How to Take and Ship a Sample: Seven Mistakes That Spoil an Analysis Result

The reliability of an analysis result starts with the representativeness and condition of the sample that reaches the laboratory. Even the most advanced instrument cannot produce a correct result from a spoiled or wrongly taken sample. Here are the seven most common mistakes in samples arriving at our laboratory, and their fixes.

1. An unsuitable container

Microbiological samples must be taken in a sterile container and chemical samples in suitable glass or plastic. A used water bottle or a jar washed at home spoils the result through contamination and residues. Use containers supplied by the laboratory.

2. Insufficient sample quantity

Each method has a minimum quantity. Food microbiology needs at least 250 g, drinking-water microbiology 500 ml and soil 500 g. An insufficient amount makes repeat analysis or verification impossible.

3. A broken cold chain

Microbiological samples must be transported at 2–8 °C. Samples left in a car boot or in the sun give falsely high results through bacterial growth. Use a cool bag and ice packs; for frozen food, do not let it thaw.

4. Exceeding the time limit

Water samples must be in the laboratory within 24 hours at most and most food samples within 24 to 48 hours. When shipping before a weekend, check the laboratory's reception hours.

5. Contamination

Not wearing gloves when sampling, opening and re-closing the package, or using an undisinfected tap or spatula contaminates the sample from outside. Pay attention to sterilisation and hand hygiene.

6. A non-representative sample

A sample from a single point in the top layer of a lot does not represent the lot. If possible take from several points and mix, or follow a sampling plan. This is very important for contaminants with non-homogeneous distribution such as aflatoxin.

7. Missing label and form

If the sample's name, batch, date and requested analysis are missing, there is a risk of faulty reporting. A label in permanent marker should be on every sample container and a submission form in the box.

To make it easy

If you wish, use our sampling service: our trained team comes to your site, brings suitable containers, records the temperature and documents the chain. For details see our sample acceptance conditions page.

A quick checklist

Is the container clean or sterile? Is the quantity enough? Are the label and form complete? Was the cold chain kept? Is shipping time within 24 hours? If you can answer "yes" to these five questions, your sample is very likely suitable for analysis. If you have a question, call us before sending; we give free advice on acceptance conditions.