New IR Makes Sample Prep a Cinch

Say goodbye to the elusive art of KBr pellet making and messy NaCl plates (along with the variability they introduce) with the department’s new FT-IR spectrometer and ATR accessory.  The PerkinElmer Spectrum Two is the gold standard for rapid IR measurements and the ATR zinc selenide crystal is perfect for generation of an evanescent wave that penetrates any sample (pH range 5-9). 

Apply just enough pressure on the clamp to ensure a 1 micrometer intimacy and you’re on your way to spectral heaven.  There’s even a nifty preview feature in the software which allows you to optimize contact before scanning to prevent scratching.  An installed humidity sensor detects the best time to change desiccants, perfect for the rainy seasons we’ve been having (a.k.a. optics killers).   Still curious about how this incredible technology works?  The vid below depicts the S2 in action. (Click here to learn more about IR spectroscopy with correlation table.)

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Supercharged GC/MS

Recently, an overhaul was conducted on our Shimadzu GC/MS.  Both source and trap filaments were replaced inside the ion source box, the heart of the system.  This is where your sample gets zapped by an electron beam turning it into fragments.  The two filaments (doohickeys that produce the beam) were barely alive and have since been put out of their misery.  Additionally, the ion source box was scrubbed from top to bottom, ridding it of extraneous ions produced from the blasts.

A helium purifier has also been replaced which scrubs our carrier gas.  This provides a smoother baseline when injecting into the GC port.

Bottom line – the unit is fully optimized for its nanogram range detection limit.  Here are some tips to keep it that way:

1) Begin with 1uL of sample for GC or a “spec” of solid for direct insertion.  More than that may contaminate the system for the next person.

2) Remember to set the detector no greater than 1.10 kV.  It’s an electron multiplier that won’t give you better data if you ramp it up.  You’ll only be shortening its life.

3) Any questions contact Joe at the info provided on the instrument.  He will be more than happy to assist.

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HPLC 101

This Royal Society of Chemistry vid is the best I’ve seen to describe chromatographic principles within the context of HPLC.  According to the standard handbook, the money currently spent annually on HPLC exceeds that of any other analytical technique.

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How To Cut A GC Column

3 primary trouble shooting steps to eliminate residual contamination in a GC are changing inlet liners, replacing rubber septa, and cutting a few inches of the front of the column near the injection port.  This last step will remove the part of the column that gets battered with high temperature adhering compounds.  Tailing may also result as integrity in this area of the column is lost.  Watch this great vid by the Agilent guys that details the technique (at 3:00) .  It takes a bit of practice to get it right, so be sure to look at the end carefully to make sure it’s a clean slice.  Jagged edges will cause leaks.

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3 Quicktips For Reviving A Dormant LC

Software was recently attained and installed on an Agilent 1200 Series LC after being down for quite some time, although this didn’t solve the problem entirely.  If you encounter the same, here is everything you need to know about how to get the hardware working 

1) Flush with IPA

Isopropyl alcohol with water is the perfect solvent to wash away both polar and non-polar contaminants that have accumulated in the lines.  It is also viscous enough to get into all the cracks and crevices where air bubbles are hiding.  Prep a 50:50 mixture, replace the column with a union, and run all the lines together at 0.5 mL/min.

2) Prime

There may be enough air in the system to render the pump useless.  To attain suction, manually pull through 20 mL of your IPA/water mixture on each of your 4 lines.  Simply remove the outgoing fitting from the degasser, press firmly using a plastic syringe to create an air tight seal, turn on the pump and withdraw the syringe plunger.  Repeat the final step.  It will soon flow like a river.

3) Go to Step 1

Assuming the lamp still has life on it, the pump is the heart of the instrument and should render it functional once cleared of air and contaminants.  After sufficient washing with your IPA mixture (when the pressure stabilizes you’ll know all the air is out), check your flow rate at the waste bottle using a small graduated cylinder and stop watch.  Once validated you’re good to go.

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Fluorimetry Problems Quenched By Software Upgrade

The latest version of FL WinLab has been installed to run our Perkin Elmer LS 50B Fluorescence Spectrometer.  Features include a more easily navigable menu (shortcut icons galore!) to allow one to check electronic hardware connections, quickly set parameters, scan, and immediately port data to excel.  A newer operating system has also been put in place for quicker access to files, along with the ability to take them on the go using a flashdrive.  An ethernet jack has been activated behind the instrument so you can brag to all your friends in real time (thereby upping your street cred) about your emission spectra.  Access the manual for FL WinLab here.

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What exactly is a quadrupole MS anyway?

Many mass spectrometers (like our Shimadzu 5050A) operate by shooting an electron stream at a sample causing the molecules to fragment.  The ions formed have a +1 charge because of the electron lost by the broken bond.  Masses of interest are guided through a quadrupole, four rods that create oscillating electric fields: a filter that permits only certain ions to get to the detector.  The rest bounce off the trajectory path to be sucked up by a turbo pump (reminiscent of the sarlacc scene in ROTJ).  The result is a mass spectra depicted by a clean mass to charge ratio (m/z).  Here is a great video created by NASA that illustrates this process:

Compounds that come off the column on the left are zapped on the right by the quadrupole MS


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