Instrumentation advances improve metals analyses

Environmental NEWS - Spring 2009

Recent advances in instrumentation and accessories are revolutionizing the way trace metals are being analyzed at Lancaster Laboratories. These features allow for lower detection limits in difficult matrices. Samples that would typically be analyzed with high dilutions due to matrix issues are now being analyzed undiluted or with minimal dilutions. Highlights of the innovative new technologies being utilized by Lancaster Laboratories’ Metals Department are:

ICP-MS
Significant metals testing advances can be attributed in large part due to the advent of ICP-MS with collision/reaction cell and HMI (High Matrix Interface). The collision cell and HMI serve two unique purposes that work in tandem to achieve superior results in difficult matrices.

The HMI mainly serves the function of allowing higher TDS (Total Dissolved Solids) samples to be analyzed while minimizing matrix effects like signal suppression of the analyte and internal standard signals. The HMI operates by introducing a dilution gas (Argon) in between the spray chamber and plasma torch, effectively diluting the sample aerosol before it enters the plasma. This allows for improved matrix tolerance, significantly reduced drift and a significant reduction in the number of samples requiring dilution due to matrix induced suppression.

The collision/reaction cell primarily serves the function of preventing polyatomic ions from reaching the detector either through a collision or reaction mechanism. These polyatomic ions are primarily responsible for false positive results on a non-collision cell ICP-MS.

Use of the collision cell and HMI equates to lower reporting limits for clients due to the fact that most samples can be run without dilution and subsequent elevated reporting limits.

Lancaster Laboratories supports the analysis of water, soil and tissue by a variety of EPA methods.

ICP-OES
Lancaster Laboratories currently has five ICPs, including three new Thermo 6500 Series ICPs. All five systems are set up with high solids nebulizers that allow samples with high TDS to be analyzed. These nebulizers greatly reduce the amount of downtime due to high salts clogging the standard nebulizers. The Metals Team is also incorporating FAST autosampler technology, which both reduces total analysis time and significantly lowers the amount of sample introduced into the instrument, also reducing instrument drift and allowing for less frequent maintenance intervals. Both equate to an improved ability to complete client samples with less repeat analysis and greater speed. Lancaster Laboratories supports the analysis of water, soil and tissue by a variety of EPA methods.

Low Level Mercury
Lancaster Laboratories currently operates a Leeman Labs Hydra AF Gold+ Automated Mercury Analysis System for low level mercury analysis. This system utilizes gold traps for the preconcentration of mercury prior to release to the Atomic Flourescence detector, allowing for detection limits in the parts per quadrillion range for mercury. The Metals Team utilizes a custom enclosure with hepa-filtered air and keeps the enclosure under positive pressure to avoid potential mercury contamination from external sources such as particulate in the air.

Lancaster Laboratories offers this capability in support of EPA Method 1631E.

Mercury Cold Vapor Atomic Absorption
Lancaster Laboratories also supports the analysis of mercury in soil, water and tissue samples by EPA Method 245.1, 7470A and 7471A. Although detection limits are not as low as those offered by EPA Method 1631E, Mercury by CVAA offers detection limits in the sub-parts per billion range. All of this can be accomplished in about one minute per sample on the instrument. This instrument allows customers to meet low regulatory limits at an economical price.