General Questions
• We received our order, but could not find the protocols and MSDSs. Where can I find them? Answer: BioAssay Systems is going green. Printed protocols and MSDSs will no longer be included with kits. Starting January 1, 2018, protocols and MSDSs will only be available online at www.bioassaysys.com.
• Can your kits be used for diagnostic purposes? Answer: All our current assay kits are for research use only and may not be used for diagnostic purposes.
• How many tests can be run with one kit? Answer. The number of total tests can be found in the catalog number. For example, the QuantiChrom™ Creatinine Assay Kit (catalog # DICT-500) is sufficient for 500 tests in 96-well plate. The size of assay kits refers to the total number of assays in standard 96-well format. This total number includes the samples along with the required standards and controls (e.g. standard curves, sample blanks, etc) .
• Is the assay species-specific? Answer. Most of BioAssay Systems' biochemical assay kits are not species specific and have been tested with human, murine, rat, bovine etc samples. In rare cases the biochemical properties of enzymes from different species may require an adaption to the protocol, e.g. change in pH, before the assay can be used.
• What kind of samples can be used? Answer. Generally, our assays can be used with a wide variety of samples, including biological, food, beverage and environmental samples, provided a suitable sample preparation method exists. Typically the analyte of interest should either be in a clear liquid or easily extracted into a clear liquid, preferably aqueous. Most of BioAssay Systems' biochemical assay kits have been developed and validated with human and murine serum samples. Where indicated on the datasheet, the assays have also been tested with other samples, e.g. saliva, tissue, urine, etc.
• Where can I find the expiration date of my kit? Answer. Expiration dates vary depending on the specific kit. Please read the assay protocol or visit our website (https://bioassaysys.com) and search for the kit you are interested in. Expiration dates are calculated from the date of delivery.
• Do I need to use a standard or standard curve with each assay run? Answer. Yes, it is highly recommended.
• How can I fit standard curves that are non-linear? Answer. Determine the Sample concentration [S] by non-linear regression fitting with a single-site saturation binding function (ΔOD = a×[S]/(b+[S]). Use a nonlinear regression fitting program such as GraphPad Prism to determine the values for “a” and “b” from the standard curve (ΔOD = a×[Std]/(b+[Std]). With GraphPad Prism use the “One Site Binding (hyperbola)” equation, where “Bmax” is equivalent to “a” and “Kd” is equivalent to “b” in the saturation binding function. Once “a” and “b” are determined, the sample concentration can be computed with the following eauation: [S] = b × ΔOD/(a - ΔOD).
• Some of your assay kits are both fluorometric and colorimetric. Which method should I use? Answer. This depends on the availability of your equipment. Fluorometric assays are typically > 10 x more sensitive than colorimetric assays. This would mean that you can use much less sample if you use the fluorometric assay, which can be very desirable in cases where the sample quantity is limited.
• Can I store unused reagents for future use? Answer. Yes, unused reagents can be stored according to the assay protocol. Repeated freeze/thaw cycles of reagents should be avoided.
• Where can I find references of publications using your products? Answer. The citation literature can be found on our website at https://bioassaysys.com/citations.php. The citations are updated regularly for every product.
• What is the detection limit (LOD)? What is the difference between it and the limit of quantification (LOQ)? Answer. In analytical chemistry, the detection limit, lower limit of detection, or LOD (limit of detection), is the lowest quantity of a substance that can be distinguished from the absence of that substance (a blank value) with confidence. The detection limit is estimated from the mean of the blank, the standard deviation of the blank and some confidence factor. Typically, the LOD defined as 3 x standard deviation of the blank. The limit of quantification (LOQ) is determined similarly as for LOD, except that it is defined as 10 x standard deviation of the blank.
• Why are my readings different from the data on your assay protocol? Answer. The readings can be different depending on many factors: your instrument (spectrophotometer, plate reader) and accessories (filter or monochromator based), the type of plate (clear, white, or black) and its geometry (round well, square well, flat- or V-bottom) and accuracy of pipetting. It is therefore highly recommended to run the standards with your samples together in each assay run.
Equipment and Accessories
• I do not have a plate reader, can I use our spectrophotometer and cuvette instead? Answer. Yes. Our assays can be performed on all spectrophotometers using cuvette or on a plate reader with a microplate (e.g. 96-well plates). Most assays can be scaled to different volumes for cuvettes, 96- or 384-well format.
• How can I convert the number of tests from the microplate format to cuvette format? Answer. The conversion depends on the size of the cuvette and the final volume of the assay in 96-well plate. For example, with DICT-500, the final volume is 205 μL in 96-well format. For a 1 mL cuvette, five wells is equivalent to 1 cuvette. Thus, the number of assays in 1 mL cuvette would be 500 ÷ 5 = 100 assays per kit. Alternatively, if small volume cuvettes are used (e.g. this holds 200 μL volume), the same volumes used for 96 well plates may be used.
• What plates are recommended to use for the assays? Answer. For colorimetric assays, use clear flat bottom 96-well plates for optical density (OD) measurements. For example: Greiner catalog number 655101. For fluorescence assays, solid black plates are recommended (For example: Greiner catalog number 655209). For luminescence assays, use opaque white plates (For example: Greiner catalog number 655207).
• The assay protocol suggests reading at 550-620 nm, but my filter is 540 nm. Can I still run the assay? Answer. We generally recommend a wavelength range within which the assay will work according to specifications. We do not recommend to measure outside this given range because the sensitivity of the assay usually will be lower. In some cases, accurate measurement is impossible outside a narrow wavelength range.
• Which filter should I use to measure luminescence? Answer. It is not necessary to use a filter for luminescence detection with our assays.
Sample Treatment
• My sample is turbid. Can I still use it? Answer. All samples should be clear and free of precipitates or particles. If there are particulates, they should be removed by centrifugation (e.g. 14,000 rpm for 5 min) or filtration through a 0.45 μm filter.
• I can not run the assay today. Can samples be frozen? Answer. In principle, it is recommended to run assays on freshly prepared samples. However, most analytes are stable when stored properly (e.g. at 4, -20, -80°C or in liquid nitrogen).
• Should I use serum or plasma samples? Answer. Generally, a serum sample is preferred over a plasma sample because no anti-coagulants are present in the serum samples. However, for most of our assays, either serum or plasma can be used.
• How are cell and tissue samples prepared for assays if it is not described in the data sheet? Answer. Sample preparation methods may vary considerably depending on type of sample and analyte. A review of pertinent literature is recommended. The following is a general guideline which should work in most cases:
Tissue Samples. Start with 20-100 mg tissue, add 200-1000 μL ice-cold PBS. Lysis can be achieved by homogenization (10-20 passes in a Dounce homogenizer on ice) or by sonication (preferably performed in an ice-water bath). The degree of tissue lysis can be checked under a microscope. Centrifuge homogenate at 14,000 g for 10 min. Transfer the clear supernatant into a clean tube. It is prudent to run a pilot test of the sample at different dilutions. Choose a dilution with the readings in the detection range of the standard curve for further assays. Most samples can be stored at -80°C if not assayed immediately.
Cell Samples. Suspend about two million (2 × 106) harvested cells in 400 μL PBS on ice. Lysis can be achieved by homogenization (10-20 passes in a Dounce homogenizer on ice) or by sonication (preferably performed in an ice-water bath). The degree of cell lysis can be checked under a microscope. Centrifuge homogenate at 14,000 g for 10 min. Transfer the clear supernatant into a clean tube. It is prudent to run a pilot test of the sample at different dilutions. Choose a dilution with the readings in the linear range of the standard curve for further assays. Most samples can be stored at -80°C if not assayed immediately.
If a lysis buffer is to be used, it is recommended to first run an assay to test if components in the lysis buffer interfere with the assay. This can be accomplished by running two standard curves: one prepared in H2O (or buffer if the data sheet requires) and one prepared in the same proportion of lysis buffer that the sample will contain. If the two standard curves are the same, there is no interference and it is safe to use the lysis buffer. If there is a difference in the standard curves, the lysis buffer may still be used if the standard curve remains linear; however, the standard curve to be used for analyzing the lysate samples will need to be prepared in the lysis buffer.
• How much sample should I use for the assay? Answer. For an unknown sample, a pilot assay should be performed to assess the optimum dilution. Prepare a serial dilution of your sample and choose the dilution this lies with the detection range of the assay (ideally in the middle of the standard curve). Then dilute sample at this dilution factor and rerun the assay, multiply the results by dilution factor.
Ordering, Shipping, Receiving and Storage
• Do you offer free trial kits or discounts on kits for testing? Answer. In some special cases we may offer discounts for testing purposes. Please contact our tech support team at 510-782-9988 x 2. In general, customers are required to order their own kits for testing or evaluation.
• How can I order directly from your company? Answer. You can place an order by email, online, by fax (510-782-1588) or phone (510-782-9988 x 1). Orders are usually shipped out the same day.
• From the time of order, how soon can I expect to receive the kits? Answer. We use Fedex Express. For US customers, the standard is 2nd day air. Customer can request shipping by standard overnight (the next day by 3 pm) or priority overnight (the next day by 10 am). For international customers, please inquire by email or phone.
• Do you ship your products on ice? Answer. Some products are be shipped at ambient temperature, while others are shipped on ice pads or dry ice (this applies to kits with the first letter "E" in the catalog number, for example, ETGA-100).
• How can we purchase your products from abroad? Answer. We recommend you contact our distributor in your country or a country near you (https://bioassaysys.com/distributors.php). If your country is not listed, you could order directly from us. Please contact us (info@bioassaysys.com) before you place an order.
• What should I do when I receive the kits? Answer. Immediately open the kit and determine the proper storage conditions. Please refer to "Storage conditions" under KIT CONTENTS in the assay protocol. Store the kit components accordingly.
• What discounts are available? Answer. For purchases of more than five kits or bulk reagent, please contact our sales representative by email (info@bioassaysys.com) or phone.
