Water is a colorless and odorless liquid substance, present in a more or less pure state in nature, represents 80% of the composition of most organisms and plays a massive and decisive role in the realization of their metabolic processes. It is classified according to its state and salinity level. Natural water can contain a wide variety of impurities, which will be characteristic of the hydrological cycle you have experienced.

As humans become more dominant over nature, new needs arise, accelerating environmental degradation. This results in pollution of the water by harmful agents, which is relatively common. The migration of heavy metals from manufacturing, oil, petrochemicals, iron and steel, among others, and the growing problem of solid waste degradation in marine waters have led to an increase in pollutants.

Water contaminants are impurities that are harmful to the use for which they are intended. To determine the need and proper treatment technology, specific pollutants must be identified and measured. Spectrophotometric methods are the most commonly used to measure heavy metal pollution in water. They are based on the radiation produced or absorbed by the molecular or atomic species of interest. The principle of operation of these techniques is based on the comparison of the intensity of the light dispersed by the sample to be evaluated with that dispersed by the reference standard.

The spectrophotometer is an optical analysis instrument that projects a beam of light through a sample to determine, identify, and quantify the absorbance or transmittance of energy. The amount of light absorbed or transmitted is proportional to the concentration of the material. This difference is species-specific, which is why the equipment produces absorption spectra that are unique for each substance and are often used as a fingerprint. The spectrophotometric methods vary according to the working spectrum range, and may be of visible, UV and infrared spectrum.

Spectrophotometric techniques 

  Atomic absorption spectrophotometry

• Aluminum, in a buffer solution based on acetic acid, aluminum (selective aluminum reagent) forms with the metal a complex of red coloration, capable of colorimetric measurement at 525 nm.
• Lead, copper and nickel concentrations can also be determined.

UV spectrophotometry:

• Nitrates only in waters with low organic matter content, applicable at a wavelength of 220 nm.
• Hydrocarbons worked in the wavelength range 210-400 nm, using n-hexane as a standard.

Visible spectrophotometry

• Boro can be mixed with carminic acid to form a complex capable of colorimetric determination at a wavelength of 585 nm.
• Iron, using the orthophenantroline method based on the formation of a colored iron ion complex, which is capable of colorimetric determination at 510 nm.
• Manganese, visible at a wavelength of 525 nm, the sample can be prepared by the method of potassium periodate or ammonium persulfate, it is based on the oxidation of manganese to permanganate.
• Copper is capable of spectrophotometric determination by measuring at 540 nm. The oxalildihydrazide method is based on the formation of a complex between copper and oxalildihydrazide-acetaldehyde in a purplish color control solution at pH=9.3.
• Zinc can be determined by the ferrocyanide method, which is based on the formation of a colloidal precipitate of zinc ferrocyanide, capable of subsequent colorimetric determination operating at a wavelength of 650 nm.

Molecular spectrophotometry

• phosphorus can be detected by preparing the sample from an acid reaction between the dissolved phosphate anion and ammonium molybdate in the presence of potassium tartrate and antimony to form phosphomolybdic acid which is reduced by ascorbic acid, generating a blue coloration due to molybdenum and capable of colorimetric determination at a wavelength of 690 nm.

At KALSTEIN, we are BUILDERS , we have a wide range of equipment that will allow you to analyze the concentrations of various pollutants in water samples. We offer handheld, table, multi-angle, portable, dual-beam or single-beam desktop, visible spectrum or UV spectrophotometers. For more information, PRICES, BUY or SELL, visit our catalog HERE