Optimization Of Instrumental Parameters Research Articles

Determination of 9 fentanyl drugs in environmental water by UHPLC-MS/MS combined with solid phase extraction

In this study, sensitive and selective SPE-UHPLC-MS/MS methods were established and applied to the determination of 9 fentanyl drugs in environmental water, in order to address the lack of research on wastewater-based epidemiology for fentanyl drugs. The methods involved purifying and enriching water samples using homemade PS/DVB-WCX SPE cartridges, followed by UHPLC-MS/MS analysis. In subsequent research, the performance of four SPE cartridges were compared, and the results revealed the superior performance of PS/DVB-WCX in terms of extraction efficiency and matrix removal. Optimized instrument parameters enabled qualitative and quantitative analysis of the 9 fentanyl drugs. For different matrices, two quantitative methods were developed and their correlation coefficient (r2) were all greater than 0.9945. The LODs and LOQs of all analytes were 0.17 ng/L and 0.50 ng/L respectively. Accuracy assessment via spiking standards into environmental water samples showed recoveries ranging from 81.4 % to 109.4 % and 81.6 % to 116.7 % respectively for two methods. The results suggested that the proposed methods were able to meet the needs of 9 fentanyl drugs monitoring in environmental water. Additionally, the greenness assessment of the proposed analytical method was evaluated by three greenness assessment metrics: National environmental methods Index (NEMI), Green analytical procedure Index (GAPI), and Analytical GREEnness metric (AGREE). The results indicate that the established method is environmentally friendly.

Design and fabrication of electrochemical sensor based on NiO/Ni@C-Fe3O4/CeO2 for the determination of niclosamide

In this study, we aimed to enhance and accelerate the electrochemical properties of a glassy carbon-based voltammetric sensor electrode. This was achieved through the modification of the electrode using a nanocomposite derived from a metal–organic framework, which was embedded onto a substrate consisting of metal oxide nanoparticles. The final product was an electrocatalyst denoted as NiO/Ni@C-Fe3O4/CeO2, tailored for the detection of the drug niclosamide. Several techniques, including FT-IR, XRD, XPS, FE-SEM, TEM, and EDS, were employed to characterize the structure and morphology of this newly formed electroactive catalyst. Subsequently, the efficiency of this electrocatalyst was evaluated using cyclic voltammetry and electrochemical impedance spectroscopy techniques. Differential pulse voltammetry was also utilized to achieve heightened sensitivity and selectivity. A comprehensive exploration of key factors such as the catalyst quantity, optimal instrumental parameters, scan rate influence, and pH effect was undertaken, revealing a well-regulated reaction process. Furthermore, the sensor's analytical performance parameters were determined. This included establishing the linear detection range for the target compound within a specified concentration interval of 2.92 nM to 4.97 μM. The detection limit of 0.91 nM, repeatability of 3.1%, and reproducibility of 4.8% of the sensor were calculated, leading to the observation of favorable stability characteristics. Conclusively, the developed electrochemical sensor was successfully employed for the quantification of niclosamide in urine samples and niclosamide tablets. This application highlighted not only the sensor’s high selectivity but also the satisfactory and accurate outcomes obtained from these measurements.

Element accumulation by the holoparasitic species Cuscuta planiflora from serpentines in Bulgaria

AbstractThe holoparasitic species Cuscuta planiflora Ten. (Convolvulaceae) parasitizes the Ni hyperaccumulator Odontarrhena muralis (Waldst. & Kit.) Endl. and a non‐hyperaccumulator, Sanguisorba minor Scop., in Bulgarian serpentine areas. This study investigated the host/parasite relationship to evaluate: (1) metal accumulation in different parts of the parasite and the host and (2) its potential threat to Ni phytomining/agromining by suppressing growth of the hyperaccumulator. Elemental concentrations in soil, shoots, leaves, and inflorescences of the two host plants, and in shoots and inflorescences of the parasite, were determined. Elemental concentrations of Ca, Mg, Fe, Ni, Cr, Co, Zn, Cu, Mn, Cd, and Pb were determined after microwave digestion using inductively coupled plasma—optical emission spectrometry (ICP‐OES) under optimal instrumental parameters. Individuals of hosts, both infected and non‐infected, differed in the concentrations of essential elements (P, K) and some micronutrients. Infected individuals of O. muralis showed lower Ni concentrations in shoots, leaves, and inflorescences compared to non‐infected ones. Sanguisorba minor is an excluder plant with low tissue Ni concentrations. The parasite had higher P and K, and lower Ca, Mg, Ni, Zn, Co, and Mn concentrations, than the host. The highest Ni concentration measured in the shoots of C. planiflora was 279 mg kg−1, whereas that from S. minor was 29.9 mg kg−1. Element transfer from host to parasite appeared element‐specific and after infection Ni concentrations in all organs and biomass of hosts were reduced. We conclude that infection by C. planiflora is a potential threat to use of O. muralis for Ni agromining.

Strategies for consistent and automated quantification of HDL proteome using data-independent acquisition

The introduction of mass spectrometry-based proteomics has revolutionized the high-density lipoprotein (HDL) field, with the description, characterization, and implication of HDL-associated proteins in an array of pathologies. However, acquiring robust, reproducible data is still a challenge in the quantitative assessment of HDL proteome. Data-independent acquisition (DIA) is a mass spectrometry methodology that allows the acquisition of reproducible data, but data analysis remains a challenge in the field. To date, there is no consensus on how to process DIA-derived data for HDL proteomics. Here, we developed a pipeline aiming to standardize HDL proteome quantification. We optimized instrument parameters and compared the performance of four freely available, user-friendly software tools (DIA-NN, EncyclopeDIA, MaxDIA, and Skyline) in processing DIA data. Importantly, pooled samples were used as quality controls throughout our experimental setup. A careful evaluation of precision, linearity, and detection limits, first using E. coli background for HDL proteomics and second using HDL proteome and synthetic peptides, was undertaken. Finally, as a proof of concept, we employed our optimized and automated pipeline to quantify the proteome of HDL and apolipoprotein B–containing lipoproteins. Our results show that determination of precision is key to confidently and consistently quantifying HDL proteins. Taking this precaution, any of the available software tested here would be appropriate for quantification of HDL proteome, although their performance varied considerably.

Evaluation of an Inductively Coupled Plasma–Atomic Emission Spectrometry (ICP-AES) Method for the Determination of Macro and Microelements in Trifolium L. Species

This study aimed optimizes the inductively coupled plasma–atomic emission spectrometry (ICP-AES) conditions for the determination of macro and microelements in the flowers and leaves of Trifolium species. After the optimization of instrumental parameters, plasma robustness was achieved under the following conditions: RF power 1350 W, nebulizer flow rate 0.5 L min−1, coolant gas flow rate 12 L min−1, auxiliary gas flow rate 0.5 L min−1, flush pump rate 100 rpm, analysis pump rate 50 rpm, sample flow 0.5 mL min−1, and sample uptake delay 30 s. The limits of detection (LOD) and limits of quantification (LOQs) were lower than literature values. The most abundant microelement in leaves is Ca, followed by K, Mg, P, and Na, and in flowers was K, followed by Ca, P, Mg, and Na. The average contents of microelements decreased in the orders S > Fe > Si > Al > Zn > Mn > Cu > Ni > Co > Pb > Cr > As > Cd for flowers and S > Fe > Si > Mn > Al > Zn > Cu > Ni > Co > Pb > Cr > As > Cd for leaves. Chemometrics were used for grouping samples based upon the elemental contents.

A novel test method of load-bearing performance of sized warp yarn based on weaving load simulation and its effectiveness

To simulate the weaving process effectively and evaluate the load-bearing performance of sized warp yarn based on the tensile and friction loads of warp in weaving, a weaving load simulation tester of sized warp yarn (SWL) named JN-01 was designed and developed in this paper. It realized the simulation of warp tension, opening tensile load, and abrasion load, respectively. In addition, the SWL included three auxiliary function modules, that is, take-up and let-off, yarn breaking automatic stop, and human–computer interaction interface. The load-bearing life of sized warp yarn was measured by the number of load cycles when the yarn broke. Taking pure cotton sized warp yarn of 14.5 tex as the test sample, the effects of adjustable parameters of the SWL, such as working frequency, opening stroke, yarn tension, reed swing angle, and winding speed, on the load-bearing performance of sized warp yarn were systematically studied. Aiming at the stability of the test results of load-bearing life, the parameters of the SWL were optimized by the analysis of response surface methodology. The optimization results showed that: when the parameters were maintained at the following level, that is, working frequency of 180 rpm, winding speed of 3 mm/min, opening stroke of 32 mm, reed swing angle of 12° and yarn tension of 1.7 cN/tex, the relative deviation between the predicted value and the theoretical value of load-bearing life CV was 0.85%. The results also indicated that the optimized instrument parameters had good reproducibility.

Microwave Digestion and ICP-MS Determination of Major and Trace Elements in Waste Sm-Co Magnets

In this article, inductively coupled plasma mass-spectrometry (ICP-MS) and inductively coupled plasma optical-emission spectrometry (ICP-OES) were used for the development of an analytical procedure for analysis of the waste of Sm-Co magnets. Experimental parameters related to microwave digestion processes and acid concentrations were optimized. Microwave digestion was carried out in mixtures of HF, HCl, HNO3 and H2SO4. The complete dissolution of the samples occurred in the system: 10 mL H2O, 2 mL HNO3, 10 mL HCl and 1 mL H2SO4. The dependence of the matrix effect on the ICP-MS analysis of waste Sm-Co magnets was studied and optimal instrumental parameters were investigated (nebulizer gas flow, sampling depth and potential at the extractor lens). The optimal conditions were a nebulizer gas flow of 0.85–0.90 L/min, a sampling depth of 101, potential at the extractor lens of −400 V and a sample flow rate of 50 rpm. A recovery test and inter-method experiments were performed to verify the accuracy of the proposed method.

Application of gas chromatography coupled to triple quadrupole mass spectrometry (GC-(APCI)MS/MS) in determination of PCBs (mono-to deca-) and PCDD/Fs in Chinese mitten crab food webs

Polychlorinated biphenyls (PCBs) and dibenzo-p-dioxins and furans (PCDD/Fs) are notorious persistent organic pollutants (POPs), which may bioaccumulate through food chain and play detrimental effects to organisms even at trace levels. Quantification of PCBs and PCDD/Fs in biotic samples is a great challenge. In the present study, gas chromatography coupled to triple quadrupole mass spectrometry with an atmospheric pressure chemical ionization source (GC-(APCI)MS/MS) was studied for the isotope-dilution analysis of PCBs (mono-to deca-) and PCDD/Fs in Chinese mitten crab food webs. High-resolution mass spectrometry (HRMS) was applied for comparison. Light PCBs are compared between the two instruments for the first time. After optimization of instrument parameters, the RSDs of relative response factors of calibration curves were between 3.4% and 15.5% for PCBs and 1.7%–7.9% for PCDD/Fs. The limits of detection were between 0.021 and 0.150 pg/mL for PCBs and 0.051–0.237 pg/mL for PCDD/Fs. PCB concentrations in crab food web samples detected by GC-(APCI)MS/MS were well correlated with those detected by HRGC/HRMS. A DiCB, 3,3′-dichlorobiphenyl (PCB11), was the dominant PCB congener in aquatic food webs. Other MoCB and DiCB congeners were also widely identified; hence, low-weight PCB congeners should arouse more concern in the future. GC-(APCI)MS/MS may become an alternative instrument satisfying the PCB and PCDD/F detection.

Noble metal nanocomposites as tools for fast and reliable speciation analysis of mercury in water samples

ABSTRACT A novel non-chromatographic approach for speciation analysis of mercury was developed based on sequential application of silver and gold nanocomposites as sorbents for solid phase extraction. The nanocomposite materials consisted by AgNPs or AuNPs grafted on submicronsized silica spheres (SiO2-NH2@AgNPs and SiO2-NH2@AuNPs) were prepared by multistep synthesis procedures and characterised in details by different techniques – Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), electrokinetic measurements, UV–Vis spectroscopy and X-ray diffraction. Excellent separation and enrichment of Hg(II) and CH3Hg+ was achieved due to the specific behaviour and affinity of Ag and Au nanoparticles (NPs) towards particular Hg chemical forms. In the first extraction step, Hg(II) was strongly retained by highly selective amalgamation on the surface of Ag nanocomposite (SiO2-NH2@AgNPs). In the second extraction step, CH3Hg+ remained in the supernatant solution was sorbed on the surface of Au nanocomposite (SiO2-NH2@AuNPs). Both Hg species trapped in the sorbents precipitates were quantified by electrothermal Atomic Absorption Spectroscopy (AAS) after direct injection in the graphite atomiser under optimal instrumental parameters (Ag and Au act as modifiers). The optimal solid-phase extraction conditions were examined and defined by batch method. Recoveries achieved by the developed analytical procedure were in the range 97–102% for both Hg(II) and methylmercury with limits of detection and quantification of 0.03 and 0.1 µg L−1, respectively. The proposed analytical procedure was applied for speciation analysis of mercury in water samples.

Development of an automated micropipette coating method for drug-coated balloons.

Drug-coated balloons (DCBs) are a recent technology developed to treat peripheral artery disease (PAD). Along with a suitable formulation of antiproliferative drug and excipient, coating method is an important aspect of a DCB as these factors affect coating characteristics and drug delivery to the treatment site. The multiple release tailored medical devices DCB (MR-TMD-DCB), designed to achieve multiple inflations to treat complex PAD, contains paclitaxel (PAT) as the antiproliferative drug and polyethylene oxide (PEO) as the excipient. In our previous studies, the MR-TMD-DCB was coated using a manual dip coating method. In this study, an automated micropipette coating method was developed using a modified spray coating instrument to coat the MR-TMD-DCB. First, the coating formulation and strategy was optimized. A drug formulation of 16 wt% PAT and 4% wt/vol PEO, a polymer formulation of 2.5% wt/vol PEO, and a total of two drug layers produced a mostly uniform and thin coating with no defects and acceptable drug load. The balloon also had optimal drug uptake in arterial tissue in an in vitro flow model. Next, the reproducibility of the coating strategy was improved by optimizing the instrument parameters. The optimized instrument parameters (translational speed = 0.150 in/s, revolution rate = 100 rpm, flow rate = 0.6 ml/min) resulted in improved reproducibility of the drug load and similar coating properties as the DCB. This study demonstrated the ability to automate the micropipette process to obtain a balloon with optimal coating properties and drug tissue uptake.

Voltammetric Determination of Diethylstilbestrol in Pharmaceutical Formulation

A simple, inexpensive and highly sensitive new electrochemical method was developed to quantify Diethylstilbestrol (DES) in medication samples using carbon paste electrode (CPE). The electrode was electrochemically characterized using cyclic voltammetry (CV) and square wave voltammetry (SWV). From the cyclic voltammograms obtained in the presence of diethylstilbestrol could be observed two peaks, one of oxidation at ≈ 590 mV and other of reduction at 200 mV. The development of method for estrogen quantification under study involved optimization of instrumental parameters (frequency, amplitude and potential step) and the experimental parameter pH. The electrochemical procedure applied to diethylstilbestrol was developed using CPE under optimal conditions. Diethylstilbestrol oxidation currents exhibited linear concentration in the 0.017 - 2.08 mmol L -1 range, with a limit of detection of 14.15 nmol L -1 . The amount of DES found in the analyzed samples was 0.98 mg, with a relative standard deviation of less than 2%, indicating high agreement with the amount described in the label of the drug (1 mg). The results indicate that the method is applicable for quantifying diethylstilbestrol in pharmaceutical formulation. DOI: http://dx.doi.org/10.17807/orbital.v11i4.1326

Newly developed Laboratory-based Size exclusion chromatography Small-angle x-ray scattering System (La-SSS)

To understand a biological system, it is important to observe structures of biomolecules in the solution where the system is functionalized. Small-Angle X-ray Scattering coupled with Size Exclusion Chromatography (SEC-SAXS) is one of techniques to selectively observe the target molecules in the multi-component system. However, this technique is believed to be available only with a synchrotron-based SAXS instrument due to requirement of high beam intensity and, therefore, the limitation of the beam time was obstacle to satisfy demands from many bio-researchers. We newly developed Laboratory-based Size exclusion chromatography SAXS System (La-SSS) by utilizing a latest laboratory-based SAXS instrument and finely optimization of the balance between flow rate, cell volume, irradiation time and so on. La-SSS succeeded not only decoupling of target protein(s) from non-specific aggregates but also measurement of each concerned component in a multi-component system. In addition, an option: “stopping mode”, which is designed for improving statistics of SAXS profile, realized a high S/N data acquisition for the most interesting protein in a multi-component system. Furthermore, by utilizing a column having small bed volume, the small-scale SEC-SAXS study makes available. Through optimization of instrumental parameters and environments, La-SSS is highly applicable for experimental requirements from various biological samples. It is strongly expected that a La-SSS concept must be a normal option for laboratory-based SAXS in the near future.

Effective analysis of degree of polymerization of polysialic acids in mass spectrometry by combining novel sample preparation and dynamic instrument optimization methods

This work demonstrates a mass spectrometry technique to improve data reliability when analyzing degree of polymerization (DP) of high-mass polysialic acids (PSAs). Matrix-assisted laser-desorption/ionization (MALDI) time-of-flight mass spectrometry is the technique of choice for analyzing large molecules due to its wide mass working range; however, the observed DP of PSAs using such an instrument is unreliable owing to sensitivity bias towards low-mass ions. A multi-layer MALDI sample preparation protocol is demonstrated in the current study to improve PSA sensitivity, and a dynamic instrument optimization method (DIOM) is employed to minimize detector saturation over a wide mass range. The DP information obtained in the DIOM combines a series of mass spectral data obtained with individually optimized instrument parameters to minimize the problem of sensitivity bias in respective mass ranges. The resultant mass spectra facilitate unambiguous determination of DP in the high-mass range due to significantly improved spectral quality. The main instrument parameters involved in the optimization process include extraction delay in MALDI ion source as well as the cutoff mass of the ion detector. In comparison to conventional methods, the DIOM doubles the maximum DP that can be unambiguously identified by mass spectrometry.

Application of Inductively Coupled Plasma-Atomic Emission Spectrometry/Mass Spectrometry to Phase Analysis of Gold in Gold Ores

Abstract Inductively coupled plasma-atomic emission spectrometry/mass spectrometry (ICP-AES/MS) is a potentially powerful tool in chemical phase analysis of gold in batch mode, especially applicable to the low-grade gold ores with gold content of far below detection limit of the other methods, but it has not been used in gold phase analysis of gold ores. In this work, three types of typical gold deposits (altered rock type, quartz vein type, and microscopic disseminated type) and national standard reference materials of gold ores were used to establish and validate a method for gold phase analysis of gold ores using ICP-AES/MS. The optimum conditions of phase analysis were determined, including the sample granularity and preparation procedures, separation absorbent, pretreatment procedures of various phases of gold and optimized instrument parameters. Evaluation of the optimized method showed that this method had acceptable precision (RSD: 1.1%–10.6%) and accuracy (relative error, RE: 0.5%–6.3%), and the detection results of gold in ores were comparable with those obtained using the hydroquinone volumetric method-extraction flame atomic absorption spectrometry (VOL-AAS) and graphite furnace atomic absorption spectrometry (GFAAS) methods. The sum content of gold of the 4 phases (free gold, FAu; linked gold, LAu; sulphide-bearing gold, SAu; and other mineral-bearing gold, AAu) conformed to the total gold content and was consistent with the results of rock-mineral identification. The proposed method had a low detection limit (0.30 ng g–1) and wide linear range (5.0 ng mL–1–20.00 μg mL–1). It is a simple, rapid, and efficient method for gold phase analysis in batch form.

Small-angle X-ray scattering characteristics of mouse brain: Planar imaging measurements and tomographic imaging simulations.

Small-angle x-ray scattering (SAXS) imaging can differentiate tissue types based on their nanoscale molecular structure. However, characterization of the coherent scattering cross-section profile of relevant tissues is needed to optimally design SAXS imaging techniques for a variety of biomedical applications. Reported measured nervous tissue x-ray scattering cross sections under a synchrotron source have had limited agreement. We report a set of x-ray cross-section measurements obtained from planar SAXS imaging of 1 mm thick mouse brain (APP/PS1 wild-type) coronal slices using an 8 keV laboratory x-ray source. Two characteristic peaks were found at 0.96 and 1.60 nm−1 attributed to myelin. The peak intensities varied by location in the slice. We found that regions of gray matter, white matter, and corpus callosum could be segmented by their increasing intensities of myelin peaks respectively. Measured small-angle x-ray scattering cross sections were then used to define brain tissue scattering properties in a GPU-accelerated Monte Carlo simulation of SAXS computed tomography (CT) using a higher monochromatic x-ray energy (20 keV) to study design trade-offs for noninvasive in vivo SAXS imaging on a small-animal head including radiation dose, signal-to-noise ratio (SNR), and the effect of skull presence on the previous two metrics. Simulation results show the estimated total dose to the mouse head for a single SAXS-CT slice was 149.4 mGy. The pixel SNR was approximately 30.8 for white matter material whether or not a skull was present. In this early-stage proof-of-principle work, we have demonstrated our brain cross-section data and simulation tools can be used to assess optimal instrument parameters for dedicated small-animal SAXS-CT prototypes.

Quantifying endogenous androgens, estrogens, pregnenolone and progesterone metabolites in human urine by gas chromatography tandem mass spectrometry

A method for the quantitation of 22 urinary steroids (androgens, estrogens and the main pregnenolone and progesterone metabolites) by means of gas chromatography tandem mass spectrometry using a triple quadrupole analyzer has been developed. Two different enzymatic hydrolysis protocols were investigated; one capable of releasing steroids present as both sulfates and glucuronides (total fraction), and another with β-glucuronidase activity only.After selecting adequate internal standards and choosing the optimal instrumental parameters, i.e. chromatographic separation and ion transition conditions, the method was fully validated using both hydrolysis protocols. The method was shown to be linear (r >0.99) in the range of endogenous concentrations for all studied steroids with extraction recoveries higher than 80%. The use of labeled internal standards allowed for both a correct quantification and the evaluation of the rate of deconjugation for sulfates and glucuronides in every sample. In general, the sensitivity of the method was suitable for the detection of the endogenous levels, with limits of quantification ranging from 0.1 to 20ng/mL. Accuracies ranging from 80% to 120%, and relative standard deviations below 25% in intra- and inter- assay experiments were found for most of the analytes.The applicability of the validated method was tested by quantifying twenty-two metabolites in 24-h urine samples collected from healthy individuals. The ranges for the excretion of steroids in the total and glucuronide fractions obtained with the new method were compared with those available in the literature. By comparing the figures in both fractions, an estimation of the percentage that the sulfation represents for each steroid was also calculated. The presence of side enzymatic activities and the utility of the method for clinical studies as well as for doping control analysis is discussed.

Design and implementation of the TAROGE experiment

Taiwan astroparticle radiowave observatory for geo-synchrotron emissions (TAROGE) is an antenna array on the high mountains of Taiwan’s east coast for the detection of ultra-high energy cosmic rays (UHECRs) in an energy above [Formula: see text] eV. The antennas point toward the ocean to detect radiowave signals emitted by the UHECR-induced air-shower as a result of its interaction with the geomagnetic field. Looking down from the coastal mountain, the effective area is enhanced by collecting both direct-emission as well as the ocean-reflected signals. This instrument also provides the capability of detecting earth-skimming tau-neutrino through its subsequent tau-decay induced shower. In order to prove the detection concept, initial two stations were successfully built at 1000 m elevation near Heping township, Taiwan, in 2014–2015. Each station consists of 12 log-periodic dipole array antennas for 110–300 MHz. The stations have been operating smoothly for radio survey and optimization of instrumental parameters. In this report, we discuss the design of TAROGE, the performance of the prototype station and the future prospect.

Elucidation of Xylem-Specific Transcription Factors and Absolute Quantification of Enzymes Regulating Cellulose Biosynthesis in Populus trichocarpa.

Cellulose, the main chemical polymer of wood, is the most abundant polysaccharide in nature.1 The ability to perturb the abundance and structure of cellulose microfibrils is of critical importance to the pulp and paper industry as well as for the textile, wood products, and liquid biofuels industries. Although much has been learned at the transcript level about the biosynthesis of cellulose, a quantitative understanding at the proteome level has yet to be established. The study described herein sought to identify the proteins directly involved in cellulose biosynthesis during wood formation in Populus trichocarpa along with known xylem-specific transcription factors involved in regulating these key proteins. Development of an effective discovery proteomic strategy through a combination of subcellular fractionation of stem differentiating xylem tissue (SDX) with recently optimized FASP digestion protocols, StageTip fractionation, as well as optimized instrument parameters for global proteomic analysis using the quadrupole-orbitrap mass spectrometer resulted in the deepest proteomic coverage of SDX protein from P. trichocarpa with 9,146 protein groups being identified (1% FDR). Of these, 20 cellulosic/hemicellulosic enzymes and 43 xylem-specific transcription factor groups were identified. Finally, selection of surrogate peptides led to an assay for absolute quantification of 14 cellulosic proteins in SDX of P. trichocarpa.

High resolution parallel reaction monitoring with electron transfer dissociation for middle-down proteomics.

In recent years, middle-down proteomics has emerged as a popular technique for the characterization and quantification of proteins not readily amenable to typical bottom-up approaches. So far, all high resolution middle-down approaches are done in data-dependent acquisition mode, using both collision-induced dissociation or electron capture/transfer dissociation techniques. Here, we explore middle-down proteomics with electron transfer dissociation using a targeted acquisition mode, parallel reaction monitoring (PRM), on an Orbitrap Fusion. As an example of a highly modified protein, we used histone H3 fractions from untreated and DMSO-treated Murine ErythroLeukemia (MEL) cells. We first determined optimized instrument parameters to obtain high sequence coverage using a synthetic standard peptide. We then setup a combined method of both MS1 scans and PRM scans of the 20 most abundant combinations of methylation and acetylation of the +10 charge state of the N-terminal tail of H3. Weak cation exchange hydrophilic interaction chromatography was used to separate the N-terminal H3 tail, primarily, by its acetylation and, to a secondary degree, by its methylation status, which aided in the interpretation of the results. After deconvolution of the highly charged ions, peaks were annotated to a minimum set of 254 H3 proteoforms in the untreated and treated samples. Upon DMSO treatment, global quantitation changes from the MS1 level show a relative decrease of 2, 3, 4, and 5 acetylations and an increase of 0 and 1 acetylations. A fragment ion map was developed to visualize specific differences between treated and untreated samples. Taken together, the data presented here show that middle-down proteomics with electron transfer dissociation using PRM is a novel, attractive method for the effective analysis and quantification of large and highly modified peptides.

Characterization of polymeric system for cisplatin delivery — analytical methods for Pt determination

Abstract Abstract Cis-diamminedichloroplatinum(II) (cisplatin) was immobilized in a star-shaped polymer carrier. In order to define whether this polymer could be used as a drug delivery system for cisplatin, its characteristics, e.g. loading efficiency and release profile of cisplatin from the polymer in phosphate buffered saline (PBS), have to be assessed, and hence an appropriate analytical procedure for precise and reliable determination of Pt(II) must be established. Optimal instrumental parameters for Pt measurement by commonly used atomic spectrometric methods ETAAS and ICP-OES in various examined media were defined. Matrix interferences observed that were related to both techniques were evaluated, and analytical figures of merit were compared and critically discussed. Graphical abstract