L3K^® liquid-stable reagents

Advancements With L3K^® Liquid-Stable Reagents Yield Improved Economies for the Clinical Laboratory

Over the past decade, the clinical chemistry laboratory has experienced a steady migration away from traditional dry-fill and lyophilized reagent systems to full liquid-stable formats.  Aside from the obvious convenience that a liquid-stable format features, the inherent benefits of this design also include 1) savings in time and labor by the removal of routine reagent reconstitution procedures; 2) savings in cost by the elimination of possible reconstitution errors and resulting waste; and 3) improved test turnaround time and efficiencies as instrument uptime is extended. All of these enhancements result in overall increased laboratory productivity. However, regardless of the conveniences offered by a liquid-stable format, the challenging and problematic issues relating to reagent shelf-life, reagent drift and on-board and calibration stabilities remain.

As a direct result of these challenges and to keep in step with prevailing trends within the clinical laboratory, Diagnostic Chemicals Limited (DCL) has introduced the L3K^® line of chemistry reagents, a significantly improved and unique line of liquid-stable reagents. The core technology behind these reagents is the amalgamation of a unique manufacturing process and proprietary technologies utilizing, among others, synthetic dye complexes, synthetic enzymatic cofactor analogs (particularly for NADH) and other distinctive components. 

This permits, in the vast majority of cases, the manufacture of a single vial, liquid stable reagent system.  Additionally, the L3K technology also positively impacts assay reaction kinetics, available wavelength selections, molar absorptivity and overall reagent system stability and performance.

To demonstrate the key advantages of the technology, one need only review the Carbon Dioxide (CO₂) L3K reagent system. Traditional methods for the determination of serum/plasma CO₂ concentrations, one of the most frequently ordered tests within the clinical laboratory, have either incorporated ion selective electrode (ISE) technology, or enzymatic/colorimetric reagent systems. Not surprisingly, the most common enzymatic/colorimetric reagent systems for CO₂ utilize NADH as the primary enzymatic cofactor.  Unfortunately, NADH is only truly stable in an alkaline environment and degrades rather quickly outside of this pH range, negatively impacting overall reagent stability.  Additionally, as NADH peaks at an absorbance of 340 nm, then rapidly drops off, it leaves only a narrow band of wavelengths, usually between 340 nm to 380 nm, accessible for accurate photometric readings by the vast majority of commercially available chemistry analyzers.

Conversely, the utilization of a synthetic NADH analog improves the overall performance of the CO₂  L3K reagent system for a number of reasons. First, the synthetic analog used demonstrates a superior stability at a neutral pH.  A neutral pH greatly reduces reagent CO₂ absorption from the air, thereby prolonging both on-board and calibration stability, with no observable reagent drift. Second, a neutral pH ensures the stability of other vital enzymatic components within the reagent, again extending overall reagent stability. Last, the absorbance curve of the reaction is expanded, permitting photometric readings from 340 nm to 415 nm, thereby allowing for increased flexibility in testing.

The current offering of L3K reagents available, along with their appropriate test methodologies, include ALT/SGPT (Kinetic Modified IFCC), Ammonia (GLDH), BUN (Urease),   Carbon Dioxide (PEPC), and Ethanol (ADH), with additional assays under active development.  L3K reagents are available in a wide range of operator-oriented packaging configurations, so regardless of laboratory size or workload, a packaging format is available that best fits testing requirements. The reagents feature an average shelf-life stability of 13 months, offer exceptional on-board and calibration stability and display superior performance characteristics with regard to accuracy, precision and linearity.  As L3K reagents are fully suitable for use on automated chemistry analyzers, a comprehensive number of instrument applications are currently available, including those for instruments most frequently encountered within the clinical laboratory.

In summary, all of the inherent attributes the L3K reagent technology offers combine to result in a reagent system demonstrating an unparalleled combination of on-board stability, calibration stability, shelf life and operator convenience.  Now actively producing reliable and accurate results in some of the industry’s most demanding facilities, the availability of L3K reagents serves to benefit the needs of physician office, hospital and reference laboratories alike.  Convenience, simplicity and enhanced reagent performance have been achieved without additional expense to the clinical laboratory.