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
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.
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
DETECTORS_ PID & FUV DETECTORS PID & FUVPhotoionization Far UV Ansorbance Far UV Far UV Ansorbance
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
GC312Portable GC‐Portable GCPortable 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
GC SchematicGC 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
Packed vsPacked 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
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
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
Alkanes & BTEX on 7u MXT1 w PID & BTEX on 7u MXT1 w PID
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
Comparison of PLOT to Wide Bore Thick Film Cap sensitivity il ii iWCOT Sensitivity Thick Film 7u x 0.53 mm x 7.5M; 15 cc & 35C; PID 0.2 cc inj. X100 Compound Run PHC2H4 25 ppm Avg 3306 cts/ppm ppH2S 25 ppm Avg g 1453 cts/ppm /ppGaspro Sensitivity 30M x 0.32 mm; 5 cc & 35C: PID 0.2cc inj. X 100C2H4 25 ppm Avg. 1519 cts/ppm H2S 25 ppm Avg. 1739 cts/ppm
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.