Laboratory Unit Operation (LUO) concept

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Authored by: Steven D. Hamilton

A sequence of common laboratory steps or functions that when combined become a "unit" operation is referred to as a Laboratory Unit Operation (LUO).[1] These become the building blocks for all laboratory procedures. LUO's can be split into three main categories, each with many subcategories:

1) Sample Transport: The movement of a sample from one stage of the experimental process to another. Common transport mechanisms are:

2) Sample Processing: The experimental treatment of the sample.  Common processing LUO's include:

  • Weighing: Quantative measurement of sample mass, including taring the sample container, open/closing the balance door and recording the weight data.
  • Manipulation: The physical handling of laboratory materials.  This includes capping, crimping, labeling, sealing, reagent addition, the handling of consumables and the movement of objects such as balance doors and centrifuge lids. 
  • Separation: Includes solid phase extraction, liquid/liquid extractions, precipitation, filtration and centrifugation
  • Conditioning: Modifying or controlling the sample environment.  Includes mixing, shaking, vortexing, heating, cooling and atmospheric blanketing.
  • Grinding: Reduction of sample particulate size

3) Data Collection & Handling: Recording, analyzing and storing the date resulting from the experiment, including LUO's such as:' 

  • Measurement: Direct measurement of physical properties, usually via an electronic detection device. 
  • Data acquisition: The recording of raw direct measurement data via transfer of information from the detection device/instrument.  This can be done via electronic transfer or via electronic display and manual recording.   
  • Data processing:  Conversion of raw measurement data to useful information within the context of the experiment. 
  • Data storage:  Creating records of raw measurement and processed data. 
  • Documentation: Creating records of metadata related to the experiment, such as day, time, operator ID, sample ID, experimental conditions, reagent lot numbers, temperature, etc.

All laboratory procedures involve one or more LUO's.  Even a simple procedure, for example weighing a sample, involves several LUO's. 

  • Sample transport to/from the balance, either manually or via an automated sample transport mechanism.  
  • Measurement, in this case measuring a tare weight and the weight of the sample.
  • Data acquisition, either via visual display or electronic transmission to some host.   

In any laboratory procedure, any or all of the LUO's are candidates for automation.  The planning challenge is to determine which LUO's in a given procedure are good or poor candidates for automation, and which will provide the best benefit when automated.   The technical challenge is creating an architecture to support the automation of those LUO's.


  1. Laboratory Robotics, a Guide to Planning, Programming and Applications; W. Jeffrey Hurst and James W. Mortimer, VCH Publishers Inc. 1987
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