HPC Samplers / Testers

HPC Samplers / Testers for liquid testing

Quantitative, heterotrophic plate count samplers / testers with membrane filtration.

Water samples tested using Heterotrophic Plate Count agar generally grows an increased number of colonies. It detects slower growing species (e.g bacteria stressed by chlorine, heat or starvation) unlike nutrient rich agars that can suppress them.

These dipslides feature m-HPC culture media for the growth of oxygen requiring / tolerant bacteria. These samplers will recover healthy and stressed micro-organisms.

HPC samplers are more sensitive than traditional dipslides and are ideal for samples where the micro-organism concentration / target value is between 1 & 300 cfu/ml. This makes the samplers suitable for applications such as dental waterlines where the microbiological concentration limit guidelines are low (e.g 100-200 cfu/ml).

Bacteria, yeasts and moulds will grow with differing appearances:

Bacteria: colourless, cream, light yellow colonies. Translucent or transparent, circular or irregularly shaped.

Mould colonies: Fuzzy, whitish grey.

Yeast colonies: Opaque, satiny white or green colonies.

Please note these samplers are for liquid testing only. Long shelf life (up to 18 months) and no incubator required!

How to use

Collect Sample

Collect a sample in the 18ml sample chamber (fill up to the marked line).

Drop HPC Sampler into the chamber

Drop paddle into sample solution and close the paddle within the chamber.

Lay HPC Sampler down

Lay the sampler down on its side with the filter side facing down for 30 seconds. The pad on the paddle will absorb 1ml of liquid sample.

Empty Chamber

Empty the tester, discarding the sample liquid. Shake the paddle and chamber vigorously to remove excess sample droplets.

Incubate HPC Sampler

Place the paddle back within the chamber ensuring a tight seal. Lay sampler device down on its side again (with filter side facing down). Leave paddle to 'incubate' at room temperature. Healthy bacteria will appear in 48-72 hours and stressed bacteria in up to one week.

Count the colonies

Count the dots (colonies) and compare with the chart provided.

• Collect sample in the 18ml sample chamber. 
• Drop paddle into sample solution, close the paddle within the chamber. Lay sampler device down on its side with filter side facing down for 30 seconds. The pad on the paddle will absorb 1ml of liquid sample.
• Empty the tester, discarding the sample liquid. Shake the paddle and chamber vigorously to remove excess sample droplets.
• Place the paddle back within the chamber ensuring a tight seal. Lay sampler device down on its side again (with filter side facing down). Leave paddle to 'incubate' at room temperature. Please note, no separate incubator is required with the HPC sampler / tester. Stressed micro-organisms (such as those damaged by chlorine) will take longer to recover. Non stressed micro-organisms require room temperature 'incubation' (25 - 35 degrees C) for 48-72 hours. Stressed micro-organisms room temperature 'incubation' (approx 20 degrees C) for up to 7 days.
• Count the colonies on the pad. Counted colonies can be recorded as cfu/ml since the sample volume is 1ml. 

Reading the HPC sampler results

Colony Count	10	30	100
Example Image

Industries

• Drinking water
• Water treatment companies (industrial and drinking) 
• Laboratory water purification systems
• Dental
• Breweries
• Food / beverage
• Hygiene monitoring
• Swimming pools
• Chlorination systems

Information for Laboratory water testing applications

Example target values for microbial counts in water

The above example chart excludes Sterile Water, Water For Injectable, ultra pure water for semi-conductor industry.

Heterotrophic plate count target values for reagent grade water (based on guidance from ASTM D1193, NIH, INSPQ and NCCLS among others):

What is the difference between the HPC sampler / tester and your other dipslides?

There are a few differences. One is that our other dipslides are semi quantitative tools which means that when evaluating the results, the user counts the colonies e.g 12 and then compares this with the chart. In this case the chart would say that this is 10/3 (1000 cfu/ml) so 12 colonies equals 1000 cfu/ml.

The HPC samplers are quantitative tests. This means that if you count 12 colonies, the result is 12 cfu/ml. This is a more accurate way of testing as it is more in line with / equal to laboratory tests. The semi quantitative dipslide tests still offer a good guide of the level of micro-organisms in the sample. However, the quantitative HPC samplers offer more accurate results when testing samples with lower CFUs. The samplers would be ideal for applications where recommendations for micro-organism levels are low e.g dental DUWLs (100 - 200 cfu/ml), laboratory reagent grade water (10 cfu/ml).

So to recap, dipslides are semi quantitative e.g 12 colonies = 10/3 (1000 cfu/ml)

HPC samplers are quantitative e.g 12 colonies – 12 cfu/ml

The other differences are that the HPC samplers do not require a separate incubator and the HPC samplers have a much longer shelf life (up to 18 months compared to 6-8 months).

Additional Details

Product Reference : HPC

Internal catalogue reference : DS001-149

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