Polarography is by no means the only method suitable for the measurement of U concentration in the final solution. Spectrophotometry can also be used and is, in some cases, even more sensitive; but if spectrophotometry is used, the interference from chromium (Table I) should be considered. Chromium does not interfere in the polarographic determination since, although it extracts into TOA and back-extracts into 0.17V HC1, the reduction wave of Cr(III) appears at potentials more negative than -0.5V vs. SCEin47VHCl.The method is simple, rapid, and accurate. Six to eight determinations can be carried out per day by a trained technician. The relative standard deviation is 2% at the 95% confidence level in samples that contain 0.05 to 0.2 mg of uranium per milliliter.
Foreign ions present (weight excess over P) 0.150 0.152 + 1.33 Ca(20), Fe(10), Cu(15) 0.300 0.295 -1.67 Al(30), Si(30) 0.300 0.296 -1.33 Zn(30), Pb(20) 0.400 0.420 +5.00 Asm(10), Cd(20) 0.250 0.260 +4.00 Se(20), Te(20) 0.200 0.200 0.0 Bi(15), Cu(20) 0.350 0.335 -4.30 W(20), Sb(25), Ge(25) 0.080 0.079 -0.62 Si(15), Ni(10) " Each result is the average of two determinations in good agreement.which the Rhodamine B recovered in the final butanolchloroform phase from the complex after its formation from known amounts of phosphorus was determined fluorimetrically. Allowance for depletion of the Rhodamine B concentration in the final chloroform-butanol phase due to the chloroform extractions, which promote the dissociation of the complex by removal of the excess reagent, was made. The overall cumulative formation constant, A, defined as [RhB-MPC]/[MPC][RhB]3, under these conditions was estimated to be 1.6 ± 0.3 X 1011 liter3 mole-3.Conclusions. High sensitivity is obtained for the determination of phosphorus by the spectrofluorimetric method developed. The sensitivity achieved is higher than that for most other methods based on the formation of molybdophosphoric acid, and compares favorably with that of more complex enzymatic methods. High selectivity is achieved with the optimum conditions established. Of the ions investigated, only arsenic(V) interferes seriously, by formation and extraction of the corresponding Rhodamine B molybdoarsenate; arsenic (III), however, may be tolerated when present in moderate excess with respect to phosphorus.
multiples and submultiples thereof] form a geometric sequence with ratio loll6. Similarly, ladders with g values of loll3, 101i4, erc. are readily constructed. Frustratingly, however, the preferred values do deviate significantly from being a perfect geometric sequence. Thus, to two significant figures, 1.0, 1.5, 2.2, 3.2, 4.6, 6.8, and 10 are the numbers which form a sequence with ratio
ACKNOWLEDGMENTIt is a pleasure to acknowledge the experimental assistance of Marten G~~~~~~~ and the financial assistance of the N~-tional Research council of Canada.The possibility of analyzing the macroconstituents of a matrix by using neutron activation without utilizing any standards has been studied, provided all major constituents can be activated and detected. Equations have been derived that directly relate the concentration of each of the constituents to the ratio variations of the accumulated counts due to the activation of these elements present. The general theory has been successfully applied to the determination of gold alloy constituents. A relative standard deviation of 0.92, 3.3, and 0.91% has been obtained for gold, silver, and copper determinations, respectively. Average deviation of the results obtained by this method and atomic absorption was 0.58%.
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