With increased scrutiny of dairy products for excess nitrate and nitrite levels, it is important for measurements to be made accurately and effectively. The Flow Solution 3700 automated chemistry analyser from OI Analytical provides an automated answer that increases throughput without compromising accuracy, says the company.
The natural decomposition of organic materials in soils releases ammonia, which oxidises to form the inorganic ions nitrate and nitrite. These compounds are therefore both naturally occurring and present in the environment in both soils and groundwater.
However, nitrate is also found in fertiliser, often as potassium nitrate, which through run-off can contaminate drinking water supplies.
Though nitrates occur naturally and are essential for good health, contributing to blood pressure regulation and immune and nervous system health, excess amounts can cause birth defects and blue-baby syndrome (methemoglobinemia).
It is vitally important then that dairy products, particularly those likely to be consumed by expectant mothers, are tested for nitrate and nitrite levels.
It is also possible for both compounds to be introduced to milk and milk products such as infant formula, whey and powdered milk, during the manufacturing process itself. This is one of the reasons that dairy goods producers are under increased scrutiny with more regulations continually being placed upon them. Too high a concentration of these compounds has, in the past, caused milk shipments to be returned to suppliers.
Traditional methods for testing nitrate and nitrite levels are both labour and time-intensive. The Flow Solution 3700 automated chemistry analyser, from OI Analytical, a Xylem Company, offers an automated, safe and cost-effective alternative to traditional testing, says the cpmpany.
It uses cadmium reduction and flow injection analysis (FIA), which works by injecting a plug of sample into a flowing carrier stream, with in-line dialysis according to ISO 14673-3.
The inline dialysis is used to remove protein and fat, while the cadmium reduces nitrate to nitrite, which then reacts with sulphanilamide and N-(Napthyl) ethylenediamine dihydrochloride to give a red-coloured azo dye colorimetrically detected at 540 nm.
‘Nitrite-only’ can be detected by simply removing the reduction step, while simultaneous detection can be carried out using a two-channel analyser.
The FS 3700 automates ISO Method 14673-3, offering accurate results for milk and dairy products, including hard, soft and processed cheeses, while significantly increasing sample throughput and reducing labour costs.
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