Frequently Asked Questions - FAQ

General Questions

Q. When my product arrived, the ice packs were melted. Can I still use my kit?

A. Yes. We ship our kits to you packed with blue ice using FedEx's Priority Service or DHL's Worldwide Express to minimize variations in environmental exposure and shipping times so our products arrive to you under the most ideal circumstances. However, Crystal Chem's kits are stable at room temperature for the duration of our shipments.

Q. Will my package arrive on the weekend?

A. We understand that your lab or work is not typically open on the weekend. We try to ship products so that they do not arrive over the weekend. For US customers, we typically don't ship products on Fridays unless you specifically request it.

Q. Can you ship to my country?

A. Yes. We generally offer our products worldwide and ship our kits globally. For options in your country, please contact us.

Q. Is the assay summary on the product page the actual protocol?

A. No. The summary protocols found online are designed to give an overview of the assay procedure. Please contact us if you are interested in reviewing a complete protocol. We'd be happy to email you a copy.

Q. My well plate is not large enough to hold the reagents needed for this assay, do you have one you suggest?

A. Yes.  A couple of our enzymatic assays use >350µL of total volume. For those kits, we suggest using larger volume plates such as Nunc item 469078 (strips) or 260836 (solid plate).

Technical Questions

Q. How many samples can I run with the kit?
A. The number of samples you can run varies by kit, and you should check the product page and protocol for each specific kit. In general, the ELISA kits come with a 96-well plate, and many of our assay kits contain enough material to run 96 tests. The number of tests per kit also includes any standards or controls that should be included, and we generally suggest that all samples should be run in duplicate to obtain the most reliable results. For example, a typical 96-well ELISA kit may come with 7 calibrators. The calibrators and controls use 14 wells to run in duplicate leaving 82 wells for samples. For duplicate determination, that means the kit can run 41 different samples.

Q. What type of samples can I use with the kit?
A. Each kit has been validated for specific sample types (ie, serum, plasma, urine, cell culture) as indicated on the product page. The kits may work with additional sample types when tested by the end user, but Crystal Chem has not validated sample types other than those listed. If testing other sample types, we recommend the use of additional controls to validate the results.

Q. I'm having problems with my ELISA, what did I do wrong?
A. Depending on the type of problem, there are a few typical causes. Please consult the chart below for the most common problems that apply to all the ELISA kits. If you are still having problems, please don't hesitate to contact us for technical support.

Problem Possible Causes Solution
High background Inadequate washing Wash wells as directed in the protocol including tapping the plate firmly on a clean paper towel between washes
  Incorrect assay temperature (too warm) Check protocol and incubation temperature
  Contamination Cross-contamination could have occurred by neighboring wells or when adding reagent. Use good transfer techniques and plate covers. Run blank samples to confirm reagents have not been contaminated. Substrate solutions should be clear prior to addition. Prepare fresh reagents as appropriate.
  Long delay before reading plate Read plate immediately after the addition of stop solution (or as directed in the protocol)
  Substrate reaction done in the light Incubate plate after substrate addition in the dark as recommended in the protocol
  Excessive incubation time Check protocol
  Incorrect reagent addition Verify that quantities of reagent added match the protocol
  Metal contamination Substrate or stop solution touched metal parts of pipettes or foil covering plate
Low or no signal Reagents incorrectly prepared Check protocol and dilution calculations
  Enzyme inhibitor present Sodium azide will inhibit the substrate reactions
  Missing, or insufficient, key reagent Check protocol, procedure, and volumes
  Insufficient incubation time Check protocol
  Incorrect assay temperature (too cold) Check protocol and incubation temperature
  Incompatible sample type Check protocol
  Reagents have expired Check expiration dates
  Wells dried out Cover plate during incubations
Large variations across samples Bubbles in wells Ensure there are no bubbles in well prior to reading plate
  Inadequate washing Wash wells as directed in the protocol including tapping the plate firmly on a clean paper towel between washes
  Poor reagent preparation or storage Ensure all reagents are well mixed with no precipitates and have been stored as directed
  Inconsistent pipetting Use good pipetting technique and add reagents in the same order for each step
  Contamination Usually a result of reusing a plate seal, not covering the wells, or when preparing reagents. Prepare fresh reagents as appropriate
  Edge-effects Ensure plate and reagents are at room temperature prior to addition, and incubate plate under consistent environmental conditions
Poor standard curve Inadequate washing Wash wells as directed in the protocol including tapping the plate firmly on a clean paper towel between washes
  Incorrectly prepared standards or dilutions Use good pipetting technique and verify dilution calculations or reconstitution volumes. Mix well.
Unexpected results Wrong wavelength for readout Check protocol and instrumentation
  Sample readings off-scale Check dilution and further dilute as directed in protocol
  Interfering reagents Check protocol, reagent storage, and mixing containers for likely suspects that may be cross-reacting with materials and reagents
  Improper storage of ELISA kit Check protocol and labels