Unanswered Questions
235 questions with no upvoted or accepted answers
20
votes
0
answers
457
views
Manuals for a Cahn TG-171 Thermogravimetric Analyzer
Recently a Cahn TG-171 Thermogravimetric Analyzer was donated to my school. We did not get a service or user's manual with it, and some of it still needs to be put back together.
I have tried to ...
- 1
9
votes
0
answers
263
views
Quantitative Transfer of Volatile Standards
(Edited w/ updates) Okay, long story short I work in a lab which has been working on cannabinoid analysis (in the licensed Canadian market) and have had a lot of issues surrounding the standards/...
- 131
7
votes
0
answers
50
views
Why all commercial SPR instruments use angular interrogation?
Surface plasmonic resonance biosensor devices are used to measure analyte concentration, kinetics, affinity, and specificity without any need for labels. This technique involves the bonding of the ...
- 4,606
5
votes
0
answers
78
views
Does catechol give Tollens’ test?
Do hydroquinones like catechol or p-hydroxyphenol give Tollens’ test?
I know that β-diketones can reduce Tollens’ reagent to give a “silver mirror”, so I would guess that due to tautomerization ...
- 38.4k
5
votes
0
answers
223
views
Splitting of atomic orbitals due to Stark effect
I am performing graduate level research on ZEKE Photoelectron Spectroscopy and central to this form of spectroscopy is Rydberg states and the Stark effect. The Stark effect is caused by an electric ...
- 71.6k
5
votes
0
answers
196
views
Explanation of Specific Chemical Shifts on an H-NMR Spectrum
Recently, I've been looking into chemical shifts on H-NMR Spectrums and I came across a graph I didn't quite understand...
As you can see from the spectrum attached, the signal emitted from the ...
- 51
5
votes
0
answers
159
views
Where is my antimony going?
I work in a trace metals laboratory operating an ICP-OES. I've been having some trouble with the recovery of antimony in a weak $\ce{HCl}$ solution post-digestion.
The antimony is part of a mix of ...
- 17.6k
4
votes
0
answers
99
views
I can't understand a fragment in the Mass-Spectrum of Benzophenone
Summary:
Took multiple Mass spectra of Benzophenone; There always is a peak at $\pu{152.2}$ that I don't understand.
I made some Measurements of Benzophenone with a GC-MS. Always using EI (electron ...
- 231
4
votes
0
answers
71
views
Why wouldn't a standard addition fluorometric method return the same starting concentration of a solution used to make the standards?
I am trying out a new standard addition method and having some very basic problems. I am hoping someone could point me in the right direction.
I am using a fluorometric method to quantify ammonium in ...
- 41
4
votes
0
answers
134
views
What do we know about the structure of the amylopectin iodine complex?
I am studying a method of finding the ratio between amylose and amylopectin using the difference in color of the amylose-iodine complex(blue) and the amylopectin-iodine complex (red/brown).
Through ...
- 22.5k
4
votes
0
answers
64
views
How to determine the source of sub-nm periodic error in NIR spectra
I've run into an issue collecting measurements on deionized water in the $1050-\pu{1200 nm}$ range. To determine the sensitivity of my spectrophotometer in this range, I've acquired measurements on ...
4
votes
0
answers
2k
views
Protonated forms of EDTA and their constants of formation with metal ions
It is widely known that the fully deprotonated form of EDTA (usually written as Y4-) is the only form that is significantly involved in complexation reactions. From what I have read, this accounts for ...
- 4,606
4
votes
0
answers
133
views
CuAAC "Click" reaction giving inconsistent results
I apologize in advance for the large amount of text and thank all those who take the time to read it.
The "Click" reaction after Fokin and Sharpless is known to achieve high yields without long ...
- 1,257
4
votes
0
answers
90
views
EPR or NMR sample that will give narrow lines at 4 K
We have made a crossed coil setup (X and Y transmit/receiving coils) with a SQUID pick up loop along Z. I have built a similar CW NMR spectrometer with inductive pickup that can detect Teflon NMR with ...
- 38.4k
4
votes
0
answers
585
views
What does “at%” mean and how it differs from “mol%”?
Sorry if my question is a bit obvious, but for some reason I'm getting confused with the percentages in this question:
Concentration of $\ce{A}$ is $\pu{80 at\%}$ and concentration of $\ce{B}$ is $...
- 38.4k