Context: A new low-cost sensor made up of metal oxide nanoparticles–reduced graphene oxide composite can detect formalin in fish at room temperature in a non-invasive way. 

Scientists developed a sensor to detect formalin in fish

• It is  developed by the Nanomaterials and Nanoelectronics Laboratory of Guwahati University, Assam.
• Source material: The formalin sensor uses  tin oxide-reduced graphene oxide composite.
• Process:  Graphene Oxide (GO) was synthesized through a process called wet chemical approach and tin oxide-reduced graphene oxide composite (rGO- SnO2) was synthesized by hydrothermal route followed by calcination of the obtained product.
• The sensor is  tested for adulterated fish at lab scale and on fish available in the fish markets of the Guwahati region.
• The research is supported by DST-PURSE (Promotion of University Research and Scientific Excellence).
• The research was published in the journal ACS Appl. Nano Mater.

Formalin in fish

• It is a mixture of  water and formaldehyde, which  is usually  used on freshly caught fishes to extend its shelf life and enhance its sensory attributes such as color.
• Food Safety and Standards of India (FSSAI) regulations of 2011, has banned  the use of formalin in food products.
• Example: Kerala pathologist traces high level of formalin content in fish bought at home when she tested the sample.
• A team of researchers from Nagaon College, Assam detected the presence of 15 per cent formalin in the consignment of  fish imported from outside the state.
• Health scare: It can cause conditions such as abdominal discomfort, vomiting, renal injury, etc.

Significance of the research

• Present sensors: They are either electrochemical-based or colorimetric-based( Colorimetric sensors are a class of optical sensors that change their colour when influenced by external stimuli.)
  • Both methods are invasive and expensive. 
  • Moreover, low-level and selective detection are two major issues with these sensors
• New Sensor:  It is seen as a breakthrough in the field of food adulteration and  will open new avenues for the development of affordable formalin sensor devices.
  • shows long-term stability with a low detection limit.
  • Is comparatively cheap
  • Non-invasive in nature
  • Can detect the presence of Formalin at room temperatures.

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News source: PIB