MERX Combination Total Mercury/Methylmercury System is a combination of the MERX-M Methylmercury System and the MERX-T Automated Total Mercury System.

The MERX-M Automated Mercury Systems is the world’s first commercial automated analytical system based on US EPA Method 1630 for methylmercury analysis. Around the world, numerous national environmental agencies and leading university have quickly embraced MERX as an easy-to-use, robust, and reliable system that delivers high quality data.

Methylmercury Methodology

Sample Preparation

Prior to analysis, samples are prepared as per normal methylmercury methodology, typically distillation for water (US EPA 1630), extraction for sediment or digestion for tissue.

Vial Loading

Prepared samples are added to 40 mL vials with Teflon® lined septa caps. Samples are buffered to pH 4.9, ethylated with the addition of NaBEt4, topped off with DI water, capped, shaken and loaded into the autosampler.

Software Setup

Sample information is entered into Mercury Guru™ software, settings are selected and then sample analysis begins. MERX does the rest!

Liquid Handling

As each vial is pierced, the liquid is automatically transferred via gas pressure to a purge vessel where N2 gas volatilizes ethylated Hg species to a Tenax® trap.

Trap Processing

The first trap is dried while another trap collects ethylated Hg species from the next vial. After drying, another vial is purged onto a third trap while the second is dried, and the first trap, now dry, is ballistically heated to thermally release the Hg species in an argon carrier gas stream.

GC Separation

The released Hg species are separated on a GC column and then thermally reduced to elemental mercury.

CVAFS Detection

Mercury is detected using the Brooks Rand Model III cold vapor atomic fluorescence spectrophotometer (CVAFS) with patented optics for enhanced sensitivity.

Data Processing

Mercury Guru™ software integrates the detector signal and calculates results based on calibration and sample volume information. QC results are automatically flagged based on user defined criteria.

Key Features

• Ultra-Low Level: All MERX system undergoes rigorous QC testing to ensure they achieve an instrument detection limit of <0.002 ng/L
• Quantifiable range of 5000x (0.005ng/L – 25 ng/L) providing a wide linear range
• Reduced carryover contamination – With the patent pending gas-pressurized liquid handling system, the purge gas not only transfers the ethylated sample to the purge vessel, but also continues to flow through the sample vial and transfer line to remove any residual volatile mercury compounds, thus allowing the next sample to be processed immediately without a rinse cycle.
• Sharper peaks – The patent pending ballistic trap heating releases the ethylated mercury species instantly, resulting in sharper peaks and improved GC separation.
• Fast – MERX utilizes a multiple trap configuration, such that all three traps are in use simultaneously at different stages in the analytical process, resulting in runs every 6.5 minutes or less.
• Less maintenance – With the pump-free MERX system, there is no pump maintenance or constant requirements for tubing replacement. MERX has only a few replacement parts, which are all easily accessible and designed for longevity. Trap sets average over 4000 runs and most other replacement parts last much longer.

The MERX-T Automated Total Mercury System for EPA 1631 provides the highest quality data while maintaining operational efficiency.

Sample Preparation
Samples are prepared by standard total mercury methodology (U.S. EPA Method 1631) to oxidize all mercury to Hg(II).

Vial Loading
Prepared samples are added to 40 mL vials with Teflon® lined septa caps. Samples are pre-reduced with the addition of hydroxylamine hydrochloride, and then reduced with stannous chloride, capped, and loaded into the autosampler.

Software Setup
Sample information is entered into Mercury Guru™ software, settings are selected, and then sample analysis begins. MERX does the rest!

Purging
Samples are purged directly in the autosampler vials using N2 gas to volatilize elemental mercury to the gold amalgamation traps.

Multi-Trap Processing
The first collection trap is ballistically heated to release and transfer the mercury to the analytical trap, which is in turn heated to release the mercury to the detector. Simultaneously, the second vial is purged onto the other collection trap to provide near continuous sample purging for rapid throughput.

CVAFS Detection
Mercury is detected using the Brooks Rand Model III cold vapor atomic fluorescence spectrophotometer (CVAFS), with patented optics for enhanced sensitivity.

Data Processing
Mercury Guru™ software integrates the detector signal and calculates results based on calibration and sample volume information. QC results are automatically flagged based on user-defined criteria.

Key Features

• Ultra-low level – instrument detection limit of <0.03 ng/L
• Wide linear range – quantifiable range of 5,000x (0.08-400 ng/L)
• Reduced contamination – The biggest challenge to performing quality ultra-low-level mercury analysis is avoiding contamination. MERX greatly reduces sample contamination in two key areas:
  • Carryover contamination – By purging samples in the vials, only gaseous elemental mercury is transferred from the vial through an inert transfer line to the amalgamation trap, vastly reducing carryover contamination. Most other systems struggle with carryover contamination due to the use of a common pump, transfer line, and gas-liquid separator.
• Atmospheric contamination – Utilizing sealed sample containers on the autosampler prevents atmospheric mercury from contacting the sample. Other systems have open vials, therefore requiring operation in a clean room type atmosphere. Reduced reagent consumption – Rather than requiring a continuous flow of reagents common to most other systems, MERX only uses the necessary amount of reagents to effectively reduce the sample, minimizing reagent and waste disposal costs.
• Less maintenance – In addition to syringe and peristaltic pumps being a huge source of cross contamination, these pumps generally require constant maintenance and tubing replacement. With the pump-free MERX system, these issues simply don’t exist.