Development of the ELUENT4514

Our Challenge

When a need arose from long-time customers at Blue Ridge Analytical in Wytheville, VA, for a 0.45 M sodium carbonate/0.14 M sodium bicarbonate eluent concentrate for use with the AS22 Ion Chromatography column, we were excited to embark on a new challenge and assist them with their analyses. Blue Ridge Analytical is a VELAP-accredited laboratory, whose expertise covers a plethora of water testing services, including drinking water, wastewater, solids analysis testing, sample collection and pickup services, field testing, and treatment plant operational services. Blue Ridge Analytical had two requirements for the new product:

1. Match or exceed the quality of an eluent concentrate purchased from another supplier.
2. Offer the concentrate at an affordable price.

The Application

The AS22 Ion Chromatography column is widely used for anion analysis, due to its fast and efficient separation of common anions (see Figure 1). The AS22 column is designed specifically for use with US EPA Method 300.0(A) and 300.1, for the compliance monitoring of common inorganic anions in drinking water, wastewater, process streams, and scrubber solutions.

Figure 1 — Sample Chromatogram from an AS22 column with most common anion analytes. This column is extremely popular because it gives great separation of F^-, Cl^-, NO₂^-, Br^-, NO₃^-, PO₄^3-, and SO₄^2- in under 15 minutes.

When analyzing samples on this column, the instrument must continuously run diluted eluent while the instrument is turned on. Normal usage of one 250 mL bottle of eluent concentrate will allow the IC instrument to run for approximately 347 hours.

The Work for R&D

We wanted to manufacture the eluent concentrate not only for use by water testing labs following EPA Method 300.0(A), Blue Ridge Analytical in particular, but for our internal QC analyses as well. The primary requirement for the IV eluent concentrate was that it be of equal or better quality than products currently available on the market, and it was critical that we offer it at an affordable price.

The R&D team found that meeting the primary requirement of matching or surpassing the quality of alternate eluent concentrates meant that IV's ELUENT4514 would have to be completely free of all anion contaminants, specifically any nitrate or chloride. To guarantee this purity threshold, we had to ensure that all containers used during the manufacture and packaging of this product were entirely free of the latter contaminants.

R&D Findings

1. We have shown that the Inorganic Ventures' product is cleaner than the other suppliers' eluent (see Figure 2). The chromatogram of the eluent solution shows a flat line, even at an expanded conductivity scale. Noise is visible on this expanded conductivity scale.
2. Everything that touches the product must be cleaned thoroughly, to avoid contamination from hydrochloric and nitric acids that may be present in the laboratory. Strict deionized water (DI) leaching protocols must be followed to guarantee the purity of the product.
3. Improved work instructions are in place for our production departments, to ensure that no contamination takes place while making this eluent concentrate.
4. "IV's Eluent Concentrate performed very well, with low baseline conductivity and excellent peak resolution. As always, their customer service, technical expertise, and packaging are the best in the industry."

— Mychel Johnson, Blue Ridge Analytical

Figure 2 – IV eluent is the black line and the purchased eluent is the blue line. Peak at 11 min represents a contaminant. We believe the normal water dip at 2.5 min is inverted due to slightly less clean water being used in the purchased eluent.