This presentation gives a good overview of the analytical process. It starts by explaining about chemical analysis and the qualitative and quantitative analytical process. It then delves into the steps involved: sample preparation, separation, and measurement. Next, it gives a brief overview of the sample preparation and the separation step since the exact process can vary considerably depending on the type of analyte being analyzed. It then explains the different ways in which it measurement is done including the use of an analytical balance. It then gives an example of two different substances being analyzed to illustrate the difference in the exact processes used. It finally rounds up the discussion with a review of units of measurement and stoichiometry.
This infographic gives an overview of farm nutrient management plans. Essentially, this is a strategy to extract maximum return from fertilizers without degrading the quality of water sources available nearby. A basic nutrient management plan will include soil test reports, on-farm nutrient assessment, nutrient crediting (reducing your fertilizer use based on your on-farm nutrients), consistenty with the farm conservation plan (which includes soil conservation), manure inventory (calibrating your manure spreader with a platform scale), a manure spreading plan, and adherence to the 590 Nutrient Management Standard if you want to participate in federal or state cost-sharing programs.
Regulatory bodies are increasingly asking for uncertainty estimates in the measurements from testing and calibration labs. There is also a lot of confusion as to the correct approach to take when determining uncertainty for a precision scale. Devices like the analytical balance are especially confusing. This paper examines this problem. The primary issue is the inconsistency of terminology used. To compound that manufacturer specifications do not provide estimates of the uncertainty. The general literature on the subject cite several ways to estimate uncertainty which is highlighted in the paper along with a discussion on the advantages and disadvantages of the various methods for estimating uncertainty.
Quality Control (QC) is an essential part of maintaining the reliability of an analytical balance. This guide gives a good overview of the steps you must take to maintain your balance at optimal performance. The key ingredients in QC includes daily calibration, verifying accuracy with external ASTM Class 1 weights monthly, maintaining log books, recertification of the Class 1 weights annually before the certification expires, and annual professional servicing. The guide goes on to explain the steps you can take to verify the accuracy of the balance as well as corrective action to take in case it fails the accuracy test. It also offers tips on handling Class 1 weights, certifiying and recertifiying the weights, and other similar pointers that will help you keep your balance working at peak performance.
We’ve never had a good reason to feature sports on our blog before. But as they say (or don’t say!): Baseball’s time has come. Here is a very interesting discussion that explores the swing weight of a bat. The author frames in the problem thus: how is it that two bats of the same weight (within 0.2 oz of each other when weighed on a precision scale) have different apparent swing weights while two other bats of different weights (3 oz between the two) seem to have the same swing weight? Baseball fans am sure will find this fascinating. The short answer is the distribution of mass and the moment-of-inertia this causes. For the complete answer refer to the above link!
Here is a novel use of counting scales. Election ballot auditing ensures the accuracy, reliability, and security of election results. In this paper from UC Berkeley, they suggest a method of using ballot based auditing using counting scales versus the more popular precinct-based auditing. The main attraction to to ballot based auditing is the greater degree of statistical confidence for any set number of ballots that are counted. The main drawback though is the inefficiency in locating a specific ballot for auditing. The earlier methods used serial numbers for indexing the ballots. Here they suggest a procedure that will use counting scales and ballot weight to index a stack of ballots. Early results from these experiments indicate that this method could be a practical alternative giving results that is both statistically significant as well as compatible with existing hardware.
Microbiological analysis of public drinking water is a critical task. The health and even the lives of millions of people depend on the purity of the water. Consequently labs and analysts that work at these facilities have stringent EPA certification and approval requirements as spelt out in this manual. One of the critical pieces of equipment in an analytical lab is the analytical balance. The manual clearly details the care, use, and maintenance of the balance: annual service contracts are compulsory; monthly calibration checks with certified calibration weights are mandatory. Also, the certified weights should comply to appropriate ASTM or NIST standards with supporting documentation.
Here is an interesting question posed by a Grade 9-12 student. Essentially she is inquiring about the impact that a hot crucible will have on the mass when weighed on an analytical balance. The answers through the Ask a Scientist service are all over the place. Some give a definite yes that the hot crucible will have an adverse impact on the readings due to the air currents generated by the heat. Others are not so sure. The sanest advice to the budding scientist was to try it out for herself and to observe the results.
Earlier we’d blogged about quality standardization in waste water treatment facilities’ labs. This EPA handbook goes even deeper and provides you with guidelines for analytical quality control in the waste water labs. Note that the handbook is useful both for wastewater as well as for water labs. One particular area of concern is the care and maintenance of the analytical balance. This is important since the accuracy of all data in the analytical lab will depend on the accuracy of the balance. The handbook lists specific do’s and don’ts that will aid you in maintaining your balances. The information in this handbook is still valid even though the document is slightly dated (1979 to be precise). Thus, you will find mentions of the balance beam, the predecessor of the modern analytical balance. Those can be safely ignored unless you still have one of them in service!
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On the heels of our mustache weighing video we now bring you something better. The method to weigh a kiss using our Kern Precision Scales! These intrepid volunteers have donated their kisses and the Kern balance delivers the results right down to one-thousandth of a gram. Interesting observation: the weight of a kiss has no correlation to how much you weigh. Watch the video to find out more!… Read the rest