Product FAQ

I would like to use another company's kit to generate fragments for my fragment analysis run. Is this possible?

Answer

It is possible to use another company's kit. However, the vendor should be contacted to determine if they have protocol(s) for their kit(s) on the specific capillary electrophoresis (CE) instrument (specifically, the model you intend to use), and if they have reagents to run a spectral calibration or matrix run on the CE instrument with compatibility to the dyes that are part of the kit(s) in question.

Answer Id: E15247

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Product FAQ

I’m seeing other kit-related problems besides the “Standards incorrect” message with my Qubit assay. What do you suggest I try?

Answer

Here are several suggestions:

1.View the raw fluorescence value (RFU) for the standards under “Check Standards” or “Check Calibration”. Confirm that the values for the samples fall between the values of the standards (or a little above the highest standard). If they do not, the sample is out of the accurate range of the assay. Refer to the confidence ranges for each assay in the product manuals. The readout in the assay will be to 2 significant figures instead of 3 if the assay sample is out of the high confidence range.
To bring the sample into the accurate range, dilute the sample or use more or less of it (for example, 10 µL instead of 2 µL if the sample reads low).

2.Check for temperature issues: The assay is temperature sensitive and the fluorescent signal can decrease at higher temperatures. Temperature fluctuations between samples, or between samples and standards, can cause problems. Make sure that the buffer and Qubit reagent in DMSO are at room temperature. The buffer and Qubit reagent should be stored at room temperature, not in the refrigerator. Even after 2-3 hours at room temperature, buffer previously stored at 4°C can remain below room temperature. Make sure your samples and working solution are not too warm (including those straight from a centrifuge). Samples kept in the Qubit instrument too long or read multiple times can warm up. If you want to perform multiple readings of a single tube, you should remove the tube from the instrument and let it equilibrate to room temperature for 30 seconds before taking another reading. Also, do not hold tubes in your hand for very long before reading them in the instrument, since this can warm the sample, resulting in a low reading.

3.Ensure that you have prepared the Qubit working solution correctly (1:200 dilution using the buffer provided in the kit). Ensure that you have prepared the standard tubes correctly (10 µL of each standard in 190 µL of the working solution). Ensure that the tubes are filled with at least 200 µL (both standards and samples).

4.Ensure that the reagents and standards you are using are less than 6 months old, and that the standards have been stored correctly. The Qubit reagent stock solution should be protected from light as much as possible.

5.Ensure that you have selected the correct assay on the Qubit Fluorometer for the Qubit assay you are performing.

6.Ensure that the lid is completely closed when reading standards and samples.

7.Use recommended tubes (both so the tube does not obstruct the lid, and for optical clarity). Some types of tubes can have high autofluorescence that will affect the assay.

8.Did you enter the number of microliters of stock you pipetted into the working solution into the Qubit instrument? If so, the reading after giving the Qubit Fluorometer this information is the concentration of your stock solution. If you did not, the reading you got is for the concentration in the assay tube (the tube you put into the Qubit Fluorometer) and not your stock solution.

9.If you are comparing Qubit assay results to concentration obtained by UV absorbance, and the concentration based on absorbance is significantly higher, it may be because of nucleic acid or protein contamination. The Qubit assays are much more specific for DNA, RNA, or protein than absorbance readings.

Answer Id: E8149

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Product FAQ

I am getting inaccurate results/poor reproducibility with the Qubit Protein Assay Kit. Can you offer some tips?

Answer

Here are possible causes and solutions:

- The kit has expired or has been stored incorrectly: When properly stored, the components of the Qubit Protein Assay Kit should be stable for at least 6 months. Upon receipt, the kit can be stored at 4 degrees C. Components A and B can be stored at ambient temperature and Components C-E can be stored at ≤4 degrees C. Protect Component A from light. High degradation of the BSA standard 2 and 3 will result in a decrease in signal and a “Standards Incorrect” error warning upon calibration. Replace the kit.
- Old calibration data was used: Best practice is to prepare fresh calibration standards at the same time as the samples to take into account any changes in assay conditions.
- Incorrect tubes were used: Use the recommended Qubit Assay Tubes (Cat. No, Q32856) or Axygen PCR-05-C tubes. Other 0.5 mL thin-walled PCR tubes may work as well, but performance is not guaranteed. Avoid opaque tubes, as these will block the light path.
- Tubes contain bubbles or particulates that are scattering the light: Pipette gently to avoid the introduction of bubbles. Spin down tubes before measuring to remove bubbles or particulates. Spin down samples to remove particulates before adding an aliquot to the Qubit working solution.
- Inaccurate pipetting: The Qubit assay will accept 1-20 µL of sample, but pipetting very low volumes, especially 1-2 µL is typically very inaccurate, especially with viscous samples. If possible, pipette at least 5 µL for more consistent results.
- The temperature of the assay is changing: Make sure that the Component B buffer is at ambient temperature before use and avoid leaving the samples in the Qubit instrument or near an exhaust fan or other heat source that would warm up the samples.
- Contamination in buffer causing high background: High buffer contamination will show up as an increase in the relative fluorescence (RFU) of the background, measured with the standard tube 1 blank, and eventually will trigger a “Standards Incorrect” error warning on calibration. Replace the kit.
- Sample buffer contains detergents: Qubit protein assay is a detergent-based assay, utilizing an environmentally sensitive dye that fluoresces in the presence of detergents; therefore, only very low concentrations of additional detergents are tolerated in the assay, as listed in Table 2 in the manual (https://tools.thermofisher.com/content/sfs/manuals/Qubit_Protein_Assay_UG.pdf).
- Sample buffer contains other components that are affecting the assay: The Qubit protein assay is generally tolerant of reducing reagents, salts, free nucleotides, amino acids, DNA, and solvents. Table 2 in the manual (https://tools.thermofisher.com/content/sfs/manuals/Qubit_Protein_Assay_UG.pdf) lists acceptable concentrations for many common contaminants. If you have a contaminant you think is affecting the quantitation, then prepare duplicate standard tubes, and spike the contaminant into one set of tubes and run them as samples. If the effect is not too substantial, then spike the buffer into the standards when performing the calibration to account for buffer composition effects.

Answer Id: E15593

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Manual / Product Insert

Precision General-Purpose Water Baths Models 280, 281, 282, 283, 284, 285, 286, 288 Installation and Operation Manual

Version: FEB.2016
Catalog #
  • 2823(Discontinued)
  • 2824(Discontinued)
  • 2825(Discontinued)
  • 2826(Discontinued)
  • 2827(Discontinued)
  • 2828(Discontinued)
  • 2829(Discontinued)
  • 2830(Discontinued)
  • 2831(Discontinued)
  • 2832(Discontinued)
  • 2833(Discontinued)
  • 2834(Discontinued)
  • 2835(Discontinued)
  • 2836(Discontinued)
  • 2837(Discontinued)
  • 2838(Discontinued)
  • 2839(Discontinued)
  • 2840(Discontinued)
  • 2841(Discontinued)
  • 2842(Discontinued)
  • 2843(Discontinued)
  • 2844(Discontinued)
  • 2845(Discontinued)
  • 2846(Discontinued)
  • 2847(Discontinued)
  • 2848(Discontinued)
  • 2849(Discontinued)
  • 2850(Discontinued)
  • 2851(Discontinued)
  • 2852(Discontinued)
  • 2853(Discontinued)
  • 2854(Discontinued)

Manual / Product Insert

EASY-nLC Series Getting Started Guide Revision D

Version: FEB.2017

Manual / Product Insert

Manual: ABI PRISM 3100 22-cm Capillary Array for High Throughput Microsatellite and SNP Genotyping: ABI PRISM® 3100 Genetic Analyzer (English )

Version: 20 Jun 2007
Catalog #
  • 4359571
  • 4315832(Blocked)
  • 4322559(Blocked)
  • 4332345(Blocked)
  • 4357354(Blocked)
  • 4359570(Blocked)
  • 4359573(Blocked)
  • 3100-01-LSG
  • 3100-AVANT-LSG
  • 3100-AVANT-R-LSG
  • 4311588-LSG
  • 4315833-LSG
  • 4333302-LSG
  • 4333805-LSG
  • 4334785-LSG
  • 4337040-LSG
  • 4362989-LSG
  • 4362989R-LSG
  • 4362990-LSG
  • 4363006-LSG
  • 4363007-LSG
  • 4363014-LSG
  • 4363194-LSG
  • 4363196-LSG
  • 4363201-LSG
  • 4363202-LSG
  • 4363203-LSG
  • 4363204-LSG

Manual / Product Insert

TSQ Quantum XLS and TSQ Quantum GC User Guide Rev.B

Version: FEB.2016

Manual / Product Insert

User Guide: AmpFLSTR SGM Plus PCR Amplification Kit

Version: J
Catalog #
  • 4307133(Discontinued)

Product Literature

NanoDrop 8000 User Manual

Manual / Product Insert

Z´-LYTE™ KINASE ASSAY KIT – SER/THR 20 PEPTIDE

Version: 29 June 2006
Catalog #