LOD Oven – Operation and Maintenance SOP

Standard Operating Procedure (SOP) for operation and maintenance of the Oven used to determine the Loss on Drying (LOD) in the Quality Control Department. Loss on drying (LOD) is the loss of weight expressed as percentage w/w resulting from water and volatile matter of any kind that can be driven off under specified condition.

SOP for LOD Oven

1.0   PURPOSE:

    • The purpose of this SOP is to describe the procedure for the operation and maintenance of the LOD oven.

2.0   SCOPE:

    • This SOP is applicable to operation and maintenance of all LOD oven of used to determine the Loss on Drying (LOD) at the Quality control Department.


    • USP 43, NF 38;<731> Loss on Drying
    • Manual supplied by the manufacturer.


    • Analyst :LOD Oven

    • To operate and follow the procedure as per SOP.
    • To maintain the equipment history card.
    • QC Head or Designee:

    • To check the SOP.
    • Impart training to all the concerned persons before the implementation of SOP.
    • To ensure that the equipment is operated as per SOP.
    • Check the third party calibration records.
    • Quality Assurance:

    • To check the SOP.
    • To ensure the implementation of the system as per SOP.
    • Quality Head and Plant Head :

    • To review and approve the SOP.
    • To ensure that system is implemented.

    • Loss on drying: It is the loss of weight expressed as percentage w/w resulting from water and volatile matter of any kind that can be driven off under specified condition.


    • General Procedure for Handling LOD Oven:

    • For the entry of usage of instrument follow the SOP on “Instrument/Equipment usage logbook”
    • In case of any maintenance of equipment, follow SOP on “Maintenance of laboratory instrument/equipment.
    • Maintain the external calibration (third party) schedule for the equipment as per SOP,Preparation of internal and external (Third-party) calibration schedule and calibration practices.
    • Precautions during handling of LOD Oven:

    • Do not overload the LOD oven.
    • Do not place anything on top of the LOD Oven.
    • Leave a minimum of 50 mm free space from three sides and 300 mm from the backside of the equipment (LOD Oven).
    • Keep the LOD Oven equipment horizontally leveled.
    • Always close the drying oven door whether it is in use or not.
    • Operation of LOD Oven:

    • Startup:
    • Ensure that the power supply is connected to 230 A/C supply.
    • Connect the equipment cable with the power supply.
    • Check whether the “red” indicator light & digital display is ON, indicating power supply is on.
    • Equipment is ready for usage.
    • Operational:
    • Switch ON the equipment.
    • Check whether ‘red’ indicator light & digital display is ON indicating the supply is on.
    • Switch ON the equipment and set the temperature pressing the SET button.
    • Change if required with the help of a coarse and fine knob by pressing the SET key simultaneously.
    • Now check for red indicator light glowing, which indicates heater is ON and once the temperature is set.
    • After achieving the required temperature, open the door of the oven and place the sample inside the oven.
    • Switch OFF the equipment after use.
  • Procedure for Determination of Loss on Drying (LOD):

    • Mix and weigh accurately 1 to 2 g of the sample unless otherwise directed in the individual monograph.
    • If the test specimen is in the form of large crystals, reduce the particle size to about 2mm by quickly crushing.
    • Tare a glass-stoppered shallow weighing bottle, (previously dried) for 30 minutes under the same condition as the test.
    • Put the test specimen in the bottle and accurately weigh the bottle and the contents.
    • By gentle sideways shaking spread the sample evenly as possible to a depth of about 5 mm and not more than 10 mm in case of bulky materials.
    • Dry the sample for a specified time at a temperature specified within the range of ± 2°C.
    • Upon opening the chamber, close the bottle promptly and allow it to come to room temperature in a desiccator before weighing.
    • If the substance melts at a lower temperature than that specified for the determination of loss on drying, maintain the bottle with its contents for 1 to 2 hours at a temperature 5ºC to 10ºC below the melting temperature, then dry at the specified temperature.
    • Maintenance of LOD Oven:

    • When equipment is under breakdown maintenance/not functioning QC chemist/ officer affix the tag stating “Under Maintenance/Not to be used” and informs to QC head.
    • QC head informs to the equipment manufacturer/servicing person.
    • Between breakdown and service, the equipment shall be under maintenance.
    • The service engineer rectifies the problem and repairs the equipment adequately.
    • The service engineer shall prepare a service report and retain one copy of the report QC.
    • Clean the chamber of oven periodically with dry cloth when it is at room temperature.
    • Calibration of LOD Oven:

    • External:
    • Perform the Calibration of the temperature sensor and digital temperature controller by the external agency.
    • Frequency: Yearly ± 30 days


Janki Singh is experienced in Pharmaceuticals, author and founder of Pharma Beginners, an ultimate pharmaceutical blogging platform. Email: [email protected]

Leave a Reply