SeraSub®
Liquid, Protein-Free Serum Substitute For use in Manufacturing Clinical
Chemistry and Immunological Standards and Controls. This product has
been proven effective for use with drugs of abuse and pregnancy (HCG),
eliminating the need for lyophilization while stabilizing the
product at room temperature. Recovery of analytes is close to
100%. Other uses include: Testing materials for urine
contamination; Used for diaper and incontinence product development;
and, car seat protection.
INTRODUCTION AND BACKGROUND
Human or mammalian blood products, such as human serum or plasma have been generally
accepted and widely used as matrices for calibrators and reference controls since the
advent of immunoassay techniques in the late 1970’s (Yellow, 1969), Typically, two to
eight calibrators are used in an immunoassay for the purpose of constructing a
dose-response curve (standard curve) by means of which the signal responses of reference
controls and unknown specimens can be calculated in terms of concentration or mass units
of a given analyte.
The ideal calibrator solution or matrix would be one whose composition is fully defined
and would exactly match the composition of the unknown specimen except for the unknown
analyte concentration. These conditions are rarely attainable in practice due to the wide
variability of normal and abnormal physiological specimen composition.
A reasonable alternative would be a matrix which approximately matches the typical
specimen composition, such as homologous human serum-based calibrators made from pooled
analyte-free human serum for use in the assay of human serum specimens. However, some
techniques utilized for removal of endogenous analytes ("striping") frequently
result in major alterations in the lipid and/or protein concentration and/or composition.
Affinity chromatography, in contract, selectively removes the analyte without
significantly altering the matrix. But, it is a costly procedure and is generally used
only for removal of endogenous analyte present in extremely low concentrations.
A second, but less optimal alternative would be the use of calibrator matrices
containing either a heterologous animal sera or human or bovine albumin fractions, in
appropriate buffer formulations. Such protein-based matrices (including gelatin-based
matrices as in U.S. Pat.#4,379,847) encompass virtually all calibrator formulations that
are currently used in commercial immunoassay kits for the analysis of human and animal
specimens. The undefined nature and lack of homogeneity of blood-based protein fractions
frequently require extensive and costly screening and evaluation of materials from
numerous sources.
SeraSub®, a newly developed, synthetic serum, offers the industry the optimal
alternative solution to the problems of matrix compatibility.
FORMULATIONS AND PROPERTIES
SeraSub® is a synthetic polymer in buffered solution which is physically equivalent to
serum and plasma with respect to:
Specific Gravity
Viscosity
Osmolality
SeraSub® does not contain any steroids, hormones, proteins, glucose, cholesterol,
bilirubin, or any other interfering analytes. Therefore, the matrix is compatible with
virtually all analytes.
SeraSub® contains a preservative which is both bacteriostatic and bactericidal.
SeraSub® contains no azide. Preparations are available at various pH’s ranging from
6.8 to 9.2.
SUBSTANTIAL EQUIVALENCY DATA
SeraSub® has been used to demonstrate its equivalency in several commercial products.
Among these are:
T4 Theophylline
Ferritin Phenobarbital
Digoxin THC
Cortisol Benzodiazepam
Testosterone Cocaine
Gentamicin Tobramicin
REGULATORY COMPLIANCE
SeraSub® is a synthetic serum for use as a component in preparing standards and
controls for in-vitro diagnostic tests. SeraSub® should be treated as any other component
or ingredient that has to be qualified prior to use. SeraSub®, when used in this manner,
does not require FDA approval for its use. A Device Master File for SeraSub® is pending.
SeraSub® is manufactured under the strictest quality control guidelines to ensure quality
and lot to lot uniformity.
USER’S GUIDELINES
Among the currently demonstrated applications for SeraSub® are:
Preparation of Calibrators (Standards)
Preparation of Controls
Use as the "O" standard for dilution studies (parallelism)
Use as a substitute base where needed
HOW TO PREPARE THE ANALYTE FOR SPIKING
Prepare a concentrated solution of the analyte to be spiked in an aqueous or organic
solvent. If an organic solvent is used, use the least possible amount of solvent for
solution and spiking purposes. This will assure that SeraSub® will remain effective.
|
RATIONALE
|
|
Human Serum
Or
Plasma |
|
SeraSub® |
|
YES |
Lot to lot variability |
NO |
|
YES |
Maintenance of large inventories required to minimize costly and time
consuming lot qualification |
NO |
|
YES |
Costly processing required to remove unacceptably high levels of
endogenous analytes |
NO |
|
YES |
Potential pathogenic or non-p[pathogenic microorganism contamination such
as hepatitis and/or HIV |
NO |
|
YES |
Aseptic or sterile technique and/or effective antimicrobial agents
required due to protein enhanced bacterial growth |
NO |
|
YES |
Possible contamination by infectious agents due to limitation of current
testing procedures |
NO |
|
YES |
Unpredictable analyte instability or diminished potency due to the
presence of variable levels of endogenous enzymes |
NO |
|
YES |
Widely fluctuating and high cost |
NO |
|
YES |
Unpredictable availability |
NO |
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