Restek Advantage Chromatography Newsletter Back Issues
Restek Advantage Chromatography Newsletter
2006, Volume 3
Editorial
Comprehensive 2D Gas Chromatography —
Making GC Separations Work Harder: Guest editor Dr. Phil Marriott tells
us the three primary contributions ascribed to GCGC are greater separation capacity,
greater sensitivity, and a data presentation that permits identification of related
compounds based on the molecular properties that control retention. The most significant
advantage is separation power: to be able to resolve many more compounds immediately
enables a much more complete ‘picture’ of the composition of a sample.
Clinical/Forensics
Fast Screening and Confirmation for
Gamma-Hydroxybutyrate
(GHB): Using Restek Columns in Headspace GC or GC/MS Systems
We adapted Rtx®-BAC1 and Rtx®-BAC2 columns, with their proven performance
in blood alcohol analysis, to a screening procedure for GHB, followed by confirmation
and quantification on a highly inert Rxi™-5ms column. Use of a system and column
already in use for blood alcohol analysis eliminates the need for additional equipment,
reduces system maintenance, and allows rapid and reliable screening, confirmation,
and quantification.
Drugs of Abuse Analytical Reference Materials: These exempted materials include
amphetamine and methamphetamine, barbiturates, benzodiazepines, cannabidiol and
cannabinol, cocaine/cocaine metabolites, methadone/methadone metabolites, opiates/opiate
metabolites, and other drugs, a range of blood alcohol standards from 0.010g/dl
to 0.4g/dl, and a blood alcohol resolution control standard.
Rapid Analysis of Steroid Hormones by GC/MS:
Using the New Rxi™-1ms Column
GC/MS analysis of urinary steroid hormones is a demanding application, and the Rxi™-1ms
column meets the requirements for low bleed and inertness better than any column
we have tested. We analyzed a variety of derivatized steroid sex hormones in less
than 25 minutes, with excellent resolution and symmetric peaks. At 300°C or
above, bleed from the Rxi™-1ms column was negligible.
Environmental
Enhanced Resolution of Endocrine Disrupting Hormones:
Using an Allure™ Biphenyl Column and LC-TOFMS
An Allure™ Biphenyl column provides superior separations of endocrine-disrupting
steroid sex hormones, based on π-π interactions.
The secondary separation power of the Unique® TOFMS system and software allows
column dimensions and run conditions to be optimized to reduce analysis time, while
maintaining qualitative identification.
New Rxi™-1ms Capillary GC Column:
For Low Level GC/MS Analyses
Our new, nonpolar, 100% dimethyl polysiloxane Rxi™-1ms column offers the same
superior inertness, ultra-low bleed, and excellent batch to batch reproducibility
exhibited by our Rxi™-5ms column. We analyzed a complex mixture of semivolatile
analytes, including both acidic and basic compounds, at levels as low as 0.5ng on
column. The selectivity, analyte breakdown, peak symmetry, and bleed results shown
here are strong recommendations for the new column.
Low-Level GC/MS for Semivolatiles in Drinking Water Excellent Responses at 10ng On
Column, Using an Rxi™-5ms Column: Using this new column, resolution
and peak shapes for 88 semivolatile compounds commonly analyzed in drinking water
are exceptionally good at 10ng each on column. Because the Rxi™-5ms column
performs well with analytes in a diverse range of chemical classes, we highly recommend
it for analyzing complex mixtures of semivolatiles.
Fast, Sensitive LC/MS/MS Analysis of Paraquat and Diquat Using an
API 3200™
Mass Spectrometer and an Ultra Quat HPLC Column: Developed through collaboration
with scientists at AB/MDS Sciex, this analysis allows complete resolution of paraquat
and diquat with a simple, isocratic mobile phase. It is significantly faster than
conventional methodologies and, with detection limits of 5ppb for paraquat or 0.1ppb
for diquat, sensitivity is superior — without preconcentration.
Analytical Reference Materials for Semivolatile Pollutants:
Drinking Water: US EPA Method 525.2
Listed reference mixes include organochlorine pesticides, organonitrogen pesticides,
organophosphorus pesticides, PCB congeners, internal standards, surrogates, a performance
check mix, and more.
Reliable Quantification of Brominated Flame Retardants by GC/MS:
New Rxi™-5ms Column Minimizes PBDE Breakdown and Peak Skewing
Exceptionally inert, an Rxi™-5ms column separates thermally labile polybrominated
diphenyl ethers (PBDEs) with minimal on-column breakdown or peak skewing. Of special
interest is the column's superior performance with BDE-209, a widely used PBDE particularly
susceptible to debromination, whose analysis often is characterized by very poor
peak shape and extraneous peaks from breakdown products.
Pharmaceutical
Assaying Local Anesthetics by GC/FID:
Optimizing System Suitability, Using an Rxi™-5ms Column
An Rxi™-5ms column and a wool-packed inlet liner provide the stability and
inertness needed for these basic, active analytes. Chromatography from a six-replicate
system suitability analysis was well within normal acceptance criteria. USP tailing
factors were approximately 1.00 for all analytes; retention times and area responses
were very stable.
Optimized RP-HPLC Analysis of Hydroxybenzoic Acids:
An Ultra Aqueous C18 Column Provides the Best
Retention of Polar and Weakly Polar Compounds
Among hydroxybenzoic acids, hydroxyl groups on the benzene ring vary by position
and number, creating differences in overall polarity and solubility. The unique
bonding chemistry of the Ultra Aqueous C18 phase assures high resolving power, the
best separations across a broad range of analyte polarity, and compatibility with
100% aqueous mobile phases.
Chemical/Petrochemical
GC Analysis of Total Reduced Sulfurs at ppbv Levels Using an Rxi™-1ms Column
and Sulfur Chemiluminescence Detection: Ultra-low bleed and exceptional
inertness assure complete separation of sulfur compounds (hydrogen sulfide, carbonyl
sulfide, dimethyl sulfide, mercaptans) on our new column, with excellent peak shapes
and reliable quantification at ppbv levels. A Sulfinert® treated sampling/transfer
system assures no adsorption losses of these very reactive compounds.
Sulfinert®-Treated Sample Cylinders Store Active Sulfur Compounds at ppb Levels:
Recovery of a 17ppbv test standard of hydrogen sulfide exceeded 85% after 54 hours
in a Sulfinert®-treated cylinder; recoveries of methyl mercaptan, ethyl mercaptan,
carbonyl sulfide, and dimethyl disulfide exceeded 90%. A Sulfinert®-treated
sampling/transfer system can assure accurate sulfur content data for natural gas,
beverage-grade carbon dioxide, or other samples.
How Good is Your PONA Column?:
Data-Based Decisions Help Simplify the Choice
We evaluated our 100 meter x 0.25mm ID x 0.5df PONA column and equivalent columns
from four other vendors, following ASTM D-6730 methodology (hydrogen carrier gas).
Data and chromatograms presented here show that only the Restek PONA column performed
to method specifications admirably. Column efficiency exceeded specification.
Foods, Flavors & Fragrances
Rapid, Reproducible HPLC Analysis for Flavonoids in Cocoa:
Using a Leco Unique® LC-TOFMS System
and an Ultra Aqueous C18 Column
We separated flavonoids in cacao or cocoa powder samples and returned conditions
to the initial mobile phase composition in 15 minutes. For compounds common to both
samples, retention times were equal to within 0.01 seconds. Flavonoid marker compound
profiles for 38%, 49%, and 65% cacao were easily distinguished.
LC Accessories
Kromasil® HPLC Bulk Packing Materials:
Restek — Your One Source for Kromasil® Bulk Packing Materials
Kromasil® HPLC silica products consist of spherical, porous, mechanically strong
particles in sizes from 3.5µm to 16µm or larger. The particles have
large surface areas (330m2/g for 100Å silica) and minimal metal impurities.
We supply these excellent bulk packings in a wide range of particle sizes and bonded
phases.
GC Accessories
Cool Tools:
For Thermo Instruments
Featured here are our new, innovative FID jet removing tool and injector liner cap
removing tool, and our capillary installation gauge for easily and correctly seating
a ferrule onto a column for installation into a TRACE™ or Focus SSL instrument.
Peak Performers:
Injection Port Maintenance with FastPack™ Inlet Kits
Regular injection port maintenance helps ensure the best results from your analyses,
and helps minimize downtime. Each FastPack™ inlet kit includes all the parts
you need to perform routine maintenance — inlet liner (choose from four styles),
O-ring, inlet seal and inlet seal washer, and septum — in a sealed Mylar® bag.
General Interest
Commonly Asked GC Questions: The Restek Chromatography Information Services
Group answers hundreds of questions each month. The answers provided here deal with
inquiries about guard column chemistry, column temperature limits, ghost peaks in
GC/MS analyses, pesticides breakdown on cyano-phase columns, and column cage options.
Recent Publications
These publications are available in printed form or online, as downloadable pdf
files.
Find out more.
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