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.

Laboratory Supplies: pH Electrodes Basics

pH electrodes are a basic laboratory supply for use in pH meters. Refer to the descriptions below to order or replace your electrodes.

The Electrode Pair

Sensing half-cell electrodes are the measuring portion of the electrode system and contain the pH-sensitive membrane. Reference half-cells electrodes provide the reference potential needed for pH measurement. Most of the electrodes in our catalog are combination electrodes that house both half-cells in a single probe.

Bulb Material and Design

The bulb is constructed of different types of glass, each with different properties.

General-purpose glass: various pH ranges, temperatures to 212ºF (100ºC) prevents Na+ error.

Blue glass: pH 0 to 14, temperatures to 230ºF (110ºC).

The bulb shape can be modified to provide a semi-dome for increased ruggedness, a spear tip for penetration applications, or even a flat surface.

Junction Types

Junctions can be categorized into three distinct types. Sleeve and annular (open) junctions are high-flow, and best in dirty and viscous samples. Ceramic and capillary junctions are medium flow, and ideal for everyday samples and most applications. Wick and fiber junctions are low-flow, and best for use with clean samples.

Glass vs Epoxy Body

Epoxy-body electrodes are impact resistant and are ideal for rough handling but should not be used at higher temperatures or for solvents. (Note: Even though the body of an epoxy electrode is plastic, the bulb will still be glass.) Glass-body electrodes withstand high temperatures, corrosive materials, and solvents.

Sealed vs Refillable

Sealed (also known as gel-filled) electrodes are easier to maintain than refillable liquid filled electrodes. However, they must be replaced when the fill material level is low. Refillable electrodes are long-lasting and provide a faster response.

Single- vs Double-junction

In combination electrodes, the reference junction allows H+ ions to pass freely between reference and sensing half-cells to complete the electrical circuit. A single-junction design has one place where the H+ ions pass between half-cells. The junction is located so that contaminants in your sample can also pass into the reference chamber, leaving the potential for electrode failure due to reference contamination. A double-junction design restricts the reference behind a second junction; making it twice as hard for reference contamination to occur.

View all pH electrodes.

Laboratory Supplies: pH Electrodes Basics

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