MOLECULAR WEIGHT
|
MOLES / LITER
|
GRAMS / LITER
|
PERCENT by WEIGHT
|
SPECIFIC GRAVITY
|
|
Acetic Acid
|
60.05
|
6.27
|
376
|
36
|
1.045
|
Acetic Acid, Glacial
|
60.05
|
17.4
|
1045
|
99.5
|
1.05
|
Formic Acid
|
46.02
|
23.4
|
1080
|
90
|
1.21
|
Hydrochloric Acid
|
36.5
|
11.6
|
424
|
36
|
1.18
|
Nitric Acid
|
63.02
|
15.99
|
1008
|
71
|
1.42
|
Perchloric Acid
|
100.5
|
11.65
|
1172
|
70
|
1.67
|
Phosphoric Acid
|
98
|
14.7
|
1445
|
85
|
1.70
|
Sulfuric Acid
|
98.1
|
18.0
|
1766
|
96
|
1.84
|
Ammonia (in H20)
|
17.0
|
14.8
|
252
|
28
|
0.898
|
Potassium Hydroxide
|
56.1
|
13.5
|
757
|
50
|
1.52
|
Sodium Hydroxide
|
40.0
|
19.1
|
763
|
50
|
1.53
|
Data obtained from The
Merck Index, 11th edition (1989).
This is great! Thank you for providing it.
ReplyDeleteGood morning, I run HPLC methods from the European Pharmacopoeia. Many of these methods (Impurities active ingredients), developed in reverse phase, involving the addition of significant amounts of glacial acetic acid (up to 10%) to the eluent phase in addition to the presence of the organic modifier. Could you explain the utility? These eluents cause much noise. Thank you for your Blog
ReplyDeleteWe sometimes add an acid (to acidify) our mobile phase to help suppress ionization, esp with basic compounds. We want the compound to exist in only one form (*This is a fundamental part of basic HPLC method development, so please read one of the basic introductions to HPLC to learn more about that topic).
DeleteAcids, such as acetic are often used, but for liquid chromatography they should be of the highest purity and quality or they will degrade the signal (esp in the low UV region). A common problem with acetic acid is that it goes bad very quickly when exposed to the air. My advice is to only purchase it in very small bottles, open only when needed, blanket with dry nitrogen gas and always USE FRESH acid acid for HPLC. If you observe any noticeable color in the pure solution, discard it. Alternatively, use a different buffer and "cleaner" high purity acid such as formic or phosphoric acid (if applicable to your method).