Ink Analysis by HPLC

[bunnspecial]

Out of curiosity, has anyone ever looked at ink by HPLC? It seems an obvious one, but I don't recall seeing discussion of it.

 

After moving to a new employer, I have finally, as of this morning, worked a bit of a deal to get one. It's an older unit, an HP1050, but I have a long history with this particular one(I learned how to run this one specifically, and a lot about HPLC in general, when it was donated to my undergraduate college). I'll have a bit of work to do to get it up and going, and I'm shopping now for a diode array detector to use with it(they are surprisingly inexpensive on Ebay at least as these things go. Hewlett Packard I know was big in stand-alone Diode Arrays, but I don't know how the 1050 unit is as far as sensitivity/reliability).

 

If anyone has done HPLC, can you advice on a column choice and method? Since obviously everything in inks is water soluble, I'm thinking a 70:30 methanol:water isocratic method might be in the ballpark of good separation, but I'm just guessing and obviously could/would tweak. Assuming I just have a VWD, what wavelength would be ideal? I'd think something in the visible range-say 500nm-would work. With that said, a lot of absorbance spectra for dyes I've looked at seem to at least have decent absorbance in the ~290nm range, and that would seem to get dyes plus other non-dye components.

 

For the time being, I'm going to be limited to the columns I can scrounge up, which will probably mean a 15-25cm 4.6mm C8 or C18 column. Any particular reason why that wouldn't work, or why I should maybe look for something else?

[sansenri]

sounds extreme, but interesting, would it tell us what dyes are used?

[bunnspecial]

1 hour ago, sansenri said:

sounds extreme, but interesting, would it tell us what dyes are used?

 

Not with 100% certainty, but with a diode detector it could give some information to characterize them.

 

Retention time alone(how long it takes to travel through the system in a given set of conditions-the whole separation principle is that different compounds have different attractions to the solvent vs. the column) can provide some information about if two inks have the same dyes, although not with 100% certainty. Adding the full absorbance spectrum gives an additional data point and also lets us indirectly ID the color.

 

Adding a mass spectrometer would give fairly certain identification assuming the dyes were amenable to ionization, but that's a large step up in both cost and complexity. I don't think the 1050 I have will readily interface to one(although I'd have to double check-the last LC-MS was a Finnigan, and its software could control HPLCs from several manufacturers even though I was using a Finngan HPLC with it).

 

As a maybe interesting side note, I spoke over Zoom this afternoon for about an hour with a gentleman who held the title of "Ink Chemist" at Newell-Rubbermade/Parker and was the developer of Penman inks. He shared a lot of information with me, but one thing he mentioned was analyzing warranty claim pens to see if they were used with Parker brand ink or not. He said it wasn't often done, but would come up(as I understood it) if they saw a failure they saw a particular bad failure or one they had never encountered before, and if it was determined to have been caused by ink they would see if it was Parker ink or a different brand. At the time he was there, this was done by an outside lab by GC-MS.

[LizEF]

30 minutes ago, bunnspecial said:

he mentioned was analyzing warranty claim pens to see if they were used with Parker brand ink or not. He said it wasn't often done, but would come up(as I understood it) if they saw a failure they saw a particular bad failure or one they had never encountered before, and if it was determined to have been caused by ink they would see if it was Parker ink or a different brand. At the time he was there, this was done by an outside lab by GC-MS.

I'm thinking except for the most expensive pens, the cost of the analysis was more than the cost of replacing the pen!  (Though perhaps not more than repairing the pen, depending on how difficult / time-consuming the repair.)

[A Smug Dill]

2 hours ago, bunnspecial said:

He said it wasn't often done, but would come up(as I understood it) if they saw a failure they saw a particular bad failure or one they had never encountered before, and if it was determined to have been caused by ink they would see if it was Parker ink or a different brand.

 

Ah, that sounds like Problem Management to me. Feels like home!

 

1 hour ago, LizEF said:

I'm thinking except for the most expensive pens, the cost of the analysis was more than the cost of replacing the pen!

 

Quite possibly. The objective, though, would be to nip (nib?) a highly damaging and potentially widespread problem that could affect many other units of the same type, or similar models that have the same vulnerability, when the organisation cannot contain factors outside of its control (and/or product set), but still needed to formulate a response plan in some or all of these ways: seeking or strengthening legal protection for the organisation, minimising liability, implementing change of policies and/or defensive product enhancements, issuing warnings to deter (concurrent) exposure to all of the minimum set of interacting substances and/or events that trigger the problem, etc.

 

It's always a pain for the Problem Management function to try to justify the cost when all the preventable damage and loss haven't yet happened…

 

[LizEF]

1 hour ago, A Smug Dill said:

The objective, though, would be to nip (nib?) a highly damaging and potentially widespread problem that could affect many other units of the same type, or similar models that have the same vulnerability, when the organisation cannot contain factors outside of its control (and/or product set), but still needed to formulate a response plan in some or all of these ways: seeking or strengthening legal protection of the organisation, minimising liability, implementing change of policies and/or defensive product enhancements, issuing warnings to deter (concurrent) exposure to all of the minimum set of interacting substances and/or events that trigger the problem, etc.

Ah, excellent points!  I hadn't looked at it from that end.  I was just thinking about the lab I worked in and how expensive some of the tests are!  But of course you're right, running just one of those tests could provide information that saves a lot of money in the long run.

[bunnspecial]

Again I'm paraphrasing form part of an hour long confirmation and something that was mentioned at least somewhat in passing.

 

There again, though, my understanding was that if a pen returned for warranty failed in some particularly unusual or previously unseen way, it was beneficial to thoroughly analyze how it failed, try to determine why it failed, and if necessary modify it to prevent that failure in the future. His statement was that it was part of the overall examination, but that it was something found more than once in a failure.

 

I actually picked up quite a few interesting nuggets of information too that were all over the place about ink chemistry. He did confirm my suspicions of why ink pHs are what they are(both for color control of specific dyes and also to keep everything soluble...or in other words pH is a design parameter of the ink) and also why washable blue ink is generally acidic.

[lapis]

10 hours ago, bunnspecial said:

I actually picked up quite a few interesting nuggets of information too that were all over the place about ink chemistry....

Could you perhaps elaborate a bit on the source of these nuggets? Thanks!

[bunnspecial]

1 hour ago, lapis said:

Could you perhaps elaborate a bit on the source of these nuggets? Thanks!

https://www.scribetc.com/home

 

This guy

[sansenri]

On 5/8/2021 at 2:34 AM, bunnspecial said:

Again I'm paraphrasing form part of an hour long confirmation and something that was mentioned at least somewhat in passing.

 

There again, though, my understanding was that if a pen returned for warranty failed in some particularly unusual or previously unseen way, it was beneficial to thoroughly analyze how it failed, try to determine why it failed, and if necessary modify it to prevent that failure in the future. His statement was that it was part of the overall examination, but that it was something found more than once in a failure.

 

I actually picked up quite a few interesting nuggets of information too that were all over the place about ink chemistry. He did confirm my suspicions of why ink pHs are what they are(both for color control of specific dyes and also to keep everything soluble...or in other words pH is a design parameter of the ink) and also why washable blue ink is generally acidic.

 

I'll take a guess that at least one of the reasons is that it depends on the nature of the dye, i.e. not easy to change the pH at will, when the dye has certain characteristics at that specific pH.

[bunnspecial]

1 hour ago, sansenri said:

 

I'll take a guess that at least one of the reasons is that it depends on the nature of the dye, i.e. not easy to change the pH at will, when the dye has certain characteristics at that specific pH.

 

That's exactly what he said.

To give a real world example, we know that typical washable blue inks tend to be fairly acidic. Some published source often quote pH of 3-4, but I've personally measured some in the pH 2 range(although I don't know how much I trust the pH electrode I was using).

 

In any case, washable blue, per Dr. Davies-Smith, regardless of who makes virtually always uses Acid Blue #93 as its primary if not only dye. I know that primarily as methyl blue. I've not used it terribly often, but its common as a stain in histology. 

 

In any case, Washable Blue ink has a very, very low concentration of dye-probably one of the lowest of any common ink. Methyl Blue isn't really used as an acid base indicator, but up to a point its color intensity increases(keeping the dye concentration constant) as the pH is lowered, while if allowed to go too basic will tend toward an almost pale green color.

 

Incidentally, he also said that in most traditional iron gall blue-black formulae, this particular dye is used to give a visible line until the iron begins to oxidize. We had a fun side conversation on that as I was taking notes in 4001 BB while we were talking.

 

Although his career was with Parker and his fountain pen ink experience is with Quink and Penman(he did a lot of other ink work, including certain Sharpie ink and some various gel pens) he stated that the above was generallly true of washable blue and IG Blue-Blacks from just about everyone, including Parker, Waterman, Sheaffer, Pelikan, Montblanc, Lamy, etc.Another fun little nugget mentioned in passing is that while he was there, the idea of merging some Quink and Waterman formulae was floated but never actually done, and when he left both lines were still separate products.

[sansenri]

Thanks for the interesting report.

What you say actually confirms what I was suspecting since a long time, i.e. that most blue inks in the pure Royal blue colour range are made with the same dye i.e. methylene blue, which as you say, is known since long time and is used as a  histology marker (actually interesting that methelene blue also has antibacterial properties, which explain probably why its very difficult for inks containing this dye to turn bad, even when very old).

Interesting because usually ink recipes are kept very secret even when possibly some of them are really very simple...

[bunnspecial]

36 minutes ago, sansenri said:

Thanks for the interesting report.

What you say actually confirms what I was suspecting since a long time, i.e. that most blue inks in the pure Royal blue colour range are made with the same dye i.e. methylene blue, which as you say, is known since long time and is used as a  histology marker (actually interesting that methelene blue also has antibacterial properties, which explain probably why its very difficult for inks containing this dye to turn bad, even when very old).

Interesting because usually ink recipes are kept very secret even when possibly some of them are really very simple...

To be pedantic, the dye he specifically told me was methyl blue(or there again what he called Acid Blue #93).

 

 

Methylene blue is different

 

 

 

I only had a few minutes at work the other day after our conversation to do run a couple of samples, but I also found diphenylamine, which can be a bactericide.

 

The only volatile I could turn up in GC-MS for a sample of current(2020) Made in India Quink(which I was told is supposed to be identical to the current formula made by Newell-Rubbermaid formula) was Cyclothiazide, although I'm not 100% confident in that.

Still, though, I wonder if the rather low pH of these ink formulae in and of itself deters baterial or fungal growth.

 

BTW, also, he was also very careful to tell me that all the information he was giving me was information that could be found in the public realm, such as in patents, and not trade secrets. I was given a couple of other names to search for on patents, but will have to check on what they are.

[sansenri]

 

thank you for clarification, so it's methyl blue not methylene blue, still it's interesting to know that some of the most popular inks are based on the same dye.

I think I have come across the web site in which the guy has now set up his own production and sale of inks, if I'm not mistaken... Ah yes, it's the one you linked!

A chance to get an "original" bottle of penman sapphire...

[lapis]

On 5/8/2021 at 2:52 PM, bunnspecial said:

https://www.scribetc.com/home

 

This guy

Thanks for the immediate reply and I'm sorry I didn't get around to saying so a lot earlier. I spent decades doing HPLC, but mainly of proteins. Less so pharmaceuticals but then again -- as you already said -- GC-MS is where it's at.

[bunnspecial]

6 hours ago, sansenri said:

 

thank you for clarification, so it's methyl blue not methylene blue, still it's interesting to know that some of the most popular inks are based on the same dye.

I think I have come across the web site in which the guy has now set up his own production and sale of inks, if I'm not mistaken... Ah yes, it's the one you linked!

A chance to get an "original" bottle of penman sapphire...

 

Yes, one in the same.

 

I have one bottle each of his new inks, as well as bottles of 3 original Penman inks-Sapphire, Mocha, and Ebony.

 

The Mocha and Ebony are dead ringers. Indigo-his Sapphire equivalent-isn't QUITE there with the saturation/intensity of color, but the sheen(esp. the pronounced red sheen of PPS) is definitely there.

 

One page comparison I did of Scribe Indigo vs. original Sapphire

 

[bunnspecial]

5 hours ago, lapis said:

Thanks for the immediate reply and I'm sorry I didn't get around to saying so a lot earlier. I spent decades doing HPLC, but mainly of proteins. Less so pharmaceuticals but then again -- as you already said -- GC-MS is where it's at.

 

No problem!

 

I have a love-hate relationship with HPLC, although part of it could be the systems I've used in the past. I learned-really learned-HPLC on an HP 1050, which is a system with its own quirks. More recently, I ran a couple of Perkin Elmer 200s, which were beyond terrible for a lot of reasons.

 

GC, by contrast, just works. I started a new job back in the fall and they had an HP 6890/5973 just sitting there. It had been donated to them several years ago, and they'd never done anything with it other than call Agilent and get told that it would be $10K to just have someone come out and look at it and see about setting it up.

 

I made getting it running a project, and it's been an up and down adventure with bunches of fun little things along the way. I actually ended up having to do circuit level repair on the 6890 power board(specifically transplant an on-off switch) since i couldn't justify $600 for a replacement at that point in the project. I set up a computer(fortunately had the software, although I ended up using an ancient Pentium II Dell) and managed to finally get it pumped down and running, At first, I got thermal runaway on the source, but fortunately it's relatively inexpensive to replace the thermocouple. Then, I found that I basically had no RF on the quads. I managed to get the okay to buy a tested used side board, but that didn't fix it. I finally got brave and pulled the quads, something I'd never done before on any mass spec, cleaned the electrical contacts, and amazingly it came back to life. Now, I'm tracking down peak tailing, but otherwise it works great. I'm having it converted to LAN communication and the most current version of MSD Chemstation sometime this summer.

 

Of course, though, for ink HPLC makes the most sense, so it's a necessary evil.

 

I've done a bit more bargaining, talking, and bartering services and I'm actually getting an HP 1050. I'm not just getting ANY HP 1050, but the system back in 2008 that taught me a lot of what I know about HPLC. At this point, someone else turned up a vacuum degasser from an HP 1100 that I'm getting as a freebie and will be able to get away from helium sparging, which keeps costs down. My only real task now is to try and find a diode array detector, as I really think that's more conducive to ink analysis than a VWD. I'm trying to see if the much newer and more serviceable version of the Diode detector for the 1100 can be coaxed into playing with the 1050...

[sansenri]

On 5/12/2021 at 4:09 AM, bunnspecial said:

 

Yes, one in the same.

 

I have one bottle each of his new inks, as well as bottles of 3 original Penman inks-Sapphire, Mocha, and Ebony.

 

The Mocha and Ebony are dead ringers. Indigo-his Sapphire equivalent-isn't QUITE there with the saturation/intensity of color, but the sheen(esp. the pronounced red sheen of PPS) is definitely there.

 

One page comparison I did of Scribe Indigo vs. original Sapphire

 

 

Thanks I did see your other thread about this.

Clearly there may be reasons to think why the slight difference, either the older PPS may have concentrated in the meantime, but also (I'm more inclined to think) that the inventor of the formula may have slightly adjusted it to cause less pen clogging than the original... he's entitled to that surely

[bunnspecial]

34 minutes ago, sansenri said:

 

Thanks I did see your other thread about this.

Clearly there may be reasons to think why the slight difference, either the older PPS may have concentrated in the meantime, but also (I'm more inclined to think) that the inventor of the formula may have slightly adjusted it to cause less pen clogging than the original... he's entitled to that surely

 

I didn't ask point blank about that and I suspect that he wouldn't/couldn't have given me a direct answer on that(trade secrets and all).

 

I suspect too that lifting the formulas exactly, short of full disclosure/permission, would have run afoul of any NDAs or other agreements from his time there.

 

If I had to guess, since he has some knowledge of the dye color combinations that give Penman its specific properties, he probably just matched it as closely as he could. Since we know inks have been adjusted in the past because of certain components becoming regulated, too, it may not have been possible to do it exactly. He did mention that the Scribe inks are close to neutral pH, and also he tests them in fine-nibbed Lamy 2000s.

 

As a side note, I threw together my own attempt at blue ink yesterday. I didn't have methyl blue, but used methylene blue. It tested out well using a melting point capillary to simulate a pen, so I need to load it up in a Preppy and see how it does. BTW, mine does have Phenol in it

[sansenri]

that's interesting, did you use iron in your formula? I've see a few methylene blue ink formulas jotted down, but never knew anyone actually trying one out.

Must be nice having access to chemicals, last time I could do that was MANY years ago before graduating (at the time my interest in chemicals was because of photography though...)