Direct Determination of Niobium in Uranium-Niobium Alloys

1979 ◽  
Vol 23 ◽  
pp. 177-183
Author(s):  
Jack L. Long
Keyword(s):  
Standard Deviation ◽  
Chemical Treatment ◽  
Direct Determination ◽  
Average Intensity ◽  
Niobium Alloys ◽  
Wet Chemistry ◽  
Percent Niobium ◽  
Wet Chemical ◽  
Intensity Ratios

AbstractA procedure for determining niobium in uranium-niobium binary alloys was developed. The procedure requires only that a compact be made by pressing turnings, and wet chemical treatment is avoided entirely. By eliminating the wet chemistry, time is reduced by a factor of at least three compared with previous practice.Standardization was accomplished by separating each batch of machined turnings from specially cast uranium-niobium alloys into individual strands. A composite portion of each strand was analyzed for niobium by wet chemistry. The balance of the turnings from each batchy was pressed into a compact. Seven standard compacts resulted. The average Intensity ratio of niobium-to-uranium vs. the percent niobium for fourteen determinations on each standard compact was used to calculate a correlation coefficient of 0.999.The standard deviation of the Intensity ratios between duplicate compacts (average of 52 samples) was less than the standard deviation found between aqueous duplicates (average 125 samples) by a factor of 4.

scholarly journals Indirect and Direct Determination of the Casein Content of Milk by Kjeldahl Nitrogen Analysis: Collaborative Study

1998 ◽  
Vol 81 (4) ◽  
pp. 763-774 ◽  
Author(s):  
Joanna M Lynch ◽  
David M Barbano ◽  
J Richard Fleming
Keyword(s):  
Standard Deviation ◽  
Nitrogen Content ◽  
Relative Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Raw Milk ◽  
Method Performance ◽  
Relative Standard ◽  
Milk Casein

Abstract The classic method for determination of milk casein is based on precipitation of casein at pH 4.6. Precipitated milk casein is removed by filtration and the nitrogen content of either the precipitate (direct casein method) or filtrate (noncasein nitrogen; NCN) is determined by Kjeldahl analysis. For the indirect casein method, milk total nitrogen (TN; Method 991.20) is also determined and casein is calculated as TN minus NCN. Ten laboratories tested 9 pairs of blind duplicate raw milk materials with a casein range of 2.42- 3.05℅ by both the direct and indirect casein methods. Statistical performance expressed in protein equivalents (nitrogen ⨯ 6.38) with invalid and outlier data removed was as follows: NCN method (wt%), mean = 0.762, sr = 0.010, SR = 0.016, repeatability relative standard deviation (RSDr) = 1.287℅, reproducibility relative standard deviation (RSDR) = 2.146%; indirect casein method (wt℅), mean = 2.585, repeatability = 0.015, reproducibility = 0.022, RSDr = 0.560℅, RSDR = 0.841; direct casein method (wt℅), mean = 2.575, sr = 0.015, sR = 0.025, RSDr = 0.597℅, RSDR = 0.988℅. Method performance was acceptable and comparable to similar Kjeldahl methods for determining nitrogen content of milk (Methods 991.20, 991.21,991.22, 991.23). The direct casein, indirect casein, and noncasein nitrogen methods have been adopted by AOAC INTERNATIONAL.

Determination of Pb2+ in Wastewater by Lead(II)-dithizone-xylenol Orange Tenary Complex Spectrophotometry

2014 ◽  
Vol 1030-1032 ◽  
pp. 301-304 ◽  
Author(s):  
Jian Qi Sun
Keyword(s):  
Standard Deviation ◽  
Ph Value ◽  
Xylenol Orange ◽  
Direct Determination ◽  
Sodium Cyanide ◽  
Relative Standard ◽  
Efficient Recovery ◽  
Wastewater Samples ◽  
Orthogonal Tests

An novel Lead (II)-dithizone-xylenol orange tenary complex spectrophotometry was developed for the determination of Pb2+ in wastewater. For this purpose, the parameters of spectrophotometry such as the detection wavelength, pH value, the dosage of dithizone-xylenol orange and reaction time were studied and optimized through orthogonal tests. The method was linear in the ranges from 2.1×10-3 to 6.0 μg·mL-1 for Pb2+ with R2≥ 0.999. The procedure allowed efficient recovery of the investigated Pb2+ ranging between 95 % and 103 % with a relative standard deviation (RSD) ≤ 2.1 for actual wastewater samples spiked with 1.00, 2.00 and 3.00 μg·mL-1 of standard Pb2+, respectively. These results show the method can be applied to the direct determination of Pb2+ in wastewater, avoiding the use of toxic extrant (chloroform) and masking reagent (sodium cyanide) in the traditional methods and time-consuming procedures, moreover, the investigated method is simple, accurate, reliable, and inexpensive, which implies the potential of this technique for Pb2+ monitoring in wastewater samples.

Collaborative Study of Ion Selective Electrode Method for the Direct Determination of Fluoride in Feeds

1975 ◽  
Vol 58 (3) ◽  
pp. 477-481 ◽  
Author(s):  
Laszlo Torma
Keyword(s):  
Standard Deviation ◽  
Collaborative Study ◽  
Direct Determination ◽  
Ion Selective Electrode ◽  
Official Method ◽  
Selective Electrode ◽  
Standard Curve ◽  
Electrode Method ◽  
Aoac Method

Abstract A rapid and precise method for the determination of fluoride in feeds employs HC1 extraction of the sample. Acetate buffer and sodium citrate are added to control pH and ionic strength. The amount of fluoride is calculated from a standard curve after measuring the potentials of standard and sample solutions. Eight collaborators participated in the study of the method. Statistical values on 3 pairs of samples were calculated. The standard deviation, precision, coefficient of variation, and bias, respectively, were: Pair 1, 0.005071, 0.001763, 3.09, 0.0034; Pair 2, 0.037122, 0.006475, 1.82, 0.0258; Pair 3, 0.034587, 0.013021, 2.63, 0.0227. The results from the proposed method agreed favorably with the values obtained by using the official final action AOAC method, 7.089. The average and standard deviation, respectively, for individual samples by the proposed method were: Sample 3, 0.049, 0.0029; Sample 4, 0.059, 0.0021; Sample 5, 0.334, 0.0114; Sample 6, 0.341, 0.0101; Sample 7, 0.511, 0.0219; Sample 8, 0.492, 0.0237. By the official method the values were: Sample 3, 0.049, 0.0041; Sample 4, 0.058, 0.0029; Sample 5, 0.334, 0.0055; Sample 6, 0.331, 0.0082; Sample 7, 0.517, 0.0183; Sample 8, 0.499, 0.0175. The ion selective electrode method has been adopted as official first action.

The Direct Determination of Vanadium and Nickel in Crude Oils by X-Ray Fluorescence

1959 ◽  
Vol 3 ◽  
pp. 131-137
Author(s):  
Victoria R. Lopp ◽  
C. G. Claypool
Keyword(s):  
Standard Deviation ◽  
Direct Determination ◽  
Optical Emission ◽  
Crude Oils ◽  
Internal Standards ◽  
X Ray ◽  
Trapped Air ◽  
Sample Chamber ◽  
Ray Path

AbstractA rapid method has been developed for the determination of vanadium and nickel in crude oils in concentrations above 5 ppm. Duplicate analyses for both nickel and vanadium require only one hour, and excellent precision is obtained. At a concentration level of 100 ppm of vanadium, the standard deviation is 3.1 ppm, and at a level of 30 ppm of nickel, the standard deviation is 1.6. The results are comparable to those obtained by spectrophotometric and optical emission spectrographic analysis.Conversion of the crude oils to greases by the addition of aluminum stéarate minimizes the usual difficulties of handling liquid samples in the conventional-geometry fluorescent X-ray spectrometer. Scattered tungsten emission lines from theX-ray tube serve as internal standards to correct for instrumental and matrix variations.A new sample tray that permits the insertion of four samples into the instrument at a time has been constructed. Each sample can be moved into position for analysis without opening the sample chamber, making it necessary to waitfor the helium to sweep the trapped air from the X-ray path only once for each four samples.

Analyses of Forest Foliage I: Laboratory Procedures for Proximate Carbon Fractionation and Nitrogen Determination

1994 ◽  
Vol 2 (1) ◽  
pp. 5-14 ◽  
Author(s):  
Stephen D. Newman ◽  
Margaret E. Soulia ◽  
John D. Aber ◽  
Bradley Dewey ◽  
Andrea Ricca
Keyword(s):  
Interlaboratory Comparison ◽  
Deciduous Species ◽  
Chemical Methods ◽  
Wet Chemistry ◽  
Laboratory Results ◽  
Satisfactory Method ◽  
Laboratory Procedures ◽  
Wet Chemical ◽  
Fractionation Coefficient

As part of NASA's Accelerated Canopy Chemistry Program we performed analyses for the determination of carbon constituents and nitrogen content in fresh forest foliage. Foliage from three deciduous species was collected for carbon fraction analysis. Samples were analysed using a series of extractions that yielded different carbon constituents: non-polar, polar, cellulose and lignin. Results showed this to be a satisfactory method for carbon fractionation. Coefficient of variation within and between runs was less than 10%. These results were further supported by an interlaboratory comparison involving two other labs and samples collected as part of NSF's LTER LIDET experiment. Variations in laboratory results were due in part to differences in ash correction calculations. Approximately 1000 additional samples were analysed by wet chemical methods and used as a calibration set for Visible/NIR reflectance. Results showed accuracy of spectrophotometric measurements to approach that of wet chemistry techniques.

scholarly journals THE OPTIMATION SIMULTANEUOS DETERMINATION OF LEAD(II) AND CADMIUM(II) BY ADSORPTIVE STRIPPING VOLTAMMETRY (ADSV)

2012 ◽  
Vol 5 (2) ◽  
pp. 100
Author(s):  
Deswati ◽  
Hamzar Suyani ◽  
Umiati Loekman ◽  
Nilam Sari
Keyword(s):  
Standard Deviation ◽  
Optimum Condition ◽  
Sea Water ◽  
Direct Determination ◽  
Stripping Voltammetry ◽  
Optimum Conditions ◽  
Accumulation Time ◽  
Accumulation Potential ◽  
Relative Standard

A selective and sensitive adsorptive stripping voltammetric (AdSV) method for simultaneous determination of lead(II) and cadmium(II) were proposed. The aim of this study was to get the optimum condition for simultaneuos determination of lead(II) and cadmium(II). The parameters were studied such as: variation of accumulation potential, accumulation time, pH, and variation ofcalcon concentration. In this case, the optimum conditions were reached at accumulation potential –0.7 V, accumulation time 80 s, concentration of 0.12 mM calcon, and pH 7.0. At the optimumconditions the relative standard deviation were 2.90% and 1.46% for Pb(II) and Cd(II) respectively for eight replicates (n = 8) measurements. The method was applied for the direct determination of Pb(II) and Cd(II) in sea water around Bungus, Padang City. Concentration Pb(II) and Cd(II) insample were 9.918 μg/L – 27.320 μg/L for Pb(II) and 7.997 μg/L - 32.521 μg/L for Cd(II), with recovery of 99.48%, and 103.28 for Pb(II), and Cd(II) respectively.

Direct Determination of the Metallic Elements in Wine Using Atomic Absorption Spectrometry

2013 ◽  
Vol 325-326 ◽  
pp. 819-821
Author(s):  
Na Zhu ◽  
Zhi Fen Li ◽  
Hao Liu ◽  
Li Kun Yang ◽  
Hong Wei Wang
Keyword(s):  
Standard Deviation ◽  
Nitric Acid ◽  
Direct Determination ◽  
Absorption Spectrometry ◽  
Metallic Elements ◽  
Iron Copper ◽  
Relative Standard ◽  
Copper Manganese ◽  
Preparation Period

This method of sample preparation for iron, copper, manganese and zinc in wine were studied in this paper. At the preparation period adopted a method using nitric acid to extract, which mostly reduced the losing of metals and saved the time. Determinate the iron, copper, manganese and zinc in wine by AFS, and the recovery is in the range of 102.4 %~107.8 %, and the relative standard deviation is in the range of 0.955 %~3.806 %.

scholarly journals STUDI OPTIMASI PENENTUAN KADMIUM(II) SECARA VOLTAMMETRI STRIPPING ADSORPTIF

2015 ◽  
Vol 3 (2) ◽  
pp. 122
Author(s):  
Deswati Deswati ◽  
Hamzar Suyani ◽  
Citra Buhatika
Keyword(s):  
Standard Deviation ◽  
Optimum Condition ◽  
Direct Determination ◽  
Stripping Voltammetry ◽  
Adsorptive Stripping Voltammetry ◽  
Optimum Conditions ◽  
Accumulation Time ◽  
Relative Standard ◽  
Time Accumulation

  ABSTRACT Study of optimation cadmium(II) by adsorptive stripping voltammetry has been done. The aim of this study to get optimum conditions for determination of Cd(II). Parameters were done : potential accumulation, time accumulation, pH, supporting electrolite concentration and optimum of complex concentration. In this case, the optimum conditions were reached in potential accumulation -0.7 V, time accumulation 60 second, pH 7.0, NH4Cl 0.12 M, calcon concentration 0.12 mM. In the optimum condition was obtained with the relative standard deviation was 4.61% for eight replicates, measurements of 0.01 ppm. The method was applied to the direct determination of Cd(II) in water around Batang Air Dingin Lubuk Minturun and Muara Padang. Concentration Cd(II) in sample was equal to 7.359 μg/L and 3.659 μg/L with recovery of 99.04%. Keywords: cadmiun, adsorptive, stripping, voltammetry

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