Now is this one for all you mustachioed guys. Ever wonder how much your mustache weighs? Well, take a look at this hilarious video where 8 brave souls step up to sacrifice their mustache just so that it could be weighted on Kern Precision Scale. The winner weighed in at all of 0.325gms. That’s quite a lot of mustache! (This was part of a charity event promoting the fight against prostate cancer).… Read the rest
Precision scales have a myriad uses especially in the lab. Here is one such standard operating procedure (SOP) where it plays a critical role. The Paint Filter Liquids Test is performed on samples of waste ash to find out if they contain free liquids and to assess adherence to specific CFR and EPA norms. In the process of these tests measuring and weighing the mass of the ash is an important step which is where the precision scale comes in. As we have stressed elsewhere on our blog, the SOP also notes the importance of keeping the balance in calibration and verifying it daily.
If you’ve ever been flummoxed by the concept of ‘significant figures’ then this primer will be a good refersher course. Significant figures when measuring in the lab are important to determine the degree of precision with which you would want to report your findings. For example, our Kern analytical balance which supports precision to tenth of a milligram can produce results up to 0.0001 grams. The article also highlights another important issue when working with calculators. Normal calculators can report up to 7 significant figures. The student is cautioned not to get carried away but to restrict the answer to those number of significant figures as required.
Here is another lab procedure where the analytical balance has an important role to play. The document goes into fine grained details about the various aspects of the procedure.
While the procedure is primarily designed for crude heparin, the document suggests that it may be used for analysis of heparin API samples also.
This document explains how ambroxol hydrochloride and cetirizine hydrochloride where analyzed in the tablet formulation. This was done using reverse phase liquid chromatography and absorbance ratio spectrophotometry. The methods that were developed using these techniques are rapid, precirse, accurate, specific, and sensitive. They were able to successfully determine the presence of the substances with a high recovery percentage, good accuracy, and precision that was within acceptable limits. As usual, what attracted us to this article was the use of an analytical balance. One more example of the critical importance of an analytical balance in accurately measuring milli and micro gram quantities.
This FDA advisory answers the question of depending on the built-in auto-calibration feature without external checks on performance. The FDA advices against solely relying on the auto-calibrate feature and to verify the auto-calibrate function with external checks. The reason for this is while not spelt out in the Q&A is simple: When you are dealing with quantities that are a tenth of a milligram, even a minor error in your analytical balance can have drastic consequences. The FDA recommends frequency of performance checks based on the degree of use. And also recommends verification of the auto calibration mechanism at least once a year.
If you need a template for quality assurance in for your Analytical Services organization then this manual from Columbia Analytical Services hosted on the EPA website should give you a comprehensive understanding of what all you need to cover in a QA manual. Of interest to us is the exclusive paragraph covering analytical balance care. This is in line with our own recommendations for maintaining the accuracy of your analytical balance. Analytical balance calibration needs to be a periodic activity and the procedure should be clearly defined in your quality manual.
Using an Analytical Balance requires paying attention to a few simple but extremely important details. In this video you are taken through the process of properly using an analytical balance starting from making sure that you keep the door closed to not using your hands when measuring the reagent out onto the weighing container.… Read the rest
If you dread the thought of analytical chemistry then this survival guide may be just the ticket you are looking for. The opening paragraph will set your mind at ease right away: “There is not a lot that needs to be memorized in analytical chemistry”. The author has one clear instruction to short circuit all your troubles: PRACTICE. As long as you are ready to practice regularly and turn in your assignments on time you will be able to beat the end of semester cramming.
The guide goes beyond pep talk and gives you actual tips that you can use in the lab. Example: weighing on an analytical balance is measured in grams while a chemical calculation is in moles and you will need to convert between the two. The author then goes on to illustrate the conversion with an example. Likewise he explains what you need to do when … Read the rest
Two-pan analytical balances are a dying breed. The cause is simple: the one-pan analytical balance with modern digital electronics has taken over its function in laboratories and jewelry stores almost everywhere. The reason is equally simple. They are delicate and the process of accurate weighing is time and labor consuming. Good ones can be very accurate, however. They are still used to calibrate test weights. Since their usage is shrinking, so is their availability. Soon enough, they will become collector’s items.