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The VACUettes® Auto-Dilution Method

High Range Visual Colourimetric Analysis

Tip Contact • Snap Tip • Mix • Compare

Hold the ampoule in a horizontal position while the capillary tip contacts the sample (Step 1). The capillary effect completely fills the capillary with a premeasured amount of sample solution.

Immerse the capillary end of the ampoule into the diluent (e.g. deionised water) and snap the tip of the ampoule. The correct volume of sample and diluent are automatically drawn into the ampoule where they mix with the reagent (Step 2).

Tilt the ampoule back and forth, mixing the contents of the ampoule (Step 3). In two minutes or less, compare the colour change in the ampoule with the colour standards in the round or flat comparator to quantify the results (Step 4).

Why VACUettes?

VACUettes Test Kits have a number of advantages over traditional visual (non-instrumental) water testing kits.

Minimise Dilution Errors

For highly concentrated samples, the part of a test procedure most likely to introduce errors in traditional test methods is the dilution step. Conventional dilution methods, particularly when carried out in the field, may introduce inaccuracies into test procedures. CHEMetrics VACUettes are designed for highly concentrated samples. They employ a patented auto-dilution feature that eliminates the need for a time-consuming and error-prone preliminary dilution. As a result, the entire test takes only 2 to 3 minutes, with a rate of accuracy comparable to a standard volumetric procedure.


CHEMetrics patented, self-filling ampoules simplify and speed up water testing procedures. They eliminate the potential inaccuracies associated with manual sample and reagent volume measurement in the field. There is no measuring or mixing of reagents required. The chemical reaction is contained within the ampoule so it is safer. more

Like-for-Like Comparison

Traditional water test kits often use a printed colour chart which may not exactly correspond to the colour developed in the test tube. Test strips in particular may only correspond to the colour chart in certain parts of the test range.

CHEMetrics ampoule-based comparators allow for a like-for-like comparison between the test amouple and the colour standard, enabling more consistent and accurate test results to be obtained than traditional methods. Click left to view a video or read this article for more detailed use of a colour comparator.


VACUettes ampoules are designed for maximum simplicity and accuracy. As with CHEMets, each glass ampoule is 7 mm in diameter, 100 mm in length, with a tapered, pre-scored tip, but with an capillary tip attached to the tip of each ampoule; colour forming reagents are vacuum-sealed inside.

Kits include 30 ampoules, comparator(s), accessory solution(s) (when necessary), sample cup, and instructions. Safety Data Sheets (SDSs) are available here. Refill packs of 30 ampoules and accessory solutions are available separately. Most comparators have a 2-year shelf-life.

Analyte Range

Please see the Visual Products page for a complete list of available VACUettes test kits.