AN ANALYTICAL XRAY SERVICES LABORATORY
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Posted by: In: Uncategorized 28 Nov 2018 0 comments

I often explain scientific exploration as the search for minimal uncertainty. We perform an experiment more than once to verify our results, but in actuality, we’re only reducing the uncertainty by some degree. There’s almost always some possible explanation that would negate our conclusions, but in most cases, we live with this relatively small degree of uncertainty. We’ve worked on projects which required greater degrees of scrutiny than average, but we recently took on a project unlike any we’ve worked on before.

A lawyer contacted us late on a Thursday even looking for very fast turnaround AND a very high degree of certainty in the results. This really plays to our strengths so we took on the project. It was not the 11th hour and quite urgent because another lab had tried and failed for reasons that would become obvious as we dove into this work. The goal was simple enough. We needed to verify the presence of a particular phase. As it turns out, this was a key piece of evidence to be used in ongoing patent litigation between two companies. The phase in question was very low in concentration and the key peaks were very obscured by others close by. In the end, we worked four days straight through the weekend to get a report out in time to be admitted as evidence. At one point we had three diffractometers collecting data simultaneously with one being heavily modified for maximum angular resolution.

We’d verified the presence of the particular phase and had double and triple checked the data. Our level of certainty was well beyond the norm. However, unlike any of our previous work, we found that we were no longer working against “reasonable” doubt, but rather, endless scrutiny. Any argument, no matter how ridiculous, had to be countered over the weeks preceding the court hearing. No one like to hear their work criticized, but I must admit, we’ve never been so certain about any results as we were after a team of experts tried their best to tear our conclusions apart.

The case went to trial and in the end, the expert testimony we provided proved beyond any reasonable (and even extremely prejudicial) doubt that the phase in question was present. I’m not sure if this has left me with more or less faith in how our justice system works, but it definitely opened up an area of the laboratory business we had never explored.

 

XRD sample prep is like a box of chocolates. You never know what you’re going to get… So many materials are fluffy or sticky that even after fine grinding, it’s common to have some clumps that just don’t want to break up. This became a problem for one of our clients using our side-loading tool so they added a piece of mesh to the mouth of the funnel. Their next order included a request for some type of removable solution for this so we mounted some coarse mesh in an acrylic frame that sits nicely on top of the funnel and makes it very easy to sift through sample material as it’s being loaded. We love these so they’ll be an option on all future orders!

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Clay minerology is a fascinating subset of the common powder XRD applications we work with. It seems like every lab has their own unique way of handling the various challenges presented by clays and hence the need for myriad solutions. Most recently we worked with a lab which processes large volumes of clay samples in their various Bruker XRD system and they needed a sample holder that would accommodate their 26 x 26mm glass slides on which their clays are mounted. The solution was a custom holder with a square recess for the plate which is simple enough, but in cases like this, one must take into account the real-world challenges of machining as well as usage. The edges and corners of the glass slides are the least precise part of the plate so the holder has a “moat” around the perimeter to eliminate binding or shifting due to those issues. The center is also relieved as this area does almost nothing to improve precision of the mount, but will cause dramatic displacement errors if any debris gets between the holder and plate in that area.

These were a little time-consuming to make, but the end result worked beautifully. The client was very happy and we’re happy to have another design to offer to other labs with similar needs.

 

Our lab sees a very wide variety of sample types and they are almost always 90% unknown materials. So while we’ve always offered elemental analysis by WDXRF, sample preparation has always been done by the least destructive method. That means powders and solids get crushed, ground, and pressed into pellets and liquids either get run as they are under a He flush environment or dried and filtered for particulate matter. These techniques work well for qualitative analysis and can also be extremely effective for quantitative work assuming proper preparation and a good calibration curve.

However, we’ve been working on a comprehensive calibration curve for geological materials recently and the simple fact is that the very nature of these materials makes them very difficult to measure in their natural state. The fact that the various elements may be combined in any number of different minerals as oxidized, reduced, or metallic phases makes analysis by XRF, even WDXRF very difficult. The solution to these problems is Li-Borate fusion.

I’ve resisted getting into fusion for a number of reasons, not the least of which is the substantial cost of entry if you’re going to be running much volume at all. It’s not hard to spend $70-90k on the tools for an automated preparation setup. After researching all the major manufacturers we came out with a few front-runners that are worthy of note. These are only the models we looked at so please don’t consider omission from this list as a negative comment on any company or model.

Katanax was our first on our list as a few of our clients are running these systems. The electric oven style heating is very convenient and the fully-enclosed design was also quite attractive. They also have three different models with single, up to 3, and up to 6 positions for simultaneous fusion. The touch-screen interface is large, well-laid out and easy to work with. While all this sounds great, the best part about Katanax in my estimation is their support. Talking with their applications experts was a great experience and I could tell this was not just a job, but something they truly enjoyed. I recommend Katanax for anyone new to fusion who might need some help. The only things we didn’t like about the Katanax models was the “swirling” motion style which is a simple tilt back and forth and the electric oven heating. With most crucibles, the swirling motion won’t have any effect on results, but I was partial to the 360-degree rotation style. As for the electric oven, this works great for labs with higher volumes, but we aren’t expecting large volumes of samples any time soon and the idea of heating the entire oven for just a couple samples would have ended up being time to consuming. If you know your volumes will always be low, the single-stage K1 Prime.

 

Another model recommended by several of our clients was the Phoenix sold by Premier Lab Supply. Premier deals with several different models of fusion systems with gas and electric options, but we were focused on gas by this time. The Phoenix had a few unique features like O2 injection and a mechanism by which a non-wetting agent tablet could be introduced very late in the fusion step. This is necessary with some non-wetting agents and a very nice feature to have. The Phoenix is also expandable and we liked the fact that one can specify which positions are to be used for a particular fusion so all the burners don’t need to run if we’re just running a single sample. One of our clients at USGS has been running the original Phoenix models for many, many years and I’ve heard nothing but glowing praise for it. Again, reliability and the availability of support are extremely important to us and I believe Premier would have been a great choice. The age of the Phoenix 1 was a small issue and the interface is a little dated, but it really came down to physical size. This is a big machine and would have taken up a fair bit of our sample prep area. I’m quite confident that any lab would be well served by one of these.

 

No discussion about Li-Borate fusion would be complete without a nod to Claisse. They have options for just about everyone, but we were looking at the Claisse M4. The M4 is an older model, but offers some very nice features. Their swirling mechanism is easily my favorite as the crucible rotates continuously. The machine is also remarkably space efficient for being a 3-position system. The interface was the weak link for us compared to the newer models with touch-screens. Another minor issue that I’d never considered till we actually started running a fluxer in-house was that it’s very convenient to fill the crucibles from weighing boats while they’re installed in the machine. This would be difficult to impossible on the M4. I would expect a very high level of experience and support from Claisse, but didn’t actually get that far in our conversations. I should mention that we’ve seen several of the Claisse Ox machines out and about. They seem to be a great solution for high throughput labs.

 

 

Last, but certainly not least, we have the Nieka G4 series (sold by Chemplex in the US and pictured at the top of this article). This is the unit we eventually settled on though I had never heard of it until recently. It was simply the right machine for us with a 4-position configuration, bright and relatively easy to use touch-screen and an open design. We actually ended up with a propane version which was another last-minute choice that we were very happy with. This allows for very easy installation, portability (hard to believe that’s a feature, but in our evolving lab, it’s great to know that we can move it anywhere we want with ease), and a higher energy density fuel than natural gas. The swirling motion on the G4 is a circular motion which works very well for mixing up hard-to-dissolve powders. The integrated software offers a very high degree of control which may or may not surpass the others shown here, but we really appreciated this while we refining out fusion recipe. Extending the time for a certain step, adding steps, etc were all very easy.  No PC or other interface was needed or even wanted. The open design makes working with the crucibles and loading flux/powder a breeze. If there is a caveat for the G4, it’s that while Chemplex has never failed to get us an answer to any of our applications questions, this definitely seems to be a new branch for them. I assume it will take some time to build up an in-house knowledge base, but we didn’t need too much hand-holding to get started. For users with more consistent materials, I would recommend you take them up on their offer to develop a fusion method for you. This can be done entirely remotely and would probably have been a great option for us if we didn’t have such a large variety of materials coming through.

We’re probably about 100 fusions in and the machine has not missed a beat or given us the least bit of trouble. The amount of control available is likely a large part of this. We were able to fine-tune the oxidation, fusion, pouring, and cooling phases with multiple steps for each which has allowed us to create a recipe which covers a wide range of geological materials from shales to silicate rocks.

 

Update 23-MAY-2018:

We actually had our first interaction with support for our G4. One of our crucibles cracked during the heating stage. I’m not sure what caused this and neither was Chemplex, but it appears to have been some type of stress as it was right on top of a bulge. Getting a replacement was effortless and fast though. Having good, local support is another factor in this decision that was very important to us and I’m happy to say that our first issue was taken care of very quickly. Thanks Chemplex!

You can never have enough sample holders no matter what machine you’re running. We’ve certainly found this to be true at Texray so we always try to keep a large number of them on-hand. KS Analytical Systems has always made one-off and custom sample holders for the Bruker instruments, but we’re now offering the standard PMMA powder holders as well at significant cost savings over the OEM version. The standard holder (25mm x 1mm deep well) is priced at $55 with bulk discounts starting at 20 holders.

Custom well depths, diameters, grooved floors, side-loading and zero-background versions are available.

Our PMMA holders are compatible with Bruker D8 Focus – D8 Advance (single, FlipStick autosampler, 90-position autosampler), D4 Endeavor and D2 Phaser (single only) systems. D500 and D5000 instruments can also use these holders.

We’ve brought the complete manufacturing process in-house to give us the freedom to make the custom designs our customer have always asked for. This includes custom laser etching. Company logos are a common request, but we’ve also started serializing sample holders on request. At Texray, we even etch them with barcodes for tracking samples through the data collection process.

The pictures below show a custom funnel tool for filling side-loading sample holders. The tool is machined from billet aluminum with an acrylic window on the funnel to make it easier to gauge fill level. The funnel itself is polished and the viewing plate which allows the users to see when the sample well is full is made of sapphire crystal for maximum scratch resistance.

I’ve spent time in hundreds of different businesses over the last 20 years as I traveled around the country working in labs and it’s given me a strong appreciation for the concept of “workplace culture”. It’s not really a spectrum in the sense that there are extremes on each end and compromise in the middle, but more like “culture” in the truest sense of the word. It’s a complicated system of expectations, relationships, and accomplishments. Obviously some of these systems “work” and others… Not so much.

I like to think we do pretty well at KSA and Texray. Mainly because, after many years of experimentation, I’ve come to the conclusion that I can’t change people (surprise!). An old friend at a major manufacturer of X-ray instrumentation once commented to me that when he hired a new tech, he’d know within a month if they were going to last. My first thought was that it would take longer than a month to make the new hire into the tech you needed, but I realize now that his statement embodied the same lesson it would take me years to learn. You can train, reward, chastise and incentivize all you want, but the people you hire are either right for your group or they’re not.

Around here we have easy days and hard days. It comes with the territory, but I think everyone knows that they’re appreciated and supported in what they do. Individual projects are encouraged and we try to loosen up enough to have fun without compromising performance. Behind it all is a sense of pride in the fact that we work very hard to surpass the expectations of our clients.

 

 

 

 

 

It’s relatively common for us to receive very small volumes of material for analysis. Often this is the total amount available so getting the right answers is extremely important. When these come in as powders, the answer is always to run them on a zero background plate, but sometimes that’s not the case. Luckily, there are other options for analysis of very small quantities.

The most common application for filter-membrane sample holders has always been respirable silica quantification. This is mandated by OSHA and is an extremely common industrial hygiene test. Ambient air is sampled with a fixed or mobile suction system and particles are deposited onto a PVC membrane inside a sealed cartridge. Testing procedures are defined by NIOSH7500 and since this is a total quantification method (not a relative method), it’s critical that the entire sample is measured. Unfortunately, the measurement cannot be completed on the PVC membrane as received. Transferring the sample powder to an Ag membrane is accomplished by dissolving or ashing the PVC away, diluting the remainder in a solvent and depositing it onto the Ag membrane by vacuum filtration. The end result is an extremely low loss of analyte even for very small volumes of material.

This preparation method is also very useful for other types of samples which might have crystalline particulate suspended in a solution. Drying samples can be time-consuming, heating them to boil off liquid can cause phase transitions in the crystalline analyte, and handling dry powder in very small quantities is a very good way to lose material. Vacuum filtration solves all these problems.

 

Our most popular custom sample holder is the SC40F25 which is designed to hold the common 25mm Ag membrane filters used for this type of mounting. The anodized Al body is a time-tested design that works very well and causes almost no interference with the data, unlike the original injection-molded plastic parts. However, the most common method for retaining the membrane has always been to drop a metal support disk behind it and use an ID snap ring to retain both the disk and membrane. This can be a frustrating operation even for experienced hands. Snap rings are hard to control and the high spring tension gouges the inner diameter of the Aluminum body to the point that the holders must be replaced periodically.

After watching so many clients struggling with this system, we thought we could find a better option. The first step was a simple, laser cut acrylic backer instead of the metal disk. The acrylic was thicker which limited the depth to which the snap ring needed to be set. This was an improvement but still required the snap ring.

The next step was 3D printed plugs which could be pushed into the well. These supported the membrane and held it in the plane of diffraction at the same time. A standard pair of pliers was all the was needed to grab the plug and gently rotated it to release the membrane. This seemed like the ideal solution, but we heard from one user who claimed that the plug was causing an interfering peak in his measurements. We’ve been around the block with 3D printed sample holders in general and it’s definitely true that the common thermoplastics used will crystallize when cooled rapidly. This causes lots of problems for routine analysis of powders, but this was the first we’d heard of a peak being visible through an Ag membrane. Perhaps this user had a particularly thin membrane, but regardless, we needed a new solution, both for their lab and our own.

 

Our current solution is a laser cut “spring” backer which again combines the function of retainer and support in one part. The spring is easy to install by hand and can even be removed by hand, but forceps or needle-nose pliers make this easier. These have been working very well so we’re hopeful that this is going to be a long-term solution that we can share with our clients.

 

 

 

Posted by: In: Uncategorized 03 Jan 2018 0 comments Tags: , , , ,

Most of the zero-background sample holders we make are designed with permanently affixed plates. We prefer this dramatically as loose plate are constantly getting dropped, chipped, or lost. However, a permanently affixed plate also gives us the freedom to precisely (within about 0.02mm) set the depth of the plate below the plane of diffraction. This can make a big difference in the results depending upon the volume of powder loaded as the standard “flush mount” puts the plate exactly in the plane of diffraction. This works fine for very small volumes, but it does guaranty the there will be a displacement error of some magnitude regardless of the particle size or volume. For this reason, we always offer custom recessing as an option. The only drawback to the permanently affixed style of mounting is that the offset (or flush mounting height) cannot be changed. Our preferred solution is to simply create a set of holders with various depths to accommodate different sample thicknesses, but we had a request recently for an infinitely variable mounting solution.

Complicating the project is that the holder was to be used in a D2 Phaser with a 6 position autosampler which does not use the same style of base holder as the single-sample variant or any other Bruker XRD that we’re aware of. We discussed several options. The large number of heights needed made multiple holders, spacers, and any other solution that relied on discreet steps unacceptable. The thin-walled sample bases and relatively tight dimensions made a screw-in insert unrealistic as well. The final solution was to build a custom tool for setting the ZBH at a specific depth. This requires the user to work with bare Si plates, but it meets all the design criteria and we’re hopeful that this will work well for them.

The tool is made from acetal (Delrin) plastic which is extremely resistant to chemicals, adhesion, and abrasion. It’s actually an ideal material for threaded parts and machines very well.

Posted by: In: Uncategorized 03 Jan 2018 0 comments

I spent quite a bit of time during my college career in chemistry and electronics classes, but when I think back on the most influential aspect of my education, it was my physics classes that shaped my understanding of the world more than any of the others. There was something very “pure” about the process of isolating the variables necessary to describe a mechanical event or electromagnetic interaction. These numbers fit together like pieces of a puzzle until, all at once, the answer emerged. This concept of manipulating what was available to create what was needed seems to permeate much of our work at Texray and KS Analytical Systems and it’s the most satisfying part of it for me. We’re frequently approached with problems that require a custom solution.

Much of the custom work we do revolves around holding samples in various form while they’re being analyzed, but recently we’ve had a few projects more centered around improving processes which have been interesting. For our own lab, this might mean custom racks to keep tools organized and clean, sample tools to help us avoid cross-contamination or fixtures to aid in the safe handling of some of our more expensive apparatus. We just completed a project that I found interesting for a client in CA who is running seal-cell experiments which needed to be held secure to various working surfaces. The original method involved bolting them in place each time which proved time-consuming as volume increased. The answer was a relatively simple adapter plate designed by the client which needed a little design refinement and some basic fabrication.

The project started with basic drawings so the first step was a few prototypes in acrylic plastic courtesy of the laser cutter. Small changes were made until it was ready for an Aluminum version. Here it is in action!

Posted by: In: Uncategorized 21 Jun 2017 0 comments Tags: , ,

KS Analytical Systems and Texray Laboratory Services are deeply invested in the future of science and technology in the USA. We work with undergraduate, graduate and post-doc students regularly and encourage them as much as possible with support through Texray as well as technical information. Watching XRD and XRF users in higher education develop and test their ideas is always interesting, but these are not the students who are being lost from STEM fields. The battleground for the engineers, chemists, and physicists of tomorrow is happening at a much younger age so we’re always looking for opportunities to support teachers who are working to show their students that these fields are not just endless equations and tedious experiments.

With the whole country waking up to the need for more STEM graduates, there’s no shortage of organizations and competitions set up to give kids a chance to get their hands dirty with technology. We started out by sponsoring a local high school robotics team and, most recently, a high school team entered in the NASA Human Exploration Rover Challenge. The video below is from last year and I love how they describe their early failures and determination to improve. These are not your ordinary shop-class kids. Most had never used even basic hand tools. This competition put them completely outside their comfort zone.

The 2017 competition brought new challenges and more restrictive design constraint intended to push the teams further into the realm of custom components. The obvious answer for most of these vehicles had been common bicycle wheels and tires from the beginning. Their light weight and high strength make them very attractive, but taking the easy way out is not what being an engineer, let alone a NASA engineer, is all about. Using the equipment and capabilities at hand the Parish Episcopal team developed a wheel that took everyone by surprise (including myself). Multiple layers of cardboard were sandwiched together and coated in a polymer bed-liner material intended for pickup trucks. The toothed pattern of the cardboard layers created exceptional traction and the rubber coating made them extremely durable. The 2017 rover was not without its weaknesses, but these wheels were a subject of interest to everyone from the spectators to the organizers. Parish fielded two teams which finished 26th and 27th out of a 99 team field which included universities and high schools from all over the world.

The first video is from a TED talk given by two of the older students in the program from 2016. The second is from the 2017 competition and includes some race footage.