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1.
J Chem Educ ; 95(2): 242-247, 2018 Feb 13.
Artigo em Inglês | MEDLINE | ID: mdl-29657334

RESUMO

This article examines the ways that a shared faculty experience across five partner institutions led to a deep awareness of the curriculum and pedagogy of general chemistry coursework, and ultimately, to a collaborative action plan for student success. The team identified key differences and similarities in course content and instructional experiences. The comparative analysis yielded many more similarities than differences, and therefore, the team shifted its focus from "gap analysis" to an exploration of common curricular challenges. To address these challenges, the team developed content for targeted instructional resources that promoted the success of all STEM students across institutions. This article contextualizes the interinstitutional collaboration and closely examines the interactive components (awareness, analysis, and action), critical tools, and productive attitudes that undergirded the curricular alignment process of the STEM Transfer Student Success Initiative (t-STEM).

2.
Front Psychol ; 12: 733995, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34803811

RESUMO

Calls to diversify the professoriate have been ongoing for decades. However, despite increasing numbers of scholars from underrepresented racial minority groups earning doctorates, actual progress in transitioning to faculty has been slow, particularly across STEM disciplines. In recent years, new efforts have emerged to recruit faculty members from underrepresented racial minority groups (i.e., African American/Black, Hispanic/Latinx, and/or Native American/Native Hawaiian/Indigenous) through highly competitive postdoctoral programs that allow fellows the opportunity to transition (or "convert") into tenure-track roles. These programs hybridize some conventional aspects of the faculty search process (e.g., structured interview processes that facilitate unit buy-in) along with novel evidence-based practices and structural supports (e.g., proactive recruitment, cohort communities, search waivers, professional development, enhanced mentorship, financial incentives). In this policy and practice review, we describe and synthesize key attributes of existing conversion programs at institutional, consortium, and system levels. We discuss commonalities and unique features across models (N = 38) and draw specific insights from postdoctoral conversion models developed within and across institutions in the University System of Maryland (USM). In particular, experience garnered from a 10-year-old postdoc conversion program at UMBC will be highlighted, as well as the development of an additional institutional model aimed at the life sciences, and a state-system model of faculty diversification with support from a NSF Alliances for Graduate Education and the Professoriate (AGEP) grant.

3.
Plant J ; 58(3): 401-12, 2009 May.
Artigo em Inglês | MEDLINE | ID: mdl-19144005

RESUMO

Pathogen infection leads to the activation of defense signaling networks in plants. To study these networks and the relationships between their components, we introduced various defense mutations into acd6-1, a constitutive gain-of-function Arabidopsis mutant that is highly disease resistant. acd6-1 plants show spontaneous cell death, reduced stature, and accumulate high levels of camalexin (an anti-fungal compound) and salicylic acid (SA; a signaling molecule). Disruption of several defense genes revealed that in acd6-1, SA levels/signaling were positively correlated with the degree of disease resistance and defense gene expression. Salicylic acid also modulates the severity of cell death. However, accumulation of camalexin in acd6-1 is largely unaffected by reducing the level of SA. In addition, acd6-1 shows ethylene- and jasmonic acid-mediated signaling that is antagonized and therefore masked by the presence of SA. Mutant analysis revealed a new relationship between the signaling components NPR1 and PAD4 and also indicated that multiple defense pathways were required for phenotypes conferred by acd6-1. In addition, our data confirmed that the size of acd6-1 was inversely correlated with SA levels/signaling. We exploited this unique feature of acd6-1 to identify two genes disrupted in acd6-1 suppressor (sup) mutants: one encodes a known SA biosynthetic component (SID2) and the other encodes an uncharacterized putative metalloprotease (At5g20660). Taken together, acd6-1 is a powerful tool not only for dissecting defense regulatory networks but also for discovering novel defense genes.


Assuntos
Anquirinas/genética , Proteínas de Arabidopsis/genética , Arabidopsis/genética , Transferases Intramoleculares/metabolismo , Transdução de Sinais , Arabidopsis/metabolismo , Ciclopentanos/metabolismo , Etilenos/metabolismo , Genes de Plantas , Imunidade Inata , Indóis/metabolismo , Transferases Intramoleculares/genética , Mutagênese Insercional , Mutação , Oxilipinas/metabolismo , Ácido Salicílico/metabolismo , Tiazóis/metabolismo
4.
Anal Chim Acta ; 1130: 146-154, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32892934

RESUMO

Desorption Atmospheric Pressure Chemical Ionization (DAPCI) is an ambient ionization technique for mass spectrometry (MS). DAPCI is a plasma-based ionization technique that uses inert, high-velocity gas, and solvent ions to ionize the analytes in a sample. This technique allows both volatile and non-volatile species to be analyzed and provides for more efficient and sensitive detection of low polarity compounds. DAPCI has been used in many applications such as explosives, forensics, environmental, food safety, pharmaceuticals, and biologicals. This paper is an overview of the development of DAPCI techniques, followed by an overview of its applications.


Assuntos
Substâncias Explosivas , Espectrometria de Massas por Ionização por Electrospray , Pressão Atmosférica , Íons , Solventes
5.
Artigo em Inglês | MEDLINE | ID: mdl-32313592

RESUMO

Deaf undergraduates are eager to engage in research but often feel marginalized due to lack of appropriate accommodations to allow for effective communication within heterogeneous research teams consisting of hearing peers and/or mentors. In this case study, we interviewed four American Sign Language (ASL) interpreters who provided full-time accommodations to teams consisting of one deaf student and two hearing peers during a six-week internship. We queried the interpreters on their role and experiences in supporting the research teams. Our findings indicate that the interpreters can be a valuable asset to heterogeneous teams by supporting both deaf and hearing individuals and advocating for the deaf student. That said, interpreters also had to overcome challenges unique to interpreting in the research environment, such as deciding when and how to interpret. The insights provided by the interpreters interviewed here are valuable as undergraduate research programs evaluate how to provide appropriate accommodations to deaf students engaged in research. In addition, they also highlight the need for research experience coordinators and mentors to consider supporting diverse teams in developing effective communication strategies and applying universal design for learning to the research environment.

6.
UI J ; 11(1)2020.
Artigo em Inglês | MEDLINE | ID: mdl-32766571

RESUMO

The benefits of mentored undergraduate research to student success, retention, and persistence in science, technology, engineering, and mathematics (STEM) have long been identified. However, many students miss out on the opportunity to engage in research often due to unfamiliarity of various research opportunities or how to approach potential research mentors. To address this, we developed a scalable online badge, Introduction to Research, that draws on aspects of the Entering Research curriculum (Branchaw, Pfund, & Rediske, 2010) to help students explore and prepare for undergraduate research in the biomedical and behavioral sciences. Students in the BUILD Training Program, part of the larger STEM BUILD at UMBC Initiative, completed the badge in conjunction with a 3-week classroom-based undergraduate research experience (CURE) before the start of their second year of undergraduate study at the University of Maryland, Baltimore County (UMBC). We were interested in investigating how this intervention, online badge plus CURE, correlated to students engaging in undergraduate research before the end of their second year at UMBC. We did this through student self-report, comparing students who had participated in the online badge plus CURE (BTP) to those who participated in neither (Control). Our data demonstrate that students who participated in the Introduction to Research Badge and CURE entered into mentored research at a significantly higher rate than students who were exposed to neither. Further, previously validated instruments of students 'research self-efficacy and science identity were used to compare how the Introduction to Research Badge and CURE may impact these two psycho-social variables. Students who participated in the Introduction to Research Badge and CURE had significantly higher gains in research self-efficacy compared to the control group. However, no change was observed in science identity for either group. Collectively, our results suggest that students who engage in the Introduction to Research Badge in combination with a CURE engage in mentored research within a year of completion at higher levels than students who engage in neither.

7.
Ethn Dis ; 30(4): 681-692, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32989368

RESUMO

Objective: The biomedical/behavioral sciences lag in the recruitment and advancement of students from historically underrepresented backgrounds. In 2014 the NIH created the Diversity Program Consortium (DPC), a prospective, multi-site study comprising 10 Building Infrastructure Leading to Diversity (BUILD) institutional grantees, the National Research Mentoring Network (NRMN) and a Coordination and Evaluation Center (CEC). This article describes baseline characteristics of four incoming, first-year student cohorts at the primary BUILD institutions who completed the Higher Education Research Institute, The Freshmen Survey between 2015-2019. These freshmen are the primary student cohorts for longitudinal analyses comparing outcomes of BUILD program participants and non-participants. Design: Baseline description of first-year students entering college at BUILD institutions during 2015-2019. Setting: Ten colleges/universities that each received <$7.5mil/yr in NIH Research Project Grants and have high proportions of low-income students. Participants: First-year undergraduate students who participated in BUILD-sponsored activities and a sample of non-BUILD students at the same BUILD institutions. A total of 32,963 first-year students were enrolled in the project; 64% were female, 18% Hispanic/Latinx, 19% African American/Black, 2% American Indian/Alaska Native and Native Hawaiian/Pacific Islander, 17% Asian, and 29% White. Twenty-seven percent were from families with an income <$30,000/yr and 25% were their family's first generation in college. Planned Outcomes: Primary student outcomes to be evaluated over time include undergraduate biomedical degree completion, entry into/completion of a graduate biomedical degree program, and evidence of excelling in biomedical research and scholarship. Conclusions: The DPC national evaluation has identified a large, longitudinal cohort of students with many from groups historically underrepresented in the biomedical sciences that will inform institutional/national policy level initiatives to help diversify the biomedical workforce.


Assuntos
Pesquisa Biomédica/educação , Diversidade Cultural , Programas Governamentais/estatística & dados numéricos , Estudantes/estatística & dados numéricos , Universidades , Adolescente , Adulto , Negro ou Afro-Americano/estatística & dados numéricos , Asiático/estatística & dados numéricos , Escolaridade , Feminino , Hispânico ou Latino/estatística & dados numéricos , Humanos , Renda/estatística & dados numéricos , Masculino , Pessoa de Meia-Idade , National Institutes of Health (U.S.)/economia , Havaiano Nativo ou Outro Ilhéu do Pacífico/estatística & dados numéricos , Estudos Prospectivos , Inquéritos e Questionários , Estados Unidos , População Branca/estatística & dados numéricos , Recursos Humanos , Adulto Jovem , Indígena Americano ou Nativo do Alasca/estatística & dados numéricos
8.
Talanta ; 199: 155-163, 2019 Jul 01.
Artigo em Inglês | MEDLINE | ID: mdl-30952240

RESUMO

For detection using pulsed electrochemical detection (PED), analytes must preadsorb to the working gold electrode. Indirect pulsed electrochemical detection (InPED) exploits this requirement by including a PED-active reagent in the mobile phase. The background signal provided by oxidation of this reagent is attenuated by the adsorption of analyte molecules to the electrode. In this paper, a method has been developed to allow the use of InPED in combination with high-performance reversed-phase liquid chromatography (RPLC). Biotin was used as a probe molecule to determine that the use of acetonitrile as the organic modifier in the mobile phase provided superior results to the use of methanol. In addition, a silica-based, high surface area C18 column (i.e., Varian Pursuit XRs) was found to give better results than a polymer-based reversed-phase column (i.e., Dionex IonPac NS1). Optimized experimental conditions were used todetermine lipoic acid, tiopronin, and penicillamine, obtaining detection limits of ≤1 µM (30 pmol injected). The analytical utility of RPLC-InPED was demonstrated by an assay of an over-the-counter-formulation containing lipoic acid.

9.
J Coll Sci Teach ; 47(4): 83-91, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-29681667

RESUMO

Using a cooperative learning framework in a quantitative reasoning laboratory course, students were assigned to static teams of four in which they adopted roles that rotated regularly. The roles included: team leader, protocol manager, data recorder, and researcher. Using a mixed-methods approach, we investigated students' perceptions of the team roles and specifically addressed students' understanding of the roles, students' beliefs in their ability to enact the roles, and whether working with assigned team roles supported the teams to work effectively and cohesively. Although students expressed confidence in their understanding of the team roles, their understanding differed from the initial descriptions. This suggests that students' understanding of team roles may be influenced by a variety of factors, including their experiences within their teams. Students also reported that some roles appeared to lack a purpose, implying that for roles to be successful, they must have a clear purpose. Finally, the fact that many students reported ignoring the team roles suggests that students do not perceive roles as a requirement for team productivity and cohesion. On the basis of these findings, we provide recommendations for instructors wishing to establish a classroom group laboratory environment.

10.
Nat Biomed Eng ; 2(9): 675-686, 2018 09.
Artigo em Inglês | MEDLINE | ID: mdl-31015674

RESUMO

Manufacturing technologies for biologics rely on large, centralized, good-manufacturing-practice (GMP) production facilities and on a cumbersome product-distribution network. Here, we report the development of an automated and portable medicines-on-demand device that enables consistent, small-scale GMP manufacturing of therapeutic-grade biologics on a timescale of hours. The device couples the in vitro translation of target proteins from ribosomal DNA, using extracts from reconstituted lyophilized Chinese hamster ovary cells, with the continuous purification of the proteins. We used the device to reproducibly manufacture His-tagged granulocyte-colony stimulating factor, erythropoietin, glucose-binding protein and diphtheria toxoid DT5. Medicines-on-demand technology may enable the rapid manufacturing of biologics at the point of care.


Assuntos
Produtos Biológicos/química , Proteínas/química , Animais , Células CHO , Linhagem Celular , Cricetulus , DNA Ribossômico/química , Eritropoetina/química , Fator Estimulador de Colônias de Granulócitos/química , Humanos , Sistemas Automatizados de Assistência Junto ao Leito
11.
BMC Proc ; 11(Suppl 12): 24, 2017.
Artigo em Inglês | MEDLINE | ID: mdl-29375665

RESUMO

BACKGROUND: UMBC, a diverse public research university, "builds" upon its reputation in producing highly capable undergraduate scholars to create a comprehensive new model, STEM BUILD at UMBC. This program is designed to help more students develop the skills, experience and motivation to excel in science, technology, engineering, and mathematics (STEM). This article provides an in-depth description of STEM BUILD at UMBC and provides the context of this initiative within UMBC's vision and mission. KEY HIGHLIGHTS: The STEM BUILD model targets promising STEM students who enter as freshmen or transfer students and do not qualify for significant university or other scholarship support. Of primary importance to this initiative are capacity, scalability, and institutional sustainability, as we distill the advantages and opportunities of UMBC's successful scholars programs and expand their application to more students. The general approach is to infuse the mentoring and training process into the fabric of the undergraduate experience while fostering community, scientific identity, and resilience. At the heart of STEM BUILD at UMBC is the development of BUILD Group Research (BGR), a sequence of experiences designed to overcome the challenges that undergraduates without programmatic support often encounter (e.g., limited internship opportunities, mentorships, and research positions for which top STEM students are favored). BUILD Training Program (BTP) Trainees serve as pioneers in this initiative, which is potentially a national model for universities as they address the call to retain and graduate more students in STEM disciplines - especially those from underrepresented groups. As such, BTP is a research study using random assignment trial methodology that focuses on the scalability and eventual incorporation of successful measures into the traditional format of the academy. IMPLICATIONS: Critical measures to transform institutional culture include establishing an extensive STEM Living and Learning Community to increase undergraduate retention, expanding the adoption of "active learning" pedagogies to increase the efficiency of learning, and developing programs to train researchers to effectively mentor a greater portion of the student population. The overarching goal of STEM BUILD at UMBC is to retain students in STEM majors and better prepare them for post baccalaureate, graduate, or professional programs as well as careers in biomedical and behavioral research.

12.
J Chromatogr A ; 1118(1): 125-33, 2006 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-16546198

RESUMO

On-line in vitro microdialysis (MD) sampling followed by HPLC separation and UV absorbance detection (HPLC-UV) was used to monitor carbohydrate enzyme systems. Fundamental parameters (i.e., K(m) and V(max)) of hydrolysis reactions of 4-nitrophenyl-beta-D-glucopyranoside, 4-nitrophenyl-beta-d-galactopyranoside, and 4-nitrophenyl-beta-D-xylopyranoside were determined for a model enzyme, almond beta-glucosidase. Accurate quantitation was achieved via internal standard methodology and compared to spectrophotometric data and literature K(m) values, which were found to be 2.6+/-0.5 mM (MD), 2.7+/-0.4 mM (spec), and 2.5 mM (lit), for the substrate 4-nitrophenyl-beta-d-glucopyranoside. A previously unpublished K(m) value for the substrate salicin was also determined by this method. An application is shown for monitoring the glycoside salicin and its hydrolysis product saligenin in a commercially available willow bark product that is used for making tea. This versatile method has far-reaching applications to monitoring a variety of carbohydrates in enzymatic processes without complex sample preparation procedures and without volume loss.


Assuntos
Soluções para Diálise/análise , Glicosídeos/metabolismo , Microdiálise/instrumentação , beta-Glucosidase/metabolismo , Álcoois Benzílicos/química , Álcoois Benzílicos/metabolismo , Cromatografia Líquida de Alta Pressão/instrumentação , Cromatografia Líquida de Alta Pressão/métodos , Soluções para Diálise/química , Enzimas/metabolismo , Glucosídeos , Glicosídeos/química , Hidrólise , Cinética , Microdiálise/métodos , Estrutura Molecular , Casca de Planta/química , Reprodutibilidade dos Testes , Salix/química , Espectrofotometria Ultravioleta/instrumentação , Espectrofotometria Ultravioleta/métodos
13.
Nucleic Acids Res ; 31(21): e135, 2003 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-14576335

RESUMO

A new method for rapid purification and structural analysis of oligoribonucleotides of 19 and 20 nt is applied to RNA hairpins SL3 and SL2, which are stable secondary structures present on the psi recognition element of HIV-1. This approach uses ion-pairing reversed-phase liquid chromatography (IP-RPLC) to achieve the separation of the stem-loop from the transcription mix. Evidence is presented that IP-RPLC is sensitive to the different conformers of these secondary structures. The purity of each stem-loop was confirmed by mass spectrometry and PAGE. IP-RPLC purification was found to be superior to PAGE in terms of time, safety and, most importantly, purity.


Assuntos
Cromatografia Líquida/métodos , HIV-1/genética , Conformação de Ácido Nucleico , RNA Viral/química , RNA Viral/isolamento & purificação , Sequências Reguladoras de Ácido Ribonucleico/genética , Sequência de Bases , Eletroforese em Gel de Poliacrilamida , Oligorribonucleotídeos/química , Oligorribonucleotídeos/genética , Oligorribonucleotídeos/isolamento & purificação , RNA Líder para Processamento/química , RNA Líder para Processamento/genética , RNA Líder para Processamento/isolamento & purificação , RNA Viral/genética , Espectrometria de Massas por Ionização por Electrospray , Fatores de Tempo
14.
Talanta ; 146: 594-602, 2016 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-26695308

RESUMO

The mechanism of detection in pulsed electrochemical detection (PED) requires preadsorption of the analyte to the working electrode prior to its subsequent oxidation. Indirect detection is accomplished by the addition of a PED-active reagent to the mobile phase, whose signal is attenuated by an analyte that more strongly adsorbs to the electrode surface. Here, indirect PED (InPED) is applied to the determination of aliphatic carboxylate-containing compounds separated using high performance anion-exchange chromatography (HPAEC). Limits of detections of 0.05-2 ppm (10-400 pmol) are found for most analytes tested using an optimized potential-time waveform at a gold working electrode. The analytical utility of InPED is demonstrated for assays of gabapentin, biotin, proline and several over-the-counter formulations.

15.
J Vis Exp ; (112)2016 06 20.
Artigo em Inglês | MEDLINE | ID: mdl-27404400

RESUMO

This manuscript outlines how to visualize mass spectrometry ambient ionization sources using schlieren photography. In order to properly optimize the mass spectrometer, it is necessary to characterize and understand the physical principles of the source. Most commercial ambient ionization sources utilize jets of nitrogen, helium, or atmospheric air to facilitate the ionization of the analyte. As a consequence, schlieren photography can be used to visualize the gas streams by exploiting the differences in refractive index between the streams and ambient air for visualization in real time. The basic setup requires a camera, mirror, flashlight, and razor blade. When properly configured, a real time image of the source is observed by watching its reflection. This allows for insight into the mechanism of action in the source, and pathways to its optimization can be elucidated. Light is shed on an otherwise invisible situation.


Assuntos
Espectrometria de Massas , Hélio , Nitrogênio , Fotografação
16.
J Am Soc Mass Spectrom ; 27(2): 352-8, 2016 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-26471042

RESUMO

Molecular ionization-desorption analysis source (MIDAS), which is a desorption atmospheric pressure chemical ionization (DAPCI) type source, for mass spectrometry has been developed as a multi-functional platform for the direct sampling of surfaces. In this article, its utility for the analysis of thin-layer chromatography (TLC) plates is highlighted. Amino acids, which are difficult to visualize without staining reagents or charring, were detected and identified directly from a TLC plate. To demonstrate the full potential of MIDAS, all active ingredients from an analgesic tablet, separated on a TLC plate, were successfully detected using both positive and negative ion modes. The identity of each of the compounds was confirmed from their mass spectra and compared against standards. Post separation, the chemical signal (blue permanent marker) as reference marks placed at the origin and solvent front were used to calculate retention factor (Rf) values from the resulting ion chromatogram. The quantitative capabilities of the device were exhibited by scanning caffeine spots on a TLC plate of increasing sample amount. A linear curve based on peak are, R2 = 0.994, was generated for seven spots ranging from 50 to 1000 ng of caffeine per spot.


Assuntos
Cromatografia em Camada Fina/instrumentação , Cromatografia em Camada Fina/métodos , Espectrometria de Massas/instrumentação , Acetaminofen/análise , Cafeína/análise , Calibragem , Desenho de Equipamento , Espectrometria de Massas/métodos , Salicilamidas/análise
17.
Biotechnol Prog ; 21(1): 292-9, 2005.
Artigo em Inglês | MEDLINE | ID: mdl-15903268

RESUMO

Currently, little is known about the mechanical properties of filamentous fungal hyphae. To study this topic, atomic force microscopy (AFM) was used to measure cell wall mechanical properties of the model fungus Aspergillus nidulans. Wild type and a mutant strain (deltacsmA), lacking one of the chitin synthase genes, were grown in shake flasks. Hyphae were immobilized on polylysine-coated coverslips and AFM force--displacement curves were collected. When grown in complete medium, wild-type hyphae had a cell wall spring constant of 0.29 +/- 0.02 N/m. When wild-type and mutant hyphae were grown in the same medium with added KCl (0.6 M), hyphae were significantly less rigid with spring constants of 0.17 +/- 0.01 and 0.18 +/- 0.02 N/m, respectively. Electron microscopy was used to measure the cell wall thickness and hyphal radius. By use of finite element analysis (FEMLAB v 3.0, Burlington, MA) to simulate AFM indentation, the elastic modulus of wild-type hyphae grown in complete medium was determined to be 110 +/- 10 MPa. This decreased to 64 +/- 4 MPa for hyphae grown in 0.6 M KCl, implying growth medium osmotic conditions have significant effects on cell wall elasticity. Mutant hyphae grown in KCl-supplemented medium were found to have an elastic modulus of 67 +/- 6 MPa. These values are comparable with other microbial systems (e.g., yeast and bacteria). It was also found that under these growth conditions axial variation in elastic modulus along fungal hyphae was small. To determine the relationship between composition and mechanical properties, cell wall composition was measured by anion-exchange liquid chromatography and pulsed electrochemical detection. Results show similar composition between wild-type and mutant strains. Together, these data imply differences in mechanical properties may be dependent on varying molecular structure of hyphal cell walls as opposed to wall composition.


Assuntos
Aspergillus nidulans/química , Aspergillus nidulans/citologia , Parede Celular/fisiologia , Microscopia de Força Atômica/métodos , Proliferação de Células , Parede Celular/ultraestrutura , Elasticidade
18.
Artigo em Inglês | MEDLINE | ID: mdl-15899369

RESUMO

A group of 18-mers of the same base sequence, but with differing alkyl modifications is used to investigate effects of these modifications on retention of oligonucleotides using ion-pairing reversed-phase liquid chromatography (IP-RPLC). It is shown that IP-RPLC is able to distinguish between oligonucleotides differing only by a single alkyl group. The identity of the nucleobase and position and length of the alkyl adduct affect retention of the oligonucleotide. These separation phenomena result from changes in charge and hydrophobicity upon alkylation. As demonstrated in this paper; chromatographic selectivity, unique to IP-RPLC, greatly facilitates the purification process of modified oligonucleotides.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Oligonucleotídeos/isolamento & purificação , Sequência de Bases , Cromatografia por Troca Iônica , Primers do DNA , Eletroforese Capilar
19.
J Pharm Biomed Anal ; 37(1): 19-25, 2005 Feb 07.
Artigo em Inglês | MEDLINE | ID: mdl-15664739

RESUMO

Pulsed electrochemical detection (PED) following liquid chromatographic separation has been applied to the direct (i.e., without derivatization) determination of two major sulfur-containing compounds used as pharmaceutical additives, isopropyl-thio-beta-D-galactopyranoside (IPTG) and monothioglycerol (MTG). Limits of detection of IPTG and MTG were found to be 1 ppb (0.2 pmol, 50 microL) and 0.2 ppb (0.1 pmol, 50 microL), respectively, using optimized potential-time waveforms applied to a Au electrode. In addition to high sensitivity as compared to optical detection, the simultaneous detection of free thiols and disulfides can be used to study the kinetics of these conversions, as is shown for MTG. A practical application of HPLC-PED is demonstrated in determining MTG in a pharmaceutical formulation. The high selectivity of PED for thiocompounds reduces sample preparation and produces simpler chromatograms in a variety of matrices.


Assuntos
Preparações Farmacêuticas/análise , Compostos de Sulfidrila/análise , Biofarmácia , Cromatografia Líquida de Alta Pressão/métodos , Eletroquímica/métodos , Preparações Farmacêuticas/química , Compostos de Sulfidrila/química
20.
Anal Chim Acta ; 861: 1-11, 2015 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-25702269

RESUMO

Pulsed electrochemical detection (PED) has progressed as a highly sensitive and selective detection technique following aqueous-based separation systems over the past three decades. The application of on-line pulsed potential cleaning to electrocatalytic noble metal electrodes has significantly increased the number of applications formerly achieved with conventional electrochemical (EC) detection. Electrochemical cells are easily miniaturized, providing the ability to apply detection by PED at microelectrodes and onto microchips utilizing electrophoretic separations. In addition, recent advances in PED waveforms and instrumentation have enabled the detection technique to be easily coupled with high pressure separation systems which require rapid detection to maintain separation integrity. As a result, advanced applications for the determination of carbohydrates as well as the expansion of PED for the detection of other organic aliphatic compounds have been recently accomplished. This review will focus on developments and methods utilizing PED following liquid chromatography (LC) and capillary electrophoresis (CE). Publications are reviewed in chronological order to emphasize the advancement of the detection method and the sustained relevance of its applications.

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