I am writing up a "wish list" for my inorganic chemistry lab. I seek advice. Johnson-Matthey has the magnetic susceptibility balance (MSB) that seems like "the standard" for educational lab. Can anyone advise on getting the "Mark I" vs. the "Auto MSB?" Also, do you know the approximate prices for each of these two instruments?
The relevant URL is: http://pureguard.net/Library/data_sheets/MSB_Brochure.pdf
I have the Johnson Matthey Mark I Balance for my teaching lab. I have students make different paramagnetic metal acac complexes, Cr(acac)3, Mn(acac)3, Fe(acac)3, and Cu(acac)2, and they determine the magnetic susceptibilities using both the Johnson Matthey balance and by the Evans NMR method. Both methods work well on these complexes. I don't have any real complaints about this balance except for the expense of the replacement tubes. And every year, I seem to lose one or two tubes. I am not sure if the "extra" features on the Auto MSB balance would be worth it. Probably depends on what you intend to do with the balance.
In reply to Mark I Balance by Maggie Geselbracht / Reed College
I also have the Johnson Matthey Mark I Balance. I'm not sure if it is appropriate to list the cost in this forum, so I'll write that in 2007 the Mark I was halfway to five digits in USD. E-mail me if you want a more detailed price.
Maggie is correct that the fragile tubes are the only consumable expense. Anticipate that a couple tubes will be lost or broken per year (~$25/ea). I don't know much about the Auto MSB, so I can't provide any additional information.
I have the AUTO balance in my lab, which was used this semester for the same experiments that Maggie describes. In my experience, both work equally well. I haven't tried to use all the features, but the main differences (that the AUTO continually auto-zeroes and corrects for the empty tube reading in the sample measurement) haven't been that useful. I don't know about price differences of the models, but I wouldn't pay much extra for the AUTO for these extra features.
I have a similar balance and will need to buy some replacement tubes.
Sibrina Collins, PhD College of Wooster
Are you purchasing the tubes from Alfa Aesar? These tubes are expensive!
Sibrina Collins, PhD College of Wooster
I had our machine shop build a new sleeve for our Johnson-Matthey MSB (vintage ~1989) that has an opening large enough for a 5 mm NMR tube. These are much cheaper than the "official" tubes, specially if you are cutting down a tube whose tip has been broken by a clumsy student or professor. Although you need more sample than the narrower diameter tubes that come with the balance, this is not normally a problem for labs such as the synthesis of M(acac)3.
I am preparing to teach Inorganic Chemistry Lab for the first time ever on our campus. Not only do I have to set up the lab equipment but I also need to figure out which experiments to perform. I was planning on doing an experiment with wthe evans method and magnetic susceptibility. Can you provide details on the acac experiment that you mention. I would greatly appreciate it.
I've used the M(acac)3 synthesis at both the general chem and inorganic levels. It's included (as #12) in Girolami, Rauchfuss, Angelici's book of inorganic chemistry lab experiments. I'd be happy to email you our local version. We've had good luck with a number of different metals. The results are very colorful, and it's been a popular lab.
This past fall, two of my inorganic students made some M(acac)3 complexes and had good luck with the Evans method. (Sealing the tiny capillary tubes to go inside the NMR tubes was probably the best part.) Adam Johnson's LO was very helpful in learning how to approach our data analysis. In the past, we've had our students grow single crystals for XRD analysis. If you have that option, HIlary Eppley's LO about crystal growing techniques is very useful.
We also have a new type of learning object on the site - the syllabus LO. You can check out my inorganic lab course here.
Feel free to shoot me an email with any questions, or post them here. Inorganic lab has become one of my favorite courses.
PS I think I have successfully embedded all sorts of links into this message. Here's hoping they work.
I've used the MSB-1 as well, to determine the percent paramagnetism in the copper(II) acetate dimer. My frustration is in loading the sample into the tube, and getting it out again, drying the tube for the next use. Tubes are expensive, and hard to work with. Otherwise, the MSB-1 has worked well, reliable and holds calibration. It was about $20K a few years back.
I would appreciate if someone can give me a link to companies that have Johnson Matthey Mark I MSB?
I seem to find nothing authentic except a link from Alfa Aesar in the US.
I found a lot of PDFs but the phone number do not work or no one picks up.
I purchased a Sherwood Scientific Magnetic Susceptibility balance in 2018 from Alfa Aesar, through Thermo Fisher Scientific. Information below. I don't know if it's still valid.
Thermo Fisher Scientific
DBA Alfa Aesar edu
2 Radcliff Road
Tewksbury MA 01876