Why can't power plug configurations be universal?

We have all this excess noise in the lab, mostly from instrumentation, not from chatty n00bie employees. The lab I work in has two icp optical emission spectrometers and one icp mass spectrometer. Each instrument has a chiller and the mass spec also has a big ole vacuum pump. So, to prevent us from having to yell "WHAT" across the lab to one another, the boss had the idea to put the two chillers and the vacuum pump in another little room right next to the lab. That conversation was two months ago.

All we had to do was put some holes in the wall and get some longer power cords for everything. Sounds easy, but of course, it wasn't. The easy thing to do would be to plug the stuff in in the little room. But it all has to be on UPS and the only UPS outlets are in the lab. One chiller has a 110V power cord, not a problem at all, that is the normal plug in your house. The mass spec chiller has a 220V plug and it's from Europe. I never knew there were so many different power cord configurations. The power cord from the vacuum pump is also 220V, European, and different than the chiller cord from Europe.

There's a bunch of phone calls made, some red tape in the way, so we decide to move the mass spec right in front of the hole we made in the wall, so we don't need longer power cords. Genius.

Have a Guinness!

Unheard of ICPMS drift: Rabbit Pump Drift

Fellow mass spectrometerists, check this out. I'm running some calibration standards and all the sudden, from the 100ppb to the 200ppb, internal standard recovery changes from 100% to 80%. Naturally thought it was sample introduction; checked for clogs, changed cones, changed to new nebuliser, still same drift, sometimes after 5 cups. Then it eventually, 5 cups or so, it kind of creeps back up around 100%.

Today, I was looking at the real time display, in deep thought while I watched the 115In and 209Bi signal intertwine bouncing across the 20 in. flat screen when I figured it out. I accessed the accessory window and switched the peristaltic pump into rabbit mode[1]. Sure enough, the signal drops, probably around 80%, but just going off counts per second at the time. Let it equilibrate and switch it back to regular pump speed, 24%. Oh, man, took like 3 or 4 minutes for the counts to get back up to where they were before rabbit pump.

Edited ACL script, no rabbit pump, calibrated fine, loaded samples, got to name a new type of drift: Rabbit Pump Drift.

I also named Seesaw Drift, this is when the low mass internal standards drift up while the high mass internal standards drift down, or the other way around.

[1] This is what the software that runs the ICPMS calls max speed pumping. Good for washing the probe during rinse.

Silver crashes

The other day I took on the rather long task of making a multi-element solution. A multi-element solution is exactly what it sounds like, a solution (a mixture of dissolved stuff), the dissolved stuff being many different elements. This particular solution was to be composed of 27 different metal elements such as chromium, arsenic, and manganese. One way to start making this solution is to dissolve different metallic salts, like As2O3, into a diluted acid (HNO3 or nitric acid) solution. But, I don't have to do that, we buy the metals already dissolved in acidic solutions.



So all I have to do is successfully pipette certain amounts like 10mL, 1mL, or 0.1mL. Then dilute the solution to 1 or 2L in a class A volumetric flask. It's not that hard if you got good lab technique, but you do have 27 chances to accidently add the wrong amount. Anyways, silver is always a little tricky to get into a solution. It always wants to precipitate out. I think it forms AgCl. The Cl anions come from the HCl I add to the solution along with the HNO3 to stabilize the metals. One way to prevent precipitation is to add the HCl last after the silver has already been added and is diluted throughout everything else. But in general, silver can't be put in a multi-element solution above 500ppb. Well for some reason I forgot everything I knew for 30 seconds and messed up the entire solution on the 27th metal, silver. As soon as I pipetted 0.5mL of a 1000ppm silver solution into about 1L of other dissolved metals + acid + water it crashed out into a white haze in the flask and eventually combined into what looks like normal table salt at the bottom of the volumetric flask, but I wouldn't put that salt on my fries.

Backwards chromatography with Mass Spec

I've been trying to run the FIAS analysis for three days now, the column just doesn't seem to be doing its job. I think the problem might be that I have it backwards. I believe the way the flow should be is into the large end and out the small end. This way, the front of the column will bind the most metals, then, when the flow reverses to rinse the metals off the column with dilute acid, the metals will be at the end of the column, so they come off together.

Busy as Hell

Sometimes you're waiting around for the chemistry to happen, but I haven't been. It goes like this, I run the mass spec everyday which includes first, turning it on. Sometimes the plasma flickers, arcs, and starts melting the torch. This pisses me off, and it pisses my boss off because they are over $300 bucks. I still use them if they didn't melt all the way through.

Then, I move on to "optimizing" the "signal." This consists of aspirating a "tuning" solution and looking at a real time graph of "intensity" vs. time. And basically, you just move some voltages around to create high intensity of what you want, while creating low intensity for things you don't want.

Getting mid-way throught the morning now, I need to find some time to review the run from last night and prepare all the data in a type of lab report. The best time to start this is right after I start the calibration. I usually see some drift during the first calibration, so I restart it right about lunch time, so the lab keeps working while I'm off the clock.

Getting back from lunch, I have to quickly check the calibration and find some samples to run because there is no point in even thinking of running any samples until I know the instrument is going to work right. So I type in a sample sequence, make sure the QC is kosher, and then start making dilutions for pretty much everything but freshwater samples.

Now it's about 4pm and I have to finish reviewing yesterdays data, make any solutions that need to be made, and deal with email. Then I just schedule the MS to shutdown when it's done, which is usually between midnight and 3 in the morning.

Copper in seawater

This is the worst analysis ever, it's called Time Transient Resolved Analysis (TTRA) or Flow Injection Analysis of Seawater (FIAS). The methods are the same, they remove the salt from the seawater so I can measure the concentration of copper. The problem is the flow, there are two pumps, two valves, four lines, a 5mL loop, column, and six way valve, and the flow has got to be steady. A simple calculation reveals 7 to the 10th ways for it to screw up.

I have to use a bunch of para-film to keep the tube joints together because the pump builds up so much pressure in the peri pump tube to push everything throught the column.

The sample flows through a tube, mixes with a buffer (the whole shabang is pH sensitive), and flows onto the column. The metals, including copper and sodium, stick to the resin in the column. The column is rinsed with water, supposedly, the sodium washes off. Then the column is rinsed with diluted nitric acid and the copper comes off and goes into the spectrometer. The metals binding strength to the iminodiacetate resin in the column depends on pH.

Message board

My original idea was to create a message board where mass spec researchers and analysts could discuss trouble shooting. I suggested it to the company which makes the mass spec I work with, but I havn't recieved any reply and didn't really expect it.

So, I'm taking it upon myself. I am currently an environmental chemist using mass spectrometry to analyze water and sediment samples for metals. The mass spec I use uses a quadrupole to filter the ions and it also has a type of collision cell that all the companies are putting out now. The collision cell is supposed to reduce interferents by colliding the interferents with other gas molecules supplied into the collision cell. It also has kinetic energy discrimination which uses some various lens voltages within the collision cell to limit the range of kinetic energies in the ion beam coming out of the collision cell.

I've got everything working pretty well after battling for 6 to 8 months. But I still have some elusive problems which is why I'm creating this blog, or message board.

Anybody analyze Arsenic in salt water with a collision cell? I can't get rid of some interferent at mass 75 which gives me a constant result of 6 - 10ppb in salt water samples that are confirmed having less arsenic by a optical method (ICP emission.) I can discuss a lot more if anybody else knows anything about this.