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PubMed1990

Structural characterization by mass spectrometry of native and recombinant human relaxin.

Mass spectrometry has played a key role in characterizing the primary structure of native and recombinant relaxin, a peptide hormone that induces ripening of the cervix prior to childbirth. The peptide is composed of two chains, A and B, and is formed from a single-chain prohormone, as is insulin. Aside from conserved cysteines, though, it has little sequence homology with insulin. Due to the small amounts of native peptide initially available (less than 10 pmol), traditional techniques could not provide information on the blocked A-chain sequence, on the carboxyterminal sequences, nor on other possible post-translational modifications. Mass measurements by fast atom bombardment (FAB) were made on reduced human relaxin isolated from corpora lutea. The detection limit by FAB for reduced relaxin was 500 fmol. The B-chain was four amino acids shorter than expected from comparison of the previously known cDNA sequence with homologous rat and porcine sequences. The A-chain, as predicted, was 24 amino acids in length and had a pyroglutamic acid residue on the amino-terminus. The purified samples were homogeneous with no other post-translational modifications. The recombinant relaxin molecule was also extensively characterized by mass spectrometry. In addition to the intact molecule, all tryptic peptides were characterized by FAB. A capillary high-performance liquid chromatography continuous-flow FAB system, developed for high-sensitivity peptide mapping, aided in these analyses. Finally, the three disulfide bonds were shown by tandem mass spectrometry to match those of insulin.

Amino Acid Sequence↗

PubMed1991

The characterization of synthetic by-products by B/E linked scanning and high-resolution thermospray mass spectrometry.

Characterization of unknown synthetic by-products from a test synthesis of the experimental inhibitor of HIV-1 reverse transcriptase, BI-RG-587, is presented. Seven impurities were separated and characterized by thermospray liquid chromatography/mass spectrometry using low-resolution, high-resolution, and B/E linked scanning methods. The high-resolution mass measurements which were obtained were accurate to within 10 ppm of structures proposed for synthetic by-products present at the 0.1% level. Linked scans produced daughter ion spectra for each impurity to further aid in the characterization.

Antiviral Agents↗

PubMed1994

Characterization and differentiation of diglycosyl flavonoids by positive ion fast atom bombardment and tandem mass spectrometry.

This study shows that fast atom bombardment (FAB) in combination with collisional activation and tandem mass spectrometric techniques is useful for the characterization of, and the differentiation between, O-diglycosyl, O-C-diglycosyl and di-C-glycosyl flavonoids. A quick differentiation between the three types of glycosyl flavonoids is possible by simply examining FAB mass spectra. Low-energy product ion spectra of [M+H]+ ions have been used for determining the carbohydrate sequence in O-diglycosyl flavonoids and characterizing the terminal monosaccharide in O-C-diglycosyl flavonoids. The data obtained for per-O-deuterated precursor ion species of O-diglycosyl flavonoids indicate that O-linked hydrogen atoms are involved in the formation of Yn+ ions. High-energy product ion spectra of [M+H]+ ions enable further characterization and differentiation of isomeric di-6,8-C-glycosides.

Carbohydrate Sequence↗

PubMed2006

Synthesis, characterization, and theoretical study of stable isomers of C70(CF3)n (n = 2, 4, 6, 8, 10).

Reaction of C70 with ten equivalents of silver(I) trifluoroacetate at 320-340 degrees C followed by fractional sublimation at 420-540 degrees C and HPLC processing led to the isolation of a single abundant isomer of C70(CF3)n for n = 2, 4, 6, and 10, and two abundant isomers of C70(CF3)8. These six compounds were characterized by using matrix-assisted laser desorption ionization (MALDI) mass spectrometry, 2D-COSY and/or 1D 19F NMR spectroscopy, and quantum-chemical calculations at the density functional theory (DFT) level. Some were also characterized by Raman spectroscopy. The addition patterns for the isolated compounds were unambiguously found to be C1-7,24-C70(CF3)2, C1-7,24,44,47-C70(CF3)4, C2-1,4,11,19,31,41-C70(CF3)6, Cs-1,4,11,19,31,41,51,64-C70(CF3)8, C2-1,4,11,19,31,41,51,60-C70(CF3)8, and C1-1,4,10,19,25,41,49,60,66,69-C70(CF3)10 (IUPAC numbering). Except for the last compound, which is identical to the recently reported, crystallographically characterized C70(CF3)10 derivative prepared by a different synthetic route, these compounds have not previously been shown to have the indicated addition patterns. The largest relative yield under an optimized set of reaction conditions was for the Cs isomer of C70(CF3)8 (ca. 30 mol % of the sublimed mixture of products based on HPLC integration). The results demonstrate that thermally stable C70(CF3)n isomers tend to have their CF3 groups arranged on isolated para-C6(CF3)2 hexagons and/or on a ribbon of edge-sharing meta- and/or para-C6(CF3)2 hexagons. For Cs- and C2-C70(CF3)8 and for C2-C70(CF3)6, the ribbons straddle the C70 equatorial belt; for C1-C70(CF3)4, the para-meta-para ribbon includes three polar hexagons; for C1-7,24-C70(CF3)2, the para-C6(CF3)2 hexagon includes one of the carbon atoms on a C70 polar pentagon. The 10.3-16.2 Hz 7JF,F NMR coupling constants for the end-of-ribbon CF3 groups, which are always para to their nearest-neighbor CF3 group, are consistent with through-space Fermi-contact interactions between the fluorine atoms of proximate, rapidly rotating CF3 groups.

Journal Article↗

PubMed1991

Ultrasonic backscatter tissue characterization in cardiac diagnosis.

Ultrasonic tissue characterization has shown the potential to yield information about structural and functional properties of cardiovascular tissue. The development of real-time two-dimensional integrated backscatter imaging has made feasible clinical investigations of ultrasonic tissue characterization, including detection of stunned myocardium in patients with acute ischemia, recognition of remote infarction, detection of cardiac allograft rejection, and study of diffuse myocardial involvement with systemic diseases such as diabetes mellitus. Technical improvements and scientific advances in the understanding of the interaction between ultrasound and tissue may open an even wider range of clinical applications. Even in its present, relatively preliminary form, tissue characterization appears to have the potential for clinical application. Additional clinical experience will stimulate refinements and increases in the diagnostic power of this promising approach.

Echocardiography↗

PubMed2004

A relevant immunomagnetic assay to detect and characterize epithelial cell adhesion molecule-positive cells in bone marrow from patients with breast carcinoma: immunomagnetic purification of micrometastases.

BACKGROUND: The efficient detection and characterization of micrometastatic cells in the bone marrow of patients with breast carcinoma are of prognostic and therapeutic importance. The technique used must overcome the challenges that result from the small number of target cells (1 per 1 million hematopoietic cells) and the heterogeneous expression of micrometastatic cell markers. In this study, the authors assessed and improved the current methods for purifying and characterizing rare disseminated carcinoma cells. METHODS: The authors developed a single-step assay that does not require density-gradient separation. This assay can be performed directly on crude human bone marrow aspirates and is based on the use of immunomagnetic beads coated with an antibody that recognizes an epithelial cell-surface epitope, the epithelial cell adhesion molecule (EpCAM). To determine the specificity of the assay, the authors evaluated bone marrow specimens from 46 control patients. RESULTS: The novel method was highly reproducible and was capable of detecting as few as 10 carcinoma cells among 50 million hematopoietic cells. The yield was nearly 100%, with only 0.01% nonspecific cell draining. The authors found that 68 +/- 51 cells were trapped per 50 million cells in control crude aspirates and that density-gradient separation increased this number by 2-fold to 29-fold. These trapped cells expressed EpCAM, represented 1.4 x 10(-4) % of the sample, and were characterized as of hematopoietic cell origin (CD45 positive) or progenitor cell origin (CD34 positive). CONCLUSIONS: The authors developed a highly efficient and reproducible, single-step immunomagnetic assay that may be performed directly on crude human bone marrow aspirates. The authors believe the current study is the first to demonstrate that some rare bone marrow cells (CD45-positive or CD34-positive cells) may express EpCAM and, to some extent, may contaminate the purified micrometastatic cell fraction. Thus, a universal marker for micrometastatic cells remains to be discovered.

Aged↗

PubMed2004

Cytoarchitectonic characterization of the parahippocampal region of the guinea pig.

The cytoarchitectonic features of the parahippocampal region (PHR) in the guinea pig are described, based on coronal, horizontal, and sagittal 50-microm sections stained for Nissl substance, zinc, parvalbumin, or calbindin. We differentiate between perirhinal (PRC), postrhinal (POR), and entorhinal (ERC) cortices. PRC is divided into areas 35 and 36 occupying the fundus and the dorsal bank of the rhinal fissure, respectively. POR is located caudal to the PRC. POR and area 36 show a dense, clustered cellular layer II and a thinner layer III in comparison to the adjacent neocortex, and they differ from each other with respect to the orientation of the somata of layer VI neurons. Area 35 is characterized by a thin layer II that is not very different from layer III. Layer IV is (dys)granular in area 36 and POR, and is absent in area 35 and ERC. ERC, located ventromedial to the PRC and POR, is subdivided in six fields, of which field 5 is adjacent to area 35. In both area 35 and field 5, no clear differentiation between layers II and III is present. Field 5 shows a darker cellular stain and exhibits a cell-free zone or lamina dissecans between layers III and V. Medial to field 5, an area characterized by large cell clusters in layer II is designated field 4. The latter field is replaced by field 3 rostromedially, which also typically shows clustering of layer II neurons. These cell clusters in field 3, however, are much more constant in size in spacing compared to those in field 4. The caudomedial portion of ERC is subdivided into fields 1, 1', and 2. The latter, characterized by a homogeneous distribution of neurons in all layers with large darkly stained neurons in layer V is positioned rostral to field 1 and caudomedial to fields 4 and 5. In field 1, layers V and VI are thinner, and layer II neurons are smaller then in field 1' and field 2. We conclude that the architectonic features of the guinea pig PHR are comparable to those described in other mammals, particularly the rat.

Animals↗

PubMed2007

Physico-chemical characterization of nanofiltration membranes.

This study presents a methodology for an in-depth characterization of six representative commercial nanofiltration membranes. Laboratory-made polyethersulfone membranes are included for reference. Besides the physical characterization [molecular weight cut-off (MWCO), surface charge, roughness and hydrophobicity], the membranes are also studied for their chemical composition [attenuated total reflectance Fourier spectroscopy (ATR-FTIR) and X-ray photoelectron spectroscopy (XPS)] and porosity [positron annihilation spectroscopy (PAS)]. The chemical characterization indicates that all membranes are composed of at least two different layers. The presence of an additional third layer is proved and studied for membranes with a polyamide top layer. PAS experiments, in combination with FIB (focused ion beam) images, show that these membranes also have a thinner and a less porous skin layer (upper part of the top layer). In the skin layer, two different pore sizes are observed for all commercial membranes: a pore size of 1.25-1.55 angstroms as well as a pore size of 3.20-3.95 angstroms (both depending on the membrane type). Thus, the pore size distribution in nanofiltration membranes is bimodal, in contrast to the generally accepted log-normal distribution. Although the pore sizes are rather similar for all commercial membranes, their pore volume fraction and hence their porosity differ significantly.

Journal Article↗

PubMed2002

Optical compartmentation of vegetating algae species as a basis for their growth-specific characterization.

BACKGROUND: The number of microalgal strains known to date is enormous and continuously growing, and their characterization accordingly requires quick and reliable methodologies. METHODS: Asynchronously growing logarithmic (3- and 6-day cultures) and stationary (9-day cultures) phase cell populations of two algae species that are difficult to distinguish microscopically (one Chlorella sp., C. vulgaris [c-27], and another that might belong to the same genus, SA-3 algae exsymbiotic from Paramecium bursaria) were characterized by means of flow cytometry (FCM). Forward light scatter (FSC) of algae was monitored in association with their 90 degrees side light scatter (SSC) and fluorescence of endogenous chlorophyll (FL3-height). RESULTS: Two-parameter FSC versus SSC and FSC versus FL3-height plots distinctly showed growth-specific compartmentation of algae into discrete cell subpopulations staying at a particular stage of the life cycle, and numbers of cells constituting these subpopulations could be quantitated. The growth pattern of C. vulgaris (c-27) differed substantially from that of SA-3 algae, particularly in the late-logarithmic (6-day) cultures. At this phase of growth, C. vulgaris (c-27) cells compartmentalized into three subpopulations, whereas SA-3 cells compartmentalized into two subpopulations. Different compartmentations of optical signals from late-logarithmic phase SA-3 algae and C. vulgaris (c-27) likely were caused by the differences in timing of the life cycle stages of these types of cells. CONCLUSIONS: Growth-specific compartmentation of vegetating microalgae by FCM provides a good basis for characterization of morphologically similar algae species. Because algae are also present in symbiotic relationships with other organisms, this tool might be of potential interest for the study of symbiosis mechanisms.

Cell Compartmentation↗

PubMed2002

A new cytometric method for the immunophenotypic characterization of bone-derived human osteoclasts.

BACKGROUND: Osteoclast cell function relates to bone resorption. Isolation and characterization of these cells from in vivo sources remain difficult. The aim of this study was to show the feasibility of using flow cytometry to identify and characterize human mature osteoclasts obtained from bone tissues. METHODS: Bone femoral heads obtained as discarded surgical material were used. To check the nature of 121F(+) (a monoclonal antibody specific for human osteoclasts) cells by flow cytometry, we used laser scanning cytometry to analyze simultaneously the immunophenotype and DNA cell content of osteoclast-like cell-enriched bone samples. RESULTS: Results were compared with conventional morphologic and cytochemical studies. The percentage of cells that showed both cytochemical (tartrate-resistant acid phosphatase [TRAP](+)) and immunophenotypic (121F(+)) osteoclast-associated characteristics was very similar (12.5 +/- 6.2 versus 14.7 +/- 11.7; P = 0.46). Laser scanning cytometry showed that 121F(+) cells were bigger (P = 0.04) and they had a higher DNA cell content (P = 0.04) and more nuclei per cell (P = 0.04) than the 121F(-) cells present in the same sample. DISCUSSION: This study relied on the combined use of the 121F(+) antibody and different cytometry-based techniques to characterize the osteoclast populations from human bone.

Acid Phosphatase↗

PubMed2005

Multiparametric characterization by flow cytometry of flow-sorted subpopulations of a human hepatoma cell line useful for drug research.

BACKGROUND: Primary cultured hepatocytes are the closest model to the liver for drug research. However, to overcome its limited availability, the search for hepatic cell lines as an alternative to primary cultures is a matter of current interest. In particular, highly differentiated hepatocellular carcinomas have been proposed as in vitro tools for routine experiments in hepatotoxicity and drug metabolism. METHODS: Cell populations were selected by fluorescence-activated cell sorting based on low and high relative expressions of P-glycoprotein. These cell lines were characterized after 21 days in culture by multiparametric analysis with flow cytometry providing direct information on key cellular functions (stability in culture, intracellular ionic homeostasis, plasmatic and mitochondrial membrane-related parameters, red-ox status, drug transport, and metabolism). RESULTS: Two subpopulations (ADV-1 and ADV-2) from the differentiated and well-characterized human hepatoma BC2 cell line showed increased activity of drug transport and drug biotransformation capability (cytochrome P450 [CYP] 1A2, CYP2B6, CYP3A4, and CYP2Cs). These subpopulations were characterized extensively by multiparametric flow cytometric analysis. CONCLUSION: ADV-1 subpopulation showed greater stability in culture, better efficiency regarding intracellular pH maintenance through the operation of Na+/H+ exchange antiporter, and significantly greater CYP-dependent biotransformation activity than the BC2 parental cells and ADV-2 cells.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed2005

An integrated approach to the characterization of cell movement.

BACKGROUND: Most phenomena in developmental biology involve or depend upon cell migration. This article describes a comprehensive framework for the characterization and analysis of trajectories defined by cell movement. The following two perspectives are considered: (a) the behavior of each individual cell and (b) interactions between neighboring pairs of cells. METHODS: The measurements considered for individual trajectories include the velocity magnitude and orientation, maximum spatial dispersion, displacement effectiveness, and displacement entropies. Interactions between two trajectories are characterized by comparing the respective velocities. RESULTS: The potential of the overall framework is illustrated using data of moving cells in different biological environments. The work shows that it is possible to use the new algorithm presented here to characterize cell motility. CONCLUSIONS: The features of the algorithm were successful in determining the motility changes under different experimental conditions.

Algorithms↗

PubMed2006

Setup and characterization of a multiphoton FLIM instrument for protein-protein interaction measurements in living cells.

BACKGROUND: Fluorescence lifetime microscopy (FLIM) is currently one of the best techniques to perform accurate measurements of interactions in living cells. It is independent of the fluorophore concentration, thus avoiding several common artifacts found in Förster Resonance Energy Transfer (FRET) imaging. However, for FLIM to achieve high performance, a rigorous instrumental setup and characterization is needed. METHODS: We use known fluorophores to perform characterization experiments in our instrumental setup. This allows us to verify the accuracy of the fluorescence lifetime determination, and test the linearity of the instrument by fluorescence quenching. RESULTS: We develop and validate here a protocol for rigorous characterization of time-domain FLIM instruments. Following this protocol, we show that our system provides accurate and reproducible measurements. We also used HeLa cells expressing proteins fused to Green Fluorescent Proteins variants (CFP and YFP) to confirm its ability to detect interactions in living cells by FRET. CONCLUSIONS: We report a well-designed protocol in which precise and reproducible lifetime measurements can be performed. It is usable for all confocal-based FLIM instruments and is a useful tool for anyone who wants to perform quantitative lifetime measurements, especially when studying interactions in living cells using FRET.

Bacterial Proteins↗

PubMed1997

Proteome studies of Saccharomyces cerevisiae: identification and characterization of abundant proteins.

Two-dimensional (2-D) gel electrophoresis can now be coupled with protein identification techniques and genome sequence information for direct detection, identification, and characterization of large numbers of proteins from microbial organisms. 2-D electrophoresis, and new protein identification techniques such as amino acid composition, are proteome research techniques in that they allow direct characterization of many proteins at the same time. Another new tool important for yeast proteome research is the Yeast Protein Database (YPD), which provides the sequence-derived protein properties needed for spot identification and tabulations of the currently known properties of the yeast proteins. Studies presented here extend the yeast 2-D protein map to 169 identified spots based upon the recent completion of the yeast genome sequence, and they show that methods of spot identification based on predicted isoelectric point, predicted molecular mass, and determination of partial amino acid composition from radiolabeled gels are powerful enough for the identification of at least 80% of the spots representing abundant proteins. Comparison of proteins predicted by YPD to be detectable on 2-D gels based on calculated molecular mass, isoelectric point and codon bias (a predictor of abundance) with proteins identified in this study suggests that many glycoproteins and integral membrane proteins are missing from the 2-D gel patterns. Using the 2-D gel map and the information available in YDP, 2-D gel experiments were analyzed to characterize the yeast proteins associated with: (i) an environmental change (heat shock), (ii) a temperature-sensitive mutation (the prp2 mRNA splicing mutant), (iii) a mutation affecting post-translational modification (N-terminal acetylation), and (iv) a purified subcellular fraction (the ribosomal proteins). The methods used here should allow future extension of these studies to many more proteins of the yeast proteome.

Databases, Factual↗

PubMed1998

Capillary column chromatography improves sample preparation for mass spectrometric analysis: complete characterization of human alpha-enolase from two-dimensional gels following in situ proteolytic digestion.

Two-dimensional polyacrylamide gel electrophoresis (2-DE) in combination with mass spectrometry is an extremely powerful tool for characterizing complex mixtures of proteins. In many cases, the success of this approach relies upon the ability to recover peptides at high concentrations and free of interfering artifacts from in-gel and/or on-membrane enzymatic digests. In previous studies, we demonstrated that capillary or microcolumn (< 350 microm ID) reversed-phase high performance liquid chromatography (RP-HPLC) is a powerful microseparation technique for proteins and peptides (Moritz, R. L. and Simpson, R. J., J. Chromatogr. 1992, 599, 119-130). Here we evaluate various capillary column RP-HPLC/mass spectrometric approaches for identifying and characterizing 2-DE resolved proteins. For these studies, stable and efficient 0.20 mm and 0.32 mm internal diameter (ID) fused-silica columns with hydrophilic polyvinylidene difluoride (PVDF) frits were fabricated and slurry packed with 7 microm spherical, 300 A pore size, C8 bonded phase silica particles. We show that capillary column chromatography is a rapid and efficient desalting/concentrating (ON/OFF) technique for sample cleanup prior to protein identification by peptide-mass fingerprinting using matrix-assisted laser desorption ionization (MALDI)-time-of-flight mass spectrometry. While marginally more peptide mass information can be obtained by stepped elution of the peptide mixture with increasing concentrations of organic solvent, best results were obtained by fractionation of the peptide mixture using a linear 60 min gradient. One salient feature of this study was the observation that, in contrast to the stepped elution and gradient approaches, the ionization of peptide T1 (m/z 2402.2 SGETEDTFIADLVV(PeCys)TGQIK) was almost completely suppressed using the ON/OFF approach. Maximal amino acid sequence coverage, a necessary prerequisite for complete characterization of a protein, was accomplished using a capillary column (0.2 mm ID) directly coupled with an electrospray ionization (ESI) ion-trap tandem mass spectrometer. For example, from an in situ tryptic digest of alpha-enolase isolated by 2-DE from the human breast carcinoma cell line MDA-MB231, 71% of the amino acid sequence was obtained. In addition to identifying two possible N-terminal acetylated alpha-enolase variants, Asn153Asp and Ile152Asp/Asn153Ile, the tandem mass spectrometric data revealed the presence of a number of process-induced modifications of alpha-enolase such as methionine oxidation and cysteine amidoethylation.

Amino Acid Sequence↗

PubMed1998

Use of capillary electrophoresis methods to characterize the pharmacokinetics of antisense drugs.

As antisense drugs become mature for clinical trials, analytical techniques to analyze antisense DNA in biological media for characterization of their pharmacokinetics will be in demand. Due to the superior resolving power of capillary gel electrophoresis (CGE), CGE will likely be a preferred method in quantifying intact oligonucleotides as well as the putative metabolic products. Nonetheless, biological mediums can influence the stability of the gel column, making a CGE assay time-consuming. In one approach, high-performance liquid chromatography (HPLC) was used to quantify the total amount of antisense compounds to increase the sample throughput and CGE was used to determine the relative percentage of the intact and metabolic species on specific samples. Alternatively, extensive sample pretreatment procedures were performed and the samples were quantified and characterized directly by CGE alone with the use of an internal standard. Both methods have been used to characterize the pharmacokinetics of antisense compounds. This review focuses on the instrumental and technical aspects of analyzing antisense DNA in biological mediums using CGE either as a single or a combined method towards better understanding of the pharmacokinetics of antisense DNA. Moreover, the newer analytical technologies of capillary electrophoresis (CE), which hold great potential to be used for pharmacokinetic applications, such as the replenishable sieving matrix combined with an innovative coupling approach and microchip CE, will also be explored.

Animals↗

PubMed2004

Application of capillary electrophoresis- electrospray-mass spectrometry to the separation and characterization of isomeric lipopolysaccharides of Neisseria meningitidis.

A capillary electrophoresis-electrospray-mass spectrometry technique for the characterization of lipopolysaccharides (LPSs) was developed, permitting the separation of trace-level O-deacylated LPS isoforms for subsequent structural characterization using tandem mass spectrometry (MS/MS). The separation buffer and electrospray interface were optimized first using O-deacylated LPS samples from large-scale preparations. It was found that with microelectrospray or sheath-solution interface, we could separate LPS in anionic forms and detect them using either negative or positive ion mode MS. For negative ion detection mode MS, 30 mM morpholine with addition of 5% v/v methanol was employed as separation buffer. When positive ion detection mode MS was required, 10 mM ammonium acetate with addition of 5% methanol was used as separation buffer. The structural assignments obtained from MS/MS and capillary zone electrophoresis-electrospray-MS (CZE-ESMS) analyses enabled the identification of isomeric glycoforms. Application of this technique to the analysis of LPS from the galE mutants of Neisseria meningitidis strain BZ157 B5+ revealed the presence of isomeric glycoforms, in which the location of a functional group phosphoethanolamine was found to be in either inner core or lipid A-OH regions. The described technique was also applied to the analysis of LPS samples from the galE mutant of N. meningitidis strains F1576 A4+ and A4-. The occurrence of isomeric LPS glycoforms differing by the location or presence of neutral sugar residues, such as hexoses, can also be characterized using MS/MS.

Acetylation↗

PubMed2003

Characterization of pharmaceutical drugs by a modified nonaqueous capillary electrophoresis--mass spectrometry method.

A simple method for the separation and characterization of a group of nine basic compounds, comprising seven tricyclic antidepressant and two bronchodilator drugs, by nonaqueous capillary electrophoresis (NACE) employing ultraviolet and mass spectrometry detection is described. After optimization of the electrophoresis separation conditions, including the compositions of the electrolyte and the organic solvent, a reliable separation of all nine basic analytes was achieved in 80 mM ammonium formate dissolved in a methanol-acetonitrite (80:20 v/v) mixture, having an apparent pH of 8.7. The volatile nonaqueous electrolyte system used with a normal electroosmotic flow polarity also provided an optimal separation condition for the characterization of the analytes by mass spectrometry. When results were compared with reversed-phase gradient and isocratic high-performance liquid chromatography (HPLC) methods, the NACE method provided greater efficiency, achieving baseline resolution for all nine basic compounds in less than 30 min. The NACE method is suitable for use as a routine procedure for the rapid separation and characterization of basic compounds and is a viable alternative to HPLC for the separation of a wide range of pharmaceutical drugs.

Antidepressive Agents, Tricyclic↗