Chromatography Forum

Hello all,

A biologist here, with an HPLC question. A client of ours has provided us with an analytical method for a material we are testing for them which calls for the use of a perchloric acid mobile phase. One of our senior people here pronounced this an undesirable and dangerous method because he says that perchlric acid is highly explosive in an HPLC environment and must be of extremely high purity. I have googled this several times and have not seen anything about it being prohibitively explosive in HPLC use. Any comments? Thanks.

Someone seems to be confusing perchloric acid in a heated/oxidizing reaction and as mobile phase for HPLC....

I have never heard of anyone having this type of hazard with perchloric acid HPLC methods, however this is one of the stronger acids used in chromatography. The use of this acid in the mobile phase has the potential to significantly reduce column life, especially at high concentrations or elevated temperatures.
Acetic Acid and Formic Acid are generally a better choice for low temperature pH control, while Trifluoroacetic acid (TFA) is used if some ion pairing effects are preferred to improve peak shape.

Perchloric acid is quite often used as eluent in ion-exclusion chromatography. Here the acid strenght is an advantage. The concentration is the in the low mmol/L range. The chemist who brings this solution to explode will be a candidate for the Nobel prize.

@Kumar11: your statement about shortened column life might be correct for silica based columns. but many polymer based columns do have a much larger applicable pH-range.

One of our senior people here pronounced this an undesirable and dangerous method because he says that perchlric acid is highly explosive in an HPLC environment and must be of extremely high purity.

I hope that senior person is also aware of the hazards of dihydrogen monoxide and the safety precautions that must be taken for its use:
SPECIAL PRECAUTIONS
KEEP CONTAINER TIGHTLY CLOSED. SUITABLE FOR ANY GENERAL CHEMICAL STORAGE
AREA. DIHYDROGEN MONOXIDE IS CONSIDERED A NON-REGULATED PRODUCT, BUT
REACTS VIGOROUSLY WITH SOME MATERIALS. THESE INCLUDE SODIUM, POTASSIUM
AND OTHER ALKALI METALS; ELEMENTAL FLUORINE; AND STRONG DEHYDRATING AGENTS
SUCH AS SULFURIC ACID. IT FORMS EXPLOSIVE GASES WITH CALCIUM CARBIDE.
AVOID CONTACT WITH ALL MATERIALS UNTIL INVESTIGATION SHOWS SUBSTANCE IS
COMPATIBLE. EXPANDS SIGNIFICANTLY UPON FREEZING. DO NOT STORE IN RIGID
CONTAINER AND PROTECT FROM FREEZING.
http://www.dhmo.org/msdsdhmo.html

Tom - dihydrogen monoxide causes many deaths yearly. And damages thousands of homes, buildings, businesses.

And yet really thirsty people lost in the desert crave it.

perchloric acid is used only for CROWNPAK CR(+) & CROWNPAK CR(-) columns to adjust pH 1 .
Note : perchloric acid is used in concentration 0.3% .

ph/Amr Tarek
Instrumental Unit Head at Otsuka pharmaceuticals