LAMBDA 265 UV/Vis Spectrophotometer

This application note shows the versatility of PerkinElmer’s LAMBDA 265 and LAMBDA 465 PDA UV/Visible Spectrophotometers for quantification of the total phenol content in the wines, and also wine color to be measured to determine quality and any potential contamination.

The data shows the suitability of the LAMBDA 265 for producing rapid, high-quality spectra. It also shows that the instrument is able to measure the higher nanoparticle sizes, even though these scatter light to a greater extent due to the increased particle size and also settle out more quickly.

Chemical Oxygen Demand (COD) is used as an indirect measurement of the sum of oxidizable matter in water and measures the equivalent amount of oxygen required to oxidize organic compounds. Wastewater commonly contains organic compounds, as a result of industrial processes, which can oxidise in the presence of dissolved oxygen in the water. Low levels of dissolved oxygen can be detrimental to aquatic life but high levels may cause corrosion of metal pipes. It is important to use COD as an indicator of water quality. In this application, quantitative analysis of COD was performed using the LAMBDA 265TM UV-Vis spectrophotometer and Merck Spectroquant® COD mercury free cell test.

Nitrate ions react with 2,6-dimethyl phenol (DMP) in sulfuric and phosphoric solution to form 2,6-dimethyl-4-nitrophenol (Figure 2) which can be detected spectrophotometrically at 340 nm and is directly proportional to the nitrate-nitrogen concentration. The Merck test kit allows the concentration to be determined without the use of a calibration curve by multiplying the measured absorbance at 340 nm by a known factor. In this application, the quantitative analysis of nitrate was performed using the LAMBDATM 265UV-Vis spectrophotometer and Merck Spectroquant® cell test. The method used is analogous to DIN 38405-9.

Nitrite, occurs naturally in the environment as an intermediate of the nitrogen cycle through microbial decomposition of organic matter. However, nitrite contains nitrogen in a reasonably unstable oxidation state and readily oxidizes to nitrate. As a result, nitrite is present at considerably lower concentrations in ground and surface waters than nitrate1. Higher concentrations of nitrite are indicative of pollution by industrial wastewater or agricultural run-off. In this application, the quantitative analysis of nitrite-nitrogen was performed using the LAMBDA™ 265 UV-Vis spectrophotometer and CHEMetrics nitrite test kit.

Chromium (VI) ions react with diphenylcarbazide in weakly phosphoric solution. The product, diphenylcarbazone, is a red-violet complex which can be detected photometrically at 550 nm. The chromate cell test kit is suitable for the concentration range of 0.11 – 4.46 mg/L chromate allowing the concentration of chromium(VI) in a water sample to be determined without the use of a calibration curve by multiplying the measured absorbance at 550 nm with a known factor.

Ammonia-nitrogen (NH3-N) occurs naturally in groundwaters at concentrations below 0.2 mg/L and up to 12 mg/L in surface waters, as a result of decomposition of organic matter. High concentrations of ammonia in surface waters are toxic to aquatic life and are indicative of contamination from industrial effluent, raw sewage and agricultural runoff. Ultimately the pH value of the water determines whether ammonia-nitrogen is found as NH4+, NH4OH or NH3. 1 In this application, the quantitative analysis of ammonia-nitrogen was performed using the LAMBDA 265™ UV/Vis spectrophotometer and CHEMetrics ammonia nitrogen cell test.

In this application, the quantitative analysis of formaldehyde was successfully executed using the LAMBDA 265 UV/Vis spectrophotometer and Merck Spectroquant formaldehyde cell test kit. Principle Formaldehyde reacts with chromotropic acid in sulphuric solution to form a violet dye which can be detected photometrically at 565 nm. The formaldehyde cell test kit is appropriate for the concentration range of 0.10 to 8.00 mg/L formaldehyde allowing the concentration of formaldehyde in a water sample to be determined without the use of a calibration curve by multiplying the measured absorbance at 565 nm by a known factor.

Iron is rarely found in its elemental form in nature due to the high tendency of its ions, Fe(II) and Fe(III), to form oxygen and sulphur containing compounds. Concentrations of iron found in surface waters are typically no greater than 1 mg/L, unless contaminated by industrial effluents, whilst much higher concentrations are found in ground waters. The World Health Organization guideline for iron in drinking water is 0.3 mg/L as undesirable bacteria growth in water systems occurs above this concentration. In this application, the quantitative analysis of iron was performed using the LAMBDA 265™ UV/Vis spectrophotometer and CHEMetrics iron cell test kit.

In surface waters, phosphorus commonly exists in its phosphate form. A high concentration of phosphate in water is indicative of domestic waste, industrial effluent, and agricultural runoff which can lead to eutrophication. Eutrophication causes an increase in plant and algal growth, which decreases the dissolved oxygen in the water, often leaving the water uninhabitable to organisms. In this application, the quantitative analysis of ortho-phosphate was performed using the LAMBDA 265 UV/Vis spectrophotometer and CHEMetrics ortho-phosphate cell test kit.