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121.
Marcello G Trevisan 《Analytica chimica acta》2003,493(1):69-81
Direct determination of doxorubicin (DXR), a cytotoxic anthracycline antibiotic, in human plasma was accomplished based on excitation-emission matrix (EEM) fluorescence measurements and multi-way chemometric methods based on parallel factor analysis (PARAFAC) and N-PLS. Several different procedures, such as residual analysis, core consistency diagnostic (CONCORDIA) and split-half analysis were employed to determine the correct number of factors in PARAFAC. These procedures converged to a choice of two factors, attributed to DXR and to the sum of two fluorescence species present in the plasma. Sample PARAFAC loadings were employed to build a regression model against concentration, resulting in a RMSECV of 0.060 μg ml−1. N-PLS using two factors produced a RMSECV of 0.045 μg ml−1. Figures of merit (FOM), such as sensitivity (SEN), selectivity (SEL) and limit of detection (LD) were determined for both PARAFAC and N-PLS. 相似文献
122.
A. Lakshmi Sailaja K. Kishore Kumar D. V. R. Ravi Kumar C. Mohan Kumar N. M. Yugandhar G. Srinubabu 《Chromatographia》2007,65(5-6):359-361
A simple, rapid, and sensitive high-performance liquid chromatographic method for estimation of efavirenz in human plasma
has been developed and validated. Chromatography was performed with C18 analytical column and 50:50 acetonitrile–phosphate buffer (pH 3.5) as mobile phase. Compounds were monitored by UV detection
at 247 nm. The retention time for efavirenz was 6.45 min and that for the internal standard, nelfinavir, was 2.042 min. Response
was a linear over the concentration range of 0.1 μg–10 μg mL−1 in human plasma. The method was simple, specific, precise and accurate and was useful for bioequivalence and pharmacokinetic
studies of efavirenz. 相似文献
123.
An end-channel amperometric detector with a guide tube for working electrode was designed and integrated on a home-made glass microchip. The guide tube was directly patterned and fabricated at the end of the detection reservoir, which made the fixation and alignment of working electrode relatively easy. The fabrication was carried out in a two-step etching process. A 30 μm carbon fiber microdisk electrode and Pt cathode were also integrated onto the amperometric detector. The baseline separation of dopamine (DA), catechol (CA) and epinephrine (EP) was achieved within 80 s. Relative standard deviations of not more than 5.2% were obtained for both peak currents and migration times of DA and CA (n=5). Using standard adding method, DA in tLrine and plasma samples was detected. The recoveries were in the range of 83%—103%. 相似文献
124.
Muliadi Ramli Nasrullah Idris Kenichi Fukumoto Hideaki Niki Fujio Sakan Tadashi Maruyama Koo Hendrik Kurniawan Tjung Jie Lie Kiichiro Kagawa 《Spectrochimica Acta Part B: Atomic Spectroscopy》2007,62(12):1379-1389
A TEA CO2 laser (350 mJ–1.5 J, 10.6 μm, 200 ns, 10 Hz) was focused onto a metal sub-target under He as host gas at 1 atmospheric pressure with a small amount of impurity gas, such as water and ethanol vapors. It was found that the TEA CO2 laser with the help of the metal sub-target is favorable for generating a strong, large volume helium gas breakdown plasma at 1 atmospheric pressure, in which the helium metastable-excited state was then produced overwhelmingly. While the metal sub-target itself was never ablated. The helium metastable-excited state produced after the strong helium gas breakdown plasma was considered to play an important role in exciting the atoms. This was confirmed by the specific characteristics of the detected H emission, namely the strong intensity with low background, narrow spectral width, and the long lifetime. This technique can be used for gas and solid samples analysis. For nonmetal solid analysis, a metal mesh was introduced in front of the nonmetal sample surface to help initiation of the helium gas breakdown plasma. For metal sample, analysis can be carried out by combining the TEA CO2 laser and an Nd–YAG laser where the Nd–YAG laser is used to ablate the metal sample. The ablated atoms from the metal sample are then sent into the region of helium gas breakdown plasma induced by the TEA CO2 laser to be excited through the helium metastable-excited state. This technique can be extended to the analysis of other elements, not limited only to hydrogen, such as halogens. 相似文献
125.
Ionization of esters of carboxylic acids RCOOR' (R = H, alkyl; R' = alkyl) within the air plasma of the Atmospheric Pressure Chemical Ionization (APCI) source occurs largely via H(+)-transfer and, to a minor extent, via NO(+) association. The protonated ester MH(+) is normally observed as M(2)H(+) and as higher aggregates (M(3)H(+), M(3)H(+)(H(2)O)) also at high source temperature. The behavior of M(2)H(+) upon collisional activation is consistent with the reported dissociation of proton-bound dimers to MH(+) species that, in turn, fragment according to the known paths of lowest energy. In addition, other important product ions form within the plasma, some in very high relative abundance, which are attributed to ion-molecule condensation reactions between neutral M and either MH(+) or M(2)H(+) resulting in the elimination of CO, R'OH, alkene from the alkoxy moiety of the ester and HCOOH. A general scheme is proposed to account for the experimental observations, which suggest that the encounter complex formed between MH(+) and M or between M(2)H(+) and M may either collisionally relax to the protonated dimer or trimer, respectively, or react via covalent bond forming and cleaving steps to eliminate stable neutral molecules. The proposed scheme is supported by both the observed concentration dependence and the temperature dependence of the products relative abundances within the plasma. Such reactions can be the dominant process, as in the case of formate esters. A second significant ionization route involves addition of NO(+) to form M(n)NO(+) (n = 1, 2, 3). An additional product corresponding to [M(2)NO(+) - CO(2)] is also observed with iso- and n-butyl formate esters. 相似文献
126.
Javad Mostaghimi Pierre Proulx Maher I. Boulos 《Plasma Chemistry and Plasma Processing》1984,4(3):199-217
A theoretical investigation of the effect of different parameters on the flow and the temperature fields in a radiofrequency
inductively coupled plasma is carried out. The parameters studied are: central injection gas flow rate, total gas flow rate,
input power, and the type of plasma gas. The results obtained for argon and nitrogen plasmas at atmospheric pressure indicate
that the flow and the temperature fields in the coil region, as well as the heat flux to the wall of the plasma confinement
tube, are considerably altered by the changes in the torch operating conditions. 相似文献
127.
Based on carbon nanofibers (CNFs) as a solid phase extraction adsorbent, a microcolumn preconcentration method coupled to inductively coupled plasma mass spectrometry (ICP–MS) was developed for the determination of trace elements (Mn, Co and Ni). The effect of various experimental parameters such as pH, sample flow rate and volume, elution solution and interfering ions on the retention of the studied ions have been investigated systematically. During all the steps of the experimental process, Mn, Co and Ni could be quantitatively sorbed on the microcolumn containing CNFs in the range of pH 6.0–9.0, and then eluted completely with 0.5 mol ml− 1 HNO3. A preconcentration factor of 150-fold was obtained. The detection limits for Mn, Co and Ni were 40, 0.4 and 8.0 pg ml− 1, respectively, with relative standard deviations less than 6.0%. In order to validate the proposed method, two certified reference materials of human hair (GBW 07601) and mussel (GBW 08571), and water sample were analyzed with satisfactory results. The recoveries were between 95.0 and 114%. 相似文献
128.
Mohamed Boumerzoug Marcel Boudreau Peter Mascher 《Plasma Chemistry and Plasma Processing》1997,17(2):181-192
Real-time optical emission spectroscopy (OES) was used to monitor the deposition of TiN both from mixtures of tetrakis(dimethylamino)titanium
(TDMATi)-N2 and TiCl4-H2-N2 in an electron cyclotron resonance chemical vapor deposition system. The accurate control of the ratio of the emission intensities
of ionized nitrogen at 391.4 nm and molecular nitrogen at 357.7 nm (N
2
+
/N2) led to low temperature deposition of stoichiometric TiN (Ti/N ≈ 1) and very low resistivity in both cases. It was found
that high ion density plasmas are crucial for a considerable reduction of the deposition temperature while maintaining good
film quality. OES shows that the abundance of certain excited plasma species is not only dependent on the gas mixture and
the deposition parameters, such as total pressure and microwave power, but also is strongly affected by the magnetic field
configuration. The deposition rate and the film resistivity can be related to the emission intensity ratio, I(N
2
+
)/I(N2). Finally, the two processes are compared in terms of the quality of as-deposited and heat-treated films. The comparison
shows that the films obtained with TDMATi exhibit lower resistivity and are thermally more stable than with TiCl4. 相似文献
129.
J. Al Andari A. M. Diamy J. C. Legrand R. I. Ben-Aim 《Plasma Chemistry and Plasma Processing》1993,13(1):103-116
Electron temperature and ion density are measured in an air microwave-induced plasma (2450 MHz) by means of a floating double probe. A 'cinetic scheme for ion formation and decay is set up, and a relationship between atomic oxygen and ion densities is obtained. From this relationship an order-of-magnitude of atomic oxygen concentration in the discharge is derived and compared with results obtained by optical actinometry in another work. 相似文献
130.