Development and Validation of a New Method for Determination of Pb and Cr in Marine Organisms by Total Reflection X-Ray Fluorescence (TXRF) Spectroscopy

Abstract

Lead and chromium contamination represents one of the most serious problems in the aquatic environments. The aim of this work was to develop and validate an accurate, sensitivity, and rapid method for the simultaneous determination of Pb and Cr at trace levels in tissues and fat of marine organisms such as turtle (Chelonia mydas), shark (Rhizoprionodon terraenovae), and dolphin (Tursiops truncatus), utilizing the total reflection X-Ray fluorescence (TXRF) spectroscopy. Working solutions were prepared in 10 mL of a solution 0.005 mol·L−1 EDTA and 1 mol·L−1 HNO3. In order to correct possible instrument drifts, 20 μg·L−1 of gallium was used as internal standard (IS). The results showed that TXRF method was linear over the concentration ranges of 5.242–100 μg·L−1 for Pb and 2.363–100 μg·L−1 for Cr. Limits of detection (LOD) achieved were 1.573 and 0.709 μg·L−1 for Pb and Cr, respectively, while limits of quantification achieved were 5.242 μg·L−1 for Pb and 2.363 μg·L−1 for Cr. The validated method was accurate and precise enough for determination of these heavy metals in samples of marine organisms as indicated by acceptable values of recovery between 90–101%. In addition, a certified reference material (BCR-279, sea lettuce) and a Centrum tablet were satisfactory analyzed, and the T-test for comparison of means revealed that there were no significant differences at the 95% confidence level between the values obtained with the proposed TXRF method and the certificated values. The repeatability of the method, expressed as relative standard deviation (RSD), was 5.1% and 4%, for Pb and Cr, respectively. In addition, other features of the developed method were a low sample volume of 10 μL, and the sample frequency achieved was 20 h−1.

Toxicity and bioaccumulation of manganese and chromium in different organs of common carp (Cyprinus carpio) fish

“…The limit of detection (LOD) was predicted from three times the standard deviation (SD) of ten replicates of the blank divided by the slope of the calibration curve. The limit of quantification (LOQ) was calculated from ten times the SD of ten replicates of the blank divided by the slope of the calibration curve [ 21 ].…”

Total Reflection X-Ray Fluorescence Spectroscopy (TXRF) Method Validation: Determination of Heavy Metals in Dietary Supplements

“…[3,20]. e present work utilized a digestion procedure using concentrated HNO 3 + HCl + H 2 O 2 for the determination of Pb, As, Cr, and Hg in six dietary supplements [2,24].…”

“…en, their studied ranges were as follows; HNO 3 concentration (0.01-1 mol•L −1 ), EDTA concentration (0 -0.1 mol L −1 ), and sample-reading time (100 -500 s). e range of independent variables was based on preliminary experiments and determined literature [24]. e experimental design points consist of the 2 3 factorial points, six axial points, and six central points.…”

“…Advantages include the element and its concentration being unaffected by matrix effects, its low sensitivity (ppb), requiring small amounts of sample (μg or μL), the use of small quantities of reagents, and not utilizing argon or nitrogen gases. e low background levels result in improved LODs and even 2 pg may be detected for a variety of elements with a counting time of 1,000 s [23][24][25]. Actually, the development and commercialization of TXRF instrumentation, which offers simple operations with a low-cost compact design, have promoted its application in many different fields [24].…”

Summary of ISO standard 20289: Total reflection X‐ray fluorescence analysis of water

“…It was then further exploited in other application fields where there was a demand for measuring low mass volumes where the sample was then deposited onto X‐ray reflective surfaces. Material surface analysis remains at the heart of TXRF, but more recently, the availability of commercial benchtop TXRF instrumentation has increased the use of TXRF for analysing many different types of samples: Nowadays, TXRF is used widely to perform elemental analysis of water, soils, bio‐monitors, food, and biological matrices . In these contexts, the community has so far been focused on developing specific sample preparation protocols to ensure the analytical performance of the method .…”