Podcasts about liquid chromatography

(***TIMESTAMPS in description below) ~ Ryan Wood is regarded as a leading authority on the Top Secret classified Majestic-12 intelligence documents and the 1941 Cape Girardeau, Missouri UFO Crash amongst others. He is the author of MAJIC EYES ONLY: Earth's Encounters with Extraterrestrial Technology, a landmark synthesis of over 100 UFO crash retrievals along with authenticity discussions of many of the majestic documents. PATREON https://www.patreon.com/JulianDorey FOLLOW JULIAN DOREY INSTAGRAM (Podcast): https://www.instagram.com/juliandoreypodcast/ INSTAGRAM (Personal): https://www.instagram.com/julianddorey/ X: https://twitter.com/julianddorey RYAN'S LINKS Website: https://www.majiceyesonly.com/ Books: https://www.amazon.com/stores/author/B0CP4KKS5R/allbooks?ingress=0&visitId=6853d60e-bee3-4121-9075-a78149740069 LISTEN to Julian Dorey Podcast Spotify ▶ https://open.spotify.com/show/5skaSpDzq94Kh16so3c0uz Apple ▶ https://podcasts.apple.com/us/podcast/trendifier-with-julian-dorey/id1531416289 ****TIMESTAMPS**** 00:00 - Richard Dolan (UFO Crash Retrieval Program), Meeting Stanton Friedman & Father's Interest (1967) 08:39 - Brian Scott Abduction Cases, Danny Sheehan, Government Disclosure Confusion, Anti-Gravity Secret 19:21 - Alien Abduction (Male to Female Ratio) Issues, Historical Mount Ararat UFO Story, Burying Alien Story 27:35 - Jim Mars UFO Investigative Reporter, UFO Dex AI Tool 32:11 - Majestic 12 Breakdown, James Forrestal 41:47 - Majestic 12 Debunk or Truth? 55:03 - National Archives Hiding UFO Information, Tim Cooper UFO Leaks 01:04:21 - Vernon Bowman Encyclopedia UFO Files, Liquid Chromatography, Roswell Crash Parts 01:13:01 - Ryan's Dad Theory on UFOs, AI Alien Theories 01:23:31 - Cape Girardeau UFO Case, Joe McMonagle Stargate Program, Hieroglyphics in UFO 01:37:29 - UFO Mexico Crash (Kill People), Simulating UFO Abductions 01:50:21 - UFOs & Nukes, James Erwin Astronaut, Einstein Posed w/ Alien Colonization 02:02:31 - Government's Massive Secret (Manipulate Gravity), Theories on Aliens 02:09:47 - Skunk Works, Men in Black Recovering Crashed UFOs 02:18:03 - CIA Level 7 (Alien Convos), David Grusch Coming Forward 02:26:11 - Hitler Germany & UFOs Tied to Foo Fighters, DARPA Connections (Dr. Brandenburg) 02:32:11 - Transmedium UFOs Crashes, What is Next? 02:40:37 - Nuclear Fusion, Israel UFO Confirmation of Alien Life 02:49:07 - Belief in God CREDITS: - Host & Producer: Julian D. Dorey - In-Studio Producer & Editor: Alessi Allaman - https://www.youtube.com/@alessiallaman Julian Dorey Podcast Episode 258 - Ryan Wood Music by Artlist.io Learn more about your ad choices. Visit megaphone.fm/adchoices

Early in her career, Dr. Jessica Reiner realized that she cared more about ensuring the accuracy of the measurements she was making than making the measurements themselves. This realization, combined with experience in working with PFAS, led to her current role as Research Chemist at the National Institute of Standards and Technology (NIST).Join us to hear an insider's perspective on the PFAS topic, with a deep dive into the analytical methods used to detect, quantify, and identify PFAS species. Jessica and her team use LC-MS, anion exchange chromatography, and other orthogonal methods in their work and they focus on creating, validating, and maintaining reference materials (RM) and standard reference materials (SRM) that are used to help ensure that PFAS measurements are accurate and comparable with those made in other laboratories around the world. From challenges around defining a PFAS, to creating a stable, ultra-low concentration standard, to detecting ultra-high concentrations PFAS, Jessica provides an ace analytical chemist's perspective grounded in the metrology of it all.As always, and in addition to the great science, you'll get to learn about Jessica's personal career path, the ups and downs of her work, and hear her advice for career development. Related episodes: Season 4, Ep.2: The father of green chemistrySeason 2, Ep.7: Fresh urban waterSeason 1, Ep.3: There's chemistry in the air!Bonus content!Access bonus content curated by this episode's guest by visiting www.thermofisher.com/chemistry-podcast for links to recent publications, podcasts, books, videos and more.View the video of this episode on www.thermofisher.com/chemistry-podcast.A free thank you gift for our listeners! Request your free Bringing Chemistry to Life t-shirt on our episode website.Use code 0chemRcks in August, and BCTLisn3R in September. We read every email so please share your questions and feedback with us! Email helloBCTL@thermofisher.com

After realizing at a young age that rock and roll might be a better hobby than a career, our guest chose chemistry and chromatography as his path, and he's rocked that career choice!In this fun and engaging conversation, you'll meet Frank Steiner, PhD, Senior Manager of Product Applications, and Scientific Advisor at Thermo Fisher Scientific, who has earned much respect for his contributions to the field of high-performance liquid chromatography (HPLC). He and his team are customer number one for new HPLC products and generate much of the data used to support product launches. Steeped in the theory and fundamentals of HPLC, they provide us with a very approachable summary of the technique and considerations that must be balanced across diverse applications. Follow Frank and Paolo as they uncover insights on the evolutionary arc of HPLC, what challenges still exist, and why Frank believes it to be the technique that is most widespread and effective in affecting our lives. As always, we promise to let you get to know Frank, his personal story, and some bits of sage advice from a man that's been there and done that. Related episodes: Season 1, Ep.3: There's chemistry is in the air!Season 1, Ep.7: Stronger magnets, stronger scienceSeason 4, Ep.7: From an F in chemistry to 40 years in chemicals Bonus content!Access bonus content curated by this episode's guest by visiting www.thermofisher.com/chemistry-podcast for links to recent publications, podcasts, books, videos and more.View the video version of this episode on www.thermofisher.com/chemistry-podcast. A free thank you gift for our listeners! Visit the episode website and request your free Bringing Chemistry to Life t shirtUse Podcast Code:  2023wrap in December 2023 or Ba++ery in January 2024 Share your feedback with us! Email helloBCTL@thermofisher.com About Your HostPaolo Braiuca grew up in the North-East of Italy and holds a PhD in Pharmaceutical Sciences from nearby esteemed University of Trieste, Italy. He developed expertise in biocatalysis during his years of post-doctoral research in Italy and the UK, where he co-founded a startup company. With this new venture, Paolo's career shifted from R&D to business development, taking on roles in commercial, product management, and marketing. He has worked in the specialty chemicals, biotechnology, and pharmaceutical markets in Germany and the UK, where he presently resides. He is currently the Director of Global Market Development in the Laboratory Chemicals Division at Thermo Fisher Scientific™ which put him in the host chair of the Bringing Chemistry to Life podcast. A busy father of four, in what little free time he has, you'll find him inventing electronic devices with the help of his loyal 3D-printer and soldering iron. And if you ask him, he'll call himself a “maker” at heart.

Hear NY Owner Jenny & from Jill-The Industries Preferred High-performance liquid chromatography Machine on the MITA Unshackled Podcast, the premier podcast in the cannabis industry.Keep watching and subscribe today! Support our sponsors:Dr. George Stantchev Pure 5 Extraction https://pure5extraction.com/Jack Herer https://www.jackherer.com/Calyfx https://www.calyfx.com/MITA YOUTUBE / @mitausa MITA Website https://mita.us/MITA LINKEDIN https://www.linkedin.com/company/mita...MITA INSTAGRAM https://www.instagram.com/mitausa/ Recorded at MJUnpacked NYC: https://mjunpacked.com

In this podcast, we spoke with Cory Hinz, Engineering Manager at Asahi Kasei Bioprocess about the different methods that are available for liquid chromatography mobile phase solutions and the benefits of inline blending. Cory also describes how to implement binary blending feeding of a liquid chromatography process using inline blending. Liquid Chromatography Mobile Phase Solutions I began the discussion by asking Cory if he could tell listeners about the different methods that are available for liquid chromatography mobile phase solutions. He explained that for chromatography, it's important to remember that the process and the chemistry should drive the method used. Some chromatography processes use prepared mobile phase solutions that don't require inline mixing, while others blend two or more solutions together to formulate. The mobile phase takes these blends and changes their composition over the course of the elution. Each of these methods is driven by the needs of the process. Inline Blending Next, I asked Cory if he could tell us about the benefits of inline blending. He said that inline blending allows solutions to be prepared at their point of use, not just for chromatography processes, but any blending process. This increases the consistency of the blended solution, reduces dependency on the accuracy of raw materials, allows for real time quality assurance, and eliminates the risks and extra resources and space required for traditional tank approaches. Inline blending also adds an element of flexibility, allowing functions such as buffer preparation to become more of a utility than an additional process. Binary Blending Feeding of a Liquid Chromatography Process using Inline Blending Cory then provided details about how to implement a specific solution for binary blending feeding of a liquid chromatography process using inline blending. He explained that binary blending is the most common configuration they see for their chromatography equipment customers, because medium and high-pressure liquid chromatography require a dedicated pump to supply the pressure dictated by the process. It is important to design the binary blending at the suction side of the pump. This is done by employing two modulating control valves, one for each of the two components of the mobile phase, and ensuring sufficient supply pressure to each one. He then told us about the role that each of the valves play in creating the ideal blend. He described how the control valves do most of the heavy lifting for binary blending. The first valve controls the diluent, which will be the purified water or buffer that comprises the majority of the mobile phase blend. The second valve controls the component that is getting diluted. These valves each react to a different process parameter to achieve high accuracy. The second valve is the most intuitive, the component being diluted can have its proportion increase or decrease based on the movement of the control valve. For example, if the concentrate is below target, the valve will open to allow more concentrate through. This can be based on flow connectivity or any critical process parameter that can be measured inline. The first valve is less intuitive. It is controlled by the pressure in the system after the two streams have combined. If the blending pressure is too low, for example, the valve will open to increase that pressure. The result of this configuration is that if the two valves react to one another via the process but are not linked by a system control algorithm. This results in flexibility and accuracy and also provides a way to monitor and mitigate pump cavitation. Next I asked Cory about controlling the incoming process pressures of each of the valves. He said that in order for the binary blending scheme to work optimally, the incoming supply pressures of each stream should be controlled to prevent fluctuation that can disrupt the automatic blending control.

In this episode, podcast host Dr. Dwight Stoll talks with Dr. Deirdre Cabooter, a professor working in the Department of Pharmaceutical and Pharmacological Sciences at KU Leuven in Leuven, Belgium, about her pathway to separation science, her research on fundamental aspects of band broadening in liquid chromatography and emerging work on the use of machine learning in method development, and her work as organizer of the HTC conference and Editor of the Journal of Chromatography A. Drs. Stoll and Cabooter talk about the importance of continuing to dig deeper and understand more about dispersion processes nearly 70 years after the famous van Deemter equation was first published, as well as the increasing importance of multi-dimensional separations in a variety of research areas.

Cory Hinz talks about the different methods that are available for liquid chromatography mobile phase solutions and the benefits of inline blending. Cory also describes how to implement binary blending feeding of a liquid chromatography process using inline blending.

Eberhardt Kuhn with Shimadzu Scientific Instruments joins us on the HempList this week, hosted By Chase Nobles, Founder of Kush.com Chase and Dr. Eberhardt Kuhn have a great discussion starting with some basic Chemistry questions surrounding the differences between different cannabinoids like THC and CBD. Then Dr. Kuhn explains the differences between different methods of testing cannabis such as Liquid Chromatography, mass spectrometry, how they work, and what is specifically used for Cannabis. Chase also has a ton of cannabinoid questions for the PHD Chemist, everything from reading Cannabis Test Results on labels, to CBN conversion in cannabis smuggled from Mexico! Shimadzu is the leading provider of analytical measurement and testing instrumentation for a broad range of applications in science and industry, including foods and cannabis. Shimadzu instruments are used by top researchers across the globe, customers who can count on the stability, experience, and support only Shimadzu offers. https://www.ssi.shimadzu.com/ Subscribe for more interviews each week, also available on Spotify and podcast apps. Learn more and create your account now at Kush.com

For our tenth episode of Research Aromatica, Experiences Behind the Expertise, we have on Priyanka Chitranshi.We Discuss in our Conversation with Priyanka: Recommendations she would give to others interested in mass spectrometry.The common mistakes that she sees.Sample Preparation for chromatography.Method DevelopmentKey Quote:"The better your sample preparation, the better your data will look"A Bit About Priyanka:Priyanka Chitranshi is an LCMS Applications Scientist at Shimadzu Scientific Instruments. Priyanka has a degree in Pharmacy and a Ph.D. in Bioorganic Chemistry. During her postdoctoral appointment at the National Center for Toxicological Research at the Food and Drug Administration (FDA), she developed an unfortunate addiction towards liquid chromatography mass spectrometry (LCMS). Since she has worked on a variety of molecules using LCMS ranging from brominated vegetable oils in soft drinks, analysis of metabolites of antibacterial and antiretroviral drugs, fluorinated compounds in water, and impurity analysis in pharmaceuticals to name a few. She communicates her work through peer-reviewed publications, application notes, and through presentations at national and international conferences. In her spare time, Priyanka enjoys to listening to audiobooks and podcasts.Link to Priyanka's Webinar:https://www.researcharomatica.org/post/priyankaPlease Enjoy!-Follow Research Aromatica on:Website: https://www.researcharomatica.com/Instagram: https://www.instagram.com/researcharomatica/?hl=enFacebook: https://www.facebook.com/AromaticPlantRCYoutube: https://www.youtube.com/channel/UCd6Rea4SEAsxRIbB8q5CkPA-Made Possible By:This podcast is made possible by APRC, Aromatic Plant Research Center. APRC was created to provide access to uncompromising research, analysis, and testing services for essential oil communities.

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.10.334342v1?rss=1 Authors: Feng, X., Zhang, W., Kuipers, F., Kema, I., Barcaru, A., Horvatovich, P. Abstract: Liquid chromatography-mass spectrometry (LC-MS) based lipidomics generate a large dataset, which requires high-performance data pre-processing tools for their interpretation such as XCMS, mzMine and Progenesis. These pre-processing tools rely heavily on accurate peak detection, which depends on setting the peak detection mass tolerance (PDMT) properly. The PDMT is usually set with a fixed value in either ppm or Da units. However, this fixed value may result in duplicates or missed peak detection. Therefore, we developed the dynamic binning method for accurate peak detection, which takes into account the peak broadening described by well-known physics laws of ion separation and set dynamically the value of PDMT as a function of m/z. Namely, in our method, the PDMT is proportional to mz^2 for FTICR, to mz^1.5 for Orbitrap, to mz for Q-TOF and is a constant for Quadrupole mass analyzer, respectively. The dynamic binning method was implemented in XCMS and the adopted source code is available in the Appendix. Our further goal was to compare the performance of different lipidomics pre-processing tools to find differential compounds. We have generated set samples with 43 lipids internal standards differentially spiked to aliquots of one human plasma lipid sample using Orbitrap LC-MS/MS. The performance of the various pipelines using aligned parameter sets was quantified by a quality score system which reflects the ability of a pre-processing pipeline to detect differential peaks spiked at various concentration levels. The quality score indicates that the dynamic binning method improves the performance of XCMS. The modified XCMS software was further compared with mzMine and Progenesis. The results showed that modified XCMS and Progenesis had a similarly good performance in the aspect of finding differential compounds. In addition, Progenesis shows lower variability as indicated by lower CVs, followed by XCMS and mzMine. The lower variability of Progenesis improve the quantification, however, provide an incorrect quantification abundance order of spiked-in internal standards. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.10.04.325548v1?rss=1 Authors: Zhang, H., De Silva, D., Dissanayaka, D., WARKENTIN, T. D., Vandenberg, A. Abstract: A validated method for B vitamin separation and quantification using ultra-performance liquid chromatography-selected reaction monitoring mass spectrometry (UPLC-SRM MS) was reported. For B vitamin extraction from lentil seeds, the use of three enzymes (acid phosphatase, {beta}-glucosidase, and rat serum) with a 4 h incubation was sufficient to convert bound B vitamins into their free forms. 20 B vitamers were selected and a 5-min UPLC-SRM MS method was optimized for rapid analysis. This method was applied to quantify B vitamin concentration during lentil seed germination. Total B vitamins increased up to 1.53-fold on day 5 (from 38.2 ug/g to 58.4 ug/g) comparing with dry seeds. Vitamin B5 (pantothenic acid) was the most abundant B vitamin in both dry seeds (32.7%) and in germinated seeds (16.5%-22.4% of total B vitamins), B8 (biotin) and B12 (cyanocobalamin) were not detected in lentil samples. Copy rights belong to original authors. Visit the link for more info

Link to bioRxiv paper: http://biorxiv.org/cgi/content/short/2020.09.26.315150v1?rss=1 Authors: Ng, W. Abstract: Mass balance analysis is a highly useful tool for chemical engineering analysis of biological processes. Specifically, composition and amounts of inputs to a cell could be correlated with measurement of metabolic byproducts and outputs for inferring metabolic fluxes flowing through specific cellular metabolic pathways. However, the composition of many common microbiological growth medium remains ill-defined with batch-to-batch variation. Thus, a need exists for developing methods for effective fractionation and separation of common growth medium. Using 5 g/L yeast extract, 10 g/L tryptone, and LB Lennox medium as model systems, this work attempted the fractionation of the three complex growth mixtures using C-18 reversed phase high performance liquid chromatography (RP-HPLC). Results revealed no effective fractionation of the three mixtures. More importantly, experiment results indicated that appropriate choice of detection wavelength for visualizing the chromatogram made a huge difference to understanding the effectiveness of fractionation achieved. Specifically, in the case of yeast extract, tryptone and LB Lennox medium, 194 nm may be a more appropriate detection wavelength compared to 280 nm. Collectively, C-18 RP-HPLC was not effective in separating 5 g/L yeast extract, 10 g/L tryptone and LB Lennox medium with hydrophilic mobile phases (ethanol/water mixture). Copy rights belong to original authors. Visit the link for more info

Part 2. Sharing Knowledge High Performance Liquid Chromatography. Materi dapat di download di https://linktr.ee/alfan.arbianto --- This episode is sponsored by · Anchor: The easiest way to make a podcast. https://anchor.fm/app --- Send in a voice message: https://anchor.fm/alfan-danny-arbianto/message Support this podcast: https://anchor.fm/alfan-danny-arbianto/support

Introduction Part-1 High Performace Liquid Chromatography Please Download the material on https://linktr.ee/alfan.arbianto (Free). Jika ada kekurangan dan kesalahan dalam menyampaikan materi mohon email ke: alfan.arbianto@gmail.com Thank you, Enjoy your Day with My Podcasts. Follow me IG: @alfan.arbianto FB:alfan danny arbianto tweeter: @AlfanArbianto|

Phenomenex Technical Specialists discuss the similarities and differences between liquid and gas chromatography techniques. Listen in if you are interested in learning a little more about both techniques. It is a fun and lively discussion!

Measurement of serum thyroglobulin may be complicated by the presence of endogenous anti-thyroglobulin auto-antibodies which have the potential to interfere with immunoassays and cause false negative results.

Background: Extensive sets of data are required to investigate the potential use of a therapeutic drug monitoring with individualization of dosage of the antimycotic compound caspofungin. The goal was to develop an improved liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for this aim. Methods: Following protein precipitation, on-line solid phase extraction was performed for sample preparation. As the internal standard compound the veterinary drug tylosin was used. A standard validation protocol was applied. Results: Good reproducibility and accuracy of the method were observed. On-line solid phase extraction resulted in a convenient work-flow and good robustness of the method. Conclusions: This improved LC-MS/MS method was found reliable and convenient. It can be suggested for further work on the clinical pharmacology of caspofungin in the setting of clinical research laboratories.

Background: The goal of this study was to develop and to validate an improved isotope-dilution-liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for the quantification of methylmalonic acid (MMA) in urine. Methods: A previously described sample preparation protocol requires two solvent extraction steps, including evaporation. The first extraction is to extract the analyte from the sample, and second occurs following derivatization of the extract. In the method described here, the second evaporation step was substituted by on-line solid phase extraction employing column-switching and a permanent co-polymer based extraction cartridge. A standard validation protocol was applied to investigate the performance of the method. Results: The method was found to be linear in the clinically relevant range of concentrations (6-100 mu mol/L). Total coefficients of variation were below 10% and inaccuracy was

Transcript -- Analysis by mass spectrometry

Analysis by mass spectrometry

Transcript -- Analysis by mass spectrometry

Analysis by mass spectrometry

Background: Posaconazole is now widely used for prophylaxis of invasive fungal infections in immunocompromised patients. The pharmacokinetic properties of the drug argue for therapeutic monitoring, but so far described analytical methods have shortcomings with respect to application in a routine setting. The aim of our work was to develop an analytical method suitable for routine use. Methods: Liquid chromatography-tandem mass spectrometry (LC-MS/MS) was used. For sample preparation, protein precipitation followed by on-line solid phase extraction was used. SCH 56984, a posaconazole related compound provided by the manufacturer of posaconazole, was used as internal standard. Results: The method was characterized by short hands-on time and an analytical run time of four minutes. Validation data demonstrated acceptable analytical performance. Conclusions: LC-MS/MS with on-line solid phase extraction for sample preparation allows the implementation of a convenient and reliable method for pharmacokinetic monitoring of posaconazole.

Athletes are racing to get the most out of the human body and are using new technology to do it. But there is a dark side. Anabolic steroids and other performance enhancing drugs have been injected into the mix. But how do they really work? And can new technology catch the cheaters?

Background: Liquid chromatography tandem-mass spectrometry (LC-MS/MS) is an efficient technology for routine determination of immunosuppressants in whole blood; however, time-consuming manual sample preparation remains a significant limitation of this technique. Methods: Using a commercially available robotic pipetting system (Tecan Freedom EVO), we developed an automated sample-preparation protocol for quantification of tacrolimus in whole blood by LC-MS/MS. Barcode reading, sample resuspension, transfer of whole blood aliquots into a deep-well plate, addition of internal standard solution, mixing, and protein precipitation by addition of an organic solvent is performed by the robotic system. After centrifugation of the plate, the deproteinized supernatants are submitted to on-line solid phase extraction, using column switching prior to LC-MS/MS analysis. The only manual actions within the entire process are decapping of the tubes, and transfer of the deep-well plate from the robotic system to a centrifuge and finally to the HPLC autosampler. Whole blood pools were used to assess the reproducibility of the entire analytical system for measuring tacrolimus concentrations. Results: A total coefficient of variation of 1.7% was found for the entire automated analytical process (n=40; mean tacrolimus concentration, 5.3 mu g/L). Close agreement between tacrolimus results obtained after manual and automated sample preparation was observed. Conclusions: The analytical system described here, comprising automated protein precipitation, on-line solid phase extraction and LC-MS/MS analysis, is convenient and precise, and minimizes hands-on time and the risk of mistakes in the quantification of whole blood immunosuppressant concentrations compared to conventional methods.

A convenient liquid chromatography-tandem mass spectrometry method for the quantification of the triazole antifungal agent voriconazole in plasma samples is described. Fenbuconazole is used as an internal standard. After protein precipitation, automated solid-phase extraction is applied. Electrospray ionization in the positive mode is used and the following mass transitions are recorded: voriconazole, 350 -> 127; and fenbuconazol, 337 -> 125. The analytical run time is 4 min. The response was linear from 78 to 5000 mu g/L. The total coefficient of variation (n=16) was 12.6% for a low-concentration pool (143 mu g/L), 4.7% for a medium-concentration pool (419 mu g/L), and 5.0% for a high-concentration pool (4304 mu g/L). The method is proposed for future investigations that should be performed to test the hypothesis that therapeutic drug monitoring of voriconazole is clinically useful.

In a growing number of laboratories the technique of liquid chromatography-tandem mass spectrometry is used for the quantification of cyclosporin A in whole blood, employing cyclosporin D as the internal standard. Cyclosporin A is extensively metabolized in vivo; in liquid chromatography-tandem mass spectrometry respective metabolites can give rise to both parent and product ions that are isobaric with ions commonly used for the detection of cyclosporin A and cyclosporin D, respectively. In this article it is demonstrated that limited chromatography with co-elution of such metabolites together with cyclosporin A and cyclosporin D can lead to incorrect results.

Es wurde eine Analysemethode für die High-Performance-Liquid-Chromatography (HPLC) mit elektrochemischer Detektion (ECD) zur gleichzeitigen Messung von 3-Methoxy-4-hydroxyphenolglycol(MHPG), 5-Hydroxyindolessigsäure (5-HIAA)und Homovanillinsäure (HVA)im Liquor von Patienten mit Fibromyalgiesyndrom (FMS)und neurologischen Erkrankungen etabliert. Beim anschließenden Gruppenvergleich fanden sich signifikante positive Korrelationen zwischen 5-HIAA und HVA in allen Patientengruppen, signifikant erhöhte Konzentrationen an HVA bei Patienten mit FMS sowie signifikant erhöhte Konzentrationen an MHPG bei Patienten mit FMS ohne Einnahme interferierender Pharmaka.

In this paper a method for the simultaneous quantification of the anti-fungal drug itraconazole and its co-active metabolite hydroxyitraconazole in plasma employing liquid chromatography tandem-mass spectrometry and automated solid-phase extraction is described. The method proved rugged, enables short turn-around times and is highly specific. Since there is growing evidence for the importance of therapeutic drug monitoring of itraconazole in the prophylaxis and treatment of invasive fungal infections, the method described here is of interest for a large number of tertiary care hospital laboratories.

In severely ill patients low concentrations of the corticosteroid binding globulin are typically found; the aim of this study was to quantify directly free bioactive cortisol concentrations in the sera of postoperative cardiosurgical patients. Serum samples of 12 consecutive patients undergoing aortocoronary bypass surgery taken preoperatively and on the postoperative days 1 to 4 were analyzed. Total serum cortisol was quantified using liquid chromatographytandem mass spectrometry with an online sample extraction system and trideuterated cortisol as the internal standard, and free serum cortisol was measured after overnight equilibrium dialysis. Whereas on the first postoperative day, the median total serum cortisol concentration was approximately twofold increased compared to preoperative samples (preoperatively, 245 nmol/l (interquartile range (IQR) 203293 nmol/l); first postoperative day, 512 nmol/l (IQR 410611 nmol/l)), median dialyzable free cortisol concentration was almost sevenfold increased (preoperatively, 14.2 nmol/l (IQR 10.920.7 nmol/l); first postoperative day, 98.3 nmol/l (IQR 81.3134 nmol/l)). On the fourth postoperative day, median free cortisol was still significantly increased compared to baseline sampling (p < 0.05), whereas median total cortisol was not. A median of 5.7% (IQR 5.47.0%) of total cortisol was found as free cortisol on the preoperative day, 21.2% (IQR 18.9 23.5%) on the first postoperative day and 10.5% (IQR 9.814.0%) on the fourth postoperative day. It is concluded that during the postoperative period the freeto bound ratio of cortisol is highly variable and that during the acute phase response direct quantification of free bioactive cortisol concentrations seems to be biologically more appropriate than the measurement of total cortisol concentrations.

This review provides a concise survey of liquid chromatography tandem mass spectrometry (LCTMS) as an emerging technology in clinical chemistry. The combination of two mass spectrometers with an interposed collision cell characterizes LCTMS as an analytical technology on its own and not just as a more specific detector for HPLC compared with conventional techniques. In LCTMS, liquid chromatography is rather used for sample preparation but not for complete resolution of compounds of interest. The instrument technology of LCTMS is complex and comparatively expensive; however, in routine use, methods are far more rugged compared to conventional chromatographic techniques and enable highthroughput analyses with very limited manual handling steps. Moreover, compared to both gas chromatographymass spectrometry (GCMS) and conventional HPLC techniques, LCTMS is substantially more versatile with respect to the spectrum of analyzable compounds. For these reasons it is likely that LCTMS will gain far more widespread use in the clinical laboratory than HPLC and GCMS ever did. In this article, the key features of LCTMS are described, method development is explained, typical fields of application are discussed, and personal experiences are related.

Quantification of the new immunosuppressant sirolimus (syn. rapamycin; Rapamune((R))) in whole blood by chromatography is essential for its clinical use since no immunoassay is available although monitoring is mandatory. Here we report on a rapid and convenient liquid chromatography (LC)-tandem mass spectrometry method and describe our practical experience with its routine use. Whole blood samples were hemolyzed and deproteinized using an equal volume (150 mul) of a mixture of methanol/zinc sulfate solution containing the internal standard desmethoxy-rapamycin. After centrifugation, the clear supernatants were submitted to an on-line solid-phase extraction procedure using the polymeric Waters Oasis HLB(R) material, with elution of the extracts onto the analytical column in the back-flush mode by column switching. For analytical chromatography a RP-C18 column was used with 90/10 methanol/2 mM ammonium acetate as the mobile phase. A 1:10 split was used for the transfer to the mass spectrometer, a Micromass Quattro LC-tandem mass spectrometry system equipped with a Z-spray((R)) source and used in the positive electrospray ionization mode. The following transitions were recorded: sirolimus, 931>864 m/z, and desmethoxy-rapamycin (I.S.), 901>834 m/z. The analytical running time was 5 min, including on-line extraction. The method has a linear calibration curve (r>0.99; range 1.6-50 mug/l) and is rugged and precise with monthly CVs

A liquid chromatographic-mass spectrometric method for the determination of cortisol in serum using atmospheric pressure electrospray ionization and tandem mass spectrometry is described. During sample preparation, 150 mul of serum were deproteinized with methanol/zinc sulfate followed by on-line solid phase extraction employing column switching. Tri-deuterated cortisol was used as the internal standard. The following transitions were monitored: cortisol, 363 > 309 m/z; d3-cortisol, 366 > 312 m/z. The total run-time was 5 minutes. The method proved linear (0-500 mug/l; r=0.999), precise (total coefficient of variation between 5.0% and 3.2% at a mean cortisol concentration of 15.1 mug/l and 269 mug/l, respectively; n=16) and specific with regard to relevant endogenous and exogenous steroids.

Fri, 1 Jan 1982 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2898/ http://epub.ub.uni-muenchen.de/2898/1/065.pdf Steiner, R.; Wieschhoff, H.; Scheer, Hugo Steiner, R.; Wieschhoff, H. und Scheer, Hugo (1982): HIGH-PERFORMANCE LIQUID CHROMATOGRAPHY OF BACTERIOCHLOROPHYLL 6 AND ITS DERIVATIVES AS AN AID FOR STRUCTURE ANALYSIS. In: Journal of Chromatography, Vol. 242: pp. 127-134.

Sun, 1 Jan 1978 12:00:00 +0100 http://epub.ub.uni-muenchen.de/2581/ http://epub.ub.uni-muenchen.de/2581/1/027.pdf Schoch, S.; Lempert, U.; Wieschhoff, H.; Scheer, Hugo Schoch, S.; Lempert, U.; Wieschhoff, H. und Scheer, Hugo (1978): High-performance liquid-chromatography of tetrapyrrole pigments. Pheophytin esterified with different diterpene alcohols, isomeric biliverdins and synthetic bilins. In: Journal of Chromatography, Vol. 157: pp. 357-364. Biologie