid chromatography (HPLC) on a Spherisorb 5 ODS/AMINO column using two different chromatographic conditions: phosphate buffers at pH 2.8 and 6.0. Detection was carried out using an on-line inductively coupled plasma mass spectrometer (ICP-MS). Trimethylselenonium ion and two unknown selenium species in urine samples were found. Selenium species were shown to have stability problems, with the maximum allowed storage time of 1 week.     

Ultra-performance liquid chromatography coupled to quadrupole-orthogonal time-of-flight mass spectrometry

Ultra-performance liquid chromatography (UPLC) utilizes sub-2 microm particles with high linear solvent velocities to effect dramatic increases in resolution, sensitivity and speed of analysis. The reduction in particle size to below 2 microm requires instrumentation that can operate at pressures in the 6000-15,000 psi range. The typical peak widths generated by the UPLC system are in the order of 1-2 s for a 10-min separation. In the present work this technology has been applied to the study of in vivo drug metabolism, in particular the analysis of drug metabolites in bile. The reduction in peak width significantly increases analytical sensitivity by three- to five-fold, and the reduction in peak width, and concomitant increase in peak capacity, significantly reduces spectral overlap resulting in superior spectral quality in both MS and MS/MS modes. The application of UPLC/MS resulted in the detection of additional drug metabolites, superior separation and improved spectral quality.     

高效液相色谱-电感耦合等离子体质谱联用检测食品中的五种硒形态

建立了高效液相色谱-电感耦合等离子体质谱(HPLC-ICP-MS)联用检测硒酸盐(SeVI)、亚硒酸盐(SeIV)、硒代蛋氨酸(SeMet)、硒代胱氨酸(SeCys2)和硒代乙硫氨酸(SeEt)的方法。采用Hamilton PRP X-100色谱柱（250 mm×4.6 mm, 5 μm）,使用5 mmol/L的柠檬酸溶液(pH 4.5)作为流动相,电感耦合等离子体质谱(ICP-MS)检测,在21 min内可以完全分离5种硒形态。各形态硒的线性相关系数均大于0.9995, SeVI、SeIV、SeMet、SeCys2、SeEt的检出限分别为0.4、0.4、5.6、0.9、1.2 μg/L。探讨了不同提取方法的提取效果,鲜蘑菇和猪肉样品加标回收实验表明,对水溶性良好的无机硒和硒代蛋氨酸而言,采用柠檬酸溶液提取的效果非常好,SeIV和SeVI的回收率均在100%左右,SeMet的回收率为85.0%～95.3%;用蛋白酶水解提取,SeCys2和SeEt的回收率为79.9%～91.5%。该方法可完全满足食品中这5种硒形态的准确定量分析。     

Characterization of metabolism of (+)-praeruptorin B and (+)-praeruptorin E in human and rat liver microsomes by liquid chromatography coupled with ion trap mass spectrometry and time-of-flight mass spectrometry

Peucedani Radix is a Chinese medicinal herb noted for its effects on treatments of respiratory and pulmonary disorders. As a part of a systematic pharmacokinetic evaluation of the herb in our laboratory, the present study investigated, for the first time, the metabolic profile of (+)-praeruptorin B (dPB) and (+)-praeruptorin E (dPE), two main bioactive constituents of Peucedani Radix in pooled liver microsomes of rats (RLMs) and humans (HLMs). dPE was eliminated faster than dPB in both species. The incubation of dPB with RLMs and HLMs resulted in eight (B1-B8) and nine (B1-B9) metabolites, respectively, while both RLMs and HLMs converted dPE into 13 metabolites (E1-13). Structures of all the metabolites were proposed through comparing their mass data obtained via tandem mass spectrometry on an MSD ion trap system (IT-MS/MS) coupled with high-resolution mass measurement by time-of-flight mass spectrometry (TOF-MS) with those of the respective parent compound. B1 and E1 were unambiguously identified as (-)-cis-khellactone. The formations of all the metabolites were NADPH-dependent. Oxidation and hydrolysis were demonstrated to be two predominant metabolic pathways of dPB and dPE. Oxidation initiated at either the C-3' or C-4' substituent, while hydrolysis only started from the C-3' substituent. Fragmentation of all metabolites followed similar pathways to those of the parent pyranocoumarins. The information on metabolic properties of dPB and dPE and the mass fragmentation profiles of their metabolites obtained in the present study will aid in characterization of metabolic profiles of other angular-type pyranocoumarins and further investigation of in vivo fates of these pyranocoumarins and the herb.     

Sensitive sulphur-specific detection of omeprazole metabolites in rat urine by high-performance liquid chromatography/inductively coupled plasma mass spectrometry

The use of high-performance liquid chromatography/inductively coupled plasma mass spectrometry (HPLC/ICPMS) with sulphur-specific detection was investigated as a method for obtaining metabolite profiles for the drug omeprazole administered as a 1:1 mixture of (32)S- and (34)S-labelled material. Analysis based on the monitoring of the chromatographic eluent at either m/z 32 or 34 was not successful due to insufficient sensitivity caused by interferences from polyatomic ions. However, reaction of sulphur with oxygen in the hexapole collision cell, combined with monitoring at m/z 48 (for (32)S) or m/z 50 (for (34)S), provided a facile method for metabolite profiling. Detection of m/z 48 was superior in sensitivity to detection of m/z 50.     

Characterization of constituents in Sini decoction and rat plasma by high-performance liquid chromatography with diode array detection coupled to time-of-flight mass spectrometry

A high‐performance liquid chromatography with diode‐array detection coupled to time‐of‐flight mass spectrometry (HPLC/DAD/TOFMS) method was established to clarify the chemical composition of Sini decoction (SND) and rat plasma after oral administration of SND. With dynamic adjustment of fragmentor voltage in TOFMS, an efficient transmission of the ions was achieved to obtain the best sensitivity for providing the molecular formula for each analyte and abundant fragment ions for structural information. By accurate mass measurements within 5 ppm error for each molecular ion and subsequent fragment ions, 53 compounds including diterpenoid alkaloids, flavonoids, triterpenoids and gingerol‐related compounds were identified in SND. Major compounds identified from SND were further assigned in the three individual herbs. After oral administration of SND, 33 compounds and five metabolites in rat plasma were detected and identified by comparing and contrasting the compounds measured in SND with those in the plasma samples by HPLC/DAD/TOFMS. The results provided helpful chemical information for further pharmacology and active mechanism research on SND. Copyright © 2010 John Wiley & Sons, Ltd.     

Determination of arsenic species by inductively coupled plasma mass spectrometry with ion chromatography

Five arsenic species, trimethylarsine oxide, dimethylarsenic acid, monomethylarsonic acid, arsenobetaine and sodium arsenite, in urine were analysed by inductively coupled plasma mass spectrometry with ion chromatography (IC ICP MS). Since the toxicities of different arsenic compounds are different, speciation of arsenic compounds is very important in the investigation of metabolisms. In this paper, we applied ion chromatography (IC) as a separation device and inductively coupled plasma mass spectrometry (ICP MS) as a detection device. For separation of the five arsenic compounds, an anion-exchange column and, as mobile phase, tartaric acid were used. The eluent from the IC column was introduced directly into the nebulizer of the ICP MS and analysed at 75 amu. Detection limits were from 4 to 9 pg as arsenic.     

微波灰化-高效液相色谱-电感耦合等离子体质谱(ICP-MS)法测定茶叶中的铬酸铅

为了准确测定茶叶中铬酸铅的含量,为市场监管提供判断依据,本文建立了微波灰化-高效液相色谱-电感耦合等离子体质谱仪测定茶叶中铬酸铅的方法。茶叶样品经微波灰化仪在500 ℃的条件下,灰化50 min后,用0.25 mol·L-1的NaOH和0.14 mol·L-1的Na2CO3混合碱性提取液在90 ℃-95 ℃温度下不间断搅拌提取10 min,提取液经色谱柱分离后,用ICP-MS测定52Cr。研究表明该方法在5.00 μg·L-1-500 μg·L-1范围内,线性良好,相关系数为0.9998,方法检出限低至2.5 mg·kg-1,三水平加标回收率为91.30 %～95.33 %,精密度在1.14 %～1.99 %之间。与电炉灼烧茶叶相比,微波灰化茶具有检出限低,精密度高,准确度良好等特性,能够满足茶叶中铬酸铅的测定。 关键词 微波灰化;高效液相色谱-电感耦合等离子体质谱法;铬酸铅;茶叶     

Determination of sunitinib in human plasma using liquid chromatography coupled with mass spectrometry

An original method based on liquid chromatography with single quadrupole electrospray ionization mass spectrometry was developed for the determination of sunitinib in human plasma. The quantitation limit of the method at 0.10 ng/mL is comparable to that of tandem mass spectrometry assays. The handling of all solutions containing sunitinib was performed under low‐intensity red light to avoid the isomerization of sunitinib and enable quantitation using a single peak. Liquid–liquid extraction with a mixture of n‐hexane/isopropanol (90:10 v/v) allowed recoveries at the level of 70%. Measurements were performed using a Zorbax SB‐C₁₈ column (3.0 mm × 150 mm, 3.5 μm) and isocratic elution with (A) 0.1% aqueous formic acid and (B) acetonitrile/methanol (80:20 v/v) in an A/B ratio of 55:45 at 35°C. Under these conditions, sunitinib is eluted at 3.8 min in 6 min of the total run time. The linearity of the calibration curve ranges from 0.10 to 150 ng/mL. The baseline separation of sunitinib and its primary metabolite, N‐des‐ethyl sunitinib (SU12662), as well as sharp peak shapes, suggest a possibility of extending the applied methodology to the quantitative determination of both compounds. Isotopically labeled sunitinib was used as the internal standard. All required validation tests met the acceptance criteria and proved the method's reliability and robustness. The method may be conveniently applied to study the pharmacokinetics of sunitinib in humans.     

High-performance liquid chromatography-UV diode array,inductively coupled plasma mass spectrometry (ICMPS) and orthogonal acceleration time-of-flight mass spectrometry (oa-TOFMS) applied to the simultaneous detection and identification of metabolites of 4-bromoaniline in rat urine

Summary The paper describes the role and tasks of environmental analysis and monitoring. It emphasises the leading role played by gas chromatography, especially when coupled with suitable sample preparation. This is demonstrated by some literature evidence and mainly by the author's original work on the design of sample preparation apparatus and development of GC-based methods of determination of a wide variety of organic pollutants in environmental samples. A typical example is the physical speciation of PAHs and PCBs in river environment with the use of a home-made filtration vessel coupled with SPE cartridges to prepare samples for GC-MS analysis; thin layer head space with self-generation of aqueous concentrate to prepare humane urine samples for DAI (direct aqueous injection)-GC-ECD analysis for the content of volatile chloro-organic compounds; studies on capillary denuders in sampling organic air pollutants; passive dosimeters in indoor air quality measurements; design and application of thermal desorbers for the introduction of analytes into GC columns and modification of a speciation analyser for organometalic environmental pollutants. Presented at Balaton Symposium '01 on High-Performance Separation Methods, Siófok, Hungary, September 2–4, 2001     

Quantitative determination of DNA adducts using liquid chromatography/electrospray ionization mass spectrometry and liquid chromatography/high-resolution inductively coupled plasma mass spectrometry

The quantitative determination of nucleotides from DNA modified by styrene oxide is described using a combination of inductively coupled plasma high-resolution mass spectrometry (ICP-HRMS) and electrospray ionization mass spectrometry (ESI-MS), both interfaced to reversed-phase high-performance liquid chromatography (HPLC). LC/ICP-MS (resolution > 1500 to discriminate against 15N16O+ and 14N16OH+) was employed to determine quantitatively the content of modified nucleotides in standard solutions based on the signal of phosphorus; phosphoric acid served as an internal standard. By means of the standard addition technique the sensitivity of the LC/ESI-MS approach was subsequently determined. Since a comparison of UV, ICP and ESI-MS data suggested that in ESI-MS the ionization efficiency of the adducts is identical within the error limits, quantitative determination of all adducts is possible. For LC/ESI-MS with single ion monitoring, the detection limit for styrene oxide adducts of nucleotides was determined to be 20 pg absolute or 14 modified in 10(8) unmodified nucleotides in a 5 micrograms DNA sample, which comes close to the best methods available for the detection of chemical modifications in DNA.     

Spontaneous and deflected drift-trajectories in orthogonal acceleration time-of-flight mass spectrometry

Orthogonal acceleration is a method for gating ions from an ion beam into a time-of-flight (TOF) mass spectrometer. The technique involves a pulsed electric field to apply acceleration directed orthogonally to an ion beam. This approach is useful for coupling continuous ion sources to TOF mass analyzers. Most instruments of this type, which have been described in the literature, use steering electrodes after the orthogonal acceleration step. Those velocity components of ions originating from the ion beam velocity are minimized so that the deflected drift-trajectory is parallel to a transverse flight tube. In an alternative geometry the ion beam velocity is conserved and the drift-trajectory after the orthogonal acceleration step is spontaneous. The differences between the space-time focusing ability with spontaneous and deflected drift-trajectories are discussed and investigated. Trajectory calculations indicate that deflection fields placed after the orthogonal acceleration step distort the ion packet because, in this geometry, the flight-time to the detector is dependent on the position that the ions enter the steering optics. Increasing the duty-cycle efficiency by sampling longer sections of the continuous ion beam leads to a degradation of resolving power. Employing a spontaneous drift-trajectory after orthogonal acceleration provides the advantage that the arrival time spread for isobaric ions is, in principle, independent of the length of the ion beam sampled. The major implication of these findings is that simultaneously optimized sensitivity and resolving power may not be achievable with the deflected drift-trajectory instruments. The calculations are in agreement with results from the published data of a number of groups who have built instruments based on the orthogonal acceleration principle.     

Arsenic and its speciation analysis using high-performance liquid chromatography and inductively coupled plasma mass spectrometry

It is known that arsenic has different toxicological properties dependent upon both its oxidation state for inorganic compounds, as well as the different toxicity levels exhibited for organic arsenic compounds. The field of arsenic speciation analysis has grown rapidly in recent years, especially with the utilization of high-performance liquid chromatography (HPLC) coupled to inductively coupled plasma mass spectrometry (ICP-MS), a highly sensitive and robust detector system. Complete characterization of arsenic compounds is necessary to understand intake, accumulation, transport, storage, detoxification and activation of this element in the natural environment and living systems. This review describes the essential background and toxicity of arsenic in the environment, and more importantly, some currently used chromatographic applications and sample handling procedures necessary to accurately detect and quantify arsenic in its various chemical forms. Applications and work using only HPLC-ICP-MS for arsenic speciation of environmental and biological samples are presented in this review.     

Metabolic profiling of yeast culture using gas chromatography coupled with orthogonal acceleration accurate mass time-of-flight mass spectrometry: Application to biomarker discovery

Yeast and yeast cultures are frequently used as additives in diets of dairy cows. Beneficial effects from the inclusion of yeast culture in diets for dairy mammals have been reported, and the aim of this study was to develop a comprehensive analytical method for the accurate mass identification of the ‘global’ metabolites in order to differentiate a variety of yeasts at varying growth stages (Diamond V XP, Yea-Sacc and Levucell). Microwave-assisted derivatization for metabolic profiling is demonstrated through the analysis of differing yeast samples developed for cattle feed, which include a wide range of metabolites of interest covering a large range of compound classes. Accurate identification of the components was undertaken using GC-oa-ToFMS (gas chromatography-orthogonal acceleration-time-of-flight mass spectrometry), followed by principal component analysis (PCA) and orthogonal partial least squares discriminant analysis (OPLS-DA) for data reduction and biomarker discovery. Semi-quantification (fold changes in relative peak areas) was reported for metabolites identified as possible discriminative biomarkers (p-value <0.05, fold change >2), including d-ribose (four fold decrease), myo-inositol (five fold increase), l-phenylalanine (three fold increase), glucopyranoside (two fold increase), fructose (three fold increase) and threitol (three fold increase) respectively.