5 Monivong Boulevard, P.O Box. 983, Phnom Penh, Cambodia accueil@pasteur-kh.org

Recommendations

-------------------------------------------

Conditions of Sampling, Packaging & Transportation

of Water Samples For Microbiological Analysis

 

These recommendations are in accordance of the following international standards:

- NF EN ISO 5667-3: Preservation and handling of water samples

- NF EN ISO 19458: Sampling for water analysis

- FD T90-520: Guide technique de prélèvement pour le suivi sanitaire des eaux en application du code de le Santé Publique (réglementation française)

1. General recommendations

  • The customer must make an appointment with the laboratory specifying the type of water analysis and microbiological parameters requested.

  • Written guidelines/procedures/methodology in Khmer and in English to collect the samples and recommendations for their storage/transportation are available in the LMMAE and could be requested by the customers at the bottles collection.

Sterile vials for single use polyethylene are available for samples with a capacity ranging from 500 ml, 1000 ml to 2000 ml. – these bottles are added or not of sodium thiosulfate to a final concentration of 20 mg /l.

  • Container labels should withstand wetting, drying and freezing without detaching or becoming​​ illegible. The labelling system shall be waterproof to allow use on site.

  • The exact information given in the sampling report and on the sample labels depends on the objectives of the particular measurement programme. In all cases, an indelible label shall​​ be secured to the sample container. For each sample, at least the following information shall be available.

— date, time and location of sampling

— sample number

— description of sample

— name of sampling personnel

— details of sample preservation, or fixation used;

— details of sample storage used

— any information regarding integrity and manipulation of the sample;

— any other information, as necessary

__ a unique identifier, traceable to sample date, location, and sample number shall appear on the label​​ of the sample container

__ all other information is supplementary and should be detailed in the sample report

2.​​ Conditions of transport and storage

  • Keep the time between sampling and analysis in the laboratory as short as possible. For drinking waters,

  • Analysis should ideally be started within​​ the same working day.

  • Cool samples — ideally (3-5) °C — during transport (e.g. by using ice packs or melting ice), unless otherwise stated in specific standards. Take care not to freeze them (except for viruses). Protect samples from Sunlight.

  • For samples​​ transported for periods over 8 h, it is necessary to monitor and record the temperature.

For samples transported for periods over 8 h, it is necessary to monitor and record the temperature.

Transport conditions shall be documented. Nevertheless be careful:

​​ not to put ice-packs in direct contact with the sample, as this can result in freezing it.

​​ to adjust the number, volume and position of ice packs according to samples number, mass and initial temperature.

Document the procedure required for longer transport times (8 h).

  • Warm and cold samples shall be transported separately.

3.​​ Delivery time of samples to the laboratory

  • The following table provides a chart of recommendations for the maximum period of delivery. The times listed are estimates: they depend​​ on the type of water, the physiological state of microorganisms (eg disinfection or not) or even the method of analysis.

  • In case of delay exceeding the recommended time of delivery, the results must be interpreted carefully and subject to control by another analysis.


 
 

Recommended (R)​​ &​​ acceptable (A) values​​ 

for maximum sample storage times including transport time​​ 

&​​ temperatures unless otherwise specified in specific standards

 

 

 

Maximum sample​​ storage time (h) including transport

 

Storage water temperature (°C)

 

Observation

R

A

R

A

 

 

General

Culturable microorganisms (22, 30 or 36 °C)

 

 

8

 

12

 

5+3 °C

 

 

Faecal indicators, vegetative bacteria

- E. coli​​ (and coliform bacteria)

- Enterococci

-​​ Clostridium perfringens​​ (vegetative cells)

 

 

 

12

 

 

 

18

 

 

 

5+3°C

 

 

Spores

-Spores of sulfite-reducing bacteria

(Clostridium​​ spp.)

 

24

 

72

 

5+3°C​​ 

 

Die-off observed in raw waters after 24 h

Viruses

Bacteriophages

 

48

 

72

 

5+3°C

 

 

Faecal pathogens

Salmonella​​ spp.​​ and other​​ Enterobacteriaceae

 

Cryptosporidium​​ oocysts

 

Giardia​​ cysts

 

 

12

 

24

 

24

 

 

18

 

96

 

96

 

 

5+3°C​​ 

 

5+3°C​​ 

 

5+3°C​​ 

 

 

 

 

Ambient

 

 

 

Other microorganisms

Amoebae

 

Pseudomonas aeruginosa

 

 

Legionella​​ spp.

 

 

 

Helminth eggs

 

24

 

8

 

 

24

 

 

 

48

 

96

 

12

 

 

 

 

48

 

72

 

1 week

 

5+3°C​​ 

 

Ambient

 

 

5+3°C​​ 

 

5+3°C

 

5+3°C​​ 

 

5+3°C​​ 

 

 

 

 

5-3°C

 

 

Ambient

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Sample stabilized at pH = 2