Cristina Flores, M. Graça Dias, Mariana Santos
ACCURACY EVALUATION IN THIAMIN QUANTIFICATION IN FOOD MATRICES

The performance evaluation of an RP-HPLC method to determine thiamine using different food matrices and reference materials, showed the method suitability to its purpose and to be submitted to accreditation. Intermediate precision evaluate through the relative standard deviation (RSD%) was under 8% for all food matrices tested an all the z-scores obtained for the reference materials were < 1.5.The estimated expanded measurement uncertainty was 13%.

Catarina André, Inês Delgado, Susana de Jesus, Ana Ramos, Carlos Brandão, Nelson Felix, Isabel Castanheira
CONTRIBUTION OF METROLOGY ON DETERMINATION OF ACRYLAMIDE IN FOODSTUFFS

The aim of this study was the determination of acrylamide in food with high consumed in Portugal. Samples were bought randomly from local supermarkets and from Escola Superior de Hotelaria e Turismo do Estoril. Sample preparation involved SPE (Solid Phase Extraction). Two chromatographic methods were developed, UPLC-PDA and UPLC-MS/MS which was more suitable and quantify unequivocally acrylamide.
The acrylamide content in bread and pastries samples analyzed were above the indicative values published by EFSA.

C. S. Veldman, T. M. Lefenya
PERFOMANCE EVALUATION OF TWO LOW FREQUENCY AIR BEARING VIBRATION EXCITERS

The National Metrology Institute of South Africa designed an air bearing linear translation stage (LTS) used for primary low frequency accelerometer calibration. The LTS serves as a replacement of a commercial LTS. The motivation for the new design consideration is touched on. The performances of both LTSs were evaluated in terms of their flatness, straightness, roll, pitch and dynamic transverse motion; the results and findings of which are reported in some detail. The influence of the mechanical connection between the LTS and the electrodynamics exciter was also investigated.

Qiao Sun, Hong-bo Hu
INVESTIGATION AND PILOT COMPARISON OF LOW INTENSITY SHOCK CALIBRATION BY LASER INTERFEROMETRY

This paper first presents the investigation work of the pilot comparison of low intensity shock calibration by laser interferometry. Two main technical concerns for a possible comparison are variety of primary shock calibration systems covered and feasibility of comparison artifact investigated. For the primary calibration system, homodyne or heterodyne laser interferometer is included as measurement standard, but the mechanical excitation is of three different types: hammer-anvil collision, pneumatic driven projectile impact and Hopkinson bar. The shock pulses generated are smooth monopole shape (half-sine or sine squared) by the first two types with air bearings, but dipole shape by the third type. For the comparison artifact, a standard accelerometer of single-ended type with a charge amplifier consists of an accelerometer measuring chain whose nonlinearity of amplitude and phase frequency responses is investigated. Based on the nonlinear fact of comparison artifact at frequency domain and the spectrum range difference of mechanical excitations of the calibration system, strict comparison conditions had to be laid down for measurement of shock sensitivity at specific acceleration levels and pulse durations. For the monopole excitation, the comparison acceleration range is from 500 m/s² to 5000 m/s² and pulse duration is from 0.3 ms to 3 ms, with the reference of 2 ms at an acceleration of 1000 m/s². For the dipole excitation, the acceleration level is fixed as 1000 m/s² and pulse duration is from 0.03 ms to 0.2 ms, with the reference of 0.1 ms.
The pilot comparison of low intensity shock calibration, coded as APMP.AUV.V-P1, is successfully organized by Technical Committee of Acoustics, Ultrasound and Vibration (TCAUV) of Asia Pacific Metrology Program (APMP). Some comparison results of both monopole excitation and dipole excitation are shown with the expanded uncertainty. The degrees of equivalence calculated from the measurement results by the four participants support the uncertainty of measurement reported by them. The completion of this pilot comparison can serve as part of the basis for a planned key comparison targeted at a low intensity shock range at Consultative Committee level.

Ioan Ursu, Adrian Toader, Daniela Enciu, Dan Mihai Ştefănescu
ADVANCED MEASUREMENTS IN STAR SPACE PROJECT ON STRUCTURAL HEALTH MONITORING

Accurate specimens representing aluminum spacecraft structures with piezoelectric wafer active sensor (PWAS) bonded on them were subjected to extreme temperature variations and radiations. The structure itself is affected by mechanical damages caused by fatigue and aging. The signature of structure’s health is the real part of electromechanical impedance spectroscopy (EMIS) curves of a PWAS bonded on structure. Based on these EMIS records, damage metrics were calculated as root mean square deviation from healthy to damaged specimen. This paper presents a concise description of four investigative measurements, carried out with advanced electronic, optical and acoustic means.