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1.0 OBJECTIVE
To provide a guideline for operation, cleaning and calibration procedure of Kjeldahl apparatus.
2.0 SCOPE
This SOP is applicable for the operation, cleaning and calibration procedure of Kjeldahl apparatus (Eq. ID.: QC/220) at Quality Control Department (Company Name).
3.0 RESPONSIBILITY
3.1 Operating personnel is responsible for carrying out the procedure.
3.2 Overall responsibility for training, implementation & follow-up with the Head of QC or his/her nominee.
4.0 ACCOUNTABILITY
4.1 Head of Quality.
5.0 PRECAUTIONS
5.1 Operate the Digester in a fume hood with sufficient ventilation to directly withdraw fumes.
5.2 Do not touch cracks or bits of broken glass with bare hands.
5.3 Digester must be connected to a scrubber for removing released gases and gaseous substances.
5.4 Do not bring peroxide into contact with highly combustible material.
5.5 Do not touch any hot parts.
6.0 PROCEDURE
6.1 Operation of Kjeldahl Distillation
6.1.1 Switch on the instrument and wait until the steam generator is ready.
6.1.2 Insert the sample tube containing the sample diluted in water. The dilution with water prevents a too violent reaction when subsequently adding the sodium hydroxide solution. The sample must be diluted in a ratio of approximately 1 part of acid to 2 parts of water.
6.1.3 Prepare a conical flask or a similar receptacle with a volume of about 250 ml as receiving vessel. Fill boric acid solution 4% and 2-3 drops of indicator in the receiving vessel.
6.1.4 Add sodium hydroxide solution by pressing “REAGENT”. Recommended alkali concentration is 32%. Add alkali to the sample in a ratio of about 1 part of acid to 3 volume of sodium hydroxide solution. The volume of the added sodium hydroxide solution is measured on the scale behind the sample tube. The added volume selected must produce a clear shift in color to brown or blue.
6.1.5 Set the required distillation time.
6.1.6 Start the distillation by pressing “START”
6.2 Operation of Kjeldahl Digestion
6.2.1 Start-up the speed digester.
6.2.2 Let the system heat up (Preheat function in automatic mode)
6.2.3 Prepare the sample tubes according to the type of digestion under safe conditions. The samples are now ready to be digested.
6.2.4 Place glass caps in to every unused position of the rack
6.2.5 Place insulation caps in to every unused position at the insulation plate.
6.2.6 To securely withdraw harmful fumes, switch on the suction unit (Scrubber or water jet pump) before inserting the racks in to the instrument
6.2.7 The scrubber must be switched on.
6.2.8 If the scrubber is directly connected to the K-439, it will start as soon as “Step 1” of the selected method starts and stops after the cooling-down time defined within the method is finished.
6.2.9 At the end of an automatic digestion confirm the corresponding information message “Digestion done” by pressing OK. At the end of a manual digestion press stop to finish the process, then switch off the instrument via the main switch.
6.3 Operation logbook
6.3.1 Record the information’s in the operational log book- “LOG BOOK FOR BUCHI DISTILLATION & WET DIGESTION SYSTEM (KJELDAHL APPARATUS)” FRM No.: FQC/489.
6.4 Calibration
6.4.1 Pump Performance check
6.4.1.1 Control the filling level of the supply tank for NaOH.
6.4.1.2 Connect an empty sample tube to the K-350.
6.4.1.3 Insert a empty receiving vessel (Glass beaker of ≥ 200 ml).
6.4.1.4 Set the distillation time to e.g. 1 sec. by using the up and down button.
6.4.1.5 Keep pressing the REAGENT button until a volume of approximately 100 ml is reached.
6.4.1.6 Measure the volume in a graduated cylinder and enter this value in the table below.
6.4.1.7 Press the START button to save the volume.
6.4.1.8 Press the STOP button.
6.4.1.9 Press the START button again.
6.4.1.10 Repeat the measurement for three times.
6.4.1.11 Acceptance criteria: Entered Volume ± 3 ml.
6.4.2 Steam generator performance check
6.4.2.1 Connect an empty sample tube to the K-350.
6.4.2.2 Insert an empty receiving vessel (Glass beaker) of minimal 200 ml volume.
6.4.2.3 Carry out a distillation procedure of 5 min in total, make sure no reagents are added.
6.4.2.4 Collect the distillate in the receiving vessel for the duration of the distillation. After distillation transfer the distillate to a graduated measuring cylinder of 200/250 ml and measure the volume in milliliters.
6.4.2.5 Acceptance criteria: ≥ 130 ml
6.4.3 Temperature transfer and distribution Time
6.4.3.1 Enter the manual mode and set the temperature to 300°C.
6.4.3.2 Press START, to start the preheating.
6.4.3.3 All samples tubes are filled with 100 ml distilled water, by means of a 100 ml graduated cylinder.
6.4.3.4 Two boiling stones are added to every sample tube and sample tubes are placed inside the appropriate rack then mount the sanction module onto the sample tubes.
6.4.3.5 When the preheat is finished the rack is placed in the heating position of the K-4369.
6.4.3.6 Press Reset to reset the run time. The time until all sample position start boiling is recorded.
6.4.3.7 Continue same procedure for three times.
6.4.3.7 Acceptance criteria: The boiling time of all positions ≤ 15 min.
6.4.4 Timer accuracy Check
6.4.4.1 Enter Automatic in the main menu.
6.4.4.2 Press timer and enter 5 min by using + button, finally press ok to confirm.
6.4.4.3 Press START and start the stop watch immediately as well.
6.4.4.4 Continue same procedure for 20 min and 30 min.
6.4.4.5 Acceptance criteria: The specified and the measured time should not differ more than 5 seconds.
6.4.5 Heating chamber temperature accuracy check
6.4.5.1 The heating chamber temperature accuracy check shall be done using a calibrated digital thermometer. Since the facility is not available at BPL, the same facility existing with precisa techno trade shall be used until the facility is developed in-house. However, a copy of the valid calibration certificate must be attached with the calibration document.
6.4.5.2 Set 200°C and wait for 20 min/ until the buzzer peeps/display is flashing and measure the temperature of the heating chamber (Both Left and Right) with a digital calibrated thermometer.
6.4.5.3 Again set 300°C and wait for 20 min/until the buzzer peeps/display is flashing and measure the temperature of the heating chamber (Both Left and Right) with a digital calibrated thermometer.
6.4.5.4 Again set 500°C and wait for 20 min/until the buzzer peeps/display is flashing and measure the temperature of the heating chamber (Both Left and Right) with a digital calibrated thermometer.
6.4.5.5 Acceptance criteria: Set temperature ± 5.0°C.
6.4.6 Calibration frequency: One year ± 10days.
6.5 Cleaning
6.5.1 Clean all sealing’s with distilled water.
6.5.2 Disconnect all tubing/connector and rinse them thoroughly with water.
6.5.3 If a glass tube breaks, the glass splinters and the spilled liquid should be removed carefully.
