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.

Determination of Stoichiometry in Lanthanum Strontium Manganates(III)(IV) by Wet Chemical Methods

1994 ◽  
Vol 113 (2) ◽  
pp. 320-326 ◽  
Author(s):  
I.G.Krogh Andersen ◽  
E.Krogh Andersen ◽  
P. Norby ◽  
E. Skou
Keyword(s):  
Chemical Methods ◽  
Lanthanum Strontium ◽  
Wet Chemical

Analysis of undried grass silage by near-infrared spectroscopy

1994 ◽  
Vol 1994 ◽  
pp. 119-119
Author(s):  
H W Morris ◽  
S Fisher ◽  
J R Newbold ◽  
S Wilson ◽  
C W Ashby ◽  
...  
Keyword(s):  
Infrared Spectroscopy ◽  
Near Infrared Spectroscopy ◽  
Near Infrared ◽  
Volatile Components ◽  
Chemical Methods ◽  
Grass Silage ◽  
Nutrient Value ◽  
Wet Chemical ◽  
Calibration Equations

The analysis of grass silage by near-infrared spectroscopy (NIR) of dried samples is established as a valid alternative to wet chemical methods. Analysis of undried samples offers potential advantages in terms of :d of analysis and accuracy of determination of volatile components, provided calibration equations can be validated against independent populations of silage. Accumulation of analyses for a large number of pies allows relationships between silage nutrient value and management factors such as additive use, which are poorly understood, to be examined.

scholarly journals A NEW METHOD FOR THE DETERMINATION OF TOXIC DYE USING FTIR SPECTROSCOPY

2010 ◽  
Vol 9 (2) ◽  
pp. 27-38 ◽  
Author(s):  
Mohammad Elwathig Saeed Mirghani ◽  
Nassereldeen A. Kabbashi ◽  
Isam Y. Qudsieh ◽  
Faiz A. Elfaki
Keyword(s):  
Ftir Spectroscopy ◽  
Partial Least Square ◽  
Least Square ◽  
New Method ◽  
Calibration Model ◽  
Chemical Methods ◽  
Toxic Dyes ◽  
Wet Chemical ◽  
The Difference

A new method was developed to determine toxic dyes content in textileand other products using Fourier Transform Infrared (FTIR) spectroscopy withAttenuated Total Reflectance (ATR) element and KBr transmission cell. Thewavelengths used were selected using pure dyes and dye mixtures. Transmittance valuesfrom the wavelengths regions 3500 – 2650 and 1675 – 1500 cm-1 and partial least square(PLS) regression method were used to derive FTIR spectroscopic calibration model fordyes containing –N=N– in their structure. The coefficient of determinations (R2) for themodels were computed by comparing the results obtained from FTIR spectroscopyagainst the actual values of the dyes concentrations. R2 were 0.9321 and 0.9819 for twosamples of toxic dyes respectively. The standard errors (SE) of calibrations were 1.84and 1.36 respectively. The calibration model was cross validated within the same set ofsamples and the standard deviation (SD) of the difference for repeatability and accuracyof the FTIR method were determined. With its speed and ease of data manipulation,FTIR spectroscopy is a useful alternative method to wet chemical methods for rapid androutine detection of azo dyes as toxic dyes in such products for quality control.

COMPARISON OF WET-CHEMICAL METHODS FOR DETERMINATION OF LIPID HYDROPEROXIDES

2003 ◽  
Vol 10 (1) ◽  
pp. 35-50 ◽  
Author(s):  
NINA SKALL NIELSEN ◽  
MAIKE TIMM-HEINRICH ◽  
CHARLOTTE JACOBSEN
Keyword(s):  
Lipid Hydroperoxides ◽  
Chemical Methods ◽  
Wet Chemical

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.

The Application of X-Rays to the Analysis of Container Glass

1961 ◽  
Vol 5 ◽  
pp. 457-463
Author(s):  
Stephen H. Laning
Keyword(s):  
Sodium Carbonate ◽  
Matrix Effects ◽  
Container Glass ◽  
X Rays ◽  
Chemical Methods ◽  
X Ray ◽  
Gravimetric Determination ◽  
Wet Chemical ◽  
Modern Instrumentation

AbstractContainer glass, which is derived from the fusion of sand, sodium carbonate, limestone or dolomite, and feldspar, along with small amounts of colorants, reducing agents, and other modifiers, offers quite a challenge to the analyst, whether it be by conventional wet-chemical methods or by modern instrumentation. An analysis for 12 elements, which would take many days by standard wet methods, can now be done in 3–4 hr for a single sample, or 2 hr when analyzed in groups of three or more samples.X-ray procedures have been developed and calibration curves obtained for SiO2, CaO, MgO, K2O, Al2O3, Cr2O3, Mn2O3, Fe2O3, CoO, BaO,TiO2, SrO, ZrO2, As2O5, and SO3 In glass. With a gravimetric determination of Na2O added to the elements determined by Xray, the total should approach 100%. An analysis Is considered satisfactory if the combined determinations total within ±0.3% of 100%. Various X-ray procedures and matrix effects shall be discussed.

Determination of the Composition of Lignocellulosic Biomasses from Combined Analyses of Thermal, Spectroscopic, and Wet Chemical Methods

2021 ◽  
Vol 60 (9) ◽  
pp. 3502-3515
Author(s):  
G. Susana Cano-Díaz ◽  
Alberto Rosas-Aburto ◽  
Eduardo Vivaldo-Lima ◽  
Leticia Flores-Santos ◽  
Miguel A. Vega-Hernández ◽  
...  
Keyword(s):  
Chemical Methods ◽  
Wet Chemical

Chemical analysis of olivines by the electron microprobe

1965 ◽  
Vol 34 (268) ◽  
pp. 436-459 ◽  
Author(s):  
J. V. Smith ◽  
R. C. Stenstrom
Keyword(s):  
Electron Microprobe ◽  
High Speed ◽  
Reference Value ◽  
Specimen Preparation ◽  
Chemical Methods ◽  
Small Deviations ◽  
Straight Line ◽  
Wet Chemical ◽  
Fundamental Reference

SummaryThirty-one natural olivines, of which 25 had been previously analysed by wet chemical methods, have been analysed for Mg, Fe, Mn, Ca, Ni, and Co by electron-microprobe techniques. The totals of the olivine molecules Fo, Fa, etc., calculated from the above metals vary from 97·6 to 101·5 with a mean of 99·6%. Twenty-one of the specimens had been used previously by Yoder and Sahama to prepare a determinative curve between mole per cent. Fo and the lattice spacing d130. Yoder and Sahama had found that the data for natural olivines showed large random displacements from a straight line, and that the best straight line deviated for low Fo values from that for synthetic olivines. A plot of Fo determined from the microprobe vs. d130 corrected for lattice expansion caused by Ca and Mn shows no systematic deviation between natural and synthetic specimens, and only small deviations from the best continuous curve (maximum 4% in Fo assuming no error in d130). The maximum contents found for Mn, Ca, Ni, and Co were 3·2, 0·54, 0·33, and 0·03%, respectively. For these minor constituents, some of the wet chemical analyses agreed very well with the microprobe results while others showed large deviations. Although the substitution of Ca is small, it can affect considerably the determination of mole per cent. Fo from d130.After specimen preparation and calibration have been carried out, microprobe analyses for most major and minor (but not trace) elements in common silicates can be made with an accuracy of about 0·5 to 5% of the amount present in about one minute for each group of three elements. Although standard chemical methods applied to large homogeneous samples will retain their fundamental reference value, microprobe techniques with their high spatial resolution, relative freedom from contamination problems, high speed, and moderate to good accuracy promise to revolutionize analytical programmes in mineralogy and petrology.

Interlaboratory Comparison for the Determination of 24,25-Dihydroxyvitamin D3 in Human Serum Using Liquid Chromatography with Tandem Mass Spectrometry

2017 ◽  
Vol 100 (5) ◽  
pp. 1308-1317 ◽  
Author(s):  
Stephen A Wise ◽  
Susan S-C Tai ◽  
Michael A Nelson ◽  
Carolyn Q Burdette ◽  
Johanna E Camara ◽  
...  
Keyword(s):  
Vitamin D ◽  
Human Serum ◽  
Interlaboratory Comparison ◽  
Standard Reference Materials ◽  
Vitamin D Metabolites ◽  
External Quality Assessment Scheme ◽  
Dihydroxyvitamin D3 ◽  
Laboratory Results ◽  
24,25 Dihydroxyvitamin D3

Abstract Six laboratories associated with the Vitamin D Standardization Program (VDSP) participated in an interlaboratory comparison of LC with tandem MS (MS/MS) methods for the determination of 24,25-dihydroxyvitamin D3 [24,25(OH)2D3] in human serum. The laboratories analyzed two different serum-based Standard Reference Materials (SRMs) intended for use in the determination of 25-hydroxyvitamin D and 30 samples from the Vitamin D External Quality Assessment Scheme (DEQAS). All laboratorymethods for 24,25(OH)2D3 were based on isotope dilution LC-MS/MS; three of the methods used derivatization of the vitamin D metabolites before LC-MS/MS. Laboratory results were compared to the National Institute of Standards and Technology (NIST) results, which were obtained using their newly developed candidate reference measurement procedure for 24,25(OH)2D3. Laboratory results for the SRM samples varied in comparability to the NIST results, with one laboratory in excellent agreement (−1.6% mean bias), three laboratories at 10–15% mean bias, and the remaining laboratory at 36% mean bias. For the 30 DEQAS samples, the mean bias for the five laboratories ranged from 6 to 15%; however, the SD of the bias ranged from 8 to 29%. As a result of this intercomparison study, one laboratory discovered and corrected a methodcalculation error and another laboratory modified and improved their LC-MS/MS method.

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