The metals lab at GBMSD analyzes a wide variety of samples including municipal and industrial wastewater, treatment process streams, sludges, surface waters, and sediments.  The samples are analyzed using atomic Absorption Spectroscopy, Inductive Coupled Plasma and Atomic Fluorescence methods.  The following metals are routinely analyzed by GBMSD: Aluminum (Al), Antimony (Sb), Arsenic (As), Barium (Ba), Beryllium (Be), Cadmium (Cd), Calcium (Ca), Chromium (Cr), Copper (Cu), Iron (Fe), Lead (Pb), Magnesium (Mg), Manganese (Mn), Mercury (Hg), Molybdenum (Mo), Nickel (Ni), Potassium (K), Selenium (Se), Silver (Ag), Sodium (Na), Thallium (Tl), Zinc (Zn), and Hardness As CaCO3.

Metals Analysis

Atomic Absorption Spectroscopy is a common method used to analyze samples for metals in many laboratories. Flame Atomic Absorption is a process where a sample is nebulized and introduced to a flame.  The atoms become excited and are absorbed and electronically measured. This method is capable of analyzing metals in the part per million (mg/L) range.

Graphite Atomic Absorption is a process where a very small sample (20 micro liters) is added to a graphite tube. The tube is electrothermically heated to the point of atomization, the atoms become excited and then absorbed and electronically measured. This method is capable of analyzing metals in the part per billion (ug/L) range.

Inductive Coupled Plasma is the main method used to analyze metals at GBMSD. A sample is nebulized and introduced into Argon plasma at 6000° K. The sample is then desolvated, vaporized, atomized and ionized. At that point the Segmented-array Charged-coupled device detector (SCD) separates atomic emission lines. The detection levels for metals using ICP methods can range from mg/L to ug/L.

Mercury

The GBMSD laboratory has four techniques for analyzing mercury.  Wastewater and industrial pretreatment samples are analyzed using a cold vapor atomic absorption technique (EPA 245.1).  Solids, sludges and sediments are analyzed using EPA 245.7 where results are measured in mg/kg on a dry weight basis.  Surface waters are analyzed using Atomic Fluorescence (EPA 245.7).  Final effluent is analyzed using the ultra low level EPA 1631 method.  The current detection limit for this technique is 0.2 parts per trillion (ng/L).