Date post: | 27-Mar-2015 |
Category: |
Documents |
Upload: | molly-curtis |
View: | 214 times |
Download: | 0 times |
LIMITS OF DETECTION OF AN TOTAL REFLECTION SYSTEM WITH DOUBLE REFLECTION
MODULE
V. F. Nascimento Filho1,2, V. H. Poblete3 P., P. S. Parreira1,4, E. Matsumoto5, S. M. Simabuco5, E. P. Espinoza1 V., A. A. Navarro1
1 Laboratório de Instrumentação Nuclear/CENA/USP 2 Departamento de Física e Meteorologia/ESALQ/USP 3 Laboratório de Fluorescencia de Rayos X/CCHEN, Chile 4 Departamento de Física/CCE/UEL 5 Departamento de Recursos Hídricos/FEC/UNICAMP
Financial support: FAPESP
INTRODUCTION CHARACTERISTICS OF THE TECHNIQUE:
MULTIELEMENTAR, SIMULTÂNEOUS AND INSTRUMENTAL
ATOMIC NUMBER > 13
HIGH GEOMETRIC EFFICIENCY DETECTION
LOW SAMPLE VOLUMES
MATRIX EFFECT CORRETION NOT NECESSARY
LOW LIMITS OF DETECTION
CAN BE USED FOR :• ENVIRONMENTAL MONITORING
• BIOLOGICAL FLUIDS
• CONTROL QUALITY OF HIGH PURITY PRODUCTS
• SOLID SAMPLES (AFTER DIGESTION)
Photo and scheme: Total reflection fluorescence system (TXRF): visualization of the tower with the X-ray tube (XRT), high voltage generator (HVG), X-ray detector (XRD) and the total reflection module (TRM).
OBJECTIVES
DOUBLE REFLECTOR MODULE ADJUSTMENT
ELEMENTARY SENSITIVITIES DETERMINATION
LIMITS OF DETECTION DETERMINATION
MATERIALS and METHODS X-RAY TUBE: X-RAY TUBE: Mo targe, Zr filter, 45 kV/20 mAMo targe, Zr filter, 45 kV/20 mA
TOTAL REFLECTION MODULE: TOTAL REFLECTION MODULE: SORAD, ChileSORAD, Chile
X-RAY DETECTOR: X-RAY DETECTOR: semicondutor Si(Li), 30 mmsemicondutor Si(Li), 30 mm22
PULSE HEIGHT MULTICHANNEL ANALYZER: PULSE HEIGHT MULTICHANNEL ANALYZER: CanberraCanberra
X-RAY SPECTRA FITTING: X-RAY SPECTRA FITTING: AXILAXIL
ELEMENTS ELEMENTS Cr, Fe, Cu e ZnCr, Fe, Cu e Zn
STANDARD SOLUTIONS: STANDARD SOLUTIONS: 2,17 - 8,33 - 15,38 e 31,25 ppm2,17 - 8,33 - 15,38 e 31,25 ppm
INTERNAL STANDARD: INTERNAL STANDARD: YY
SAMPLE SUPPORT: SAMPLE SUPPORT: quartzquartz
SAMPLE VOLUME ON SUPPORT: SAMPLE VOLUME ON SUPPORT: 5 microliters5 microliters
EXCITATION/DETECTION TIME: EXCITATION/DETECTION TIME: 500 segundos500 segundos
QUANTITATIVE ANALYSIS
• Ci = concentration of the element i
• Si = relative sensitivity of the element i
• Ri = relative intensity of the element i
• Ii = intensity of the element i
• Iy = intensity of the internal standard
• Cy = concentration of the internal standard
iii CSR .
YY
ii CI
IR
/
CONCLUSIONS
LIMIT OF DETECTIONLIMIT OF DETECTIONvolume of the sample on the support: 50 microliters volume of the sample on the support: 50 microliters
excitation/detection time: 1000 secondsexcitation/detection time: 1000 seconds
CHROMIUM IRON COPPER ZINCliquid samples: 18 9 7 6 ppbsolid sample: 10 mg digestion; 1 ml final volume
1.8 0.9 0.7 0.6 ppmaerosol filter: 10 m3 collected volume; digestion; 1 ml final volume 1.8 0.9 0.7 0.6 ng/m3
Financial support: FAPESP
RELATIVE SENSITIVITY
LIMITS OF DETECTION
REGRESSION LINES