mgL

mg/L stands for milligrams per liter and is a unit of concentration used to express the amount of a solute dissolved in one liter of solution. In dilute aqueous solutions, mg/L is numerically equivalent to parts per million (ppm), because 1 liter of water has a mass close to 1 kilogram. Thus, for practical purposes in water chemistry, 1 mg/L ≈ 1 mg/kg.

mg/L is widely used in environmental science, water quality, nutrition, and pharmacology to report concentrations of dissolved substances such as nutrients, contaminants, and minerals. Common examples include reporting levels of nitrate, phosphate, chloride, and dissolved metals in drinking water, wastewater, rivers, and lakes. Regulatory agencies often specify limits in mg/L or in related units, and mg/L can be converted to other units as needed for comparison.

Measurement and calculation: mg/L is a ratio of mass to volume. To determine mg/L, measure the mass of solute in milligrams and divide by the volume of solution in liters. Analytical techniques such as spectrophotometry, ion chromatography, inductively coupled plasma mass spectrometry (ICP-MS), and atomic absorption spectroscopy are commonly used to quantify substances at mg/L levels. For simple calculations, the concentration in mg/L equals the mass in milligrams divided by the solution volume in liters; to convert to micrograms per liter, multiply by 1000.

Limitations: mg/L reflects mass concentration, not chemical activity or bioavailability, and can be affected by solution density or temperature. It remains a convenient, widely adopted unit for reporting and comparing concentrations in liquid-based contexts.