Interlaboratory proficiency testing: Intercomparison in relation to the measurement of alumina, iron(III) oxide and Titania present in homogenised china clay

For establishing technical competence in testing and calibration, a laboratory has to participate in proficiency testing (PT) program from time to time. An intercomparison in the field of chemical analysis using classical and instrumental methods of analysis has been carried out by 17 accredited as well as non accredited laboratories in India as per requirement of National Accreditation Board for Testing and Calibration Laboratories(NABL), New Delhi. Central Glass and Ceramic Research Institute(CGCRI), Kolkata acted as a nodal laboratory and conducted this PT programme during 2000–2001. This paper reports the analytical results and statistical evaluation of the results using Z-score.