Suggestions For An Approach Or Methodology To Chromatography?

[Susan3141]

Thank you so much for this post and to all the contributors. I am fascinated by chromatography, and this is such a helpful discussion.

[bunnspecial]

Thanks.

 

I saw those listed on Amazon.com, when I was looking hard at this in the past few weeks, but Amazon itself doesn't sell them, and those third-party sellers on Amazon Marketplace won't ship the products to Australia (never mind that it probably wouldn't be economical to do so even if they would ship them). They aren't listed on Amazon.com.au and eBay, as far as I can see, and I'm probably just not keen enough to look at local suppliers whose primary clientele are professional laboratories and who charge accordingly. Trying to get clear ammonia solution (to dilute) for pen cleaning was difficult enough, as it isn't something I can just get from the supermarket or the local pharmacist; I ended up travelling way out and buying a large bottle (it had to be either 5L or 20L) from an industrial supplier that sells to dry cleaning businesses, probably at fivefold the per-unit-volume cost Americans expect to pay buying from Walmart, and if I tried to source it from lab supplies retailers it'd be fivefold that yet again. So, I'll just make do with what I can get on eBay relatively easily, in the name of hobbyist pursuit as a rank amateur; the more money I have to sink into the project, the less likely I'll want to share any information coming out of it.

Totally understandable on that.

 

I spent quite a bit of time in the stockroom at my last university(and since my current one doesn't have a stockroom manager now, I'll most likely be spending more time there, but that's another story). In any case, at the last place, there were two or three boxes of the stuff. It was one of those things that I'd get a request for once every year or two, and it was rarely more than a few pieces at a time. The folks who wanted it often were working with younger students to do paper chromatography, but found that for their purposes the much less expensive filter paper or even coffee filters worked just as well.

 

Unfortunately, the "retail" prices from the big chemical suppliers are often eye-popping. Schools rarely pay list price just by virtue of our contracts with them and also that they know we're going to cross-shop different vendors(and often my preferred supplier-Fisher-would price-match or even beat other vendors when they could just because their sales from us were low) but as individuals we don't have that luxury. BTW, another fun tip-but one that took more leg work-was if possible going direct to the manufacturer rather than buying through a vendor, but that's increasingly become less of an option as the "big three" in the US(Millipore-Sigma, VWR, and Fisher) keep gobbling up the smaller makers of specialty products. That's a side note, though.

 

Also, as another side note, if you do buy ammonia from a chemical supplier, check the concentration of it. Household ammonia is usually around 5%, give or take a bit. Chemical suppliers often supply a concentrated solution, which is 18M, or around 37%. Aside from the fact that it will knock you silly if you open a bottle without enough ventilation, it's fairly corrosive and not exactly the kindest thing to handle. You can certainly use it if you dilute it first, but do so outside unless you have a fume hood.

[A Smug Dill]

Aside from the fact that it will knock you silly if you open a bottle without enough ventilation, it's fairly corrosive and not exactly the kindest thing to handle. You can certainly use it if you dilute it first, but do so outside unless you have a fume hood.

Thank you for the advice.

 

The commercial grade ammonia solution used in dry-cleaning is nominally 25%, but I was given to understand that there may be up to a whopping 5% (!) variation. When I transferred about 1L of it into a smaller bottle, the fumes made my eyes water and choked me something bad.  Silly me, I did that inside a bathroom with no windows, on account of having access to a tap and basin that can be easily washed clean in case there was spillage, and also to contain the expected smell so as not to disturb my wife.

 

I certainly won't be doing that again! There is no 'outside' in this apartment, and even the balcony is enclosed by floor-to-ceiling glass windows (that will only open outwards in a limited way, now even more limited than ever after limiters have been retrofitted a couple of years ago in compliance with building safety regulations), but I'll do it in the kitchen where there's a large sliding window right by the sink, and keep all the other windows in my apartment open.

[A Smug Dill]

The format on which I've more or less decided is to use pages of polypropylene pockets for 2ʺ×2ʺ slides, with 20 pockets in five rows on a page,

 

Grrrr, bloody Amerecalcitrant users of imperial measurement units! The 100-pack of "Print File^® 35mm Slide Pages Holds Twenty 2x2" Mounted Transparencies" I ordered, sold and shipped by Amazon US, was delivered to my door by DHL service today.

 

I choose the product partly on account of it being made in the US; I also ordered some Ultra PRO^® clear polypropylene display pages (with pockets of a different size) for the same reason, over something made in China, thinking that it can get at least that much right and do a better job of it.

 

Two inches is 50.8mm in SI units which the vast majority in the world today uses.

 

A piece of 220gsm 'mixed media artist paper', which would certainly not be thicker than a stiff mount for a 35mm transparency slide, that I've cut to 50.8mm wide would not fit inside the pockets. 50.0mm, yes, with a hint of strain, on the presumably strong welds between the two sheets of polypropylene that make up a page of pockets that were designed to withstand it. 50.8mm? No.

 

I wish I have an old Kodak "2-inch" slide on hand to check whether it's the terminology that is loose (i.e. it doesn't mean 50.8mm-wide), or that the product is just defective in that it doesn't meet the specifications. As much as many average citizens seem to like to pile the hate on Amazon, I'm sure the behemoth retailer would just fully refund my order, and tell me not to bother to ship the product back at its expense, in the name of good customer service if I can show that an all-American Kodak 2-inch slide wouldn't fit neatly into the pockets on the specific product. Amazon US is one of the things I actually like about America.

 

Yes, (fortunately) I can just trim my "swatch cards" to be slightly narrower to fit the product that I have received. But that's bloody annoying, when I expect the pockets to fit 50.8mm-wide objects, even if it gives no more leeway than that exact measure. I don't require plus-or-minus N% tolerance; just accommodating exactly what "2 inches" mean in SI units without undue strain on the material and/or welds will do.

[LizEF]

I'd bet someone on here has those slides and a set of calipers and can do an exact measurement for you - though you may need to post the request in Chatter or a photography-related board. As I recall, 35mm slides aren't square - but it's been a long time and my memory could be off. Certainly the negatives aren't.

[bunnspecial]

I also still dabble in photography(including film) and shoot a fair bit of transparency(slide) film.

 

I buy those printfile pages you're talking about in packs of 100(along with ones to hold 35mm strips, 120 strips, and 4x5 sheets-Printfile is the go-to brand for this kind of stuff).

 

The standard for 35mm still "full frame" images is 24x36mm. With that said, a standard slide mount is 2"x2". The cut-out in the mount is actually a bit smaller than 24x36(some older "semi pro" cameras like the Nikon FM/FM2 have viewfinders that only show ~92% of the exposed film area, and some photographers prefer that because it's more representative of what will be seen in a mounted slide) Square slides are desirable because, when projecting, it's easy to flip so that you project in the desired orientation(horizontal vs. vertical).

 

These sizes have to be pretty darn close, too, as the gates on projectors are tight. There are basically two makers of slide mounts now. Gepe makes plastic ones that snap together to hold the film in place and also the uncommon glass, while a different company(not sure who) makes thin cardboard mounts with a heat-activated adhesive-the film chip is closed in the mount, and a purpose-made iron cements it together.

 

I don't actually have a Printfile page in front of me, but the 35mm slide pages have slots that are a bit wider than 2". The reason for this is that slides have a decent amount of thickness(maybe 1mm or so) and the extra width is needed so they actually fit.

 

Obviously, though, they didn't fit, so I'm not sure.

 

One other potential source is a numismatic(coin collecting) supplier. Many times, coins are stored in 2x2 cardboard or plastic "fiips" and binder pages are available to hold these. Since a silver dollar in a flip, or alternatively any of the snap-together plastic holders, can be fairly thick, these can be a bit roomier than slide pages. I don't like them for slides since the plastic can stick to the film(Printfile pages are considered archival plastic, and shouldn't ever stick) but they might serve your purposes well.

[A Smug Dill]

I don't actually have a Printfile page in front of me, but the 35mm slide pages have slots that are a bit wider than 2". The reason for this is that slides have a decent amount of thickness(maybe 1mm or so) and the extra width is needed so they actually fit.

 

Obviously, though, they didn't fit, so I'm not sure.

 

 

Exactly why I was unpleasantly surprised. I'd have thought that pockets to fit 2"×2" would have to be at least 52mm wide, unless 2"×2" is just a shorthand for an industry standard size that does not mean literally 50.8mm×50.8mm two-dimensionally but something narrower than that. Amazon is prepared to send me a prepaid return label, but I still need to find something that works. Ultra PRO is the other brand that I'm looking at, but even though they do make 2"×2" slide 20-pocket pages (as well as many other-sized pocket pages), that's the only variant of that brand I can't find on Amazon it seems. For roughly the same price, I'd prefer to make a acid-free, UV-blocking, certified-this-and-that product made in the US as opposed to some random or no-name Chinese product, on the assumption that it would be better quality — but that means nothing if the American product isn't how it is specified on paper.

[bunnspecial]

Next time I can(will probably be a week or two) I will measure some slides and report what I find.

 

Gepe glassless mounts come in a couple of different types, and range from 1.8 to 2mm thick. I tried to pull up their spec sheet to see if 2"x2" was a nominal size or an "exact" size, and if nominal what the exact size was, but couldn't find anything.

 

My first projector was an old Agfa where you had to painstakingly load every single slide into a metal carrier. I remember those had some "wiggle room" in the carriers, but I was never sure if that was to allow you to tweak the position or to allow for slides larger than normal.

 

Similarly, if you look at a Carousel-type projector(the single most common design in the US) there's a bit of side-to-side room in the trays and also everything in the mechanism that touches slides could handle something larger than the slide mounts I get back from the lab now(and have for the last 15 years I've been shooting slides). Still, though, I suspect as much as anything that the mechanism is intentionally "sloppy" because it relies on slides dropping into the gate by gravity, and also needs to be able to quickly and efficiently pop them back out into the tray so that you can advance to the next slide. My Nikon scanner doesn't allow much side-to-side wiggle when you put a slide in it, but I also don't know if it has springs or other things to account for different sizes.

 

One thing worth a side note, too, is that back in the day there were things called "Super Slides." They used 127 film(46mm wide) shot in a 4cmx4cm format, which was once common for both Kodak Brownie type cameras also also some advanced amateur or even pro and the like(there was even a Hasselblad magazine that took 127 film). At 4x4cm, they could fit into a 2x2" slide mount and be projected in a standard 35mm projector while giving much larger images than a 35mm slide(projectors for 120 format-6x6cm or 6x7cm-are big, bulky, and usually not standardized the way 35mm are). I have some Super Slides my great grandmother took, and I think the mounts are a bit larger than those used for 35mm film. If I remember correctly, I ended up not filing them as they were reluctant to fit in file pages.

[A Smug Dill]

Next time I can(will probably be a week or two) I will measure some slides and report what I find.

Thank you very much in advance.

 

Gepe glassless mounts come in a couple of different types, and range from 1.8 to 2mm thick. I tried to pull up their spec sheet to see if 2"x2" was a nominal size or an "exact" size, and if nominal what the exact size was, but couldn't find anything.

I'd have thought that pockets to fit 2"×2" would have to be at least 52mm wide, unless 2"×2" is just a shorthand for an industry standard size that does not mean literally 50.8mm×50.8mm two-dimensionally but something narrower than that.

I got around to digging out my digital callipers, and made several attempts at more precise cutting, until I got one that's exactly 50.8mm (which, according to the callipers when I switched to inches as the measurement unit, 1.9995in). The 210gsm card stock is 0.3mm in thickness; and, yes, one card would fit inside the pocket. A stack of two such cards was a little bit of a struggle, and a stack of three (0.89mm in total thickness) cause noticeable strain in the polypropylene sheet against the linear welds.

[LizEF]

On 8/23/2020 at 11:28 PM, A Smug Dill said:

I call it Koala is mad that its head got transplanted onto a penguin.

Hooray, it's back!   I have to say, I like this avatar.

[A Smug Dill]

9 minutes ago, LizEF said:

Hooray, it's back!   I have to say, I like this avatar.

 

Haha, I was just testing whether changing the profile photo would trigger a notification to those who are following me, as part of some research I'm doing. Glad you like it!

[mizgeorge]

She's not alone - I'm very keen on this one too