Part 3: How to Know if Your Calibration Curve is Correct

You’ve bought some standards and you made a multi-point curve.  You might think your work to improve laboratory accuracy is over, but then doubt starts to creep into your mind.  What if something’s gone wrong!?!  What if you run a sample and you expect one answer and your instrument tells you another?!  Is the sample bad, or is there a problem with your calibration curve?  Has something gone wrong somewhere in your plant’s process, or do you have a bad batch of calibration standards!?

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The first step in ensuring that your calibration curve is up to par is checking the Correlation Coefficient.  I know, I know….more math….but stick with me here because it’s important!  The R2 value of your calibration curve has a large amount of statistical power.  No one wants to talk about statistics, but it has a lot to do with how well your instrument is calibrated.

In a nutshell, the correlation coefficient gives you an idea of how well the standards relate to each other.  R2 values statistically can range from -1.0 to +1.0, but on your instruments, you should look for a value as close to 1.0 as possible!  Values of R2=0.9987, R2=0.99943, or R2=0.9963 are examples of what you are looking for.  The closer to 1.0 your R2 value is, the stronger the relationship between your standards.  A strong relationship between standards leads to more confidence in the reported results for your samples.  Remember that your standard value points hug your samples, and no one likes crappy, wet noodle armed hugs! It’s listed somewhere in your instrument’s software, you might just have to look around for it.

So you’ve got a strong curve, but calibration curves can be strong….but wrong!  How can you check the accuracy of the standards you used to make the curve?

There is a way to prove that you standards and instrument are operating correctly.  We are going to employ the Dr. Sheldon Cooper of standard….the validation standard!  Just like Dr. Copper, the validation standard knows more than you, and it isn’t afraid to tell you when you’re calibration is wrong!

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The validation standard should be a standard SEPARATE from your curve!  Buy it from an alternative supplier, buy a different lot of a standard you use in your curve, or buy 4 standards and just pick one to use only as a validation….just don’t use your validation standard as part of your calibration curve.

If you just analyze one of your calibration standards again as a sample, you will get the right answer 100% of the time….because somewhere in the software you’ve entered those values in as the answer.  This might look promising, but it tells you ZERO useful information about the accuracy and correctness of your calibration curve.  The validation standard’s “job” is essentially to be an unknown sample, that you secretly know the answer to.

A good basic rule of thumb is that the difference between the known value of your validation standard and the instrument’s reported result based on your curve should vary no more than 10%.  We’ll call this “Validation Recovery” for ease of terminology.  For most applications, 10% is much larger than the recovery should be, but if you’re just started down the path of improving your laboratory accuracy….it’s a good basic place to start.

From here we are going to have to dive into a bit more math, and I think we can all agree that one math topic per post is frankly too much math!

Next week I’ll cover the basic statistics of calculating a more precise validation recovery range for your instrument, tracking validation recovery, and how you can use that information to access the performance of your instrument!

I’ve Got A Brand New Blog

I was asked to start writing a science blog for work.  I’m not sure how much interest there will be, or how interested any of my current readers might be in this info, but I thought I might start sharing them here as well.

A few fun facts and some science knowledge never hurt anyone after all!  Currently, the plan is that I’ll post for work weekly.  That might taper off, but we have some events coming up and we wanted to drum up some interest and talking points with some customers before the events.  I will also be keeping up on my “personal” blog posts….which I have been bad about but hopefully all of this extra blogging will keep me on a schedule!

So….without further ado….I present my new blogging topic–

Common Calibration Conundrums and Other Laboratory Queries

Hey!

I’m coming at you to discuss some common science questions and issues I get asked in the lab frequently.  I thought I would start with a little mini-series on calibration issues, and then hopefully we can move on to other issues and questions you face in the lab on a daily basis.

If there is a specific topic or question you liked me to address, just leave a comment on this post and I’ll get back to you!

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Part 1: When to Calibrate

You should calibrate as often as practically feasible for your laboratory process and timelines!  It will not hurt your instruments to calibrate them too often, but it will hurt your results if you do not calibrate often enough.

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I know you might think that calibrating often is a waste of time…….and you’re busy…and the plant operators want their results…and the results seem fine so you’ll just ignore recalibrating your instruments until something bad happens.

Just take a minute and think about all the parameters around your instruments that change….even weekly.

Did you consider factors like-

  • Did you change mobile phase?
  • Standards will gradually degrade over time.
  • Wear and tear on the instrument components themselves

Even one of those small changes can compound and lead to catastrophic effects on your results over time.

Calibrating an instrument is a bit like potty training a new puppy.  Puppies only know what you tell them.  Imagine you tell the puppy one day to go outside.  The puppy might remember that knowledge for a day….maybe two.  Eventually, if you don’t remind the puppy what good behavior is, that puppy is going to forget.  When that happens, you’re going to come home to a disaster zone!!

Instruments only know what area counts corresponds to want concentration because you tell them….with standards and a calibration curve!  The instrument might be able to hold onto that curve and that knowledge for a day….or two, but eventually it’s going to drift too far to be accurate.  When that happens you wouldn’t be able to supply anyone with valid data, and you’ll end up behind a backlog of samples trying to figure out where it all went wrong.

I’ll be covering more about calibration data in the next couple posts so be sure to keep an eye out for those!  In the meantime, if you have any specific questions or you would like me to cover another lab related issue you find yourself facing, don’t hesitate to contact me about it!

 

UPGRADES!!

We are only a couple weeks into the spring turkey season, and The Engineer and I have been scouting, planning, and working for a turkey on some local public land.  It’s hard work, but we’ve seen some cool things while out and about on our adventures together.  I want to share all our fun discoveries and strategies, but I don’t want to blast you with daily upgrades, so I need to figure out a good organization for all the fun.  Fingers crossed one of these times out I get an arrow into a big ‘ol thunder chicken!

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The Engineer….can’t hear me yell from one room away….hears distance gobbles from far away counties!

In the meantime I thought I’d share some fun news!

I bought my domain!

Actually, I was hoping that it would get rid of the wordpress part of the web address, but it didn’t.  It did however get rid of the ads so now you don’t have to deal with strange ads while you’re trying to enjoy the adventures!  Overall I was really hoping that the upgrade would be more exciting, but it’s still an exciting step forward for me!  The upgrade did let me change the background color though so I swapped out the weird green/grey/baby poop color for something a big more festive!

 

I’m Having Technical Difficulties

Soo….I was working on getting a blog posted, but my internet has been very sketchy today so I lost progress several times and couldn’t ever get my photos transferred.

I’ll post an extra long one this week to make up for it.  Technology has been a bitch to me all week, I guess it’s just continuing.

On a side note, I actually sat through an episode of Game of Thrones with The Engineer, so he was pretty excited about that.  Also…..we maybe napped through what was an acceptable dinner time, so we had corn on the cob on the couch while watching the show……it was maybe a little weird.  I’m not sure corn on the cob is a thing people eat on the couch at 8:30PM for a snack…..but it’s a thing we did.

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Chapter 4: The Slow Fade

I think one of the most annoying aspects of modern dating has to be the slow fade.  I’m sure people have been utilizing some version of this method for decades, but I have a feeling it’s become more prevalent in recent years.  Personally, I think online dating and cell phones have created a “perfect storm” situation where we don’t need to be near to or actually talk to the people we are trying to date.  It’s too easy to stay in touch with people now, so we get lazy, and we just don’t do it.  Dating, at least in my recent experience, starts out much more impersonally, and I think that makes slow fading someone easier.

For those who might not know, the slow fade is when either you or the other party just slowly stops talking.  This is slightly different from say a cliff dive scenario where someone just…..all the sudden stops talking!  That’s annoying too, but in a different way.  Slow fading is the modern version of the phrase, “letting someone down easy.”  You like them enough to not drop your departure on them like a ton of bricks, but not enough to actually tell them why you don’t want to date them.  Usually, let’s be honest, that reason is, “I’m just not that into you.”  I’m maybe being a bit hypocritical here, because it isn’t like I’ve never used the slow fade on someone.  I think that I differ slightly from the typical slow fade user though.  Even if I don’t want to date you, I’ll stil talk and probably hang out with you.  I’f I’m really just not feeling it at all, I’ll start the fading process by just “being busy”.  Now, realistically, I’m almost never too busy to hang out with someone, but I guess you make time for what is important.  My constant state of busy basically puts the ball in the other person’s court.  If you want to slow fade me at this point, great!  The feeling is mutual, I just don’t ever really want to be the one to crush some poor guys hopes and dreams.

If after a significant period of time the poor guy just isn’t grasping the “friend zone” concept I’m trying to roll with, I’ll perform a slow fade.  Just slowly stop answering texts and definitely don’t answer phone calls!  Frankly, I really only prefer this technique on people I haven’t gone on face to face dates with.  Not only do I prefer it, I totally accept it!  If we haven’t bothered to meet in person and it’s been several months, we clearly aren’t all that into each other.  I have enough friends, I don’t need an extended circle of random dudes I met online.  Thanks, but no thanks!

The use of the slow fade that I don’t understand is when you’ve meet someone in person, had a good time together, agree to meet up again, and then bam….the slow fade.  I mean, I get that sometimes you’re just not that into someone.  I also understand that even if you’ve casually been seeing someone, when it comes time to move on, it can sometimes feel like you have to “break up” with someone you weren’t actually dating.  Trust me, that’s a feeling I’m well acquainted with!  However, have we really become so fragile that we can’t just tell someone we aren’t interested?  Again, I think it’s laziness.  It’s just easier to give someone the slow fade, but that doesn’t make it right.  I should clarify that the mutual slow fade is a rare gift, a mystical unicorn of modern dating.  If you find yourself in a mutual slow fade, count your lucky stars and have a celebratory drink!!  It truly is a “get out of jail free card”.

As someone who has been on both the receiving and giving end of a slow fade, it’s a complicated topic.  On the giving side, you want an easy way to remove yourself from a situation, all whilst causing the least amount of emotional trauma.  On the receiving end, sometimes it would really be nice to know why you can’t hold down a relationship.  I think generally we should all be less accepting of the slow fade!  It’s really not helping anyone, and it’s use is probably just adding to an already high amount of dating anxiety!  However, no one wants to be the crazy one who demands explanations for everything, so we all just accept the slow fade.

I’ll be the first to admit that hearing about my flaws is only something I want from close family and friends, and even then it’s still not enjoyable.  However, my friends and family really aren’t likely to tell me the reasons why I send guys disappearing into the shadows.  They probably don’t know the reasons honestly!  There probably isn’t a good answer to the slow fade problem which plagues the dating scene.  I understand the appeal of giving someone the slow fade, however I’d really prefer people didn’t use that method on me.  Maybe we are just destined to be hypocrites in a slow fade world.