Lab Testing Methods Explained for Consumers

What it tests: Metals and trace elements: lead, arsenic, cadmium, mercury, chromium, copper, zinc, selenium, and 60+ other elements simultaneously.

Sensitivity: Parts per billion (ppb) or even parts per trillion. The gold standard for trace metal analysis.

How it works: Sample is nebulized into a plasma torch at ~10,000 K, atomizing and ionizing all elements. Ions are separated by mass-to-charge ratio in a mass spectrometer. Each element has a unique mass signature.

When it is used: Water testing (EPA 200.8), supplement heavy metal screening, food contaminant testing, soil analysis, biological samples (blood lead levels).

Cost: $50-$200 per sample for a standard metals panel. Full multi-element scan $150-$400.

What it tests: Organic compounds in solution: vitamins, PFAS, mycotoxins, active pharmaceutical ingredients, artificial sweeteners, some pesticides.

Sensitivity: Parts per billion to parts per million depending on detector. LC-MS/MS (HPLC coupled with tandem mass spectrometry) reaches low ppt levels for PFAS.

How it works: Liquid sample is pushed through a column packed with stationary phase material at high pressure. Different compounds interact differently with the column, separating by retention time. A detector identifies and quantifies each compound as it elutes.

When it is used: PFAS testing (EPA 537.1 uses LC-MS/MS), vitamin potency verification, mycotoxin screening (aflatoxins in nuts/grains), pharmaceutical quality control.

Cost: $100-$300 per sample for standard panels. PFAS testing via EPA 537.1: $200-$500 per sample.

What it tests: Volatile and semi-volatile organic compounds: pesticides, herbicides, VOCs (benzene, toluene), PAHs, PCBs, residual solvents.

Sensitivity: Parts per billion. Extremely precise identification through mass spectral library matching.

How it works: Sample is vaporized and carried through a long coiled column by an inert carrier gas (helium). Compounds separate based on boiling point and interaction with the column coating. The mass spectrometer identifies each compound by its fragmentation pattern.

When it is used: Pesticide residue testing in food (multi-residue screens test for 200+ pesticides simultaneously), VOC testing in water, cannabis terpene and residual solvent analysis.

Cost: $100-$300 per sample for a multi-residue pesticide screen. VOC panels $75-$200.

What it tests: Surface elemental composition: lead, cadmium, mercury, arsenic, and other metals. Primarily used for solid materials, coatings, and screening.

Sensitivity: Parts per million (less sensitive than ICP-MS). Handheld units are less accurate than benchtop lab instruments.

How it works: X-rays excite atoms in the sample, causing them to emit characteristic fluorescent X-rays. Each element emits at unique wavelengths. Non-destructive -- the sample is not consumed or altered.

When it is used: Lead paint screening, jewelry and toy safety testing, soil contamination screening, recycling material sorting. Used by Lead Safe Mama for consumer product testing.

Cost: Handheld XRF analyzers: $25,000-$50,000 to purchase. Per-test lab analysis: $25-$75. Fast screening tool, not a definitive quantitative method for trace levels.

What it tests: Trace metals in drinking water and wastewater via ICP-MS. The regulatory method for compliance testing of lead, arsenic, cadmium, chromium, mercury, and other metals in public water systems.

Sensitivity: Sub-ppb detection limits for most metals. Lead detection limit typically 0.1-1.0 mcg/L.

How it works: Standardized sample preparation (acid preservation, digestion) followed by ICP-MS analysis. Method specifies quality control requirements: calibration verification, blank analysis, matrix spike recovery, and duplicate analysis.

When it is used: Municipal water compliance testing. Required by the EPA for Safe Drinking Water Act reporting. The method you want to see cited on a water brand's COA for heavy metals.

Cost: $50-$150 per sample at accredited labs. Results typically in 5-10 business days.

What it tests: Per- and polyfluoroalkyl substances (PFAS) in drinking water. Method 537.1 covers 18 PFAS compounds including PFOA and PFOS. Method 533 expands to shorter-chain PFAS.

Sensitivity: Low parts per trillion (ppt). Detection limits of 2-20 ppt for individual compounds, appropriate for the EPA's health advisory levels of 4 ppt for PFOA and PFOS.

How it works: Solid phase extraction concentrates PFAS from a large water sample (250-500 mL), followed by LC-MS/MS analysis. The extreme sensitivity required makes this one of the more technically demanding water analyses.

When it is used: Municipal water PFAS compliance testing. Bottled water PFAS screening. Well water testing near military bases, airports, or industrial sites where AFFF firefighting foam was used.

Cost: $200-$500 per sample. Full PFAS panels (30+ compounds) at the higher end. Limited number of labs are equipped for this analysis.