Waters XTerra and XTerra Prep Columns - Manual (Page 6)

[ Care and Use ManUal ]
XTerra Columns 6
Table 3: XTerra buffers for use from pH 1-7
Table 4: XTerra buffers for use from pH 7-12
Table 5: XTerra buffers for use from pH 9-12 with alternative buffers
b. pH Range
XTerra columns have a widened useable pH range over silica based columns. The pH range is pH 1-12 for the MS columns and 2-12 for the RP
columns. Lifetime although greater is still finite and will vary depending upon what buffers are used, the concentration of those buffers and the
temperature at which they are used. Here is a table of recommended and non-recommended buffers to be used as a guideline when developing
methods. Note that high pH use of Phosphate is not recommended even though it will generally give longer lifetimes than silica based columns.
For a table on appropriate buffers to use, please see Tables 3, 4 and 5.
Additive or Buffer pka Buffer Range
(± 1 pH unit)
Volatile or
Non-Volatile
Recommended Use with XTerra ® Packagings
TFA <1.0 Volatile Yes (0.02-0.1%)
Acetic Acid 4.76 Volatile Yes (0.1-1.0%)
Formic Acid 3.75 Volatile Yes (0.1-1.0%)
Acetate (Ammonium) 4.76 3.76-5.76 Volatile Yes (1-10mM) note Na+, K+ salts are not volatile
Formate (Ammonium) 3.75 2.75-4.75 Volatile Yes (1-10mM) note Na+, K+ salts are not volatile
Phosphate 1 2.15 1.15-3.15 Non-Volatile Yes
Phosphate 2 7.2 6.20-8.20 Non-Volatile pH’s >7.0 lifetime decreases significantly with this buffer. See
also note on Phosphate 3 below. The lower the temperature and
buffer molarity, the longer the column lifetime achievable.
Additive or Buffer pka Buffer Range
(± 1 pH unit)
Volatile or
Non-Volatile
Recommended Use with XTerra ® Packagings
4-Methyl-Morpholine ~8.4 Volatile Yes (10mM)
Ammonia 9.2 Volatile <10 mM and <30 °C
Ammonium BIcarbonate 10.3 (HCO
3
)
9.2 (NH
4
)
7.8 (H
2
CO
3
)
9.3-11.3
8.2-10.2
6.8-8.8
Volatile Yes 5-10 mM (keep source >150 °C)
(do not use carbonate)
(total pH range 6.-11.3, natural pH=8.4) adjust pH with either
ammonium hydrocide or acetic acid
Ammonium (Acetate) or
(Formate)
9.2 8.2-10.2 Volatile Yes (1-10mM)
Borate 9.2 8.2-10.2 Non- Volatile
1-Methyl- Piperidine
(Acetate or Formate) 10.3 9.3-11.3 Volatile Yes
Triethylamine (Acetate or
Formate)
10.7 9.7-11.7 Volatile Yes (0.1-1%)
Pyrrolidine 11.3 10.3-12.3 Volatile
Phosphate 3 12.3 11.3-13.3 Non- Volatile
Additive or Buffer pka Buffer Range
(± 1 pH unit)
Volatile or
Non-Volatile
Recommended Use with XTerra ® Packagings
Glycine 9.8 8.8-10.8 Yes
CAPSO 9.7 8.7-10.7 Yes (0.1-1.0mM)
CAPS 10.5 9.5-11.5 Yes (0.1-1.0mM)