The first 96-well plate was created during an influenza epidemic in Hungary in the 1950’s. Dr. Gyula Takatsy developed the well plate alternative due to a shortage of pipettes, test tubes, and other supplies needed to perform titrations and serial dilutions. Dr. Takatsy crafted a 96-well plate manually out of Lucite as a substitute for test tubes. He then developed calibrated droppers to be used with the well plates in what he referred to as a “micro method” for performing titrations and serial dilutions on a smaller scale. This original prototype is still the basis for laboratory use of multi-well plates today. Analytical methods have been developed on a smaller scale specifically with these plates in mind, and many discoveries have been made using the 96-well plate.
A well plate is an alternative option to using individual vials or tubes when performing various analytical methods including liquid chromatography applications. Well plates are also known as microplates, microwells, microtiters, or multiwell plates. They are flat plates that contain multiple tiny wells; one of the most common plates is the 96-well plate, which as you may have guessed contains 96 wells. The plates are typically made with polystyrene and are rectangular with a 2:3 ratio in size, and the volume of the wells can vary from several nanoliters to several milliliters. Polystyrene is also resistant to and compatible with organic liquids and solvents. Certain plates may also be made of glass for certain analyses.
The 96-well microtiter plate is designed in an 8 x 12 format. Each microwell has standard markings so the user can identify each unique well. The rows are labeled A-H, and the columns are numbered 1 – 12. One of the benefits of the 96 well plates is that they can be used manually or with a multiwell compatible autosampler. The microplates have multi-faceted uses in biological and chemical laboratories, and the plates offer many advantages when used by researchers and technicians.
When compared with the option of using vials, multiwell plates are typically preferred by laboratory technicians because they save time; there is no crimping of vials and no handling of vials, so all wells can be filled consecutively with no interruption to handle equipment. Sample isolation and preparation are typically the most time-consuming elements of analytical methods. The plates are low in cost and do not require the same reagent use when compared to using vials. In addition, methods such as ELISA (enzyme linked immunosorbent assay) use microwells as a standard laboratory research tool. The ELISA method is commonly known to scientists and is used frequently in medical diagnostic testing in humans and animals. ELISA tests for antibodies using color change to identify a specified antigen in a liquid or wet sample. Microtiter plates are commonly found in chemical and pharmaceutical laboratories as well as in life science applications: biology, virology, serology, and microbiology laboratories.
There are several variations of microplates, so the use of the plates must be known prior to selecting the appropriate plate. Pigmented variations are available for optical absorbance and luminescence detection (white pigment) and fluorescent biological assays (black). The white pigment allows for easy identification of luminescent signals and prevents crossover from one well to the next, as the black pigment does for fluorescence. Transparent plates can be used for colorimetric assays and for cell culture and cell storage. The shape of the 96 well plates also varies. Well shapes can be C-, F-, U-, or V-shaped, and each may have a specific filter depending on method requirements. The surface can be non-treated, or it can be treated for immunological, and cell culture plates. Organic solvent extraction can also be performed in the 96-well plates in preparation for liquid chromatography analysis.
Multiwell plates are used in a multitude of chromatographic analyses. These plates can be used for liquid or solid phase extractions and reverse phase chromatography in conjunction with LC (liquid chromatography), HPLC, (high performance liquid chromatography) and/or MS (mass spectrometry). Various films and seals, including heat seals, can be used in conjunction with the 96-well plates to perform the required extraction, separation, or relevant chromatographic analysis. The high throughput allowed by utilizing the microwell plates is beneficial particularly when the volume of samples to be analyzed is high. The plates work with automated, semi-automated, or manual chromatography laboratory procedures.
Various techniques and methods have also been developed with the multiwell plates in mind as alternatives to standard column chromatography. Dry chromatographic matrices, filters, and column loaders have been implemented in many laboratories to perform chromatography analysis using multititer plates. Organic liquids and solvents can be analyzed using these plates as well. The microplates for chromatographic analysis are compatible with and resistant to organic solvents and can be sealed for separation and for autosampler analysis. Preparation of organic samples including filling and sealing, is typically quicker using microplates than with vials. In addition, smaller sample volumes and aliquots are required when using multiwell plates. Due to the time savings allowed by microplates, an increased number of samples can be processed and analyzed.
A 96 well template is a useful tool that can be used as a reference for the 96-well plate. Different templates range in their complexity. A template is a chart or excel sheet that helps the analyst identify each sample by row and column combination, so each sample has a unique identifier and location. More complex spreadsheets can be used with multiple formulas and DNA sequence codes. Various formulas can be used for calculation of sample results, or within a method to identify aliquot size and method requirements for each step of the process. The 96-well template is an easy way to document the experiment or test and is used in conjunction with mutiwell plates. Many different examples to templates are available online, and most can be downloaded for free. Adjusting the template to your own specific testing is another time-saving option when using the microwell plates in the laboratory.