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Hi, I am new here! I am working on Bruker 600 MHz over 10 years, but now I have problem to get 35Cl NMR spectrum. I used NaCl in D2O and CDCl3, but nothing! SW 1000 ppm, d1 1 s, tuning and matching super, but nothing in spectra! Please, help me how to do it to get peak on baseline! Thank You! Marijana from Croatia

asked Jul 02 '13 at 05:51

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gugica
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Hi Marijana,

NaCl in D2O should give a sharp line (maybe 10Hz wide, I guess). Should come at 0ppm (100mM in D2O, will be slightly different at different concentration). Set aq reasonably short (100ms), process with 10Hz LB, you should easily get a signal in a single scan with 1M concentration. You might see some probe ringing which will distort the baseline, but the real signal should be much sharper than that. Chloroform will give a very broad 35Cl spectrum (1000s of Hz), so it's not worth trying that to start with. Anything with covalent bonds will give a very broad spectrum, you may need to use a pulse sequence that suppresses the probe ringing if the real samples you want to look at have covalently bonded Cl.

Can you get a 23Na spectrum on your NaCl sample? 23Na will give a similar linewidth but is about 25x more sensitive than 35Cl and you won't have problems with probe ringing. Should come at 0ppm again, use aq=100ms, should be very easy to see a signal in a single scan. That should give you an idea of how much S:N to expect in the 35Cl sample.

What RG value do you have for your 35Cl spectrum? The ringing signal could cause RGA to give a very low value which could reduce the S:N a lot. If RGA gives much less than 256, try increasing DE (say to 20us) then do RGA again, if you then get >256 acquire again. If RGA still gives much less than 256, try de=50us, that should definitely allow RGA to give a reasonable value. That might improve the S:N enough that you see something.

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answered Jul 03 '13 at 15:23

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Pete Gierth
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Hi, Pete,

Thank you very much for helping me! After I followed your instructions, I got sharp signal for NaCl and broad signal for CDCl3. RG was always much more higher of 256. But, in spectra of my sample (Ag-comlex of small organic molecule) there was nothing. I do not know true concentration, but it is high. It was running all over this weekend. Pulse sequence was aring2.

Have a nice day, Marijana

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answered Jul 08 '13 at 01:34

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gugica
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Linewidth of Cl depends on the rotational correlation time, so larger molecules or complexes will tend to have broader lines. It is possible that your complex has lines much broader than CDCl3.

If the Cl is bound directly to Ag, it may have a large chemical shift.

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answered Jul 10 '13 at 07:30

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Tony Bielecki
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updated Jul 10 '13 at 07:32

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Asked: Jul 02 '13 at 05:51

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