Food & soil

Heavy metals in food and soil: why testing matters and how portable sensors help

VidyuthLabs · 14 October 2026

Heavy metals in water get most of the attention, but the same metals move from soil and irrigation water into crops, and from there into food. Testing soil and food is how that chain gets broken.

How heavy metals reach food

• Irrigation with contaminated water, including untreated wastewater near cities and industrial areas.
• Soil contamination from mining, smelting, industrial waste and some fertilisers and pesticides.
• Processing and packaging, such as contaminated equipment or adulterated ingredients.

Leafy vegetables, rice and some root crops can take up cadmium, lead and arsenic from soil and water. Fish and seafood can accumulate mercury.

The rules in India

Limits for metal contaminants in foods are set by the Food Safety and Standards Authority of India (FSSAI) under the Food Safety and Standards (Contaminants, Toxins and Residues) Regulations, 2011. Exporters must also meet the limits of the destination market, which are often stricter. In both cases, businesses need regular, documented testing.

Preparing soil and food samples

Unlike water, soil and food are solids, so the metals must first be brought into solution:

• Soil: dried, sieved and extracted with an acid or extracting solution. The extract is then measured.
• Food: digested or extracted to release metals from the sample matrix.

Sample preparation is often the slowest part of the test. Simplifying it is as important as the measurement itself if testing is to happen close to the farm or the factory.

Where portable electrochemical sensors fit

Once a sample is in solution, the same anodic stripping voltammetry used for water can measure lead, cadmium and other metals in the extract. A portable potentiostat with a disposable screen-printed electrode makes it practical to:

• screen fields before planting or before harvest,
• check incoming raw materials at a processing unit,
• run frequent spot checks and send only suspect samples to an accredited laboratory,
• keep a timestamped record of every test.

How VidyuthLabs approaches it

The AnalyteX portable potentiostat uses one instrument for every application. For soil and food, the NanoX sensor and the method change while the device stays the same. We are developing these applications with BITS Pilani, Hyderabad Campus.