What is the difference between an analytical balance and a precision balance?

An analytical balance provides readability of 0.1 mg or better, while a precision balance typically reads to 0.001 g or 0.01 g. Analytical balances include draft shields and are designed for highly sensitive measurements. Precision balances handle larger samples and are less affected by environmental conditions.

What readability do I need for my lab application?

You need a readability that is at least one-tenth of your smallest sample weight or required measurement increment. For example, measuring 100 mg samples may require 0.01 mg readability, while gram-level work may only need 0.01 g. Selecting higher readability than necessary increases cost without improving results.

Do lab balances need to be calibrated?

Yes, all lab balances require regular calibration to maintain accuracy. Calibration ensures measurements remain traceable to certified standards. Internal calibration simplifies this process by automating adjustments, while external calibration requires manual verification with certified weights. In regulated environments, calibration records must be documented and retained.

What is the difference between readability and repeatability?

Readability is the smallest increment of weight a balance will display. Repeatability is the degree of agreement between multiple measurements of the same mass, on the same balance, under the same conditions.

What is the best way to clean my balance to ensure accurate readings?

Inspect and clean before each use. A flannel cloth or soft brush works well for dusting and light cleaning. Use a non-abrasive cleaner for light spills, and a dry flannel cloth for glass parts. Set a regular maintenance schedule for deep cleaning to ensure optimal performance and instrument longevity.

Can vibration affect the accuracy of my balance?

Yes — even slight vibration from a heavy footstep can affect accuracy. Place the balance on a sturdy benchtop away from high-traffic areas such as hallways, elevators, stairways, and doors. If that placement is not possible, an anti-vibration table should be considered.

Analyzing Samples for Metals (Part Two)

Manufacturers with NPDES permits must detect and quantify specified metals on a regular basis. In part one, we detailed the process of metals digestion. What happens next?

The Process: Post Digestion Filtration

After digestion, samples are diluted to fill lines in digestion cups. To filter the sample, a FilterMate^®filter assembly is pushed through the sample and the detachable plunger is removed. The sample is now ready for analysis or to be capped for storage.

The Process: Metals Analysis

Next, samples are analyzed to determine which metals are present. The sample composition is assessed using one of the following methods of metals analysis:

Flame AA: There are very few Flame AA instruments in use. Flame AA analysis may not reach the detection limits required for water analysis. Standards can be an issue as some Flame AA instruments require the standard to be preserved in a certain way.
Graphite Furnace Atomic Absorption (GFAA): The graphite furnace vaporizes the sample and atomizes the analyte in this process of measuring concentration. Matrix Modifiers are used to optimize recoveries during testing. They help target the analyte and raise its vaporization temperatures, preventing the analyte from being lost during the pyrolysis step.
ICP / ICP-MS: Inductively coupled plasma-mass spectrometry detects metals at low level concentrations. In addition to this instrument, related items include sampler and skimmer cones, electron multipliers, spray chambers, nebulizers, and torches.

The Significance of Running Metals

Unlike other types of pollutants, there is often no visible indication of metals contamination. According to the EPA, all metals are toxic at some level and some metals are toxic in minute amounts. Between the biological effects of metals on wildlife and the adverse impact on human health, metals analysis is a crucial and necessary process in research, production, and environmental science.

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Analyzing Samples for Metals (Part Two)

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