The 1993 QUASIMEME laboratory-performance study: Nutrients in sea water and standard solutions

1994 ◽  
Vol 29 (4-5) ◽  
pp. 159-165 ◽  
Author(s):  
Alain Aminot ◽  
Don S. Kirkwood
Keyword(s):  
Sea Water ◽  
Performance Study ◽  
Laboratory Performance ◽  
Standard Solutions

scholarly journals The determination of silicate in sea water

1951 ◽  
Vol 30 (1) ◽  
pp. 149-160 ◽  
Author(s):  
F. A. J. Armstrong
Keyword(s):  
Sulphuric Acid ◽  
Sea Water ◽  
Picric Acid ◽  
Colorimetric Method ◽  
Ammonium Molybdate ◽  
Potassium Chromate ◽  
Distilled Water ◽  
Yellow Colour ◽  
Standard Solutions

Silicon in sea water may be present in suspension, in particles of clay or sand, as a constituent of diatoms, etc., or in solution. Some silicon in solution occurs in the form of silicate. This is usually estimated by the colorimetric method of Diénert & Wandenbulcke (1923), which makes use of the yellow colour of the silicomolybdic acid which is formed when ammonium molybdate and sulphuric acid are added to the water (Atkins, 1923). The colour may be compared with that of standard solutions of picric acid (Diénert & Wandenbulcke, 1923) or potassium chromate (Swank & Mellon, 1934). The method is simple but the colour in sea water is often faint and is not easy to match visually, nor is its intensity strictly proportional to the concentration of silicate. Less colour is produced in sea water than in standard solutions made with distilled water and this ‘salt error’ must be allowed for (Brujewicz & Blinov, 1933; Wattenberg, 1937; Robinson & Spoor, 1936).

Flame Photometer Specialized for Cesium

1968 ◽  
Vol 22 (2) ◽  
pp. 109-114 ◽  
Author(s):  
T. R. Folsom ◽  
C. Sreekumaran ◽  
W. E. Weitz ◽  
D. A. Tennant
Keyword(s):  
Beam Splitter ◽  
Sea Water ◽  
Optical Filter ◽  
Emission Spectra ◽  
Statistical Fluctuation ◽  
Flame Photometer ◽  
Flame Emission ◽  
Differential Circuits ◽  
Replicate Measurements ◽  
Standard Solutions

A new photometer system is described that allows very small traces of an element, such as cesium, to be determined quantitatively with greater precision than previously possible with flame-emission spectra. For example, with the new system it is possible to replicate measurements of the cesium in quantities that are normally present in one liter of sea water (about 0.3 μg) with standard error less than two percent. Dilute cesium standard solutions can be compared significantly within a few parts per billion. This, apparently, has not been reported for any previous flame photometer. The system consists of two photomultiplier tubes observing a flame simultaneously, from the same aspect, but each having a different optical filter interposed. Use is made of a beam splitter and two interference filters, one filter passing only a narrow band centered at the 8521.1-Å line of cesium, the other filter passing a nearby band not containing much of this emission but rather passing a sample of the background of the flame that contributes much of the total statistical fluctuation. Signals from these two phototubes are compared by suitable differential circuits, and are continuously recorded. A specialized automatic sample-changing system was developed to provide for precise timing of the burning of the sample and the standard solutions and to carry out aspirator washings immediately following the burning of each sample. Finally, means are provided for continuously monitoring the aspiration rate by recording the brightness of the background (off-peak) signal independently.

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