structure of ibuprofen and numbering system
Rapid advances in biological sciences have led to an increased demand for the chemical and structural information about biological systems. The massspectrometry (MS) plays a
Evolved gas analysis (EGA) has been developed to be a widely used tool in thermal analysis. Ahead of spectroscopic techniques (TA-FTIR) and gas chromatographic approaches (TA-GC) the coupling of massspectrometry
This work provides an assessment of suitable forensic indicators that may be measured by portable mass spectrometry systems.
Traditional assessments of nuclear fuel cycle manipulation or other nuclear activities often depend upon analyses of uranium
and plutonium isotopes in the nuclear fuel. Any entity engaging in shortened fuel cycle activity will recover U and Pu during
reprocessing. Fission, capture, and activation products are less valuable and generally regarded as waste products. This work
determined isotopic ratios that distinguish nuclear weapons and shortened nuclear fuel cycles from commercial nuclear reactors.
Modeling of fuel cycles was conducted via ORIGEN-S, MCNPX, and through custom calculations.
The dominant development in the radiometrics techniques for the analysis of short and medium-lived radionuclides in the environment
was the utilisation of large volume Ge detectors in underground laboratories with additional anti-cosmic shielding. In the
mass spectrometry sector, applications of Accelerator Mass Spectrometry (AMS) and Inductively Coupled Plasma Mass Spectrometry
(ICPMS) for the analysis of long-lived radionuclides in the environment are the most important recent achievements. These
developments in both sectors did not only considerably decrease the detection limits for several radionuclides (up to several
orders of magnitude), but they also enable to decrease sample volumes so that sampling, e.g. of the water column, can be much
easier and more effective. Applications of radiometrics and mass spectrometry techniques in isotope oceanography, specifically
on the distribution of 3H, 14C, 90Sr, 129I, 137Cs, 239Pu and 240Pu in the water column of the North Pacific and South Indian Oceans are presented and discussed.
The potential of hyphenating thermogravimetry (TG) and soft photo ionisation mass spectrometry (EBEL-SPI-MS) for fundamental
and applied research and material analysis has been demonstrated by a newly developed TG-SPI quadrupole MS coupling (TG-SPI-QMS).
Thermal decomposition of three common plastics, polyethylene (PE), polystyrene (PS) and polyvinylchloride (PVC) has been studied.
While the decomposition of PE and PS in inert atmosphere takes place in a one step process (main mass loss at about 490 and
420 °C, respectively), PVC decomposes in a two step mechanism. The organic signature of the PE decomposition shows homologous
series of alkenes and polyenes, while PS is forming mainly styrene mono- and oligomers. In the PVC decomposition, firstly
hydrogen chloride (HCl) is eliminated in a hydro-dechlorination reaction (1st mass loss step: 285–305 °C), this is accompanied
by the emission of the carbon skeletons of small aromatics (predominately benzene and naphthalene). In the second step (2nd
mass loss step: 490–510 °C), the residual cross-linked polyolefin moieties decompose under release of heavily alkylated aromatics,
including larger PAH. Chlorinated aromatics are formed only in trace levels.
A new quantitative densitometric high-performance thin-layer chromatographic (HPTLC) method was developed and validated for the analysis of ranolazine (RZ) both in bulk and formulations. RZ was separated and identified on silica gel 60 F254 HPTLC plates with butanol—acetic acid—water (6:2:2 v/v) as the mobile phase. Densitometric quantification was performed at λ = 270 nm by reflectance scanning which facilitated well-resolved band for the main drug (RF 0.56 ± 0.02). Response to RZ was a linear function of concentration in the range of 100–400 ng, with a correlation coefficient, slope, and intercept of 0.99912 ± 0.00017, 8.684 ± 0.582, and 492.147 ± 2.67, respectively. The minimum amount of RZ that could be authentically detected and quantified was 14.90 and 49.67 ng band−1, respectively. Additionally, the peak identities as well as the purities were confirmed by mass spectrometry. The electrospray ionization (ESI+) mass spectra showed the [M + H]+ ion for RZ detected at m/z 428.3 being acquired directly from the sample bands by an elution-based interface. The proposed method was validated with respect to linearity, precision, accuracy, and specificity.
For very complex multicomponent mixtures, it is preferable to use different variants of multidimensional (planar) chromatography. In multidimensional separations, the modes of planar chromatography commonly applied are comprehensive 2D planar chromatography on mono and bilayers, coupled-layer chromatography, combination of multidimensional planar chromatographic (MDPC) techniques, and also hyphenated methods. Different multidimensional (planar) chromatography techniques and hyphenated methods may be alternative modes for separation and identifcation of pesticides in environmental analysis, especially after coupling with modern detection techniques. Proper identifcation and quantitative analysis of the analytes are possible through the use of sensitive detection techniques such as high-resolution mass spectrometry (HRMS).
, 2009; Becker et al., 2014 ). Similar to the emergence of polymerase chain reaction, the backbone of modern molecular biology, matrix-assisted laser desorption ionisation–time of flight massspectrometry (MALDI-TOF MS) has also become a paradigm
High-performance thin-layer chromatography (HPTLC)–densitometric method of haloperidol (HP) and its two metabolites (reduced haloperidol [RHP], 4-(4-chlorophenyl)-4-hydroxypiperidine [CPHP]) from human plasma has been developed by use of mobile-phase additives. The influence of the type of inorganic/ organic additive on the retention of the studied compounds was evaluated. The chromatographic process was carried out with traditional mobile phase modifiers and 1-alkyl-imidazolium ionic liquid as separation enhancers, in the presence of chlorpromazine as internal standard. 1-Ethyl-3-methylimidazolium tetrafluoroborate ([emim][BF4]) ionic liquid offered good selectivity in comparison with traditional mobile phase additives. The studied drugs were well distributed as the RF values were 0.31 for chlorpromazine hydrochloride (CPZ), 0.38 for HP, 0.44 for CPHP, and 0.58 for RHP, respectively, with no apparent broadening and overlapping of spots. The test compounds were extracted using acetonitrile as precipitation agent. The identity of the bands from human plasma was additionally confirmed by rapid and contamination-free CAMAG thin-layer chromatography–mass spectrometry (TLC–MS) interface. The limit of detection (LOD) values obtained by densitometry scanning were 0.1807, 0.3158, and 0.3924 μg spot−1 (for HP, RHP, and CPHP), whereas the limit of quantification (LOQ) values for the presented method were 0.5476, 0.9570, and 1.1892 μg spot−1 (for HP, RHP, and CPHP). Recovery values of all tested compounds were in the range from 95.43% to 99.60% (intra-day) and 96.13% to 103.18% (inter-day); %RSD did not exceed the value of 5%. The results confirm the positive effect of ionic liquids in the separation process related to their silanol blocking properties and their suitability for use in thin-layer chromatography/mass spectrometry method.
Accelerator mass spectrometry (AMS) is a sensitive and robust technique typically applied to the quantification of long-lived radioisotopes in samples too small to be decay-counted. AMS is characterized by a high rejection of interferences and a low susceptibility to matrix components, which reduce the demands on sample preparation chemistry. At Lawrence Livermore National Laboratory (LLNL), Center for Accelerator Mass Spectrometry (CAMS), we have developed an AMS capability for the measurement of actinide concentrations and isotopic ratios. To date, this capability has been primarily devoted to the measurement of 239Pu and 240Pu in bioassay and environmental samples including soils, sediments, waters, and human urine. For these analyses, a known amount of 242Pu is added to the samples as a reference isotope for normalization. Measurements of standard and intercomparison samples have shown that quantification is accurate and precise from at least 106 to 1011 atoms/sample. Recently, the ratios of 240Pu, 241Pu, 242Pu, and +Pu to intrinsic 239Pu have been successfully measured in soil samples from nuclear test sites. In addition, initial measurements of U and Np isotopes have yielded results consistent with the Pu measurements with respect to sensitivity, accuracy, precision, and linear range.