Liquid Chromatography Instrument Research Articles

Determination of Catecholamines in a Small Volume (25μL) of Plasma from Conscious Mouse Tail Vein.

The determination of plasma catecholamine levels is commonly used as a measure of the sympathetic nervous system's response to stress and is highly important for diagnosis, therapy, and prognosis of cardiovascular diseases, catecholamine-secreting tumors arising from the chromaffin cells of the sympathoadrenal system, and affective disorders. Diseases in which catecholamines are significantly elevated include pheochromocytoma, Parkinson's disease, Alzheimer's disease, neuroblastoma, ganglioneuroblastoma, von Hippel-Lindau disease, baroreflex failure, chemodectina (nonchromaffin paraganglioma), and multiple endocrine neoplasia. Plasma norepinephrine levels provide a guide to prognosis in patients with stable, chronic, and congestive heart diseases. The method described here for the determination of plasma catecholamines is based on the principle that plasma catecholamines are selectively adsorbed on acid-washed alumina at pH 8.7 and then eluted at a pH between 1.0 and 2.0. Upon injection, catecholamines in elutes were separated by a reversed phase C-18 column. After separation, the catecholamines present within the mobile phase enter the electrochemical detector. Electrochemical detection occurs because electroactive compounds oxidize at a certain potential and thereby liberate electrons that create measurable current. Catecholamines readily form quinones under these conditions, get oxidized, release two electrons, and create current. The electrochemical detector detects this electrical current that linearly correlates to the catecholamine concentration loaded into the ultra-performance liquid chromatography instrument. A 15-min mixing time during the adsorption and desorption steps was found to be optimal. If the washing step was omitted, the catecholamines could not be eluted from the acid-washed alumina. To prevent dilution, the alumina had to be centrifuged and not aspirated to dryness after the washing step. We report here that by changing the range in the electrochemical detector, plasma catecholamines were measured with only 12.5μL of plasma and more reliably with 25μL of plasma. The detection limit was 1ng/mL. This assay method is very useful as blood can be collected from the tail vein in a conscious mouse and the same mouse can be used for time-dependent or age-dependent studies.

Pengembangan Dan Validasi Metode Analisis Amlodipin Besilat Dan Cemarannya Dalam Sediaan Tablet

Amlodipine besylate belongs to the class of oral dihydropyridine calcium channel blockers that can be used to hypertension and angina therapy. Amlodipine as a pharmaceutical preparation must meet the criteria for a good pharmaceutical preparation, namely safe, efficacious and quality. In terms of safety, the presence of organic impurity in pharmaceutical products can affect the safety of medicinal products. Because the difficultness to obtain a standard of impurity, it is necessary to develop an analytical method to analyze the presence of contamination by stress testing. The analytical method was developed using a High Performance Liquid Chromatography (HPLC) instrument with Eclipse Plus C18 column 5 m (150 x 4.6 mm), mobile phase triethylamine (TEA): methanol in a ratio of 40:60 with isocratic elution and a flow rate of 1 mL/minutes and a wavelength of 237 nm with an injection volume of 10 µL. The results of the method validation showed good linearity with R2 of 0.9996, detection limit of 18.46 µg/mL and quantization limit value of 61.54 µg/mL. The value of the coefficient of variation on the precision parameter is 1.18-1.26%. The percent recovery accuracy value is 93.07-105.44% and the range value for proportional samples is in the concentration range of 24-84 µg/ml with R2 = 0.9993. The HPLC system meets all requirements for acceptance of the system conformity test. The results of this experiment showed that there were 2 out of 5 peaks of degradation products whose chemical structure was known. The application of the analytical method on commercial samples showed levels between 90.79-95.68% and there was no impurity in the product samples.

Association of IgG N-glycomics with prevalent and incident type 2 diabetes mellitus from the paradigm of predictive, preventive, and personalized medicine standpoint.

Type 2 diabetes mellitus (T2DM), a major metabolic disorder, is expanding at a rapidly rising worldwide prevalence and has emerged as one of the most common chronic diseases. Suboptimal health status (SHS) is considered a reversible intermediate state between health and diagnosable disease. We hypothesized that the time frame between the onset of SHS and the clinical manifestation of T2DM is the operational area for the application of reliable risk assessment tools, such as immunoglobulin G (IgG) N-glycans. From the viewpoint of predictive, preventive, and personalized medicine (PPPM/3PM), the early detection of SHS and dynamic monitoring by glycan biomarkers could provide a window of opportunity for targeted prevention and personalized treatment of T2DM. Case-control and nested case-control studies were performed and consisted of 138 and 308 participants, respectively. The IgG N-glycan profiles of all plasma samples were detected by an ultra-performance liquid chromatography instrument. After adjustment for confounders, 22, five, and three IgG N-glycan traits were significantly associated with T2DM in the case-control setting, baseline SHS, and baseline optimal health participants from the nested case-control setting, respectively. Adding the IgG N-glycans to the clinical trait models, the average area under the receiver operating characteristic curves (AUCs) of the combined models based on repeated 400 times fivefold cross-validation differentiating T2DM from healthy individuals were 0.807 in the case-control setting and 0.563, 0.645, and 0.604 in the pooled samples, baseline SHS, and baseline optimal health samples of nested case-control setting, respectively, which presented moderate discriminative ability and were generally better than models with either glycans or clinical features alone. This study comprehensively illustrated that the observed altered IgG N-glycosylation, i.e., decreased galactosylation and fucosylation/sialylation without bisecting GlcNAc, as well as increased galactosylation and fucosylation/sialylation with bisecting GlcNAc, reflects a pro-inflammatory state of T2DM. SHS is an important window period of early intervention for individuals at risk for T2DM; glycomic biosignatures as dynamic biomarkers have the ability to identify populations at risk for T2DM early, and the combination of evidence could provide suggestive ideas and valuable insight for the PPPM of T2DM. The online version contains supplementary material available at 10.1007/s13167-022-00311-3.

Hand-Portable Miniaturized Liquid Chromatography for the Determination of Chlorogenic Acids in Dietary Supplements.

With the explosive growth of the dietary supplements industry, new demands have emerged that cannot be faced with the sophisticated instrumentation available in well-equipped laboratories. In particular, there is a demand for simplified and easy-to-use instruments, capable of providing results in short times of analysis. In this study, a hand-portable miniaturized liquid chromatograph (portable LC) has been tested for the determination of chlorogenic acids (CGAs) in products intended to supplement the diet and elaborated with green coffee extracts. CGAs offer several health benefits due to their antioxidant properties, and an increasing number of dietary supplements are marketed with claimed high contents of these compounds. The results obtained with the proposed portable LC approach have been compared with those obtained with two other miniaturized benchtop liquid chromatography instruments, namely, a capillary liquid chromatograph (capLC) and a nano liquid chromatograph (nanoLC). Although compared with the methods that used the benchtop instruments, the sensitivity attainable was lower, the portable LC instrument provided a comparable analytical performance for the quantification of the main GCAs at low mg g-1 levels, and it was clearly superior in terms of speed. The proposed portable LC-based method can be applied to assess the content and distribution profile of the predominant CGAs in this kind of dietary supplement. It can be also used to estimate the antioxidant power due to CGAs, as well as their preservation state.

Simultaneous Determination of B1, B2, B3, B6, B9, and B12 Vitamins in Premix and Fortified Flour Using HPLC/DAD: Effect of Detection Wavelength

Simultaneous determination of water-soluble B vitamins is a troublesome analytical procedure since they have greatly variable structures and acid-base properties which imposed difficulties on eluting them in short time and selecting wavelength of detection. The aim of the present study was to develop a simple method that overcomes these difficulties. The method was successful in simultaneous determination of B1, B2, B3, B6, B9, and B12 in premix and fortified flour by extracting vitamins with 0.1% (w/v) of ascorbate and ethylene diamine tetra-acetic acid (EDTA) solution followed by eluting using gradient mobile phase consisting of 0.03% trifluoroacetic acid aqueous solution (pH 2.6) and acetonitrile on high performance liquid chromatography (HPLC) instrument coupled with diode array detector (DAD). Elution of vitamins was completed within 9.3 min, and the lowest values obtained for limit of quantification (LOQ) for B1, B2, B3, B6, B9, and B12 were 0.6, 0.2, 0.8, 0.3, 0.5, and 0.7 μg/mL, respectively, at four wavelengths of 361, 280, 265, and 210 nm. In general, variation of wavelength of detection in the range from 210 to 361 nm affects sensitivity but had a marginal effect on the linearity and LOQ of the developed method and its application for determining B vitamins in premix and fortified flour. The 210 nm wavelength exhibited the highest sensitivity though resulted in higher values of B vitamins in fortified flour with respect to 265, 280, and 361 nm. Noteworthy, determination of B2 and B12 in the premix at 361 nm had relatively high RSD values compared to the lower wavelengths. Thus, wavelengths in the range from 265 to 280 may be more favorable over 210 and 361 nm. The method reported in the present work does not require any sample cleanup/preconcentration steps, and chromatographic elution was achieved in 9.3 min without the need for ion-pairing reagents.

Stability of a standardized preparation of methotrexate, cytarabine, and methylprednisolone hemisuccinate for intrathecal use.

Data about the feasibility or stability of drugs prepared for intrathecal administration are scarce, especially concerning the possibility of mixing two or more compounds in the same syringe. We evaluated the stability of an extemporaneously prepared triple intrathecal therapy containing methotrexate, cytarabine, and methylprednisolone hemisuccinate. Six mixtures containing 12.5 mg methotrexate, 50 mg cytarabine, and 40 mg methylprednisolone hemisuccinate, diluted to a final volume of 5 ml with water for injection, were prepared in polypropylene syringes on six different days. Syringes were stored protected from light either at room temperature (20°C) (n = 3) or refrigerated temperature (4°C) (n = 3). Samples were analyzed immediately after preparation and again at 0.5, 2, 4, 6, 8, and 24 h. The analysis was conducted with a high-performance liquid chromatography instrument equipped with a quaternary pump and diode array detector. pH was also assessed before every sample analysis. When mixed in a polypropylene syringe, the three drugs were stable at both temperatures tested. No degradation >10% was observed in any sample and pH remained between 7.0 and 7.5 over time. No precipitation or color change occurred. Among the three compounds, methylprednisolone hemisuccinate was the most labile as a slight temperature- and time-dependent degradation was observed. Triple intrathecal solution of methotrexate, cytarabine, and methylprednisolone hemisuccinate is stable for up to 24 h when stored in polypropylene syringes protected from light at 4°C and 20°C.

Hb Alessandria [β37(C3)Trp→Leu; HBB: c.113G>T]: a Novel Variant on the β-Globin Chain with Slightly Increased Affinity for Oxygen Detected by Capillary Electrophoresis

We report a novel mutation on the β-globin gene in a 68-year-old woman of Sicilian origin living in Alessandria, Italy. This mutation produces a hemoglobin (Hb) variant of Hb A that was detected by the capillary electrophoresis (CE) method during measurement of Hb A1c. The variant Hb did not separate from Hb A using different high performance liquid chromatography (HPLC) instruments. Direct DNA sequencing revealed a G>T transversion at codon 37 and subsequent substitution of a tryptophan residue for a leucine residue. The new Hb variant was named Hb Alessandria [β37(C3)Trp→Leu; HBB: c.113G>T]. The p50 value was slightly decreased while the stability test at 37 °C in isopropyl alcohol and the main erythrocyte parameters were normal. Overall, the patient appeared clinically normal.

Modifying the Metal Surfaces in HPLC Systems and Columns to Prevent Analyte Adsorption and Other Deleterious Effects

Interactions of certain analytes with metal surfaces in high performance liquid chromatography (HPLC) instruments and columns cause a range of deleterious effects, including peak broadening and tailing, low peak areas, and the formation of new peaks due to chemical reactions. To mitigate these effects, we have developed a novel surface modification technology in which a hybrid organic/inorganic surface based on an ethylene-bridged siloxane chemistry is applied to the metal components in HPLC instruments and columns. We demonstrate the impact of this technology on peak symmetry, peak area, and injection-to-injection and column-to-column reproducibility for several metal-sensitive analytes. We also show an example of the mitigation of an on-column oxidation reaction. A variant of this technology has recently been developed for size-exclusion chromatography of proteins. An example is shown demonstrating the use of this variant applied to size-exclusion columns for the separation of a monoclonal antibody monomer and higher molecular weight species. Together, these results highlight the importance of preventing interactions of analytes with metal surfaces in HPLC in order to achieve accurate and precise results.

Front Cover: Online monitoring of small volume reactions using compact liquid chromatography instrumentation

DOI: 10.1002/sscp.202200012 The cover picture represents the translation of repetitive reaction mixture analysis outside a fume hood using a conventional high performance liquid chromatography stack with manual syringe sampling to online analysis inside a fume hood using a simple, compact, hand-portable capillary liquid chromatograph that can be easily placed very close to the reaction vessel. The extremely small sample volume required for analysis by capillary liquid chromatography allows the use of miniature reaction vessels with minimal disturbance of the reaction mixture.

New Liquid Chromatography Columns and Accessories in 2022

This article covers liquid chromatography (LC) columns and accessories commercially released after Pittcon 2021 through this year’s virtual conference. Like in the past, LCGC sent out a survey in late 2021 and early 2022 asking vendors to supply information on products launched over the past year. Note that new products for gas chromatography (GC), LC instrumentation and software, and sample preparation are covered elsewhere. The information for this article was obtained over several months; therefore, it is possible that some information was missed or misinterpreted. The reader is encouraged to check with specific vendor sites for additional products as well as more detailed information on product usage and attributes. Links to vendor sites are provided where applicable.

Glycomic biomarkers are instrumental for suboptimal health status management in the context of predictive, preventive, and personalized medicine.

Suboptimal health status (SHS), a reversible borderline condition between optimal health status and disease, has been recognized as a main risk factor for non-communicable diseases (NCDs). From the standpoint of predictive, preventive, and personalized medicine (PPPM/3PM), the early detection of SHS provides a window of opportunity for targeted prevention and personalized treatment of NCDs. Considering that immunoglobulin G (IgG) N-glycosylation levels are associated with NCDs, it can be speculated that IgG N-glycomic alteration might occur at the SHS stage. A case-control study was performed and it consisted of 124 SHS individuals and 124 age-, gender-, and body mass index-matched healthy controls. The IgG N-glycan profiles of 248 plasma samples were analyzed by ultra-performance liquid chromatography instrument. After adjustment for potential confounders (i.e., age, levels of education, physical activity, family income, depression score, fasting plasma glucose, and low-density lipoprotein cholesterol), SHS was significantly associated with 16 IgG N-glycan traits at 5% false discovery rate, reflecting decreased galactosylation and fucosylation with bisecting GlcNAc, as well as increased agalactosylation and fucosylation without bisecting GlcNAc. Canonical correlation analysis showed that glycan peak (GP) 20, GP9, and GP12 tended to be significantly associated with the 5 domains (fatigue, the cardiovascular system, the digestive system, the immune system, and mental status) of SHS. The logistic regression model including IgG N-glycans was of moderate performance in tenfold cross-validation, achieving an average area under the receiver operating characteristic curves of 0.703 (95% confidence interval: 0.637-0.768). The present findings indicated that SHS-related alteration of IgG N-glycans could be identified at the early onset of SHS, suggesting that IgG N-glycan profiles might be potential biomarker of SHS. The altered SHS-related IgG N-glycans are instrumental for SHS management, which could provide a window opportunity for PPPMin advanced treatment of NCDs and shed light on future studies investigating the pathogenesisof progression from SHS to NCDs. The online version contains supplementary material available at 10.1007/s13167-022-00278-1.

Online Monitoring of Small Volume Reactions Using Compact Liquid Chromatography Instrumentation.

A wide variety of analytical techniques have been employed for monitoring chemical reactions, with online instrumentation providing additional benefits compared to offline analysis. A challenge in the past for online monitoring has been placement of the monitoring instrumentation as close as possible to the reaction vessel to maximize sampling temporal resolution and preserve sample composition integrity. Furthermore, the ability to sample very small volumes from bench-scale reactions allows the use of small reaction vessels and conservation of expensive reagents. In this study, a compact capillary LC instrument was used for online monitoring of as small as 1 mL total volume of a chemical reaction mixture, with automated sampling of nL-scale volumes directly from the reaction vessel used for analysis. Analyses to demonstrate short term (~2 h) and long term (~ 50 h) reactions were conducted using tandem on-capillary ultraviolet absorbance followed by in-line MS detection or ultraviolet absorbance detection alone, respectively. For both short term and long term reactions (10 and 250 injections, respectively), sampling approaches using syringe pumps minimized the overall sample loss to ~0.2% of the total reaction volume.

Pengambilan Keputusan Pemilihan HPLC (Alat Instrumen) Pada Lab. QC Dengan Metode Analitycal Hierarchy Process (AHP)

PT Bio Kusuma Pharmaceutical is a manufacturing company for pharmaceuticals, cosmetics and dietary supplements that was founded in 2003. The company is more engaged in topical medicines and creams for beauty. Increasing the existing market and productivity makes the company prioritize the success of production to increase the company's competitiveness. The increasing demand for products in the market has made PT Bio Kusuma Pharmaceutical have to increase its productivity. However, due to limited testing equipment in the laboratory, it is less effective in meeting the market. From August-October 2019, it showed a delay in testing due to too many batches of production but only one instrument in the laboratory. Production results that are not balanced with demand make the company unable to maximize its productivity due to inadequate testing equipment at the Quality Control laboratory. Based on data on comparison of production and testing in the laboratory where there is a delay in testing due to the inadequacy of the HPLC (High Performance Liquid Chromatography) testing instrument in the Quality Control (QC) laboratory, from this data the company requires additional HPLC (High Performance Liquid Chromatography) instrument tools. From the results of calculations using the AHP (Analytical Hierarchy Process) method, the HPLC (High Performance Liquid Chromatography) instrument from Acquity Arc (Waters) is obtained with a score of 0.46933 with evaluation factors for all criteria and 0.46932 with the ratio of benefits from alternatives.Keywords: Laboratory, HPLC (High Performance Liquid Chromatography), AHP (Analytical Hierarchy Process)

Size Exclusion Chromatography with Dual Wavelength Detection as a Sensitive and Accurate Method for Determining the Empty and Full Capsids of Recombinant Adeno-Associated Viral Vectors.

Gene therapy has evolved over the past decade into a promising therapeutic class for treating many intractable diseases. Recombinant adeno-associated virus (AAV) is the most commonly used viral vector for delivering therapeutic genes. Independent of the manufacturing process for AAVs, the clinical materials are inherently heterogeneous and contain both empty and full capsids. Empty capsids can impact the safety and efficacy of AAV products and therefore their level needs to be controlled. Several analytical methods have been reported for this purpose. However, some of these methods have an insufficient assay range, or rely on instruments that cannot be readily implemented in a quality control (QC) environment. In this study, we describe a fast size exclusion chromatography (SEC) assay with dual-wavelength detection (SEC-DW) to directly determine the percent full capsids of AAV samples based on their peak area (PA) ratios. The two detection wavelengths selected to represent encapsidated transgenes and capsid proteins were 260 and 230 nm, respectively, instead of the conventionally used 260 and 280 nm. The use of 230 nm instead of 280 nm to monitor the contribution of the capsid protein results in a linear relationship between the PA260/PA230 ratio and the percent full capsids, unlike the nonlinear relationship observed when the PA260/PA280 ratio is used. As a result, the method exhibits a significantly extended assay range (up to 91% full capsids). The accuracy of the SEC-DW method was confirmed by comparing the results obtained against results from orthogonal high-resolution methods such as analytical ultracentrifugation (AUC) and cryo-electron microscopy and excellent agreement was obtained when common samples were analyzed using different methods. The SEC-DW method runs on a readily accessible high-performance liquid chromatography instrument platform, provides much higher assay throughput compared with AUC and electron microscopy, and can be implemented as a release method in a QC environment or used as a rapid screening tool to support process development and product understanding.

Determination of caffeine in dietary supplements by miniaturized portable liquid chromatography

In this study three miniaturized liquid chromatography (LC) instruments have been evaluated and compared for the analysis of caffeine in dietary supplements, namely a benchtop capillary LC (capLC) system, a benchtop nano LC (nanoLC)system and a portable LC system. Commercial products derived from different sources of caffeine have been analyzed. Under optimized conditions, the methods based on benchtop systems were superior in terms of sensitivity. The limits of detection (LODs) found with the capLC and nanoLC systems were 0.01 and 0.003 µg mL−1, respectively, whereas the LOD obtained with the portable LC instrument was of 1 µg mL−1. The portable LC-based method was superior in terms of simplicity and throughput (total analysis time < 15 min). On the basis of the results obtained, a new method for the rapid measurement of caffeine in dietary supplements by portable miniaturized LC is presented. This method provided good linearity within the 1–20 µg mL−1 interval, and it allowed the quantification of caffeine even in products derived from decaffeinated green coffee extracts. The contents of caffeine found with the proposed portable LC method in the real samples analyzed ranged from 1.38 to 7 mg per gram of product, which were values statistically equivalent to those found with the benchtop capLC and nanoLC methods, being the precision, expressed as relative standard deviation (RDS), of 2 -14% (n = 3). The proposed portable LC based method can be used as a simple and rapid alternative to estimate the quality, effectiveness and safety of dietary supplements, regarding their caffeine content.

Validated Modernized Assay for Foscarnet in Pharmaceutical Formulations Using Suppressed Ion Chromatography Developed through a Quality by Design Approach

Inspired by the United States Pharmacopoeia (USP) “monograph modernization” initiative, we developed and validated an assay for foscarnet sodium injection solution (“foscavir”), following quality by design (QbD) principles, incorporating design of experiments (DoE) and multivariate data analysis to establish the design space and robust setpoint of the method. The resulting analytical procedure was based on ion chromatography (IC) with suppressed conductivity detection, employing an isocratic carbonate–bicarbonate eluent system. The assay was successfully validated at the robust setpoint conditions, according to the guidelines established by the International Council for Harmonization (ICH). The linear range stretched at least from 5 to 100 mg/L with high repeatability (relative standard deviation, RSD ≤ 0.3%) both at the target concentration (60 mg/L) and at 50% and 150% from this level. Special attention was given to establish a rugged assay that would be easily transferable between laboratories, and the recorded recoveries of 98.2–100.5% for both the formulated drug product and the drug substance during intermediate precision evaluation at different analysis situations indicated that this mission was accomplished. A multivariate assessment of intermediate precision data acquired using an experimental design scheme revealed that the assay was not adversely affected by any of the situation variables, including the use of different liquid chromatography instrument types, regardless of if they were constructed from inert materials or stainless steel that had been passivated, even though such problems have been reported in several previous methods for analysis of foscarnet.

Research advances in nano liquid chromatography instrumentation

小型化是液相色谱分离技术发展的重要趋势之一,包括仪器外形尺寸的小型化、分离材料粒径的小型化以及色谱柱内径的小型化。色谱柱内径的减小能够降低样品和流动相的消耗,具有更高的质量灵敏度,特别适合用于复杂样品体系的分离分析。纳升液相色谱一般是指使用内径小于100 μm的毛细管色谱柱,流速范围在每分钟几十至几百纳升的色谱技术。由于流速很低,色谱柱体积很小,柱外效应显著,因此对色谱仪器系统各个模块的性能以及系统柱外效应的优化提出了较高的要求。纳升液相色谱的输液装置需要能够准确稳定地输送纳升级流速,具有梯度输液模式,且拥有一定的耐压能力,以适应不同规格的色谱柱类型;进样装置需要能够进行准确重复的进样过程,进样体积及进样方式适合毛细管色谱柱,同时不产生明显的柱外效应;检测装置需要具有较高的灵敏度,且具有较小的柱外扩散;管路与连接系统需要稳定、可靠、易操作,并能够最大限度地减小柱外体积,适配纳升级流速。鉴于目前大多数纳升液相色谱系统与质谱检测器联用,因而本文主要从输液装置、进样装置、管路与连接3个方面对相关技术领域的研究论文、技术专利以及仪器厂商的宣传文件等进行了检索与归纳,综述了这些模块的技术路线与研究进展,同时简要介绍光学吸收型检测装置的优化思路与研究进展,并对部分商品化的纳升液相色谱系统进行了对比。

A Facile HPLC-UV-Based Method for Determining the Concentration of the Bacterial Universal Signal Autoinducer-2 in Environmental Samples

As a universal quorum sensing (QS) signal, autoinducer-2 (AI-2) is utilized by both Gram-negative and Gram-positive bacteria to coordinate several group behaviors, such as biofilm formation, virulence, and motility, when the bacterial cell density exceeds the thresholds. The determination of the AI-2 level is essential to understand the physiological and biochemical processes involved in bacterial communication. However, the current methods for AI-2 determination are complicated, time-consuming, and require costly equipment, such as a mass spectrometer (MS) or fluorescence detector (FLD). In this study, we present a new and easily applicable method for AI-2 determination. This method, based on the primary derivatization of AI-2 with 2,3-diaminonaphthalene (DAN), uses an affordable high-performance liquid chromatography (HPLC) instrument with a UV detector. Under optimized conditions, our method showed a good linearity (r2 = 0.999) and demonstrated the effective detection of AI-2 levels in various environmental samples, as follows: 0.38 (±0.05) μM for E. coli K12, 0.48 (±0.05) μM for Aeromonas sp. YB-2, 0.32 (±0.06) μM for the Enterobacter sp. YB-3, and 0.28 (±0.16) μM for activated sludge.

Synthesis of water‐soluble BODIPY dyes and investigation of their DNA interaction properties and cytotoxicity/phototoxicity

AbstractIn this study, water‐soluble BODIPY dyes (BDPY‐4,BDPY‐5) bearing dimethylamino and diethylamino groups were synthesized for the first time. The DNA interaction and nuclease effect of two water‐soluble BODIPY dyes were examined using absorption, competitive binding experiments, and agarose gel electrophoresis. Then, cytotoxicity and phototoxicity of the compounds were determined against A549 cells by MTT cell viability assay. The ultraviolet–visible (UV–vis) spectra ofBDPY‐4andBDPY‐5displayed hypochromism and absorption maxima shifted to the red region. In addition,Kbvalues of the compounds were calculated as 2.23 × 104and 4.84 × 104 M−1, respectively. An high‐performance liquid chromatography (HPLC) instrument without a column was used to conduct competitive binding experiments for the first time. The approach prevented the decrease in the response due to dilution and enabled the analysis to be carried out in a short time. Upon increasing concentrations of the compounds, the emission intensity of EB‐DNA significantly decreased. These obtained results suggested that the compounds bound to CT‐DNA with intercalative mode. At the same time, the Stern–Volmer constants were determined as 1.80 × 106and 1.79 × 106 M−1forBDPY‐4andBDPY‐5, respectively, which is coherent with intercalative binding mode. The compounds did not display noticeable photonuclease actions with light irradiation.BDPY‐4andBDPY‐5showed moderate phototoxic properties on light irradiation.

Assessing the impact of nonspecific binding on oligonucleotide bioanalysis.

Aim: Accurate and reliable quantification of oligonucleotides can be difficult, which has led to an increased focus on bioanalytical methods for more robust analyses. Recent advances toward mitigating sample losses on liquid chromatography (LC) systems have produced recovery advantages for oligonucleotide separations. Results & methodology: LC instruments and columns constructed from MP35N metal alloy and stainless steel columns were compared against LC hardware modified with hybrid inorganic-organic silica surfaces. Designed to minimize metal-analyte adsorption, these surfaces demonstrated a 73% increase in 25-mer phosphorothioate oligonucleotide recovery using ion-pairing reversed-phase LC versus standard LC surfaces, most particularly upon initial use. Conclusion: Hybrid silica chromatographic surfaces improve the performance, detection limits and reproducibility of oligonucleotide bioanalytical assays.