DIY scientific equipment

Off-topic conversations and chit-chat.

17 posts Page 1 of 2
Has anybody tried anything interesting?
mariosapm wrote:
Has anybody tried anything interesting?


All the time - that's what I do. You can't buy dog pee analysers off the shelf !

Cannula to get silica transfer lines through septa; APPS, P. and MMUALEFE, L. 2011. An injection cannula that enhances the versatility of split–splitless inlets. Chromatographia 73: 1229–1231.

Flow switching cryo-trap inlet: APPS, P. and MMUALEFE, L. 2012 A versatile cryo-focussing flow switching gas chromatography inlet for trace analysis of intractable compounds. Journal of Chromatography A 1257: 171 – 188.

Deans switch. APPS, P.J. 2006. Low cost, robust, in-house hardware for heart cutting two-dimensional gas chromatography. Journal of Separation Science 29: 2338-2349.

And from a previous life: ROHWER, E.R., PRETORIUS, V. and APPS, P.J. 1986. Simple press fit connectors for flexible fused silica tubing in gas liquid chromatography. Journal of High Resolution Chromatography and Chromatography Communications 9: 295 297.

APPS, P.J. 1990. High precision sampling of trace gas borne volatiles by the dynamic solvent effect with a comparative review of alternative techniques. Journal of Chromatography 504: 21 43.

APPS, P.J. 1990. High precision sampling of sub nanogram, low parts per billion solutes from liquids using the dynamic solvent effect. Journal of Chromatography 511: 271 279.

I tend not to fiddle with detectors or mass specs though.

Peter
Peter Apps
Not in the same league as Peter's serious versions, but if you want a low-cost nitrogen shower for drying samples, and have a dry hot-block or similar way to heat a rack of tubes gently, then you can always stick wide-bore hypodermic needles through the lid of a lunch-box in the right grid spacing, cut a suitable hole in the side of lunch-box with a cork-borer, and attach tubing to attach to a nitrogen supply.

The resulting pneumatic hedgehog works quite well provided the safety people never see it. A compressed-gas driven bed of hypodermics tends to freak them out a bit. But it can save many thousands of pounds' equipment purchase.
Has anybody made an aluminum block heater?
I drilled a few holes in a chunk of aluminium that I scavenged from somewhere and put it onto a heater plate.

Peter
Peter Apps
I upgraded our old Tekmar 2000 purge and trap to have trap back pressure after reading about it being a new option on the Tekmar 3000 when it came out.

I took the split/splitless pressure control assembly from an HP5890 and ran a 1/16" line from where the gas enters the back pressure controller up to the vent on the Tekmar then I went further and added a Tee to drop it to the split/splitless solenoid and connected that to the valve control on the 5890 control panel so that I could drop the pressure when in bake mode.

Ran it that way for at least 12 years :) Tekmar sales guy always laughed when he saw it.
The past is there to guide us into the future, not to dwell in.
I fiddle with detectors (which is why I have to disclaimer so often.) Also build a gas autosampler from "scratch." Build GC systems for people.

It's getting harder. I think GC is moving to black boxes which is why it is (in many ways) getting harder. Good if you build black boxes, not so good if you need to re-applicate. I think Peter would agree.

I learn something new almost every day. Okay, maybe not every day, but one should always strive....

Best regards,

AICMM
I think GC is moving to black boxes....

I hate the "black box approach". I want to fiddle with the settings and components and understand how things work.
skunked_once wrote:
I think GC is moving to black boxes....

I hate the "black box approach". I want to fiddle with the settings and components and understand how things work.


That's three of us then !

Peter
Peter Apps
Oh, I forgot another home-brew and have just been reminded by another thread.

Home-approach to improvising a syringe pump for infiltration into electrospray MS (no stand-alone syringe pump in the lab, and 15' of Peek tubing from a syringe-pump built into another instrument didn't seem sensible...). Obviously this only works on a full LC-MS system where you don't happen to want to do any chromatography today:

Attach a piece of Peek HPLC tubing to a wide-bore syringe (hypodermic type syringe). If possible, it's best to find some devious way to connect the HPLC tubing to wider-bore low-pressure chromatography tubing and include a three-way valve between the hplc tubing and the syringe...

Hold the syringe in a clamp-stand.

Now attach a 250uL Hamilton syringe (or similar) to the clamp-stand, plunger-to-plunger with the hypodermic syringe. At this stage the Hamilton syringe should be full of sample, the hypodermic syringe empty.

Attach hplc tubing to the LC system and pump at desired flow-rate. This fills the hypodermic syringe, which pushes the plunger of the Hamilton, and delivers a steady(ish) flow. It's a flow-rate transformer dependent on the diameters of the two syringes.

The valve is useful when you want to empty the hypodermic and start again.

I wouldn't recommend this one, but have used it in desperation!
Peter Apps wrote:
skunked_once wrote:
I think GC is moving to black boxes....

I hate the "black box approach". I want to fiddle with the settings and components and understand how things work.


That's three of us then !

Peter


Make it four!
The past is there to guide us into the future, not to dwell in.
lmh wrote:
Oh, I forgot another home-brew and have just been reminded by another thread.

Home-approach to improvising a syringe pump for infiltration into electrospray MS (no stand-alone syringe pump in the lab, and 15' of Peek tubing from a syringe-pump built into another instrument didn't seem sensible...). Obviously this only works on a full LC-MS system where you don't happen to want to do any chromatography today:

Attach a piece of Peek HPLC tubing to a wide-bore syringe (hypodermic type syringe). If possible, it's best to find some devious way to connect the HPLC tubing to wider-bore low-pressure chromatography tubing and include a three-way valve between the hplc tubing and the syringe...

Hold the syringe in a clamp-stand.

Now attach a 250uL Hamilton syringe (or similar) to the clamp-stand, plunger-to-plunger with the hypodermic syringe. At this stage the Hamilton syringe should be full of sample, the hypodermic syringe empty.

Attach hplc tubing to the LC system and pump at desired flow-rate. This fills the hypodermic syringe, which pushes the plunger of the Hamilton, and delivers a steady(ish) flow. It's a flow-rate transformer dependent on the diameters of the two syringes.

The valve is useful when you want to empty the hypodermic and start again.

I wouldn't recommend this one, but have used it in desperation!


That definitely has my flow meter made from a burette, 1/8" swagelok tee, tygon tubing and a dropper bulb beat :)
The past is there to guide us into the future, not to dwell in.
I certainly can't beat Mr. Apps, either but today I assembled one live quaternary pump & controller from 3 dead pumps and 2 dead controllers:

The pump drive and high pressure fluidics came from a Waters 590, which gave it's life for this...though that chassis and associated electronics may live on in something else.

The chassis and low pressure fluidics (GPV and associated bits) came from a Waters 626 which had been discarded for having been a problem child in our QC lab for years. I could never quite get the beast to run perfectly either. The electronics were from a Waters 600 whose pump drive mechanism had been destroyed (a return spring broke and destroyed 2 gears). The controllers were both old style 600 units with CRTs. One had a very, very dim CRT and the other had bad video RAM, so I swapped the CRT from the one with bad RAM into the one with the dim CRT.

Now have a fully operational Waters 600e pump and controller.
http://the-ghetto-chromatographer.blogspot.com/
juddc - :cheers: :salut:
Peter Apps
juddc wrote:
I certainly can't beat Mr. Apps, either but today I assembled one live quaternary pump & controller from 3 dead pumps and 2 dead controllers:

The pump drive and high pressure fluidics came from a Waters 590, which gave it's life for this...though that chassis and associated electronics may live on in something else.

The chassis and low pressure fluidics (GPV and associated bits) came from a Waters 626 which had been discarded for having been a problem child in our QC lab for years. I could never quite get the beast to run perfectly either. The electronics were from a Waters 600 whose pump drive mechanism had been destroyed (a return spring broke and destroyed 2 gears). The controllers were both old style 600 units with CRTs. One had a very, very dim CRT and the other had bad video RAM, so I swapped the CRT from the one with bad RAM into the one with the dim CRT.

Now have a fully operational Waters 600e pump and controller.



Hello,
I saw your blog before to discover this website, really a nice blog! Great!
I loved the common halogen spare bulb for the expensive one! :lol:
I see you like and you are able to work with hardware very well and I would like to ask you two things:

1) I want to set up a waters 600 series pump/controller for fun (a 626, hoping it will be not a problem child!). I should have the 626 at home soon but I have to buy the controller yet and I am not able to undestand the differences existing in 600 (CRT screen), 600 (LCD), 600E and 600S versions, can you explain it to me in few words, please? And above all, are all controllers able to control the 626 pump?!

2) it is not easy at all to find the power/communication cable connecting the pump and the controller, I mean the cable from the controller to the pump that powers the pump and control it. Or if I found it was not cheap at all or not sold alone... so I thought to build the cable by myself. Connectors are easy to find, I am able to solder the connections and to chose the right diameter size for the power wires but I am not able to find the pinout of the 2 connectors to make the correct connections, can you help me? Have you the pinout/datasheet? Else I need someone having the cable that can test the connections by a multimeter or I will have to open the pump and the controller to try to understand the correct connections by the electronic boards configuration.

I am fool, I know, regards,
many thanks to read me,
James
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