Zinc Test Kits

CHEMetrics offers instrumental test kits employing the well-known Zincon reagent to deliver sensitivity and accuracy within two minutes or less. Based on CHEMetrics patented Self-Filling Reagent Ampoule technology, Vacu-vials offer analysts a digital read out. Each ampoule contains pre-measured reagent for a single test. Simply snap the ampoule directly in a sample to draw in the correct volume of sample then measure the ampoule in any photometer or spectrophotometer that accepts a 13mm round cell. Premixed. Premeasured. Precise. Each kit contains 30 tests.

The Zinc Vacu-vials test kit K-9903 can be used with a Hach DR900 Colorimeter in conjunction with the CHEMetrics DR900 Vacu-vials® Adapter, Cat. No. A-0215. No endorsement by Hach Company is implied or intended.

Zincon Method

CHEMetrics' method determines soluble zinc in drinking water and wastewater. Zinc reacts with the reagent zincon in a buffered alkaline solution to form a blue complex. Interference from other heavy metals can be eliminated by the addition of cyanide. However, for safety, cyanide has not been included in the reagent formulation. Results are expressed as ppm (mg/l) Zn.

Shelf Life: although the reagent in the ampoule is stable, the indicator solution has an ten month shelf life from date of manufacture. We recommend stocking quantities accordingly.

References:
APHA Standard Methods, 22^nd ed., Method 3500-Zn B- 1997.
ASTM D 1691-84, Zinc in Water, Test Method A.

Technical Data Sheet

Applications

Zinc is a stronger reducing agent than chromium or copper providing an effective protective coating for steel (galvanised coatings and cathodic protection), in microelectronics, and is useful as an alloying agent, for example, brass, commercial bronze, nickel silver and aluminium solder. Zinc salts are useful in passivation processes in cooling water treatment and zinc plates are sometimes used to reduce corrosion in boilers. Zinc monitoring is necessary for maintaining effective corrosion control from zinc-based water treatment programs in open re-circulating cooling systems. Zinc oxide is used in pigment paints and in rubber production as a catalyst. Zinc is often used in place of lead for environmental and safety reasons.

Zinc is primarily mined from sulphidic zinc ore deposits. Refinement and smelting of such ores produce metal-rich slags. Historical mining dumps can leach zinc and industrial effluents can raise zinc levels in river water and soil. Untreated effluents can raise levels as high as 20ppm, but can be significantly lowered with proper sewage treatment. Wastewater effluent from metal plating facilities and discharges from the power generation industry are monitored for zinc concentration in order to minimise its adverse impact on the aquatic environment.

The USEPA has established a Maximum Secondary Drinking Water Standard of 5 mg/l for zinc. The EU Drinking Water Directive does not have a standard for Zinc levels in drinking water. The WHO has advised that levels above 3 mg/l may not be acceptable to consumers. At higher concentrations, zinc can impart a bitter mineral flavour and medicinal taste and cause turbidity in potable water. Testing for zinc in drinking water is necessary to maintain a high-quality product. Measuring zinc is a low-cost way to maintain quality.

What is Zinc?

Zinc is a transitional metal in the periodic table with an atomic number of 30 and with the symbol Zn. It is a brittle, gray metal at room temperature, and oxidises much slower than other metals. It is diamagnetic. Zinc has a single oxidation state, +2, similar to magnesium, and has 5 isotopes. Zinc deposits are present in much of the earth’s crust, most commonly in association with base metals like lead and copper in ores, and is thus present in freshwater and seawater as well. Zinc is an essential dietary element for humans and is the second most abundant trace metal in humans after iron. Elevated levels of zinc in natural waters as low as 2 ppm can negatively impact normal oxygen transport in the blood of fish. Elevated levels of zinc in soils over 500 ppm can interfere with plant mineral absorption.