Improved ultraviolet spectrophotometric method for determination of nitrate in natural waters

2002 ◽  
Vol 2 (2) ◽  
pp. 213-221 ◽  
Author(s):  
N. Kishimoto ◽  
I. Somiya ◽  
R. Taniyama
Keyword(s):  
Water Quality ◽  
Spectrophotometric Method ◽  
Standard Error ◽  
Coefficient Of Variation ◽  
Natural Waters ◽  
Uv Light ◽  
Rapid Determination ◽  
The Other ◽  
Extreme Conditions

An improved UV spectrophotometric method for determination of nitrate in natural waters was proposed and the determination accuracy of the method was discussed in this study. As a result of estimation of the proposed method, adoption of 215 and 220 nm for detection of nitrate and interfering substances resulted in decreasing standard error to about a half of that of a conventional spectrophotometric method. One of the reasons was thought that the coefficient of variation of relative absorbance of interfering substances (rs) at 215 nm was smaller and more stable than that at 275 nm, which was used in the conventional method. The other reason inferred was that most of the interfering substances absorbed UV light at wavelengths of 215 and 220 nm. Although rs has to be renewed when targeted water quality is under extreme conditions, the procedure of the proposed method is very simple, namely only measuring two UV absorbances of a filtrated sample, and more accurate than the conventional spectrophotometric method. Consequently, the proposed method is available for rapid determination of nitrate in natural waters.

Spectrophotometric Determination of Aminacrine Hydrochloride in Creams, Jellies, and Suppositories: Interlaboratory Study

1987 ◽  
Vol 70 (3) ◽  
pp. 560-565
Author(s):  
Elaine A Bunch
Keyword(s):  
Thin Layer ◽  
Spectrophotometric Determination ◽  
Spectrophotometric Method ◽  
Coefficient Of Variation ◽  
Visible Spectrum ◽  
Interlaboratory Study ◽  
Commercial Products ◽  
Absorbance Maximum

Abstract A previously reported visible spectrophotometric method for the analysis of aminacrine hydrochloride in creams, jellies, and suppositories was studied collaboratively by 8 laboratories. Aminacrine hydrochloride was extracted into acidic ethanol and its visible spectrum recorded. The amount present was calculated by determining the net absorbance between the absorbance maximum at about 402 nm and one-half the sum of the absorbance of the minima at about 389 and 412 nm. Each collaborator received 4 creams (0.2%), 1 jel (0.2%), 1 molded suppository (6 mg/3.198 g), and 2 gelatin-encapsulated suppository samples (12 mg/6.661 g and 14 mg/6.863 g). The cream samples included blind duplicates prepared to contain 0.212% aminacrine hydrochloride, 15% sulfanilamide, and 2% allantoin. Mean recovery for the authentic cream was 104.7% with a coefficient of variation (CV) of 9.22%. The commercial products contained these respective amounts (CVs): creams, 100.0% (2.48%) and 101.5% (2.16%); jel, 118.0% (9.58%); molded suppository, 102.7% (1.88%); and gelatin encapsulated suppositories, 93.1% (1.0%) and 94.3% (1.60%). Standard aminacrine hydrochloride provided for the study was 99.6% pure by nonaqueous titration. Thin layer chromatographic identification of aminacrine hydrochloride was also tested collaboratively. The method was not adopted by AOAC.

A Method for the Analysis of Total Nitrogen in Natural Waters

1984 ◽  
Vol 41 (5) ◽  
pp. 815-819 ◽  
Author(s):  
J. Kalff ◽  
E. Bentzen
Keyword(s):  
Sample Size ◽  
Total Nitrogen ◽  
Coefficient Of Variation ◽  
Natural Waters ◽  
Sodium Salicylate ◽  
Persulfate Oxidation ◽  
Dissolved Nitrogen

This method for analyzing total nitrogen (TN) in freshwaters is based on the persulfate oxidation of nitrogen to nitrate, followed by the analysis of this nitrate by a modified version of the sodium salicylate method. The method is simpler than other reported techniques for TN in oligotrophy and mesotrophic waters and requires equipment readily available in most laboratories. The method is linear to 1000 μg N/L, with the range extendable by changing the sample size. The variability is lowest (coefficient of variation 6.6%) between 100 and 1000 μg N/L. We have successfully used the method for the determination of TN, as well as dissolved nitrogen (DN) on filtered samples and nitrate on nonoxidized samples.

X-Ray Spectrometric Determination of Sulfate in Natural Waters

1979 ◽  
Vol 23 ◽  
pp. 133-141
Author(s):  
C. A. Seils ◽  
G. T. Tisue
Keyword(s):  
Natural Waters ◽  
Rapid Determination ◽  
Atomic Absorption Spectrophotometry ◽  
Good Choice ◽  
Small Samples ◽  
Selective Electrode ◽  
X Ray ◽  
Heavy Metal Cations ◽  
Improved Methods

A recent surge of interest in sulfur in the environment has revealed the need for improved methods of analysis for sulfate, SO4=, in rain, freshwater and sediment interstitial fluids. Ion chromatography permits the rapid determination of SO4= in the ppm range (1 ppm = 1 mgL'1 = 10 μmol L-1 sulfate) on relatively small samples with good specificity. If a suitable instrument is available, this technique is a good choice for many environmental analyses. Other approaches to sulfate analysis are based on its precipitation with organic or heavy metal cations, usually barium or lead. The amount of precipitate formed may be determined by inter alia gravimetry, turbidimetry, radiometry (using 133-Ba), atomic absorption spectrophotometry (Ba or Pb detection), potentiometry (using a Pb++ ion selective electrode) , colorimetry, or by x-ray fluorescence spectrometry (Ba, Pb or S detection)(1). Because of our experience with x-ray fluorescence analyses, we chose to develop and test a procedure using that technique.

Gas Chromatographic Methods for Determination of γ-BHC in Technical Emulsifiable Concentrates and Water-Dispersible Powder Formulations and in Lindane Shampoo and Lotion: Collaborative Study

1984 ◽  
Vol 67 (4) ◽  
pp. 834-837
Author(s):  
James W Miles ◽  
Dwight L Mount ◽  
◽  
T J Beckmann ◽  
S K Carrigan ◽  
...  
Keyword(s):  
Coefficient Of Variation ◽  
Collaborative Study ◽  
Internal Standard ◽  
The Other ◽  
Water Dispersible ◽  
Coefficients Of Variation ◽  
Aoac Method ◽  
Liquid Chromatographic ◽  
Gas Chromatographic Separation

Abstract Although the gas chromatographic separation of the isomers of BHC was demonstrated two decades ago, the present AOAC method of analysis of BHC for gamma-isomer (lindane) content is based on a separation carried out on a liquid chromatographic partition column. A method of analysis has been developed that uses an OV-210 column for separation of the gamma-isomer from the other isomers and impurities in technical BHC. Di-n-propyl phthalate was chosen as an internal standard. The same system allows quantitation of lindane in lotion and shampoo after these products are extracted with ethyl acetate-isooctane (1 + 4). The analytical methods were subjected to a collaborative trial with 10 laboratories. The coefficient of variation for technical BHC was 2.83%. For the water-dispersible powder and emulsifiable concentrate, the coefficients of variation were 2.89% and 4.62%, respectively. Coefficients of variation for 1% lindane lotion and shampoo were 4.36% and 11.92%, respectively. The method has been adopted official first action.

Rapid Determination of Alkaline Phosphatase Activity in Cheese

1977 ◽  
Vol 60 (6) ◽  
pp. 1397-1399 ◽  
Author(s):  
Dick H Kleyn ◽  
Steven T Goodman
Keyword(s):  
Alkaline Phosphatase ◽  
Alkaline Phosphatase Activity ◽  
Spectrophotometric Method ◽  
Quantitative Data ◽  
Rapid Determination ◽  
Screening Method ◽  
Spectrophotometric Measurement ◽  
Extraction Step ◽  
Visual Screening

Abstract A visual screening method specifying phenolphthalein monophosphate as the substrate was applied to cheese by analyzing the extract obtained with 7.5% butanol. In the extraction step, all of the alcohol was added at one time, and the mixture was filtered after mixing. Analysis of 10 samples of various types of cheese resulted in data identical to that obtained by the Scharer rapid method. Quantitative data obtained by dialysis of the butanol filtrate and spectrophotometric measurement of the phenolphthalein compared favorably (r = 0.96) with data obtained by the Scharer spectrophotometric method on 13 samples of cheese.

Manual Salicylate-Hypochlorite Procedure for Determination of Ammonia in Kjeldahl Digests

1982 ◽  
Vol 65 (5) ◽  
pp. 1076-1079
Author(s):  
Helen E Fukumoto ◽  
George W Chang
Keyword(s):  
Correlation Coefficient ◽  
Spectrophotometric Method ◽  
Coefficient Of Variation ◽  
Precise Timing ◽  
Coefficients Of Variation ◽  
Moderate Volume ◽  
Kjeldahl Method

Abstract The determination of nitrogen in Kjeldahl digests of urine and feces has been simplified by using a manual spectrophotometric method with salicylate and hypochlorite. It neither involves the hazards of the phenol-hypochlorite method, nor requires an automated analyzer. We determined the conditions which minimize the need for precise timing and neutralization of acidic digests and obtained coefficients of variation of about 0.8%. Agreement between the spectrophotometric method and the conventional micro-Kjeldahl method was excellent; a correlation coefficient of 0.9992 and a coefficient of variation of the estimate of 2.1% were obtained. This method is well suited for a laboratory with a moderate volume of samples. We could process at least 200 digests per day, in contrast with the 60 per day which we had previously done by the Kjeldahl distillation and titration.

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