Explanation of the specification items -Detector tubes for dissolved substances in solution -

External appearance

The external appearance of the detector tube is briefly illustrated.

Measuring range

The range of the substance concentrations that can be measured with the detector tube.

Sampling time

The waiting time to read the detector tube.

Detecting limit

The lower limit of the substance concentration that the detector tube can detect. This minimal concentration can be recognized by a slight colour change at the entrance of the detecting layer.

Colour change

Indicates how the detecting layer of the detector tube will change its colour by the reaction with the target substance. This is shown in the form of:
Original colour → Changed colour

Corrections for water temperature

For detector tubes whose indications are affected ±10 % or more by the fluctuation of water temperature, the tube readings should be corrected.
Whether or not such corrections are necessary are indicated here.
The correction data, if necessary, is provided in the instruction sheets provided with the detector tubes.

pH value

The range of pH that the detector tube should be used.

Relative standard deviation

An indicator of the accuracy of the detector tube. It represents how the tube indications may deviate from their mean value in percentage:
Relative standard deviation= Standard deviation (σ)Mean value () x 100 (%)

Shelf life

The period that GASTEC will warrant the quality of the detector tubes, provided that they are stored under the prescribed conditions

Reaction Principle

The chemical reaction of the target substance with the reagent(s) in the detector tube is briefly stated.

Possible coexisting substances and their interferences

Substances that are liable to coexist with the target substance and their influences on the tube indications are listed here. The column "Concentration" lists the lowest concentration that may affect the indication ±10 % or more, or the highest concentration that is assured of no influence to such extent.
These concentration levels are expressed either as quantitative ratios of interferences to the target substance (e.g., ≥1/5, ≥2 times) or concentrations of interferences themselves (e.g., ≥100mg/l, ≤500 ppm). Where, ≥ reads" equal to or higher than" and ≤ reads "equal to or lower than" .The presumed influence by coexistence is given in the column "Interference" where the " + " sign suggests 10% or higher indication, the " - " sign expresses - 10% or lower indication, or "No" means no influence. "Bleaching" means that this interference will cause the reaction colour to be pale. For your reference, the column "Changes colour by itself to" is given to show how the interferences will change the colour of the detecting layer if they exist without the presence of the target substance. "No" represents that no colour change will be observed. The table of this interference substances primarily expresses the interference of each coexisting substance in the concentration range, equivalent to the concentration by some of the other coexisting substances mentioned from the main purposes of using this detector tube. Therefore, the test result may be given positive result by the other substance not listed in the table. If more precise information is needed, please contact us or our distributors in your territory.

Other substance (s) measurable with this detector tube (Correction Factor / Scale)

Detector tubes are primarily designed to measure specific substances. But it is also possible to measure other substances of similar chemical properties with the aid of a correction factor or a correction scale. A correction factor is a figure which is multiplied by the concentration interpreted form the colour starting on the detector tube. The correction may also be presented as a correction scale if the correction relationship is nonlinear. Please make use of the correction factor/ scale measuring range as a reference. Moreover, this factor may vary slightly between production batches. For a more precise factor please contact your GASTEC distributor.

Calibration method

The method that is used for calibrating the detector tube or testing its accuracy.