Using Fast GC to improve detection limits of FUV & PID

1. FAST GC WITH PID & FUV DETECTORS IN FIELD
ENVIRONMENTAL ANALYSES
ENVIRONMENTAL ANALYSES
Dr. Jack Driscoll & David Walsh
Dr Jack Driscoll & David Walsh
PID Analyzers, LLC, Sandwich, MA
Booth #461
h 6
&
Dr. Phillip Smith
Dr. Phillip Smith
OSHA Labs, Salt Lake City, UT

2. INTRODUCTION
• Field environmental labs are expected to
Field environmental labs are expected to
Field environmental labs are
provide rapid sample turnaround. One
potential improvement is to utilize faster GC
potential improvement is to utilize faster GC
columns in a portable GC like the PID
Analyzers Model GC312
Analyzers Model GC312
• We are evaluating several types of columns &
detectors to provide faster and more accurate
detectors to provide faster and more accurate
detectors to provide faster and more accurate
analyses in the field.

3. Types of Samples
yp f p
• BTEX
• Chlorinated HC (TCA, TCE, PERC, MeCl2…)
Chlorinated HC (TCA TCE PERC MeCl2 )
• Gasoline HC’s
• Solvents
• ===============================
• Columns selected‐ Thick film MS Cap (0.53) & a Gas Pro
Columns selected‐ Thick film MS Cap (0.53
PLOT (0.32
PLOT (0.32)
• ===============================
• Pesticides & PCB’s‐ not considered here
Pesticides & PCB’s‐
• Better with short (5‐10M) thin film capillary column
Better with short (5‐
( ) p y

4. DETECTORS_ PID & FUV
DETECTORS PID & FUV
Photoionization Far UV Ansorbance
Far UV
Far UV Ansorbance

5. Comparison of PLOT & Thick Film
Columns
l
• Compare PLOT to Thick Film columns for
Compare PLOT to Thick Film columns for
speed for C1‐C6 anes & enes
speed for C1‐C6 anes & enes
• What are the advantages/disadvantages of
What are the advantages/disadvantages of
each?
• A
Any advantages of resistively heated
d f i i l h d
columns?
Heatup/cool down? Power utilized?
Heatup/cool down? Power utilized?
• Advantages e.g comparison of sensitiviity
Advantages e.g comparison of sensitiviity
g g p y

6. GC312
Portable GC‐
Portable GC
Portable GC‐312 Features
• Battery operated –
Battery operated – 8 hours
• Has external charger or
Has external charger or
power from car battery
• Carrier gas supply‐
Carrier gas supply‐ > 15
hours
hours
• 1 or 2 Detectors
• PID FID TCD Far UV FPD (S
PID, FID, TCD, Far UV, FPD (S
or P)
• Temperature Programming‐
Temperature Programming‐
NEW

7. GC Schematic
GC Schematic
Focus is on the column/oven
Small or no oven (direct heating of
column) provides rapid temperature
p g
programming and faster analyses
g y

8. Packed vs
Packed
Packed vs Capillary
Note the improved
separation of BTX on
capillary vs packed. The
disadvantage is the
analysis time is much
longer.
longer.
Fast GC provides better
separation & detection
limits in a much shorter
time period

9. Our Definitions
Our Definitions
• #1 What is a FAST GC?
• A FAST GC has a low mass or resistively heated column that
h l i ti l h t d l th t
can be heated and/or cooled faster than a conventional oven
• Conditions-
Conditions-
• Improved heating efficiency is a must for battery operated GCs
• Fast GC – run times in 5- 10 minutes instead of 20-30 minutes
5- 20-
• #2 What is a FAST GC column?
• Depends on the application; two examples are:
1. A 15m x 0.32 mm ID, PLOT that is resistively heated & can be
cooled faster since it has a very small thermal mass
2. A thick film (5-10 ) 7.5-30 M capillary column that can
(5- 7.5-
separate gases & Solvents

10. FAST GC
FAST GC‐Advantages
FAST GC‐
• Advantages of FAST GC
g
• Reduced run times
• Increased sample throughput
• Faster turnaround of results
• Improved signal to noise ratio
• Improved detection limits
• Wider range of analytes
Wider range of analytes
• More samples means a more accurate assessment of the site
More samples means a more accurate assessment of the site
• Disadvantages of FAST GC
• Minimal

11. Resistively Heated Column or Low
Mass Oven

12. Comparison of Oven Cool Down
times
120
Cool down times resistive (blue) & Low mass (red) ovens
100
80
n Temperature C
60
Series1
Oven
Series2
40
20
0
0 1 2 3 4 5 6
Cool down min.
Cool down min

13. C1 to C6 Alkanes w FUV on 0.32 mm thick
C1 to C6 Alkanes
(5  film Capillary
(  f l ll

14. PLOT Column (15M 00.32 mm)with TP
PLOT Column (15M 00.32 mm)with TP

15. PLOT Column
(30M 00.32
(30M 00 32
mm)with TP
)

16. Alkanes & BTEX on 7u MXT1 w PID
& BTEX on 7u MXT1 w PID

17. Differences Between TF Cap and PLOT for
C1‐C6 HC
• Main differences are for C1‐C3 HC
Main differences are for C1‐C3 HC
C1
– Separation of CH4 & C2H6‐ better on PLOT
– Separation of C2H6 & C2H4‐ better on PLOT
Separation of C &C better on PLOT
– Separation of C3H8 & C3H6‐ better on PLOT
Separation of C & C
– El ti
Elution of C4 t C6 HC – much shorter on TFC
f C to C HC
HC – h h t TFC

18. Comparison of PLOT to Wide Bore Thick
Film Cap sensitivity
il ii i
WCOT Sensitivity Thick Film 7u x 0.53 mm x 7.5M; 15 cc & 35C; PID 0.2 cc inj. X100
Compound Run PH
C2H4 25 ppm Avg 3306 cts/ppm
pp
H2S 25 ppm Avg
g 1453 cts/ppm
/pp
Gaspro Sensitivity 30M x 0.32 mm; 5 cc & 35C: PID
0.2cc inj. X 100
C2H4 25 ppm Avg. 1519 cts/ppm
H2S 25 ppm Avg. 1739 cts/ppm

19. SUMMARY
• The thick film caps can provide faster analyses with excellent separations
for a wide variety of HC & solvents than PLOT columns
• The sensitivity for the thick film column for gases (C2H4 & H2S) is similar to
the PLOT
• A Resistively heated column can provide faster analyses than a small GC
oven because of its low mass
• If we program from 30C to 100C, the total time for the RHC is 10 min.,
whereas, a small oven (fan cooled) will take nearly 20 min to run this
program.
• These two detectors FUV & PID can provide sub ppm or ppb detection of
CH4, TCA to the xylenes or decane in air, water or soil (headspace for the
latter two)
• If we use a thick film 30M x 0.32 mm column that is resistively heated, we
can do most analyses in 10‐12 min and nearly double the volume of
samples done in a normal work day.