Contaminant Detection Assays

Two contaminant detection assay kits are available under the Threshold brand: Threshold® Immunoligand Assay (ILA) and Threshold® Total DNA Assay

Threshold Immunoligand Assay measures a broad range of analytes such as proteins, peptides, sequence-specific DNA and microorganisms for biopharmaceutical development and production. Samples can range from fermentation supernatants, samples from a purification process, and other biochemical preparations to serum or other bodily fluids. Assays can be developed using a sandwich or competitive format depending on the size and characteristics of the analyte to be measured.

Threshold Total DNA Assay quantitatively measures picograms of single-stranded DNA. Unlike hybridization techniques which require DNA probes or primers with a specific nucleic acid sequence, the Threshold Total DNA Assay measures DNA with broad sequence specificity. This enables the Threshold System to measure host-cell DNA as well as other DNA that might have been introduced during the biopharmaceutical manufacturing process. In addition, since the assay does not require sequence-specific probes or primers, it can easily be applied to different samples purified from different host organisms.

Latest Resources

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Quantitation of residual DNA in final product biopharmaceuticals using the Threshold Total DNA assay system. Assay validation and determination of detection limit

Application Note

Quantitation of residual DNA in final product biopharmaceuticals using the Threshold Total DNA assay system. Assay validation and determination of detection limit

The FDA recommends that all quality control tests used for biopharmaceutical product release follow current Good Manufacturing Practices (cGMP's) outlined in the…
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A phenol-free DNA extraction method

Application Note

A phenol-free DNA extraction method

A DNA extraction method was evaluated using a commercially available extraction kit for pretreatment of biopharmaceutical samples to be tested in the Threshold® Total…
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Sequence-Specific DNA Assay

Application Note

Sequence-Specific DNA Assay

Measurement of specific DNA sequences can be achieved using the Threshold® System. Biotinylated and fluoresceinated oligonucleotide probes specific to the target…
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Protein G contaminant assay

Application Note

Protein G contaminant assay

Protein G, purified from the cell wall of Group G Streptococci, is a 30,000-35,000 Dalton protein which binds to the Fc region of antibodies1 . This characteristic is…
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Protein A contaminant assay

Application Note

Protein A contaminant assay

Protein A, purified from the cell wall of S. aureus, is a 42,000 Dalton protein. It has four binding sites for the Fc region of antibodies of which only two sites may be…
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Optimizing the labeling of proteins

Application Note

Optimizing the labeling of proteins

The Threshold® Immuno-Ligand Assay (ILA) adapts reagents used in ELISA, RIA or radioreceptor assays for the Threshold System by covalently attaching biotin or…
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Contaminant human transferrin assay

Application Note

Contaminant human transferrin assay

Human transferrin is an 80,000 Dalton glycoprotein found in human serum that facilitates transport of iron between cells. The iron-poor form, apo-transferrin, combines…
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Contaminant host cell-derived protein assay

Application Note

Contaminant host cell-derived protein assay

Polypeptides other than the biological product of interest that are produced by the host cell during cell culture or fermentation (“host cell-derived protein” or “HCP”)…
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Contaminant BSA assay

Application Note

Contaminant BSA assay

Bovine serum albumin (BSA), a 63,000 Dalton protein, is a major constituent of bovine serum. Fetal calf serum containing BSA can be used in mammalian cell culture media…
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Technology of Contaminant Detection Assays

  • Threshold® Immunoligand Assay (ILA)

    Threshold Immunoligand Assay (ILA)

    Please click here to enlarge image.

    In the reaction stage, the labeled antibodies, the sample containing the analyte, streptavidin and anti-fluorescein/urease conjugate provided in the ILA Detection Kit are incubated to form a reaction complex. Since this binding occurs in solution, all molecules are maintained in their native conformation to assure accurate measurement of the analyte and 100% activity of the antibodies. In similar fashion, a reaction complex is formed in the Total DNA Assay when biotinylated single-stranded binding protein and anti-ssDNA antibody, conjugated to urease, bind without sequence specificity to single-stranded DNA. All assay components are included in the complete Total DNA Assay Kit.

    During the separation stage, the strong affinity of streptavidin for biotin is used to capture and concentrate the reaction complexes onto a biotinylated membrane by a filtration step. The Threshold workstation contains four 8-channel filtration units with the possibility of adding two auxiliary manifolds for a total simultaneous filtration of 96 samples.

    In the detection stage, the captured reaction complex on the membrane is placed into the Threshold reader which contains the substrate urea and the light-addressable potentiometric sensor (LAPS). Inside the reader, urea is hydrolyzed by urease producing a pH change in a microvolume of less than 1 μl. Urease activity from eight different samples is simultaneously detected by the sensor during a 90 second kinetic measurement. The extreme sensitivity, precision and reproducibility of the Threshold® System is due to the combination of the small sample volume with the low-noise sensor.

    Threshold® Total DNA Assay

    Threshold Total DNA Assay

    Please click here to enlarge image.

    In the reaction stage, the labeled antibodies, the sample containing the analyte, streptavidin and anti-fluorescein/urease conjugate provided in the ILA Detection Kit are incubated to form a reaction complex. Since this binding occurs in solution, all molecules are maintained in their native conformation to assure accurate measurement of the analyte and 100% activity of the antibodies. In similar fashion, a reaction complex is formed in the Total DNA Assay when biotinylated single-stranded binding protein and anti-ssDNA antibody, conjugated to urease, bind without sequence specificity to single-stranded DNA. All assay components are included in the complete Total DNA Assay Kit.

    During the separation stage, the strong affinity of streptavidin for biotin is used to capture and concentrate the reaction complexes onto a biotinylated membrane by a filtration step. The Threshold workstation contains four 8-channel filtration units with the possibility of adding two auxiliary manifolds for a total simultaneous filtration of 96 samples.

    In the detection stage, the captured reaction complex on the membrane is placed into the Threshold reader which contains the substrate urea and the light-addressable potentiometric sensor (LAPS). Inside the reader, urea is hydrolyzed by urease producing a pH change in a microvolume of less than 1 μl. Urease activity from eight different samples is simultaneously detected by the sensor during a 90 second kinetic measurement. The extreme sensitivity, precision and reproducibility of the Threshold® System is due to the combination of the small sample volume with the low-noise sensor.

Resources of Contaminant Detection Assays

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How can we help advance your next big discovery?

Our highly-qualified teams are on the frontlines with our customers, conducting remote or on-site product demonstrations, webinars, and more to help you solve your tough research challenges. How can we help you today?

I’d like to…

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