6
Figure 10
Glycols on a uniquely selective trifluoropropyl phase column.
Figure 9
Glycols on a Stabilwax
®
column.
Figure 8
Glycols and alcohols on an
ultra-low-bleed column.
glycols are popular choices. Cleaning sol-
vents can be resolved using anRtx
®
-Wax
column (Figure 4) or anRtx
®
-VMS col-
umn (Figure 5). The latter column gives
excellent selectivity and peak shape for a
wide range of cleaning solvents.
Analysis of an all-purpose cleaner is
shown in Figure 6, and a glass cleaner is
shown in Figure 7.Analyses of glycols
and alcohols are shown in Figures 8–10.
Acids
Organic acids, such as acetic and citric
acids, are used to reduce the pH of
cleaning products, to removemineral
build-up. Inorganic acids, such as
hydrochloric, phosphoric, and sulfuric
acid also can be included in a formula-
tion. Organic acids can be analyzed
either byHPLC or byGC, but HPLC is
a better technique for dicarboxylic acids.
Figure 11 shows a separation of organic
acids on anUltraAqueous C18HPLC
column.AGC analysis of short-chain
free fatty acids is shown in Figure 12.
Rtx
®
-VMS, 60m, 0.25mm ID, 1.4µm (cat.# 19916)
Sample:
Approx. 5% sample inmethanol
Inj.:
1.0µL split injection (100:1),
4mm inlet liner (cat.# 20814)
Inj. temp.:
250°C
Carrier gas:
hydrogen, constant flow
Flow rate:
1.5mL/min.
Oven temp.:
60°C (1min. hold) to 138°C@
4°C/min. to 145°C@ 2°C/min. to
210°C@ 15°C/min. to 230°C
@ 5°C/min.
Det.:
FID@ 250°C
1.
iso
-propanol
2. butyl Cellosolve
®
GC_FF00647
Figure 7
Glass cleaner on anRtx
®
-VMS column.
1.
n
-butyl alcohol
2. ethylene glycol
3. propylene glycol
4. butyl Cellosolve
®
5. butyl carbitol
2
3
1 4
5
GC_CH00327
min. 4 8
XTI
®
-5, 30m, 0.53mm ID, 1.0µm (cat.# 12255)
Inj.:
1.0µL direct injection of glycols
and alcohols, 100ppm each
Oven temp.:
40°C to 185°C@15°C/min.
(hold 5min.)
Inj. / det. temp.: 150°C / 200°C
Carrier gas:
helium
Linear velocity: 40cm/sec. (flow rate: 5cc/min.)
FID sensitivity:
8 x 10
-11
AFS
Stabilwax
®
, 30m, 0.53mm ID, 1.0µm (cat.# 10655)
Inj.:
1.0µL direct injectionof ethylene
glycol and propylene glycol,
100 ppm each, inwater. Open-top
Uniliner
®
direct injection liner
without wool (cat.# 20843-205).
Septum purge: 5.0cc/min.
Oven temp.:
80°C (hold 1min.) to 200°C@
8°C/min. (hold 5min.)
Inj./det. temp.: 225°C/250°C
Carrier gas:
helium
Linear velocity: 50cm/sec.
Detector:
FID
min.8.0
9.0
10.0
11.0
~
1. propylene glycol
2. ethylene glycol
1
2
GC_EV00546
min.
0.20 0.40 0.60 0.80 1.00 1.20 1.40 1.60 1.80 2.00
1
2
1. ethylene glycol
2. propylene glycol
Rtx
®
-200, 30m, 0.53mm ID, 1.0µm (cat.# 15055)
Inj. / det. temp.: 220°C / 270°C
Oven temp.:
80°C (hold 1min.) to 200°C
@8°C/min. (hold 3min.)
10psi pressure
GC_EV00445
