NSWC/WOL/TR 75-35 



Corp., Bedford, Massachusetts) offers both speed and precision in 

 counting particles, in determining size distributions and in 

 characterizing shapes. It can rapidly and accurately measure such 

 parameters as diameter, longest dimension, or area. 



Samples forTTMC measurement are prepared by Millipore filtration. 

 This results in a random distribution of particles. The filters are 

 made transparent with various clearing techniques and mounted on 

 glass slides. The sample is ready for measurement. 



The sample is placed on the microscope stage and the 

 illumination and focus are adjusted while the operator is viewing 

 the sample. The camera scans the microscope image and converts its 

 contents into a video signal which is sent to the computer. The 

 computer receives the video signal and applies the logic necessary 

 to count and measure particles in the field of view. The video 

 signal then goes to the viewing monitor where the field of view is 

 reconstructed. Measurements are displayed instantly in micrometers 

 or square micrometers and can be made on individual particles as 

 well as entire fields of view. 



4.3.3.4 Particulate Carbon 



To determine the particulate carbon in water a Dohrmann total 

 organic carbon analyzer (Envirotech Corp., Santa Clara, Calif., $8, 000) 

 can be used. In the analysis a 30yl acidified water sample is 

 injected into a sample boat containing an oxidizer at room tempera- 

 ture. The boat is then advanced to the 90°C vaporization zone where 

 H2O, CO2 (from dissolved CO2 , carbonates and bicarbonates) and 

 organic carbon materials which are volatile at 90°C are swept into 

 the by-pass column. Here volatile organic carbon (VOC) is trapped 

 on a Porapak Q column at 60°C while the H2O and CO2 are swept through 

 the switching valve and vented to atmosphere. 



After sample vaporization, the valve is automatically switched 

 to the pyrolyze position and the boat is then advanced to the 

 pyroysis zone. Residual organic carbon (ROC) materials left in the 

 boat react with the oxidizer at 850°C to produce C0 2 . At the same 

 time the by-pass column is backflushed at 120°C thus sweeping the 

 VOC material through the pyrolysis zone. Both the VOC and the C0 2 

 (from the ROC) are swept by helium into the hydrogen enriched nickel 

 catalyst reduction zone where all carbon is converted to methane at 

 350°C. 



The reduction product is swept through the switching valve, 

 the water detention column and into the flame ionization detector 



55 



