AAS (atomic absorption spectroscopy)

AAS stands for Atomic Absorption Spectroscopy, a laboratory technique for measuring the concentration of individual metals. The sample is atomised in a flame or graphite furnace, and the technique measures how much light of a wavelength specific to the target metal is absorbed by its free atoms — the absorption being proportional to the metal's concentration. It is a standard, well-established method for trace heavy metals such as lead, arsenic, nickel, cadmium, chromium, zinc, copper and manganese.

In air monitoring, metals are first collected as particulate on a filter, the filter is digested in acid, and the resulting solution is measured by AAS. The same technique measures metals in water and effluent samples, making it a dual-purpose method for both the air-quality and the effluent-discharge sides of a plant's compliance. It is a laboratory method requiring sample preparation, not a field reading.

For recyclers, AAS is the method behind almost every heavy-metal number in their compliance data — ambient lead and nickel against NAAQS, and effluent lead, chromium, cadmium, copper, zinc, nickel and arsenic against the discharge standards. Since heavy metals are the defining hazard of e-waste, battery and metal recycling (and appear in tannery and plating effluent), AAS-derived metal figures are central to these sectors' environmental reporting.

The practical relevance is to use an NABL-accredited laboratory for metal analysis by AAS (or ICP for multi-element work) on correctly collected and preserved samples, and to recognise that metal results are lab-based with a turnaround of days. For battery and e-waste recyclers, the same metal-analysis capability that demonstrates compliance also supports process control and value recovery — knowing the metal content of black mass, leach liquors and residues guides both treatment and recovery.