A rapid, sensitive and reliable high performance liquid chromatographic method coupled with tandem mass spectrometry (HPLC–MS/MS) has been developed and validated for the determination of ...cilnidipine, a relatively new calcium antagonist, in human plasma. The reversed-phase chromatographic system was interfaced with a TurboIonSpray (TIS) source. Nimodipine was employed as the internal standard (IS). Sample extracts following protein precipitation were injected into the HPLC–MS/MS system. The analyte and IS were eluted isocratically on a C18 column, with a mobile phase consisting of CH
3OH and NH
4Ac (96:4, v/v). The ions were detected by a triple quadrupole mass spectrometric detector in the negative mode. Quantification was performed using multiple reaction monitoring (MRM) of the transitions
m/
z 491.2
→
122.1 and
m/
z 417.1
→
122.1 for cilnidipine and for the IS, respectively. The analysis time for each run was 3.0
min. The calibration curve fitted well over the concentration range of 0.1–10
ng
mL
−1, with the regression equation
Y
=
(0.103
±
0.002)
X
+
(0.014
±
0.003) (
n
=
5),
r
=
0.9994. The intra-day and inter-day R.S.D.% were less than 12.51% at all concentration levels within the calibration range. The recoveries were between 92.71% and 97.64%. The long-term stability and freeze-thaw stability were satisfying at each level. The present method provides a modern, rapid and robust tool for pharmacokinetic studies of cilnidipine.
A new method, based on the chloroauric acid-enhanced luminol chemiluminescence, is established for the chemiluminescent imaging detection of protein blots on nitrocellulose membranes. After ...transferring to the nitrocellulose (NC) membranes, various proteins in human serum can be easily detected using this method. Simplicity and wide applicability are achieved, without the need of expensive antibodies or tedious immunoassay procedures. Furthermore, neither noxious materials nor radioactive pollution is produced. The successful detection of proteins is due to the binding of Au(III) to the protein blots and the chemiluminescent character of the enhanced luminol signal. As a novel chemiluminescent detection method, it offers significant biological analytical potentials in biochemistry and in molecular biology.
The development of an enhanced chemiluminescence detection method for the rapid detection of haptoglobin phenotyping after polyacrylamide gel electrophoresis is described in this paper. The enhanced ...chemiluminescence detection is based upon chemiluminescent reaction between luminol and hydrogen peroxide. Increased sensitivity and dynamic range are achieved by employing ammonium persulfate to enhance the chemiluminescence signal. Detection of haptoglobin phenotypes in human blood serum was easily achieved even without the addition of hemoglobin. Different polyacrylamide gel electrophoresis results were found between pure serum and hemoglobin-supplemented serum. Applying the suggested enhanced chemiluminescence detection, the original combining forms of haptoglobin and hemoglobin can be detected. The linear range of haptoglobin is 0.1−13.3 μg/mL, with a detection limit of 1.21 ng (sample loading volume 15 μL). Other proteins, such as catalase and ferritin, can also be detected using enhanced chemiluminescence detection. All detections after polyacrylamide gel electrophoresis were completed within 15 min. The proposed detection is very fast, compared to traditional methods using staining detection (minutes versus hours).
A novel chemiluminescence (CL)-based imaging method capable of directly detecting proteins in polyacrylamide gels after electrophoresis is proposed. Human serum proteins are presently detected by a ...direct CL imaging method after native 2-D PAGE. As a consequence, some proteins, including haptoglobin (Hp), Hp precursor, hemopexin (Hpx) precursor, Ig alpha-1 chain C region, and Complement C3 precursor can be detected and identified by MS and MS/MS techniques. These proteins are all acute phase proteins, which have been defined as biomarkers for certain diseases. Moreover, serum proteins from healthy people and cirrhotic patients were analyzed. A decrease in Hp spots for cirrhotic patients could be confirmed. The CL imaging conditions were optimized, including the concentrations of H₂O₂ and luminol. The process of CL detection of proteins is simple, and there is no need for specialized equipment. In comparison with the traditional CBB-R250 staining method, the detection sensitivity was improved and the detection period decreased about 70 times. Hence, this technique possesses potentials as a rapid, convenient, and inexpensive analytical technique for protein detection and for the diagnosis of diseases.
An overview of liquid chromatographic methods, mainly employing fluorescence detection together with sample pre-treatment methods, is presented for the determination of the toxic group of fumonisin ...mycotoxins in various matrices
This review gives an overview of different separation strategies with nanomaterials and their use in capillary electrophoresis (CE) and capillary electrochromatography, as well as in microchip ...electrophoresis, including metal and metal oxide nanoparticles, carbon nanotubes, fullerene and polymer nanoparticles, as well as silica nanoparticles. The paper highlights the new developments and innovative applications of nanoparticles as pseudostationary phases or immobilized on the capillary surface for CE separation. The separation and characterization of target nanoparticles with different sizes by CE are reviewed likewise.
The development of a novel Ag(NH₃)₂⁺ probe chemiluminescence (CL)-based imaging method for the detection of various proteins after PAGE is described. The detection is based upon the probe Ag(NH₃)₂⁺ ...catalyzing the CL reaction of the luminol-potassium persulfate system. The proposed method detects various proteins labeled by Ag(NH₃)₂⁺ and expands the application scope to SDS gels. It also detects proteins directly in polyacrylamide gels, without tedious transferring procedures. Furthermore, successful identification of proteins by peptide mass profiling using ionization MS was easily performed, and no pretreatments of gel prior to digestion are needed. Detection limits for standard marker proteins match CBB-R250 staining and the linear dynamic range is superior to CBB-R250 staining and silver staining. The CL imaging conditions, including luminescent reagents, silver ion concentration, the ammonia-controlled system and the washing reagents parameters have also been optimized.
The analysis is described for separating seven β-adrenergic blocking agents (atenolol, celiprolol, clorprenaline, fenoterol, metoprolol, propranolol, terbutaline) and clenbuterol (sympathomimetic β-2 ...receptor stimulating agonist, decongestant and bronchodilator, illicit anabolic used in athletics) by CE with UV detection. In order to simultaneously separate all analytes, Tris-H₃PO₄ solution was applied containing titanium dioxide nanoparticles (TiO₂ NPs) as BGEs. The effects of important factors, such as concentration of TiO₂ NPs, optimum pH, run buffer concentration, and separation voltage, were investigated so as to achieve best CE separation. The eight analytes could be well separated applying a separation voltage of 15 kV in 75 mM Tris-H₃PO₄ buffer at a pH of 2.40, containing 6.0x10⁻⁶ g/mL TiO₂ NPs. Under these optimal conditions, the RSDs for peak areas and for migration times were less than 2.7 and 2.3%, respectively. The detection limits were 0.1 μg/mL for celiprolol, 0.1 μg/mL for propranolol, 0.2 μg/mL for fenoterol, 1.0 μg/mL for atenolol, 1.0 μg/mL for clenbuterol, 1.0 μg/mL for clorprenaline, 1.0 μg/mL for metoprolol, and 1.0 μg/mL for terbutaline. The proposed method was successfully applied for the rapid CE determination of the frequently applied antihypertensive β-blocking compounds atenolol, metoprolol, terbutaline, and propranolol in pharmaceutical tablets.
FT-Raman spectroscopy (in combination with a fibre optic probe) was evaluated as an in-line tool to monitor a blending process of diltiazem hydrochloride pellets and paraffinic wax beads. The mean ...square of differences (MSD) between two consecutive spectra was used to identify the time required to obtain a homogeneous mixture. A traditional end-sampling thief probe was used to collect samples, followed by HPLC analysis to verify the Raman data. Large variations were seen in the FT-Raman spectra logged during the initial minutes of the blending process using a binary mixture (ratio: 50/50, w/w) of diltiazem pellets and paraffinic wax beads (particle size: 800–1200
μm). The MSD-profiles showed that a homogeneous mixture was obtained after about 15
min blending. HPLC analysis confirmed these observations. The Raman data showed that the mixing kinetics depended on the particle size of the material and on the mixing speed. The results of this study proved that FT-Raman spectroscopy can be successfully implemented as an in-line monitoring tool for blending processes.
A simple method for simultaneous determination of three catecholamines using ion chromatography (IC) with direct conductivity detection (CD) based on the ionization of catecholamines in acidic medium ...without chemical suppression is developed in the present paper. The method could be used for the determination of these catecholamines in pharmaceutical preparations for the purpose of drug quality control. The recovery of catecholamines was more than 97% (
n=3) and the relative standard deviation (R.S.D.) (
n=11) was less than 2.1%. In a single chromatographic run, norepinephrine (NE), epinephrine (E) and dopamine (DA) can be determined in less than 10 min. The detection limits were found to be 0.001 μg/ml for NE, 0.01 μg/ml for E and DA respectively. Linear ranges were 0.01–50 μg/ml for NE (
r
2=0.9998), 0.1–50 μg/ml for E (
r
2=0.9995) and DA (
r
2=0.9999), respectively.
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