"Three new videos about Similar Partition Searching (SPS) are now available on Youtube" 25-Apr-2021.
There are also two recent papers on using Similar Partition Searching for identifying analytes in surface water samples. These papers were described below.
A low-cost monthly subscription to Similar Partition Searching is available on AWS. Ordering information is to the left.
Three videos have been added to our YouTube channel:
Creating Your Database
Using the Database
"Non-targeted screening of trace organic contaminants in surface waters by a multi-tool
approach based on combinatorial analysis of tandem mass spectra and open access
Emmanuel Eysseric and Pedro Alejandro Segura (Universite de Sherbrooke), Francis Beaudry (Universite de Montreal), and Christian Gagnon (Environment and Climate Change Canada) have developed a new approach for screening environmental samples for suspect compounds. Their multi-tool approach included MathSpec's SPS (Similar Partition Searching). This article is open-access, so a link is included here "Talanta Article"
"Mass Spectrometry by the Numbers, Identifying Small Molecules from Accurate-Mass Fragmentation Data, 2nd edition" 11-May-2020
Dan Sweeney's updated book on mass spectral identification was recently published. This book describes the theory of "partitioning" and how this approach was implemented as a simple Excel Add-In. This book will be very useful to anyone who is identifying small molecules using accurate-mass fragmentation. This book can be purchased on your local Amazon website: "Mass Spectrometry by the Numbers, 2nd edition." The e-pub version is always free if you have Kindle Unlimited. Kindle owners with Amazon Prime can also borrow the book at no cost through the Kindle Owners' Lending Library.
"Nontargeted Screening of Water Samples Using Data-Dependent Acquisition with Similar Partition Searching" 01-May-2020 (DOI: 10.1021/jasms.0c00031)
MathSpec's Dan Sweeney was honored to be a co-author on a recent publication in JASMS with co-authors Imma Ferrer, E. Michael Thurman, and Jerry A. Zweigenbaum. This paper describes a rapid screening method for the detection of nontargeted compounds in surface water samples that was developed using accurate-mass fragmentation data acquired by data-dependent acquisition. Eighteen surface water samples from rivers, reservoirs, and effluents from waste- water treatment plants were analyzed, generating 41625 MS-MS spectra in about 14 h. The raw data were then converted into two generic formats using the open-access program MSConvert. A combinatorial approach, similar partition searching (SPS), was then used to putatively identify analytes from the accurate mass of each analyte (adjusted for the adduct mass) and the corresponding MS-MS spectra were obtained. In this approach, the structures of about 250000 common compounds, stored in a large database as mathematical partitions of their exact mass, were compared directly to each MS-MS spectrum.
"Similar Partition Searching is now available for rapid screening of very complex samples." 15-Jul-2019
MathSpec has now launched Similar Partition Searching on Amazon Web Services. For a very reasonable cost, users can rapidly screen very complex samples. This is especially useful for food safety and environmental applications, but it can also be used with our Excel Add-in to decentralize data analysis in central service laboratories. A brief description is attached here: "Partition Searching"
"MathSpec at ASMS 2019 in Atlanta" 03-Jun-2019
MathSpec's Dan Sweeney was honored to be a co-author on a poster presented at ASMS in Atlanta with co-authors Imma Ferrer, E. Michael Thurman, and Jerry A. Zweigenbaum. This poster illustrated the critical importance of optimizing DDA (data dependent analysis) parameters prior to analyzing samples. By optimizing the mass spectral parameters, taking into account the downstream Agilent Decision Engine and Partition Searching operations, twenty aqueous environmental samples were screened very rapidly. Here a huge dataset of over 37000 MS/MS spectra was obtained and analyzed. This approach is especially useful for food safety and environmental applications. The poster is attached here; it eventually will also be available in the ASMS 2019 Proceedings: "Rapid Non-Targeted Screening of Aqueous Environmental Samples Using Auto MS/MS"
"Mass Spectrometry by the Numbers, Identifying Small Molecules from Accurate-Mass Fragmentation Data" 15-Nov-2018
Dan Sweeney's new book on mass spectral identification was recently published. This book describes the theory of "partitioning" and how this approach was implemented as a simple Excel Add-In. The book has many examples. This book can now be purchased on the Amazon website: "Mass Spectrometry by the Numbers"
Similar Partition Searching 08-Oct-2017
Rational Numbers Search was moved from our own MathSpec server to Amazon AWS. This increased CPU power now makes in possible to search every MS/MS spectrum in a chromatogram. Contact us now for your free two-week trial. To see exactly how Similar Partition Searching (SPS) works, please view our short MathSpec YouTube Video on SPS.
Similar Partition Searching 4-28-2016
Rational Numbers Search has been moved from our own MathSpec server to Amazon AWS. This increased CPU power has allowed us to also add simultaneous searching for similar compounds.
New Capabilities Added 02-19-2016
Two new worksheets have been added to the Excel Add-In.
The first worksheet is a summary of all of the elemental compositions of all assigned fragments. With built-in filters for each parameter, this makes it much easier to sort through the results that have a large number of possible molecular formulas.
The second worksheet is a high resolution isotope calculator that tabulates the expected masses of the first and second isotopes. The isotopic patterns of the first and second isotopes are then plotted in color in a normal distribution based on the selected resolution setting. (example here)
Excel® 2016 11-25-2015
The Excel Add-In is compatible with Excel 2016. Use the installation video (MathSpec YouTube) for Excel 2013.
SubFragment Color Change 11-9-2015
Based on feedback, the color of the fourth subfragment has been changed to a shade of purple, making it easier to distinguish from the other cells.