Malaysian Journal of Analytical Sciences Vol 24 No 4 (2020): 511 - 518

 

 

 

 

UNCERTAINTY OF IODINE VALUE DETERMINATION IN PALM OLEIN

 

(Ketidakpastian Penentuan Nilai Iodin dalam Minyak Sawit Olein)

 

Mohd Azmil Mohd. Noor*, Hajar Musa, Razmah Ghazali

 

Quality and Environmental Assessment Unit,

Advanced Oleochemical Technologies Division,

Malaysian Palm Oil Board, No. 6, Persiaran Institusi, Bandar Baru Bangi, 43000 Kajang, Selangor, Malaysia

 

*Corresponding author:  mohd.azmil@mpob.gov.my

 

 

Received: 1 January 2020; Accepted: 18 June 2020; Published:  11 August 2020

 

 

Abstract

The uncertainty of the iodine value determination in refined, bleached, and deodorised palm olein was investigated and calculated. The major sources of measurement uncertainty were identified as the mass of the sample, the molarity of sodium thiosulfate (Na₂S₂O₃) solution, the volume of the titrant, the repeatability, and the recovery of the method. The uncertainty sources were quantified according to the law of propagation of errors, standardised, and then combined. The expanded uncertainty calculated was 56.8 ± 1.2 (2.2%). The measurement uncertainty was compared to the precision data of the method, i.e. the repeatability limit. Good agreement was found, which indicated that the major uncertainty sources had been identified. The study also showed that the major sources of uncertainties were contributed by the repeatability component, which will be the main focus in reducing the uncertainty of the iodine value determination.

 

Keywords:  iodine value, palm oil, measurement uncertainty, precision, repeatability limit

 

Abstrak

Ketidakpastian dalam penentuan nilai iodin di dalam minyak sawit olein yang ditapis, diluntur, dan dinyah bau telah dikaji dan dikira. Sumber utama bagi ketidakpastian penentuan ini adalah berat sampel, kepekatan larutan natrium tiosulfat (Na₂S₂O₃), jumlah titran, kebolehulangan dan perolehan semula. Sumber-sumber ketidakpastian telah dikira mengikut hukum penyebaran ralat, dipiawaikan dan kemudian digabungkan. Ketidakpastian terkembang yang dikira adalah 56.8 ± 1.2 (2.2%). Ketidakpastian pengukuran telah dibandingkan dengan data ketepatan kaedah, iaitu had kebolehulangan. Nilai ketidakpastian dan had kebolehulangan bagi kedua-dua data adalah setara dan ini menunjukkan bahawa sumber-sumber utama ketidakpastian telah dikenalpasti. Kajian ini juga menunjukkan bahawa sumber utama ketidakpastian disumbangkan oleh komponen kebolehulangan, yang akan menjadi fokus utama dalam mengurangkan ketidaktentuan untuk penentuan nilai iodin.

 

Kata kunci: nilai iodin, minyak sawit, ketidakpastian penentuan, ketepatan, had kebolehulangan

 

References

1.      Thomas, A., Matthäus, B. and Fiebig, H.‐J. (2015). Fats and fatty oils. In Ullmann's encyclopaedia of industrial chemistry. Wiley-VCH, Weinheim: pp. 66-68.

2.      The Palm Oil Refiners Association of Malaysia (2012). PORAM handbook 7^th edition. PORAM, Selangor: pp. 7-8.

3.      Department of Standards Malaysia. (2007). MS 816:2007 Palm olein - Specification (Second revision). Department of Standards Malaysia, Selangor: pp. 2-3.

4.      International Organization for Standardization (1995). GUM: Guide to the expression of uncertainty in measurement. ISO, Geneva: pp. 15-17.

5.      Ellison, S. L. R. and Williams, A. (2012). Quantifying uncertainty in analytical measurement. EURA-CHEM/CITAC, Teddington: pp. 3-4.

6.      American Oil Chemists’ Society. (2017). AOCS Official method Cd 1d-92 (Reapproved 2017). Iodine value of fats and oils cyclohexane-acetic acid method. AOCS, Illinois: pp. 1-2.

7.      Drolc, A., Cotman, M. and Ross, M. (2003). Uncertainty of chemical oxygen demand determination in wastewater samples. Journal of Accreditation and Quality Assurance, 8: 138-145.

8.      Sousa, A. R. and Trancoso, M. A. (2005). Uncertainty of measurement for the determination of fluoride in water and wastewater by direct selective electrode potentiometry. Journal of Accreditation and Quality Assurance, 10: 430-438.

9.      Miller, J. N. and Miller, J. C. (2000). Statistics and chemometrics for analytical chemistry, 4^th edition. Prentice Hall, Harlow: pp. 12-14.

10.   Tomic, T., Nasipak, N. U. and Babic, S. (2012). Estimating measurement uncertainty in high-performance liquid chromatography methods. Journal of Accreditation and Quality Assurance, 17: 291-300.

11.   Choi, J. O., Hwang, E., So, H. and Kim, B. (2003). An uncertainty evaluation for multiple measurements by GUM. Journal of Accreditation and Quality Assurance, 8: 13-15.

12.   Leal, R. V. P., Borges, P. P. and Seidl P. R. (2008). Metrological evaluation of titration techniques for the determination of the iodine value in biodiesel. International Conference on Metrology of Environmental, Food and Nutritional Measurements, 10-12 September 2008.

13.   Meena, A. K., Rao, M. M., Panda, P., Padhi, M. M. and Babu, R. (2010). Evaluation and expression of uncertainty in the measurement of iodine value in mustard oil. International Journal of Chemical and Analytical Science, 1(7): 136-140.