Heavy Metals Analysis
Heavy Metals Analysis
Trace-element analysis in water and wastewater requires contamination control, matrix-appropriate preparation, calibrated instrumentation and careful interpretation of reporting limits.
## 1. Define the measurand Clarify whether the objective is dissolved metals, total recoverable metals, total metals or a specific chemical species. These are not interchangeable. Filtration, digestion and preservation choices must match the intended measurand and approved method.
## 2. Common instrument families | Technique | Principle / use | Considerations | |—|—|—| | AAS | Element-specific absorption of radiation by free atoms | Flame and graphite-furnace configurations have different sensitivity and sample throughput | | ICP-OES | Optical emission from excited atoms/ions in an argon plasma | Multi-element capability; spectral and matrix interferences require control | | ICP-MS | Mass-to-charge measurement of ions from plasma | High sensitivity; requires careful interference control and contamination management | | XRF | Characteristic X-ray fluorescence | Often used for solids; detection capability depends on matrix, instrument and preparation |
## 3. Sample preparation Use suitable containers and method-defined preservation. Decide whether filtration is required before preservation. Digestion may be needed to release analytes from suspended or particulate material. Record reagents, batch, digestion conditions, final volume and dilution.
## 4. Calibration and quality control Include calibration blanks, multi-point standards, continuing calibration checks, method blanks, laboratory control samples, matrix spikes and duplicates as required by the method. Evaluate recoveries and precision against pre-established laboratory acceptance criteria.
## 5. Interferences and data review Consider spectral overlap, matrix suppression/enhancement, carryover, memory effects, contamination and analyte stability. Review internal standards, background correction, dilution and interference correction records where applicable.
## 6. Reporting Report analyte, fraction measured, method, units, detection/reporting limit, dilution factor, qualifiers and QC status. A result below the reporting limit is not equivalent to zero concentration.