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A broadband collision-induced dissociation (bbCID) fragmentation mode was proposed for liquid chromatography-mass spectrometric targeted analysis of tryptic peptides obtained from proteins in samples of decoration paint coating. In this approach, a mass spectrometric dataset contains the information on the parent and all fragment ions. This maintains a balance between the quantity of simultaneously acquired data and the sensitivity of the method, which is beneficial under coupling with analytical chromatography. In this study, characteristic peptides were selected for casein, ovalbumin, and collagen, which are the most commonly used binder proteins in the artworks. A simplified sample preparation protocol including only protein extraction and trypsinization was tested and successfully implemented. The combination of analytical chromatography with bbCID MS technique is a lower cost alternative to the use of high-end nano-LC-MS approaches in the investigation of cultural heritage objects of regional or local importance, e.g., prior to and/or during restoration works. It was demonstrated that, for the paint coating samples, the required level of sensitivity could be acquired through the data-independent MS/MS strategy. The proposed approach was tested on a sample obtained during the restoration work at the Gromov cottage in the Lopukhin Garden (middle of the XIX century). As a result, the main protein component, collagen, was identified using 6 characteristic peptides, which may indicate the use of gelatin-based glue. For instance, the identification of the peptide GVQGPPoxGPAGPR of the incoming collagen composition α-1 was undertaken by three parameters: m/z of the precursor ion of 553.2910, m/z of the fragment ion y9 of 821.4238, and retention time of 1.9 min.

History of the development of a hollow cathode as a version of a discharge cell for optical emission spectroscopy and glow-discharge mass spectrometry is discussed. Special attention was paid to the contribution of colleagues from the Department of Analytical Chemistry at the St. Petersburg State University to research, development, and implication of analytical systems with glow discharge, including discharge in a hollow cathode. New analytical methods developed on its basis and versions of their application are described, covering direct elemental and isotopic analysis, depth profiling, determination of hardly ionized elements in solid-phase samples of different conductivity, and the determination of volatile organic compounds in the air.

Organophosphates’ toxic effect causes covalent binding to serine-198 in the active site of human plasma butyrylcholinesterase (BChE) with loss of enzymatic function (covalent inhibition). Mass spectrometric detection of modified FGESAGAAS peptide at the active site is a powerful exposure biomarker tool. The aim of this study was to develop mass spectrometry-based method for BChE adduct formation screening, avoiding the use of standard peptides. Immunomagnetic separation of proteins from plasma was optimized. Commercially available anti-butyrylcholinesterase monoclonal antibodies, immobilized on magnetic beads, resulted in stable and reusable affinity sorbent. The method was tested on horse serum BChE and real human plasma from healthy donors, treated with Russian VX (VR). The BChE isolated from blood plasma was digested with pepsin and analyzed by liquid chromatography tandem mass spectrometry (LC-MS/MS). The method was evaluated by using synthetic peptides and by comparison to the enzymatic activity Ellman's assay. The minimum concentration of VR exposure, resulting in detectable VR-adduct, was 0.2 ng/mL, which corresponded to the relative BChE inhibition of less than 2%. Adduct formation assessment was performed via monitoring of decrease in non-modified peptide LC-MS/MS signal and increase in VR-modified peptide signal. The designed approach was tested in a pilot study with 5 blood samples from healthy volunteers. Mass spectrometry-based method for BChE adduct formation was found to be in agreement with Ellman's inhibition assay, so the method is applicable for direct BChE inhibition assessment.

The determination of nonmetals, first of all, the most electronegative ones-nitrogen, oxygen, fluorine, chlorine, and bromine, poses the highest challenge for element analysis. These elements are characterized by high reactivity, volatility, high ionization energy, and the absence of intensive spectral lines in the optical spectral range. Conventional techniques of their quantification include considerable "wet chemistry" stages so the application of these techniques for the solid sample is highly laborious and prone to uncontrollable uncertainties. Additionally, current development in material science and other areas requires the quantification of the elements at lower levels with good sensitivity. Owing to their robustness and flexibility, mass spectrometry techniques provide vast possibilities for the quantification, spatial and isotopic analysis, including the solutions for direct analysis of solids. The current review focuses on the application of major mass spectrometric techniques for the quantification of N, O, F, Cl, and Br in solid samples. The following techniques are mainly considered: thermal ionization mass spectrometry (TIMS), isotope-ratio MS (IRMS), secondary ion MS (SIMS), inductively coupled plasma MS (ICP-MS), and glow discharge MS (GDMS); as the most accessible and widely applied for the purpose. General ionization issues, advantages, limitations, and novel methodological solutions are discussed. © 2020 John Wiley & Sons Ltd.

Neon glow discharge was tested for the direct analysis of solid dielectric materials by pulsed glow discharge time-of-flight mass spectrometry with an emphasis on the elements with high ionisation energy. The findings for neon were compared to conventional argon glow discharge. Fluorine doped potassium titanyl phosphate (KTP) single crystals were used for analysis. The following parameters were optimised: repelling pulse delay, discharge duration, and voltage and pressure in the discharge cell. Relative sensitivity factors were used for quantification; titanium was used for normalisation. Similar to argon glow discharge, the most effective mechanism for fluorine and oxygen ionisation was found to be attributed to high-energy electrons under short repelling pulse delays. Penning ionisation of oxygen in neon glow discharge was found to be less efficient. Overall, the use of neon significantly benefited fluorine and oxygen determination; the limits of detection for oxygen (0.0005 mass%) and fluorine (0.0002 mass%) decreased several times compared to argon glow discharge (0.001 and 0.01 mass%, respectively) as a result of more effective ionisation. The improvement was especially pronounced for fluorine, due to the alleviation of plasma-based interferences. However, for other KTP constituents – potassium, phosphorus and titanium – the analytical performance was expectedly lower, due to the lower sputtering rates in neon glow discharge. The limits of detection for potassium and phosphorus were significantly increased, being 0.008 mass% and 0.01 mass%, respectively. Notably, the performance for non-high ionisation energy elements was adequate for their single-run quantification along with oxygen and fluorine at non-trace levels. Thus, the use of neon as a discharge medium for pulsed glow discharge mass spectrometry is clearly justified for the determination of high ionisation energy elements such as oxygen and fluorine in non-conducting matrices.

A method has been developed for the determination of 24 elements (As, B, Ce, Co, Dy, Fe, K, La, Lu, Mg, Mn, Na, Nb, Nd, P, Pr, Rb, S, Sb, Si, Sm, Th, Ti, and U) in ore samples by pulsed direct curr...

Direct quantification of oxygen in dielectric materials using non-destructive or nearly non-destructive techniques still remains a nontrivial task. Simultaneous assessment of oxygen with other elements in a single analytical procedure is even more challenging. In the current study, a method of direct determination of oxygen and other matrix elements in solid samples, based on time-of-flight mass spectrometry with pulsed glow discharge in combined hollow cathode (CHC) is designed and tested. The possibility to effectively ionise oxygen owing to the electron impact mechanism under short repelling pulse delays has been shown. Stable sputtering and ionisation of dielectric samples were obtained via sample coating with thin conducting layer of silver. The parameters of oxygen quantification were optimised: duration and voltage of the discharge pulse, cell pressure, repelling pulse delay and material of the auxiliary cathode. The calibrations of oxygen, phosphorus and potassium are presented. The intensity of 16O+ was shown to be highly dependent on discharge cell pressure. The limits of detection were 0.001, 0.001, and 0.002 mass% for oxygen, phosphorus and potassium respectively. The designed approach enables direct, fast and accurate quantitative and in depth analysis of oxygen-containing samples.

A pulsed direct current glow discharge time-of-flight mass spectrometry (GD TOF MS) method for the quantification of fluorine in insoluble crystal materials with fluorine doped potassium titanyl phosphate (KTP) KTiOPO4:KF as an example has been proposed. The following parameters were optimized: repelling pulse delay, discharge duration, discharge voltage, and pressure in the discharge cell. Effective ionization of fluorine in the space between sampler and skimmer under short repelling pulse delay, related to the high-energy electron impact at the discharge front, has been demonstrated. A combination of instrumental and mathematical correction approaches was used to cope for the interferences of 38Ar2+ and 1H316O + on 19F+. To maintain surface conductivity in the dielectric KTP crystals and insure its effective sputtering in combined hollow cathode cell, silver suspension applied by the dip-coating method was employed. Fluorine quantification was performed using relative sensitivity factors. The analysis of a reference material and scanning electron microscope-energy dispersive X-ray spectroscopy was used for validation. Fluorine limit of detection by pulsed direct current GD TOF MS was 0.01 mass%. Real sample analysis showed that fluorine seems to be inhomogeneously distributed in the crystals. That is why depth profiling of F, K, O, and P was performed to evaluate the crystals' non-stoichiometry. The approaches designed allow for fluorine quantification in insoluble dielectric materials with minimal sample preparation and destructivity as well as performing depth profiling to assess crystal non-stoichiometry.

A new method of simultaneous redox speciation of iron (II/III), manganese (II/III), and copper (I/II) in cerebrospinal fluid (CSF) has been designed. For the separation of redox species strong cation exchange chromatography (SCX) with isocratic elution was employed. Species were detected using inductively coupled plasma sector field mass spectrometry (ICP-sf-MS), operating at medium resolution. The following parameters were optimized: analytical column, eluent composition and pH, CSF injection volume and dilution factor. Analytical column Dionex IonPac CS5A RFIC 4*250 mm was found to retain and separate species of interest the most effectively under the isocratic elution with a buffer, containing 50 mM ammonium citrate, 7.0 mM pyridine-2,6-dicarboxylic acid at pH = 4.2 and flow rate of 0.8 L min−1. Injection volume of 50 μL with CSF sample dilution of 1/3 (v/v) with the eluent was shown to result in minimal matrix suppression. For species identification, retention time matching with standards was used. The stability of metalloproteins (ferritin, transferrin, and ceruloplasmin) under elution conditions was evaluated. For the quantification of redox species, external calibration was employed. To avoid column contamination, a blank was run after measurement and all quantification values were blank subtracted. For recovery checks, species quantification data was verified against total content of an element, measured by dynamic reaction cell ICP-MS. Recoveries (sum of quantified species vs. total element determinations) were 82.5 ± 22% (Mn), 92 ± 11% (Fe), and 88.7 ± 12% (Cu). The method was tested using 38 real CSF samples. Limits of detection (3σ) for the CSF samples were 0.5 μg L−1, 0.6 μg L−1, and 0.8 μg L−1 for Fe, Mn, and Cu species, respectively. Retention time precision was 1–7.5% (as RSD), whereas peak area RSDs were in the range 5–11%, both depending on the species.

After the Chernobyl nuclear accident in 1986, numerous specimens of the so-called ‘fuel-containing masses’ or the Chernobyl ‘lava’ and hot particles were collected. Isotope analysis of Chernobyl specimens is the subject of special interest, since unexpected results on 238U/235U ratio has been reported previously. Although, over 30 years have passed since the Chernobyl accident, these samples are still a source of important information about the catastrophe as well as about the environmental behavior of highly radioactive materials. In the current study, glow discharge mass spectrometry with combined hollow cathode, pulse power supply and time-of-flight mass spectrometer was employed for the isotope analysis of uranium in Chernobyl-born microparticles. Six Chernobyl specimens (three crystals of artificial high-uranium zircon from the Chernobyl ‘lava’ and two hot particles) were analyzed. The method was optimized to cope the adverse oxide interferences. Simple isotope calibration with a single reference material of UO2 with known 235U content (abundance, 1.80 ± 0.03%) was used. The validity of the method was checked using the sample with natural 235U abundance (0.72%) and by comparing with sector field inductively coupled plasma mass spectrometry. The relative error of 235U determination was ca. 1%, which is comparable to or excels the values, obtained by the competitive approaches (e.g. laser ablation inductively coupled plasma mass spectrometry, accelerator mass spectrometry or resonance ionization mass spectrometry). An important advantage of the developed method is the possibility to conduct direct analysis with partial preservation of varied solid materials without preliminary dissolution, separation or concentrating procedures. Other than partial sample preservation, this provides lower hazards to the analyst, owing to shorter sample handling time and lower probability of radioisotopes volatilization or their turning to aerosols.

Biomedical analytical methods often rely on indirect measurements, such as immunoassays, which can lack effective metrological traceability. In the nephelometric determination of ceruloplasmin (Cp), an important protein whose circulating level is altered in Wilson’s disease (WD), the anti-Cp antibody used is not specific for the biologically active holoprotein so the assay can overestimate the concentration of Cp due to the presence of the apoprotein. By providing quantitation using elemental standards, the use of strong anion exchange chromatography (SAX) coupled to triple quadrupole inductively coupled plasma mass spectrometry (ICP-MS-MS) can overcome the drawbacks of methods for the measurement of metalloproteins reliant on immunoassays. In the current study, a SAX-ICP-MS-MS method for Cp quantification was designed and tested in samples of blood serum of WD patients and healthy controls. Using standards based on a copper-EDTA complex for calibration, the method provides relatively simple quantification of Cp with the limit of detection of 0.1 μg L−1 (limit of quantification 0.4 μg L−1). The method was also used to investigate the copper species separated by using a 30 kDa cut-off ultrafiltration device. The so-called "exchangeable" copper fraction is considered as an alternative clinical biomarker of WD. Using the designed speciation approach, it was shown that the ultrafiltration method can overestimate the "exchangeable" copper fraction due to a removal of copper from Cp. This was confirmed by comparing the enzymatic activity of the fractions. Thus, the specificity of the "exchangeable" copper test can be ensured only under strict maintenance of ultrafiltration conditions.

Recently glow discharge (GD) mass spectrometry, which is conventionally used to analyze solid samples, was successfully applied for ionization and the subsequent determination of volatile organic compounds (VOCs). In the present study, the possibility of direct determination of VOCs in ambient air using time-of-flight mass spectrometry with microsecond pulsed discharge in a copper hollow cathode was considered for the first time. The discharge cell of the mass spectrometer was modified for the direct analysis of gaseous samples by the introduction of a quartz capillary into the argon input channel. Various classes of compounds (aromatic and aliphatic hydrocarbons and derivatives of carboxylic acids) were studied. Particular attention was paid to the ionization mechanisms of VOCs. New mechanisms of chemical and electron ionization, resulting in the formation of associate ions with cathode material (copper) – CuM+, were demonstrated and implemented. Alternative mechanisms of organic compounds ionization in GD may be related to Penning process and proton transfer reactions. These processes are mainly responsible for the formation of molecular and protonated molecular ions. The relative contribution of all these mechanisms can be adjusted by operating parameters. In general, an extremely low degree of fragmentation of molecular ions or associates was observed. Due to its isotopic structure (only two isotopes 63Cu and 65Cu with comparable abundances), the use of copper as cathode material additionally increases the reliability of VOC identification in the form of their CuM+ associates. Such association shifts the detected ions to the region of large masses with fewer interferences and noise related to scattered ions.

A method of platinum quantification in whole blood samples after microwave digestion using sector field inductively coupled plasma mass spectrometry has been developed. The following analytical figures of merit have been established: limit of detection 1.1 µg/L for blood samples, dynamic range 3.6–200 µg/L, intra‐day precision (relative standard deviation, n = 9) did not exceed 5%. Spiked samples were analyzed for method validation. The method was used for pharmacokinetics studies of a novel anti‐cancer drug BP‐С1, a complex of cis‐configured platinum and benzene‐poly‐carboxylic acids. Main pharmacokinetic parameters (area under curve, maximum concentration, clearance, half‐life times for α‐ and β‐phase) were estimated for two dosage forms of BP‐C1 0.05 and 0.125 mass %. Pharmacokinetic curves were assessed for single and course administration. Studies were performed using rabbits (n = 6) as a model. BP‐C1 was injected intramuscularly. The study established dose proportionality of the tested dosage forms and suggested clinical dosing schedule: 5 days of injections followed by 2 days’ break. Platinum tissue distribution was studied in tissue samples collected 20 days after the last injection. Predominant platinum accumulation was observed in kidneys, liver, and muscles near injection site. ‘Slow’ phase of platinum excretion kinetics may be related to the muscles at the injection site. © 2015 The Authors. Drug Testing and Analysis published by John Wiley & Sons Ltd.

A direct method of uranium and thorium determination in non-conducting geological samples using time-of-flight mass spectrometry with pulsed glow discharge was proposed. The following rock specimens were analysed: metamict zircon, metamict rinkite, metamict samarskite (Y–Fe-niobate), pyrochlore and jacinth. For sample sputtering a combined hollow cathode cell of high purity aluminium or tantalum hollow cathodes was used. Powdered or monolith samples were pressed into the surface of the powdered metal prior to analysis. Model samples (artificial mixtures of oxides) were proposed for calibration; additionally, relative sensitivity factors, internal standardisation and standard additions were employed. For validation, IAEA artificially prepared uranium ore reference material was analysed. For additional validation, the obtained results for real mineral samples were compared to the results of inductively coupled plasma optical emission spectrometry after sample dissolution and semi-quantitative data of energy dispersive X-ray spectrometry. Limits of detection (3σ) for the designed method were 0.3 ppm for uranium and 0.5 ppm for thorium, which is comparable to laser ablation inductively coupled plasma mass spectrometry. The method was also tested for capability to measure isotope ratios for lead and uranium without specific isotope calibration. Acquired isotopic ratios of uranium and lead corresponded to their natural abundances within the experimental error.

A sector field inductively coupled plasma mass spectrometry method for the determination of Ag, Al, As, Ba, Be, Cd, Co, Cr, Cs, Cu, Fe, Mn, Ni, Pb, Se, Sr, Tl, U, V and Zn in whole blood and urine was designed. Microwave-assisted digestion with concentrated nitric acid was used for blood samples. Urine samples were analyzed after 1/50 (v/v) dilution with 5% (v/v) nitric acid. For beryllium the necessity of medium resolution mode (R=4000) was shown. Method validation was performed using blood and urine reference materials and by analyzing of spiked samples. For the designed method relative standard deviation (RSD) for the concentration range 0.01-1.0 μg/L was 5-10%. RSD did not exceed 3% when trace elements concentrations were above 1.0 μg/L. Method detection limits (3σ): Ag 0.7 ng/L, Al 16 ng/L, As 3.4 ng/L, Ba 0.02 ng/L, Be 1.5 ng/L, Cd 7.7 ng/L, Co 1.0 ng/L, Cr 2.8 ng/L, Cs 9.8 ng/L, Cu 27 ng/L, Fe 1.1 ng/L, Mn 1.8 ng/L, Ni 17 ng/L, Pb 13 ng/L, Se 0.07 ng/L, Sr 5.7 ng/L, Tl 0.2 ng/L, U 0.1 ng/L, V 0.7 ng/L and Zn 1.2 ng/L. A developed method was applied for trace element biomonitoring of occupationally exposed workers of a beryllium processing enterprise. For preliminary risk assessment technological surface dust had been analyzed by inductively coupled plasma optical emission spectrometry. Based upon results of 50 blood and 40 urine samples analyses occupational exposure evaluation was performed. Exposure risks were found not to exceed acceptable ranges. Possible health hazards were found for Be and also Al, Cr, Mn. Occupational health and safety recommendations for the biomonitored enterprise medical care unit were issued as a result of the current investigation.

In the current study, a biomonitoring of 18 hair trace elements (Al, As, Cd, Co, Cr, Cu, Fe, Hg, Mg, Mn, Ni, Pb, Se, V, Zn, Ca, Na and P) in school children from Leningradskaya Oblast' is reported. A case group, residing in a proximity to the toxic waste disposal grounds (Krasniy Bor), has been assessed vs. controls from a non-urban settlement Seltso. In total, 166 hair samples were analysed using double focusing sector field inductively coupled plasma mass spectrometry after microwave-assisted sample digestion with nitric acid. For the determination of Ca, Na and P inductively coupled plasma optical emission spectrometry was employed. For the validation, a reference material and spiked hair samples were analysed. The data obtained was processed using parametric statistics and factor analysis. Determined concentrations of trace elements were in agreement with the previously published results on chemically polluted areas. In the case group, linear correlations between Al, Cr, Cu, Fe, Ni and V were observed. Also, these metals correlated to selenium hair content in the case group. Additionally, a correlation between hair Se and P was observed in the case subjects. Several gender differences in trace content were observed within each group. However, no age- or body index-related difference was found. The obtained results show that closely located waste disposal grounds intensifies trace element exposure in school children of Krasniy Bor. However, judging from rather high values for the controls, total environmental status of the region seems to be unstable, so additional monitoring and chemical safety measures are required.

A new technique of blood thallium direct determination based on graphite furnace atomic absorption spectrometry with Zeeman background absorption correction system was designed. The developed technique does not require sample digestion. Sample treatment includes only a fivefold per volume dilution of blood sample with 0.1% (m/v) Triton X-100. L'vov integrated platform was modified with 400 μg of Rh. Matrix modifier (200 μg NH(4)NO(3) and 160 μg Pd(NO(3))(2)) was suggested for coping chloride and blood organic matter interferences. Standard reference material (Clincheck® Plasma Control for trace elements) analysis was used for validation. Additional validation was performed by analyzing spiked blood samples in the whole dynamic range. The dynamic range was 2-50 μg/L. Precision (RSD) was found12%. Blood thallium limit of detection was 0.2 μg/L.