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Lecture Comments (26)

1 answer

Last reply by: Professor Starkey
Thu Aug 4, 2016 4:37 PM

Post by Adel Althaqafy on August 3 at 09:55:45 PM

Hi Dr
thank you for explain mass spectroscopy and do you have any articles that by PDF to read it or something is short like summarize about mass spectroscopy
many thanks  

1 answer

Last reply by: Professor Starkey
Sun Oct 18, 2015 11:04 AM

Post by Jinhai Zhang on October 17, 2015

Prof. Starkey:
I have a question about the McLafferty mechanism should I use the double-headed arrow or single-headed arrow, because I google this, the web gives me a single headed arrow instead of double headed, and the mechanism is a little bit different from yours?

1 answer

Last reply by: Professor Starkey
Wed Sep 16, 2015 12:16 AM

Post by Tamrat Regasa on September 15, 2015

how can i sketch mass spectrum for 2 phenyl butane?

1 answer

Last reply by: Professor Starkey
Mon Jan 5, 2015 11:45 PM

Post by Rene Whitaker on January 5, 2015

I am still not understanding how you determine the M+ peak in chloroethane (at 20:52) and bromobutane, other than you know the compound you are looking at and so know at about what amu you should be looking at.  For example, at 20:52, if you did not know the compound was chloroethane, how would you know the peak labeled at M+ is not the base peak (since it is at 100% relative abundance)?

1 answer

Last reply by: Professor Starkey
Sun Oct 26, 2014 12:53 AM

Post by Datevig Daghlian on October 24, 2014

Professor Starkey,

  Thank you very much for your lectures! I am currently a high school student and have taken AP Chemistry and am very interested in O. Chemistry. Would you recommend I watch your lectures on O. Chemistry or should I hold off till I get to University Chemistry? Thank you!

George D.  

3 answers

Last reply by: Professor Starkey
Thu Sep 11, 2014 10:07 AM

Post by Brandon West on September 9, 2014

Do you have a systematic way of doing mass spec like you have for HNMR and IR. I really like the systematic approach you have for HNMR. In my organic class my professor will give me all 3(HNMR or c13NMR, IR, and mass spec) and I will use all three to determine the structure.

1 answer

Last reply by: Professor Starkey
Thu Jul 17, 2014 4:17 PM

Post by Kim Tran on July 17, 2014

Professor Starkey, is there anyway I can open the lecture slides in powerpoint? Thank you

1 answer

Last reply by: Professor Starkey
Tue Mar 18, 2014 12:15 AM

Post by saima khwaja on March 17, 2014

Professor Starkey,

Do you do any lectures on Organometallic Compounds?

1 answer

Last reply by: Professor Starkey
Thu Feb 13, 2014 12:17 AM

Post by Jude Nawlo on February 12, 2014

Going back to the mass spectra of aromatic compounds section: If we see 91 amu on the MS, then do we assume that our compound has the "base" with the double bond on the CH2 or does it not matter, considering the benzylic resonance forms coexist? Awesome lecture, thank you again!

1 answer

Last reply by: Professor Starkey
Fri Jan 24, 2014 10:45 AM

Post by Udoka Ofoedu on January 24, 2014

You are the best . Thank God he brought me here

1 answer

Last reply by: Professor Starkey
Fri Oct 25, 2013 10:05 PM

Post by Saif Al-Wahaibi on October 25, 2013

For the McLafferty problem, where would the positive charge be in C4H8O so that it would be observed in the mass spectrometer?

1 answer

Last reply by: Professor Starkey
Wed Sep 11, 2013 11:05 AM

Post by Ramin Sadat on September 10, 2013

Thank you for the Mass Spectrometry lecture. I have been waiting for this! Very Helpful!

Mass Spectrometry

Lecture Slides are screen-captured images of important points in the lecture. Students can download and print out these lecture slide images to do practice problems as well as take notes while watching the lecture.

  1. Intro
    • Introduction to Mass Spectrometry
    • Obtaining a Mass Spectrum
    • The Components of a Mass Spectrum
    • What is the Mass of a Single Molecule
    • Other Isotopes of High Abundance
    • Isotopic Abundance can be Calculated
    • Determining Molecular Formula from High-resolution Mass Spectrometry
    • Fragmentation of various Functional Groups
    • Mass Spectra of Alkanes
    • Mass of Common Fragments
    • Mass Spectra of Alkanes
    • Branched Alkanes
    • Mass Spectra of Alkenes
    • Mass Spectra of Aromatic Compounds
    • Mass Spectra of Alcohols
    • Mass Spectra of Ethers
    • Mass Spectra of Amines
    • Mass Spectra of Aldehydes & Ketones
    • McLafferty Rearrangement
    • Mass Spectra of Esters
    • Mass Spectrometry Discussion I
    • Mass Spectrometry Discussion II
    • Mass Spectrometry Discussion III
    • Mass Spectrometry Discussion IV
    • Mass Spectrometry Discussion V
    • Mass Spectrometry Discussion VI
    • Intro 0:00
    • Introduction to Mass Spectrometry 0:37
      • Uses of Mass Spectrometry: Molecular Mass
      • Uses of Mass Spectrometry: Molecular Formula
      • Uses of Mass Spectrometry: Structural Information
      • Uses of Mass Spectrometry: In Conjunction with Gas Chromatography
    • Obtaining a Mass Spectrum 2:59
      • Obtaining a Mass Spectrum
    • The Components of a Mass Spectrum 6:44
      • The Components of a Mass Spectrum
    • What is the Mass of a Single Molecule 12:13
      • Example: CH₄
      • Example: ¹³CH₄
      • What Ratio is Expected for the Molecular Ion Peaks of C₂H₆?
    • Other Isotopes of High Abundance 16:30
      • Example: Cl Atoms
      • Example: Br Atoms
      • Mass Spectrometry of Chloroethane
      • Mass Spectrometry of Bromobutane
    • Isotopic Abundance can be Calculated 22:48
      • What Ratios are Expected for the Molecular Ion Peaks of CH₂Br₂?
    • Determining Molecular Formula from High-resolution Mass Spectrometry 26:53
      • Exact Masses of Various Elements
    • Fragmentation of various Functional Groups 28:42
      • What is More Stable, a Carbocation C⁺ or a Radical R?
      • Fragmentation is More Likely If It Gives Relatively Stable Carbocations and Radicals
    • Mass Spectra of Alkanes 33:15
      • Example: Hexane
      • Fragmentation Method 1
      • Fragmentation Method 2
      • Fragmentation Method 3
    • Mass of Common Fragments 37:07
      • Mass of Common Fragments
    • Mass Spectra of Alkanes 39:28
      • Mass Spectra of Alkanes
      • What are the Peaks at m/z 15 and 71 So Small?
    • Branched Alkanes 43:12
      • Explain Why the Base Peak of 2-methylhexane is at m/z 43 (M-57)
    • Mass Spectra of Alkenes 45:42
      • Mass Spectra of Alkenes: Remove 1 e⁻
      • Mass Spectra of Alkenes: Fragment
      • High-Energy Pi Electron is Most Likely Removed
    • Mass Spectra of Aromatic Compounds 49:01
      • Mass Spectra of Aromatic Compounds
    • Mass Spectra of Alcohols 51:32
      • Mass Spectra of Alcohols
    • Mass Spectra of Ethers 54:53
      • Mass Spectra of Ethers
    • Mass Spectra of Amines 56:49
      • Mass Spectra of Amines
    • Mass Spectra of Aldehydes & Ketones 59:23
      • Mass Spectra of Aldehydes & Ketones
    • McLafferty Rearrangement 1:01:29
      • McLafferty Rearrangement
    • Mass Spectra of Esters 1:04:15
      • Mass Spectra of Esters
    • Mass Spectrometry Discussion I 1:05:01
      • For the Given Molecule (M=58), Do You Expect the More Abundant Peak to Be m/z 15 or m/z 43?
    • Mass Spectrometry Discussion II 1:08:13
      • For the Given Molecule (M=74), Do You Expect the More Abundant Peak to Be m/z 31, m/z 45, or m/z 59?
    • Mass Spectrometry Discussion III 1:11:42
      • Explain Why the Mass Spectra of Methyl Ketones Typically have a Peak at m/z 43
    • Mass Spectrometry Discussion IV 1:14:46
      • In the Mass Spectrum of the Given Molecule (M=88), Account for the Peaks at m/z 45 and m/z 57
    • Mass Spectrometry Discussion V 1:18:25
      • How Could You Use Mass Spectrometry to Distinguish Between the Following Two Compounds (M=73)?
    • Mass Spectrometry Discussion VI 1:22:45
      • What Would be the m/z Ratio for the Fragment for the Fragment Resulting from a McLafferty Rearrangement for the Following Molecule (M=114)?