Selected examples of recommended storage conditions.

Sample storage

Often there is no choice but to store samples. It is a requirement of many experiments especially where the analysis cannot be carried out straight away. Unfortunately, if you store the sample incorrectly it will come out of storage different to how it was when it went it.

A blank look at… blanks

There are many definitions of a “blank”. The official definitions often say something like: a sample that includes everything that will be present in the samples of interest except the analyte of interest. However, this is not what the word blank is always used to refer to.

Electrical conductivity of some common solutions

Conductivity of a solution

Conductivity of a solution appears a very simple measurement. Probe goes in, number comes out. Simple? While a number certainly comes out whether that number has any meaning requires slightly more careful handling.

Exaggerated representations of the z and t distributions


To measure the uncertainty associated with a set of results you need to repeat measurements.

Change in theoretical uncertainty with the number of times (n) a single sample is analysed.

How many repeats?

When carrying out any experiment if you only measure two samples you will not know whether one or both are, by random chance, a long way from the ‘true’ value. The better way is to carry out the experiment 5-6 times.

The difference between accuracy and precision.

Accuracy and precision

Accuracy: how close to the “true” value you are (e.g. how close to your true weight your bathroom scales weigh you to).

Example control chart

Repeatable and reproducible

When you are starting out on any set of experiments it is important to know whether the results you achieve on one day will be the same the next. If your results vary daily due to the weather or are sensitive to your mood then you might want to alter your method. In scientific parlance “you need to ensure that your method is repeatable and possibly even reproducible”.

Kawaii signs

On a holiday to Japan I fell in love with all the amazing little pictures on signs. Here are just…

Rejecting data (Outliers)

Your data may not fit your pet idea, or even the generally accepted scientific theory, but that does not they are wrong.

TIC/TOC – measuring carbon

Meausring the carbon content of soils, sediments and rocks is a key measurement in geochemistry and other related sciences.