Step 6. Determine pressure correction by 

 dividing barometric pressure by standard pres- 

 sure. 



Step 7. Determine saturation value of gas 

 from figures J-17 or J-18 using (T, of HoO). 



Step 8. Compute solubility corrected for pres- 

 sure. Saturation value for (Ti of HvO) times 

 pressure correction. 



Step 9. Compute calibration factor. Solubil- 

 ity corrected for pressure divided by coimts 

 reverted to 100 percent. 



DATA FOB DFTERMINATION OF GAS CHBOMATOGRAPITf CALIBRATlbH FACTOB 



SHIP eWSTo CRUISE /tlRfm^ HEMIST JAg DAT E X^ fl UG C^ 



OAS (Og 



'■•Q: 



ifrom AIH) STAHDARD PRESSURE 760 i 



S.'I-.O 



"C . SENSITIVITY 



^^'. 



BAROMETRIC PRESSURE^^" COUMTS (Average ) 7g S"7 

 REVERTED TO lOOt Si.2 ,3'fS 



PRESSURE CORRECTION - B.P/S.P - 

 SATURATION OP GAS (From graph )_ 





SATURATION VALUE TIMES PRESSURE CORRECTION - //• ^f 



SOUmiUTY CORRECTED FOR PRESSURE 



COUNTS REVERTED TO lOpjt 





Figurc J-16. Format for setting up calibration sheet. 



J-25i Calculations of Oxygen and Nitro- 

 gen. — ^To calculate the O2 and N2 content from 

 the comits obtained during analysis, perform 

 the following steps using the Log Sheet-CC 

 (fiff. J-14) : 



Step 1. From the Oceanographic Log Sheet- 

 A for the station involved, determine the in sitti 

 temperature (to the nearest degree) for each 

 sample and enter in T °C In Situ column, e.g. 

 -1° (Serial Number 656; Bottle Number 3). 



Step 2. From the calibration sheets, enter the 

 O2 and N2 calibration factoids in the blocks at 

 top of log sheet, e.g., 02ml./L count = 4.129 

 XlO-% Nsml./L count= 3.954x10-*. 



Step 3. Convert A + O2 Counts Read to 100 

 percent by dividing by sensitivity, e.g., 6085 

 ^.25 = 24340. Convert N2 Counts Read to 100 

 percent, e.g., 1 1428 h- .25 = 45712. Enter results 

 in columns A-t-02 Counts at 100 percent and 

 N2 Counts at 100 percent. 



Step 4. Compute the A coiTection factor with 

 the following fonnula and enter results in A 

 Factor column, e.g., 3.06 X 10"= : 



A Correction Factor= (8.0 X lO"'') (T) + (3.07 

 X 10"=) where T= m situ temperature of sample. 

 In the chromatographic analysis of air saturated 

 liquids, O, and A have equal retention times at 

 room temperature, i.e., they appear as one peak 

 on the chromatogram. 



Step 5. Multiply the N2 Counts at 100 percent 

 column by the A Factor column, and enter the 

 result in A Factor Times N2 Counts at 100 per- 

 cent coluimi, e.g., 1399. 



Step 6. Subtract A Factor Times N2 Counts 

 at 100 percent column from A-I-O2 Counts at 

 100 percent column to determine O2 count. Enter 

 in O2 Counts column, e.g., 24340-1399=22941. 



Step 7. Multiply O- Counts column by the 

 O2 calibration factor, e.g., 22941X4129X10-* 

 = 9.47. Enter result in Ooml./Liter column. 



Step 8. Multiply N Counts at 100 percent by 

 the N2 calibration factor, e.g., 45712X3.954 

 X 10-^=18.075. Enter results in Nzml./Liter 

 column. 



Step 9. After the chromatogram has been re- 

 moved from the recorder, check all computa- 

 tions carefully. 



J-26 Maintenance of Gas Chromatography 

 Equipment. — In general the gas chromato- 

 graphic equipment requires very little main- 

 tenance. If O2 samples are collected at each 

 oceanographic station, the equipment usually is 

 not secured until the cruise has ended. 



A tank of He usually will last for 4 to 6 weeks 

 at the regulated flow rate of 50 ml./min. 



A roll of chart paper usually will be ample 

 for 100 samples. 



The Ascarite drying tubes should be changed 

 when their blue color fades to pink. 



The columns in the gas partitioner should be 

 changed if the signal pen fails to return to 1.0 

 margni on chromatogram between the N2 and O2 

 peaks. 



J-21 



