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