Archive for the ‘Miscellaneous’ Category

Great Internal Standards for Pesticide Residues…SRMs too!

  In just about all of my pesticide residue work, I use a convenient multicomponent internal standard mix that contains several PCBs as well as popular internal standard compound triphenylphosphate. The mix contains the six compounds in the chromatogram below. I have been working on a method for our GC Multiresidue Pesticides Kit which has […]

Electronic Cigarettes Part VI: Vapor Analysis – Have we made our point? (hint: look for the bold)

In the last electronic cigarette blog we revealed that e-cig vapor has many more constituents than the propylene glycol, glycerin, nicotine, and flavorings on the manufacturer’s solution list. In fact, we found 82 compounds [i.e., unidentified and identified (some only tentatively)] in the vapor of one e-cigarette vendor. Now if you recall from e-cig blog […]

Swagelok® and Parker® Tube Fitting Manuals

When asked by customers for what I consider the best reference guides on Swagelok® and Parker® fittings, I send them the following links.  I thought our blog readers may also benefit from these links, so here they are (below).  I hope you find them useful. Swagelok® Tube Fitter’s Manual Parker® Instrument Tube Fitting Installation Manual […]

Electronic Cigarettes Part V: Vapor Analysis – Yes… we found formaldehyde too!

It has been over 3 months since the last electronic cigarette blog. I will spare you the excuses. However, I can proudly say that we will be releasing a full application note on electronic cigarettes in the very near future (i.e., 1 to 2 months hopefully). In the meantime I feel obliged to respond to […]

QuEChERS – Where to start?

Enjoy the tip!* I am often asked for QuEChERS product recommendations. Usually the request is something like, “I need to test pesticides in _____” and that blank can be just about anything…sometimes not even food. Unless it is something I have tested before, I usually take a quick look online to determine the approximate composition […]

Determination of Chloropropanols in Soy Sauce: Part 1, Enter The Matrix

A while back I was doing some reading and came across an application of GC-MS in food safety that caught my attention. The analysis of food products, specifically soy sauce, for contamination with chloropropanols. So how do chlorinated alcohols end up in food? During the production of a food ingredient known as  hydrolyzed vegetable protein (HVP) various vegetable protein feedstocks […]

HPLC columns for the European Pharmacopoeia methods

European Pharmacopoeia (EU) methods tend to be vague in their description for column requirements, which can make choosing the correct column a little tricky.   To simply things, I listed the Restek HPLC columns that best match the columns (phases) listed in the European Pharmacopoeia “Reagents” chapter. Hopefully this makes it a little easier to […]

How Dirty Are You? Part 4…Manual Syringe Rinsing…The Answer

So how many times do you need to rinse a syringe? Well, I can tell you the answer for the experiment we did. Let me first refresh your memory on specifically what we did. Sequence of manual syringe rinsing: 1. 20 µL draw of a 500 ppm hydrocarbon standard and expel it 2. 20 µL […]

How Dirty Are You? Part 4…Manual Syringe Rinsing…The Question

This How Dirty Are You? blog should really be credited with inspiring the entire project. I was discussing the number of times I rinse my syringes with a colleague, Michelle Misselwitz, a few years ago. We were working in the same hood and I noticed that she rinsed her syringe a lot…I do too. I […]

Lab Hack: Quickly Reducing GC Inlet Pressure on an Agilent GC Prior to Changing the Septum and/or Inlet Liner

Have you ever been changing your Agilent GC inlet liner (you do change that routinely, right?), particularly a single taper with wool type, and pulled it out to see the wool at the top of the liner (Figure 1) when it should be at the bottom of the liner (Figure 2), the proper placement where […]