Analyze 40% More Semivolatiles Samples
per Shift Using Split Injection
By Michelle Misselwitz, Innovations Chemist, and Jack Cochran, Director of New Business and Technology
Semivolatile organic compounds (SVOCs) are
usually analyzed using splitless injection
because the transfer of analytes to the head of
the column is more complete than with split
injection. While this can enhance low-level
detection, splitless injection is limited by relatively slow analysis times and injection-to-injection variability. Combined, these factors
reduce the number of samples that can be analyzed before quality control criteria are no
longer met. Here we evaluate the applicability
of split injection to semivolatiles analysis using
EPA Method 8270D.
Table I: Split injection significantly increases sample throughput compared to
Split (Fast Cycle) Split (Faster Cycle) Splitless
12-hr. shift = 10.5 hr. sample analysis period + 1.5 hr. quality control/method performance analysis period. Sample
throughput calculation based on number of samples that can be analyzed in 10.5 hours.
Using split injection, 2 oven programs starting
at 80 °C were compared to a typical splitless
program which started at 40 °C.
Figure 1 Analyzing semivolatiles in less than 13 minutes is possible with split injection, due to the
higher GC oven start temperature and faster oven temperature programming.
Split (fast cycle): 80 °C (hold 1 min.) to
280 °C at 25 °C/min. to 320 °C at 5 °C/min.
(hold 1 min.)
Split (faster cycle): 80 °C (hold 1 min.) to
320 °C at 25 °C/min. to 330 °C at 5 °C/min.
(hold 2 min.)
Splitless: 40 °C (hold 1 min.) to 280 °C at
25 °C/min. to 320 °C at 5 °C/min. (hold 1 min.).
Analyze 40% more samples
per shift using split injection!
The faster oven cycle times used with split
injection allowed up to 10 more samples to be
analyzed per shift (Table I). The fastest program resulted in reduced separation of
dibenz(a,h)anthracene and indeno(1,2,3-
cd)pyrene (Figure 1), but these compounds
were fully resolved using the alternate split
conditions. The 80 °C oven start temperature
could not be used with splitless injection, as it
resulted in extremely broad peaks that could
not be integrated.
Sample throughput for semivolatiles analysis
can be significantly increased by employing
split injection with a higher initial oven temperature and faster cycle time.
For the complete application note,
and linearity data,
and enter EVAN1298
in the search field.
Column: Rxi®-5Sil MS, 30 m, 0.25 mm ID, 0.25 μm (cat.# 13623); Sample: 8270 MegaMix® (cat.# 31850), Benzoic acid (cat.# 31879), 8270 Benzidines
Mix (cat.# 31852), Acid Surrogate Mix (4/89 SOW) (cat.# 31025), 1,4-dioxane (cat.# 31853), Revised B/N Surrogate Mix (cat.# 31887), SV Internal
Standard Mix (cat.# 31206); Diluent: Methylene chloride; Conc.: 40 μg/mL (4 ng on-column); Injection: Inj. Vol.: 1.0 μL split (split ratio 10:1), Liner:
4mm Split Precision® Liner w/ Semivolatiles Wool (cat.# 21023-231.5), Inj. Temp.: 270 °C; Oven Temp: 80 °C (hold 1 min.) to 320 °C at 25 °C/min. to
330 °C at 5 °C/min. (hold 2 min.); Carrier Gas: He, constant flow, Flow Rate: 1.2 mL/min.; Detector: MS, Mode: Scan, Transfer Line Temp.: 280 °C,
Analyzer Type: Quadrupole, Source Temp.: 250 °C, Quad Temp.: 150 °C, Tune Type: DFTPP, Ionization Mode: EI, Scan Range: 35-550 amu; Instrument:
Agilent 7890A GC & 5975C MSD
For complete conditions and peak identifications, visit www.restek.com and
enter chromatogram GC_EV1184 in the search field.
Restek Corporation, 110 Benner Circle, Bellefonte, PA 16823
1-800-356-1688 or 1-814-353-1300 www.restek.com