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Sensitive GC/MS Analysis for Drugs of Abuse
Rxi™-Sms Column Resolves Acidic/Neutral or Basic Drugs
ByKristi Sellers, Clinical/ Forensic Innovations Chemist
• New stationa ry phase, inert to acidic or basic drugs.
• Unique deact ivation for low column bleed at 330°C. new column technology!
• Column technology specially developed for GC/MS.
GC/MS is considered th e standard for confirm ing the presence of abused drugs in body fluids, including acidic dru gs (e.g.,
methaqualone), neutral dru gs (e.g., phenoba rbital), and basic dru gs (e.g., methamp hetamine). These methods are well established,
and the positive identifications mass spectral data generate are accepted as confirming evidence in courts of law. The accepted sta­
tionary phase for these analyses is a 5% phenyl / 95% methyl polysiloxane phase, because it provides the best selectivity for separat­
ing the dru gs and their metabolites. Unfortunately, not all 5% phenyl columns provide the inertness needed to accurately quanti fy
low concentra tions of reactive acidic or basic drugs.
Now, Restek's R&D chemists have developed a new 5% ph enyl stationary phase and a uniq ue column deactivatio n techn ology specif­
ically for GC/MS. The produ ct of this combination - the RxiTM-5ms column - ensures enh anced inertness for acidic or basic com­
pounds, while maint aining the selectivity of a conventional 5% ph enyl column.
Using mixtures of acidic/neu tral drugs and basic drugs in their free base form, at an on-column concentra tion of SOng for each dru g,
we evaluated a 30m, 0.25mm ID, Rxi™-5ms column for resolution, inertness, and bleed. Figure 1 shows chromatography for
acidic/n eut ral drugs and Figure 2 shows basic drugs. In either analysis, all compounds are resolved to baseline and exhibit Gaussian
peak shapes. Furthermore, there is no interference from column bleed - not even at 330°C. Note that a Siltekv treated inlet liner con­
tribu tes to these results: our uni que Silteks' surface passivation process assures the liner will have the inertness needed for accurate
low-level analyses of reactive acids or bases.
In combination, an Rxi™-5ms column and a Siltek®treated inlet liner represent a complete solution for analyzing acidic, neutral,
and basic drugs by GC/MS. For additional dime nsions of Rxi™-5ms columns, and for Siltek® treated inlet liners for your chro­
matograph , please refer to the 2006 Restek catalog - or visit our website.
Rxi" Columns, Ultimate High Performance Capillary GC Columns
Rxi" columnswere created at Restek's cutting-edge researchfacility, RestekWest, inCalifornia. Our
senior polymer chemists developed new columntechnology, based onour Crossbond" chemistry, to
create this new column line.The columns weproduce as a resultoftheir work exhibit exceptional
inertness and unsurpassed reproducibility, from columnto column and lot to lot.Acidic or basic com­
pounds chromatograph beautifully, at sub-nanogramon-column levels,with nopeak tailing. Ultra-low
bleed assurescompatibilitywith sensitivedetectors or intrace-level GC tuned this
uniquechemistry until polymer selectivity was locked in, to allowinstall-and-runuse of Rxi" columns
with retentiontime-lockingsoftware.
What makes RxiN columns differentfromothercolumns?
First, andforemost, unique deactivationand our modified Crossbond" chemistry create columns with
superior performance.The rawmaterialsweuse inthemanufacturing process - bothtubing and
chemicals- are strictly controlled. Cleanliness andprecisionarecriticalto every step intheprocess.
In addition,we looked in-depth at al other aspects ofthecolumnmanufacturingprocess, to establish
a highly reproducible process. In bothperformance and column-to-column consistency, Rxi" columns
are surpassed by noother columns.
="'ii~I","=~ developing Rxi" columns, our first step was to 1V0rk withour fusedsilica tubing supplier to establish rigorous controls on internal diameter,outer diameter, ovality, and In
surface activity.Thesecontrols guarantee our tubing is a knownstarting point.Then, we treat this highly uniformtubing with ourunique deactivation chemistry,
producing a consistent, inert surface onwhichto apply the polymer.
Next, wereformulated our polymers, takingstepsto ensure neutrality and to finetune selectivity for retentiontime locking. Aneutral polymer and
a neutral tubing surface are important contributorstowardexcellent peakshapefor both acidic and basic compounds.
To complement theseefforts, wedeveloped a new column manufacturing process that creates a very reproducible product. This is critical,
because ourcustomers' workdays aresimplifiedwhenevery newcolumnthey purchase performs exactly asits predecessor.
Overall, the results of theseefforts are columns that define unsurpassed inertness, ultra lowbleed,and totally reliable
column-to-columnperformance.
Guaranteed Quality and Reliability
Restek is committedto supplying themost reliable GCcolumnsintheindustry. Every Rxi" column is individually challenged
to pass our stringentrequirements for filmthickness, coating efficiency, selectivity, inertness, and believe Rxi"
columntechnology produces themost reliablecolumns available,anywhere, andwepromise that every Rxi" column you
receivewill be exactly asgoodasthe one it replaces.
RestekWest
Shawn Reese, Gianna Barlupi, Roy Lautamo
Website : E-mail : TelNo : 03 9762 2034 . . . in AUSTRALIA