Chemicals from Merck

[miro2009]

Dear all,
I have been trying to look for TFA (trifluoroacetic acid) of an appropriate grade for use in RP-HPLC, all I can find is TFA pre-mixed with water and acetronitrile 0.1%, I would like to buy it on its own as we sometimes use different percentages (0.8 or 0.9%), does anyone know the catalogue number?
Also for salts such as sod. chloride and sodium phosphate, is ACS reagant grade (Emsure) suitable to be used for liquid chromatography as mobile phase?
We are restricted to Merck in the current period for some logistic reasons, your feedback is appreciated.

[rwang]

Try HPLC or Spectroscopic grade TFA, the following is from Merck:

108262 Trifluoroacetic acid
for spectroscopy Uvasol®

in 25 mL, 100 mL, 1L and 2.5L bottles.

[Andy Alpert]

ACS-grade phosphate salts (and phosphoric acid) contain contaminants that can accumulate on columns during reequilibration and then elute during a gradient, resulting in artifactual peaks. HPLC-grade phosphate and phosphoric acid has been treated with a chelating resin to remove them. You can find a procedure for doing this yourself in: C.T. Mant and R.S. Hodges, Methods in Enzymology 271 (1996), pg. 12 (the entire article is pgs. 3-50).

[miro2009]

ACS-grade phosphate salts (and phosphoric acid) contain contaminants that can accumulate on columns during reequilibration and then elute during a gradient, resulting in artifactual peaks. HPLC-grade phosphate and phosphoric acid has been treated with a chelating resin to remove them. You can find a procedure for doing this yourself in: C.T. Mant and R.S. Hodges, Methods in Enzymology 271 (1996), pg. 12 (the entire article is pgs. 3-50).

I expected this as well, I have been using HPLC grade sodium phosphate (mono and dibasic) and sodium chloride from Sigma Aldrich, but due to logisitics we can no longer bring it from Sigma, do you from where can I get an alternative (I search Merck website but couldn't find, can anyone help me out with that?)

[miro2009]

And regarding TFA from Merck, anyone know about this product or have experience of using it in their work:
TX1276 Trifluoroacetic Acid
http://www.emdchemicals.com/cosmetic-in ... Ei1UdCeVD2

This is the only one I found in Merck labelled "HPLC grade"..

[Andy Alpert]

In the USA, Merck chemicals are sold through their subsidiary EMD Chemicals. They list the following:

Item# SX0709: Sodium phosphate, monobasic, monohydrate, HPLC grade.

Item# SX0723: Sodium phosphate, dibasic, anhydrous, HPLC grade.

[miro2009]

In the USA, Merck chemicals are sold through their subsidiary EMD Chemicals. They list the following:

Item# SX0709: Sodium phosphate, monobasic, monohydrate, HPLC grade.

Item# SX0723: Sodium phosphate, dibasic, anhydrous, HPLC grade.

Thanks Andy for the helpful reply, I hope this is possible to import in Egypt, so these are also manufactured by Merck? and EMD is a "distributor, or?

remains only HPLC grade sodium chloride which I also couldn't find, maybe I should go for Suprapur grade listed in Merck/EMD?

[Andy Alpert]

Sodium chloride: I don't see an HPLC grade listed on EMD's Web site. In any case, it's less important to get HPLC-grade sodium chloride than HPLC-grade phosphate salts. In my experience, there's less of a problem with contaminants in chloride salts that absorb light at low wavelengths. Incidentally, EMD is the branch (= subsidiary) of E. Merck in the USA.

Availability in Egypt: Well, a company in Egypt recently ordered several of our company's HPLC columns and then asked us to get them some additional HPLC columns that are manufactured by other (well-known) companies. It seems that some companies can't be bothered to do business with companies in Egypt, even if the Egyptian companies are subsidiaries of multinational corporations. We bought the other columns at regular retail prices and bundled them with our columns in one shipment to Egypt. This saved the Egyptian company months in getting the columns they needed, apparently (assuming they could have gotten them at all). If you're buying something from a company outside of Egypt, maybe you can ask them to get you the Merck/EMD reagents you need as well. Offer to pay them in advance so that it's your working capital that's tied up for the month, not theirs.