WTW reagents

Many different tests are available for routine analysis in a wide variety of different applications. Depending on the optical system and the wavelength employed, photometer and test set make up a matched system with different specific advantages.

For use with the pHotoFlex portable photometers and photoLab portable spectrophotometers, test sets were designed to be straightforward. The low consumption LED optics allow the use of easy-to-use and cost-effective test sets, e.g. powder tests.

WTW continues to expand their reagent offering. Not only are new tests developed, but the usability of tests with differrent instruments is being continuously expanded. Due to the different photometer optics, the same test may yield different measuring ranges for different instruments. LED photometers usually have smaller measuring ranges for the same test.

Taking Measurements Correctly
Each concentration test is only accurate to within the linear absorption range of the instrument. At the limits of the measuring range deviations should be expected within the given tolerance. Therefore it is often important to repeat the measurement using a test set with a better suited measuring range.

WTW Reagent Specifications & Prices

Prices listed are for United States and Canada only. Call or e-mail us for pricing in other countries.
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Test Factor	Measuring Range	Cuvette (mm)	# of Tests	Order Code	Price	pHotoFlex	photoLab
Al Aluminum	0.020-1.20 mg/l	10,20,50,28	300	250425	$Call	Y	Y
Au Gold	0.5-12.0 mg/l	10,16	80	250436	$Call	Y	N
Ca Calcium	5-160 mg/l	10,20,16,28	100	250428	$Call	Y	N
Cd Cadmium	0.025-1.000 mg/l	round	25	250314	$Call	Y	Y
Cl Chloride	5-125 mg/l	round	25	250353	$Call	Y	Y
Cl₂ Chlorine	0.03-6.00 mg/l	round	200	250419	$Call	Y	Y
Cr Chromate (Chromium VI and Total Chromium)	0.05-2.00 mg/l	round	25	250341	$Call	Y	Y
Cu Copper	0.05-8.00 mg/l	round	25	250408	$Call	Y	Y
F Fluoride	0.10-1.5 mg/l	round	25	250365	$Call	Y	Y
Fe Iron	0.005-5.00 mg/l	10,20,50,16,28	1000	250435	$Call	Y	Y
K Potassium	5.0-50.0 mg/l	round	25	250407	$Call	Y	Y
Mn Maganese	0.01-10.0 mg/l	10,20,50	500	250442	$Call	Y	Y
NH₄ Ammonium	0.5-16.0 mg/l NH_4-N 0.6-20.6 mg/l NH₄	round	25	250329	$Call	Y	Y
NO₂ Nitrite	0.005-1.000 mg/l NO_2-N 0.016-3.29 mg/l NO₂	10,20,50	1000	250445	$Call	Y	Y
NO₃ Nitrate	0.10-3.00 mg/l NO_3-N 0.4-13.3 mg/l NO₃	round	25	250411	$Call	Y	Y
N_Total Total Nitrogen *	0.5-15.0 mg/l N_Total (120 °C, 1 hr)	round	25	250358	$Call	Y	Y
O₂ COD Chemical Oxygen Demand *	25-1500 mg/l COD (148 °C, 2hr)	round	25	252071	$Call	Y	Y
PO₄ Phosphate	0.5-25.00 mg/l PO_4-P 1.5-76.7 mg/l PO₄	round	25	250413	$Call	Y	N
Si Silicate/Silicic Acid	0.005-5.00 mg/l	10,20,50	300	250438	$Call	Y	Y
SO₄ Sulfate	5-250 mg/l SO₄	round	25	250414	$Call	Y	Y
* Thermoreactor required for digestion. Other tests available. Please contact us for more information.

Reagent-free Tests

FAU turbidity
(EN ISO 7027) Determination of turbidity

Turbidity is caused in liquids by the presence of undissolved substances. For undissolved finely dispersed substances the turbidity can be measured by measuring the reduction in the intensity of a beam of light when passed through the liquid, or by measuring the intensity of the scattered radiation.

A formazin solution, which must be freshly prepared and is not commercially available, is used as a reference solution. According to EN ISO 7027, all instruments may be used which satisfy the following requirements: Incoming radiation at 860 nm. The results are given in FAU units (Formazin Attenuation Units) when the radiation passing through is measured.

Coloration
(EN ISO 7887: 1994)

If a layer of several meters of pure water is observed in transmitted light it appears to have a weakly blue coloration. This coloration can alter in the presence of contaminants to form a wide range of colorations. Natural waters are usually colored yellow-brown by contamination with iron or clay particles or humic matter. (A green coloration can be produced by algae.) The "true" color of water is determined after filtration through a 0.45 ìm filter.

Normally most yellow-brown colored waters and the outflows of municipal sewage treatment plants can be measured at 436 nm. The outflows of industrial wastewater treatment plants show no sharp and distinctive extinction maxima. For the investigation of such water it is obligatory to measure at 436 nm (mercury line); the two other measuring wavelengths 525 nm and 620 nm can, depending on the filter used, vary slightly from these wavelengths. For discontinuous measurements the standard permits the use of filter photometers with a spectral bandwidth of < 20 nm for measurements at 436 nm, 525 nm and 620 nm. Thus, for example, instruments with 445 nm and 520 nm interference filters with a bandwidth of 10 nm are also suitable. For comparability with the standard, however, a spectrophotometer is required. The results are presented in m^-1 together with the measuring wavelength, spectral bandwidth, water temperature and pH.

In some publications the result is given in DFZ (translucent coloration number); which is identical with the m^-1 result.

(DIN ISO 6271: 19988)
Clear liquids, determination of the color number with the platinum-cobalt scale (Hazen color number, APHA color number). Spectrophotometers are mentioned as being suitable for measuring the stock solutions at 430 nm, 455 nm, 480 nm and 510 nm. According to the standard the measurement itself is carried out with a color comparator which allows a visual comparison.

Chrome-plating bath
Reagent-free measurement of the selfcoloration of an electroplating bath. 5 ml of the sample are pipetted into a 100 ml volumetric flask, filled up to the mark with distilled water and well mixed. 4 ml of the diluted sample are pipetted into a 100 ml volumetric flask, filled up to the mark with distilled water and well mixed. 5 ml of the 1:500 dilution are placed in a screw-cap glass and 5 ml 40% sulfuric acid are added. The glass is sealed and the contents well mixed. The solution is filled into a rectangular cuvette for the measurement.

Nickel-plating bath
Reagent-free measurement of the selfcoloration of an electroplating bath. 5 ml of the sample are pipetted into a round cuvette and 5 ml 40% sulfuric acid are added. The cuvette is sealed and the contents mixed. The solution is filled into a rectangular cuvette for the measurement.

Copper-plating bath
Reagent-free measurement of the selfcoloration of an electroplating bath. 25 ml of the sample are pipetted into a 100 ml volumetric flask, filled up to the mark with distilled water and well mixed. 5 ml of the diluted sample are place in a screw-cap glass and 5 ml 40% sulfuric acid are added. The glass is sealed and the contents well mixed. The solution is filled into a rectangular cuvette for the measurement.

WTW Reagent Options & Prices

Prices listed are for United States and Canada only. Call or e-mail us for pricing in other countries.
Terms and Conditions

ORDER NOW

Thermoreactor (PN# 1P21-2)
Thermoreactor for COD and thermal digestions for up to 12 reaction cuvettes, with 3 reactor temperatures, 7 fixed programs.

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