Waters XBridge XP 2.5 µm Columns - Manual (Page 6)

XBridge XP 2.5 µm Columns 6
[ CARE AND USE MANUAL ]
Table 5. Buffer Recommendations for XBridge XP 2.5 µm Columns.
Additive/Buffer pKa Buffer Range
Volatility
(±1 pH unit)
Used for
Mass Spec
Comments
TFA 0.3 - Volatile Yes
Ion pair additive, can suppress MS signal, used in
the 0.02-0.1% range.
Acetic Acid 4.76 - Volatile Yes
Maximum buffering obtained when used with ammonium
acetate salt. Used in 0.1-1.0% range.
Formic Acid 3.75 - Volatile Yes
Maximum buffering obtained when used with ammonium
formate salt. Used in 0.1-1.0% range.
Acetate (CH
3
COO-) 4.76 3.76 – 5.76 Volatile Yes
Used in the 1-10 mM range. Note that sodium or
potassium salts are not volatile.
Formate (HCOO-) 3.75 2.75 – 4.75 Volatile Yes
Used in the 1-10 mM range. Note that sodium or
potassium salts are not volatile.
Phosphate 1 2.15 1.15 – 3.15 Non-volatile No Traditional low-pH buffer, good UV transparency.
Phosphate 2 7.2 6.20 – 8.20 Non-volatile No
Above pH 7, reduce temperature/concentration and use
a guard column to maximize lifetime.
Phosphate 3 12.3 11.3 - 13.3 Non-volatile No
Above pH 7, reduce temperature/concentration and use
a guard column to maximize lifetime.
4-Methylmorpholine ~8.4 7.4 – 9.4 Volatile Yes Generally used at 10 mM or less.
Ammonia (NH
4
+ ) 9.2 8.2 – 10.2 Volatile Yes
Keep concentration below 10 mM and
temperatures below 30 ˚C.
Ammonium Bicarbonate
10.3 (HCO
3
- )
9.2 (NH
4
+ )
8.2 – 11.3 Volatile Yes
Used in the 5-10 mM range (for MS work keep source
>150 ˚C ). Adjust pH with ammonium hydroxide or
acetic acid. Good buffering capacity at pH 10.
Note: use ammonium bicarbonate (NH
4
HCO
3
), not
ammonium carbonate ((NH
4
)
2
CO
3
).
Ammonium (Acetate) 9.2 8.2 – 10.2 Volatile Yes Used in the 1-10 mM range.
Ammonium (Formate) 9.2 8.2 – 10.2 Volatile Yes Used in the 1-10 mM range.
Borate 9.2 8.2 – 10.2 Non-volatile No
Reduce temperature/concentration and use a guard
column to maximize lifetime.
CAPSO 9.7 8.7 – 10.7 Non-volatile No
Zwitterionic buffer, compatible with acetonitrile,
used in the 1-10 mM range. Low odor.
Glycine 2.4, 9.8 8.8 – 10.8 Nton-volatile No
Zwitterionic buffer, can give longer lifetimes
than borate buffer.
1-Methylpiperidine 10.2 9.3 – 11.3 Volatile Yes Used in the 1-10 mM range.
CAPS 10.4 9.5 – 11.5 Non-volatile No
Zwitterionic buffer, compatible with acetonitrile,
used in the 1-10 mM range. Low odor.
Triethylamine
(as acetate salt)
10.7 9.7 – 11.7 Volatile Yes
Used in the 0.1-1.0% range. Volatile only when titrated with
acetic acid (not hydrochloric or phosphoric). Used as ion-pair
for DNA analysis at pH 7-9.
Pyrrolidine 11.3 10.3 – 12.3 Volatile Yes Mild buffer, gives long lifetime.