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Separations
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Rapid Separations of Complex Mixtures
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Rapid Separations of Complex Mixtures

A special issue of Separations (ISSN 2297-8739). This special issue belongs to the section "Analysis of Natural Products and Pharmaceuticals".

Deadline for manuscript submissions: closed (31 July 2021) | Viewed by 25867

Special Issue Editor

Dr. Nicholas H. Snow

E-Mail Website
Guest Editor
Department of Chemistry and Biochemistry, Seton Hall University, 400 South Orange Avenue, South Orange, NJ 07079, USA
Interests: Gas chromatography; GCxGC; GC-MS; Sample preparation; SPME; SPE; headspace; drugs; forensics; environmental; food
Special Issues, Collections and Topics in MDPI journals

Special Issue Information

Dear Colleagues,

This special issue focuses on fast separations of complex mixtures, broadly defined. Authors are encouraged to think about how they have optimized methods for speed. As complex mixtures are the topic, short retention times are not necessarily a requirement.  If the mixture is complex or if selectivity is low, a faster separation may require longer time. Speed optimization may also include the sample preparation method, automation and/or sample management that increases analytical throughput.  Methods involving speed optimization in GC, HPLC, GC-MS, LC-MS, SFC, CE, related chromatographic methods and sample preparation are welcome.  Please focus your writing on how you optimized the method or process for speed or for more rapid separation, overall analysis or sample throughput. Please feel free to contact the editor if you have questions or wish to discuss an idea. 

Dr. Nicholas H. Snow
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Separations is an international peer-reviewed open access monthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • GC
  • HPLC
  • SFC
  • CE
  • GC-MS
  • LC-MS
  • sample preparation
  • SPE
  • headspace
  • SPME
  • fast analysis
  • speed

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Published Papers (6 papers)

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Research

8 pages, 1568 KiB  
Article
Tri-Reagent Homogenate Is a Suitable Starting Material for UHPLC-MS Lipidomic Analysis
by Olatz Fresnedo, Beatriz Abad-Garcia and Yuri Rueda
Separations 2022, 9(10), 268; https://doi.org/10.3390/separations9100268 - 27 Sep 2022
Cited by 1 | Viewed by 1872
Abstract
Background: Transcriptomic and lipidomic dual analyses usually initiate with independent extractive procedures. That entails a difficulty in aligning results from both omics platforms, especially in the case of highly heterogeneous tissues, such as the kidney. Methods: Bligh and Dyer lipid extraction was performed [...] Read more.
Background: Transcriptomic and lipidomic dual analyses usually initiate with independent extractive procedures. That entails a difficulty in aligning results from both omics platforms, especially in the case of highly heterogeneous tissues, such as the kidney. Methods: Bligh and Dyer lipid extraction was performed using rat kidney homogenates prepared in PBS or commercially available Tri-reagent used for RNA extraction. Samples were analyzed by ultrahigh performance liquid chromatography-mass spectrometry (UHPLC-MS) lipidomic analysis. Results: Comparison of the lipidome obtained from phosphate-buffered saline (PBS) and Tri-reagent homogenates showed qualitative and quantitative validity of the Tri-reagent homogenate with the exception of ether lipids; the acidic nature of the mix seems to promote the hydrolysis of the ether bond, especially in plasmalogens. We tested several conditions in the sample processing, which allowed to optimize the procedure. Conclusions: Aiming to implement a method that allows the extraction of RNA and lipids from the same tissue homogenate not using external tracers, we here report the use of Tri-reagent homogenates as a suitable starting material for UHPLC-MS lipidomic analysis. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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15 pages, 2463 KiB  
Article
Experimental Study on Flocculation Effect of Tangential Velocity in a Cone-Plate Clarifier
by Yulong Zhang, Peikun Liu, Linjing Xiao, Yuekan Zhang, Xinghua Yang and Lanyue Jiang
Separations 2021, 8(7), 105; https://doi.org/10.3390/separations8070105 - 20 Jul 2021
Cited by 4 | Viewed by 2547
Abstract
A large number of particles with small size and light density in mine water are difficult to remove by traditional separation equipment. In order to improve the efficiency of mine water treatment, a cone-plate clarifier is proposed in this paper. The particle size [...] Read more.
A large number of particles with small size and light density in mine water are difficult to remove by traditional separation equipment. In order to improve the efficiency of mine water treatment, a cone-plate clarifier is proposed in this paper. The particle size distribution and their fragmentation fractal dimension were studied in 15 sampling points of the cone-plate clarifier to elucidate the process of floc growth and settling. The influence of the tangential inlet velocity size distribution characteristics was also studied. The results showed that the cone-plate clarifier can effectively improve suspended solids and turbidity removal efficiency. The floc growth and settlement courses are shown in the charts. The cone-plate clarifier was divided into four zones: micro flocculation, floc growing, settlement, and exit pipe. Because the fluid enters the cone-plate clarifier tangentially, the value of the inlet velocity and the tangential velocity are equal at the inlet feed. With the increase in tangential velocity, the flocculation efficiency first increased and then decreased. Comprehensive analysis of the particle greater than 50 μm in the effluent showed that the optimal inlet was qual to 1.63 m/s. By fitting the equations, the optimal SS and turbidity removal efficiency reached the maximum values of 92.04% and 80.18% at the inlet velocity of 1.86 m/s and 1.77 m/s, respectively. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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18 pages, 6129 KiB  
Article
Next-Generation Dried Blood Spot Samplers for Protein Analysis: Describing Trypsin-Modified Smart Sampling Paper
by Eleonora Pizzi, Trine Grønhaug Halvorsen, Christian J. Koehler and Léon Reubsaet
Separations 2021, 8(5), 66; https://doi.org/10.3390/separations8050066 - 13 May 2021
Cited by 10 | Viewed by 6973
Abstract
This paper describes smart sampling paper to be used for bottom-up protein analysis. Four different manners to immobilize trypsin on cellulose were evaluated. Untreated paper, potassium-periodate-functionalized paper (with and without post-immobilization reduction) and 2-hydroxyethyl methacrylate (HEMA)/2-vinyl-4,4-dimethylazlactone (VDM)-functionalized paper were all used to immobilize [...] Read more.
This paper describes smart sampling paper to be used for bottom-up protein analysis. Four different manners to immobilize trypsin on cellulose were evaluated. Untreated paper, potassium-periodate-functionalized paper (with and without post-immobilization reduction) and 2-hydroxyethyl methacrylate (HEMA)/2-vinyl-4,4-dimethylazlactone (VDM)-functionalized paper were all used to immobilize trypsin. For the evaluation, Coomassie Brilliant Blue staining of proteins on paper and the BAEE trypsin activity assay needed to be modified. These methods allowed, together with data from mass spectrometric analysis of cytochrome C digestions, us to acquire fundamental insight into protein binding, and trypsin action and activity on paper. All functionalized discs bind more protein than the untreated discs. Protein binding to functionalized discs is based on both adsorption and covalent binding. Trypsin immobilized on potassium-periodate-functionalized discs exhibits the highest trypsin activity when using cytochrome C as substrate. It is proven that it is trypsin attached to paper (and not desorbed trypsin) which is responsible for the enzyme activity. The use of discs on complex biological samples shows that all functionalized discs are able to digest diluted serum; for the best-performing disc, HEMA-VDM functionalized, up to 200 high-confidence proteins are qualified, showing its potential. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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11 pages, 1557 KiB  
Article
Comparison of Adsorbents Containing Carbon Nanotubes for Express Pre-Concentration of Volatile Organic Compounds from the Air Flow
by Oleg Rodinkov, Victor Postnov, Valery Spivakovskyi, Andrey Vlasov, Alexandra Bugaichenko, Svetlana Slastina, Ekaterina Znamenskaya, Roman Shilov, Sergey Lanin and Pavel Nesterenko
Separations 2021, 8(4), 50; https://doi.org/10.3390/separations8040050 - 14 Apr 2021
Cited by 5 | Viewed by 2768
Abstract
New composite adsorbents including silica supports (silica, aerosilogel, and diatomite) and carbon materials (multiwall carbon nanotubes and pyrolytic carbon) have been prepared and characterized. The analytical capabilities of the produced sorbents have been evaluated by their efficiency in the express pre-concentration of volatile [...] Read more.
New composite adsorbents including silica supports (silica, aerosilogel, and diatomite) and carbon materials (multiwall carbon nanotubes and pyrolytic carbon) have been prepared and characterized. The analytical capabilities of the produced sorbents have been evaluated by their efficiency in the express pre-concentration of volatile organic compounds (butanol and phenols) from the air stream. The prepared surface-layered adsorbents containing multiwall carbon nanotubes placed onto the surface of aerosilogel by use of the carbon vapor deposition method with preloading cobalt nanostructures as a catalyst were found significantly more efficient than traditionally used graphitic carbon-based adsorbents Carbopacks B, C, and X. Additionally, a new adsorbent composed of diatomite Porochrome-3 support coated with a pyrocarbon layer was prepared. This low surface area composited adsorbent allowed both quantitative pre-concentration of phenol and isomeric cresols from the air and their thermal desorption. The developed adsorbents provided fast pre-concentration of selected phenols with a concentration factor of 2 × 103 in 5 min and were used for gas chromatographic determination of analytes in the air at low concentration levels starting from several μg/m3 with a flame ionization detector. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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11 pages, 891 KiB  
Article
Eco-Friendly Direct GC–MS Method for Estimation of Niacin and Related Impurities Involving Pyridine in Food Supplements
by Atiah H. Almalki, Ibrahim A. Naguib and Fatma F. Abdallah
Separations 2021, 8(4), 46; https://doi.org/10.3390/separations8040046 - 6 Apr 2021
Cited by 3 | Viewed by 4264
Abstract
Niacin is a water-soluble vitamin whose deficiency causes many disorders and diseases, including pellagra and high blood cholesterol. Herein, niacin and four common impurities, isonicotinic acid (ISO), 5-ethyl-2-methylpyridine (MP), pyridine-2, 5-dicarboxylic acid (PDC) and pyridine PYR, are simultaneously analyzed, where PYR is known [...] Read more.
Niacin is a water-soluble vitamin whose deficiency causes many disorders and diseases, including pellagra and high blood cholesterol. Herein, niacin and four common impurities, isonicotinic acid (ISO), 5-ethyl-2-methylpyridine (MP), pyridine-2, 5-dicarboxylic acid (PDC) and pyridine PYR, are simultaneously analyzed, where PYR is known as potentially nephrotoxic and hepatotoxic. The separation of a mixture using gas chromatography–mass spectroscopy (GC–MS) without any derivatization steps was the main target. Many studies have been published to study Niacin and its impurities using colorimetry and HPLC. GC–MS was selected to study the analyzed mixture owing to its known sensitivity and selectivity. In this study, a single quadrupole mass spectrometer operated in selected ion monitoring (SIM) mode at an electron ionization energy of 70 eV was applied for the quantitative analysis of Niacin. Helium was used as the carrier gas and adjusted to run through an HP-5ms (5%-phenyl)-methylpolysiloxane column. Statistical analysis proved that this method is equally effective as the previously reported method. Importantly, this study was eco-friendly as compared to the reported high performance thin layer chromatographic method (HPTLC). Finally, this study provides a new and valid eco-friendly method analysis to determine the concentration of niacin and its common impurities at very low concentration. Conclusion: A simple, rapid accurate and green GC–MS analytical method was developed and validated to determine niacin and its related official impurities. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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17 pages, 2709 KiB  
Article
Rapid Determination of Ethylene Oxide and 75 VOCs in Ambient Air with Canister Sampling and Associated Growth Issues
by Jason Hoisington and Jason S. Herrington
Separations 2021, 8(3), 35; https://doi.org/10.3390/separations8030035 - 22 Mar 2021
Cited by 9 | Viewed by 6250
Abstract
A canister-based sampling method along with preconcentrator-Gas chromatography-Mass Spectrometry (GC-MS) analysis was applied to ethylene oxide (EtO or EO) and 75 other volatile organic compounds (VOCs) in ambient air. Ambient air can contain a large variety of VOCs, and thorough analysis requires non-discriminatory [...] Read more.
A canister-based sampling method along with preconcentrator-Gas chromatography-Mass Spectrometry (GC-MS) analysis was applied to ethylene oxide (EtO or EO) and 75 other volatile organic compounds (VOCs) in ambient air. Ambient air can contain a large variety of VOCs, and thorough analysis requires non-discriminatory sampling and a chromatographic method capable of resolving a complex mixture. Canister collection of whole air samples allows for the collection of a wide range of volatile compounds, while the simultaneous analysis of ethylene oxide and other VOCs allows for faster throughput than separate methods. The method presented is based on US EPA Method TO-15A and allows for the detection of EtO from 18 to 2500 pptv. The method has an average accuracy of 104% and precision of 13% relative standard deviation (RSD), with an instrument run time of 32 min. In addition, a link between canister cleanliness and ethylene oxide growth is observed, and potential mechanisms and cleaning strategies are addressed. Full article
(This article belongs to the Special Issue Rapid Separations of Complex Mixtures)
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