(10 sec ramp), charred at 650 C for 40 sec (no ramp), followed by 
atomization at 2500 C for 8 sec with a 3-sec stop of gas. 
RESULTS AND DISCUSSION 
Partially Developed Methods 
One of the objectives of this work was to apply quantitative 
methods developed for other metals and organometallic compounds 
to tin and organotin compounds. The approach was to separate 
organotin compounds from one another via gas liquid chromato¬ 
graphy (GLC) and to allow the effluent from the GLC to pass 
through a heated transfer tube to an atomic absorption spectro¬ 
photometer (AA) which would detect tin. Thus, those compounds 
which contained tin would be detected by the AA. The method is 
in use in several laboratories for other metals (Brinckman et 
al. 1976, Parris et al. 1977, Trachman et al. 1977) and contact 
was maintained with workers at the National Bureau of Standards 
throughout the project. Due to time pressures, further develop¬ 
ment of the method was stopped before it was ready for use on 
this project. Success was achieved in separating mono-, di-, 
tri-, and tetra-methyltin via GLC, although the system is not 
yet sensitive enough for direct application to environmental 
samples. The A?, unit is close to being used as a detector for 
organotin compounds eluted from the GLC. Not the least of the 
difficulties was an 11-month delay in receiving the heated 
transfer line from the sole manufacturer. Work on this aspect 
of the project is continuing and support of this contract will 
be acknowledged in all publications. 
Physical and Chemical Data on Samples 
Physical and chemical data for samples taken on cruises and 
excursions in April 1978 and July 1979 are summarized in 
Tables 20 and 21. Temperatures and salinities were as expected 
for these sites in spring and summer seasons, respectively. pH 
values, which were taken only for the summer 1979 samples, were 
significantly higher at the freshwater sites than at the estu¬ 
arine sites; they were highest at the two Tenneco sites. Values 
for dissolved oxygen were higher in April 1978 than in July 1979, 
as expected for spring and summer seasons, respectively. It is 
noteworthy that in summer 1979, dissolved oxygen was dangerously 
low near the bottom at the Buoy Rock site, which did not suffer 
extensive oyster mortality; while dissolved oxygen was only 
slightly higher at Spaniard Bar. Both oyster bars gave lower 
summer readings for dissolved oxygen than were found in Balti¬ 
more Harbor. A very high reading was obtained at the Tenneco 
pond in July 1979. A comparison of physiochemical data for the 
healthy bar. Buoy Rock, and the data for Spaniard Bar, show only 
dangerously low dissolved oxygen near the bottom as a potential¬ 
ly lethal condition. None of the physiochemical data from the 
freshwater sites gives a direct clue to the extensive kill of 
91 
