A MDL was established for each analysis based on at least seven repeated measurements (within 
a run) of a low level standard. 
Table B.4 Precision, accuracy, and recovery for total nitrogen and phosphorous analyses. 
Measure 
Total Nitrogen 
Total Phosphorous 
Precision, % 
98.7 
96.7 
(n=39) 
(n= 36) 
Accuracy, % 
101.8 
97.7 
Digestion Recovery, % 
96.3 
98.5 
Handheld YSI Meters 
The handheld multiparameter Yellow Springs Instruments (YSI) meters were checked 
prior to use with manufacturers (YSI) conductivity standard. To check the dissolved oxygen 
reading the DO probe was placed in a 100% saturated environment for several minutes. If the 
percent saturation value was several points away from 100% the electrodes were cleaned, a new 
KCL solution was reapplied and the membrane was replaced. Another percent saturation reading 
is taken after the DO probe has been serviced. All QA/QC checks and calibrations recorded in a 
database (Microsoft " Office Access 2003). The frequency of checks and calibrations was 
intermittent and depends on how often the units are being used. 
YSI Multiparameter Sonde 
YSI 6600 Multiparameter Sondes were calibrated prior to deployment following the 
manufacturer’s recommendations. Conductivity was calibrated with a one-point calibration 
using standards with conductivity values closest to the expected salinity range (50 mS cm' 1 for 
high salinity stations, 10 mS cm' 1 for mesohaline and 1 mS cm' 1 for low salinity stations). 
Turbidity was calibrated with a two-point calibration; using reverse osmosis water (RO) 
followed by a 123 NTU YSI standard solution. The dissolved oxygen (DO) sensor was 
calibrated for dissolved oxygen in air at sea level using the saturated air in water method. The 
DO anode was cleaned and fresh KCL solution added prior to applying a new membrane film. 
The probes were set in a calibration cup with a small amount of water for maximum water vapor 
saturation for 15 minutes before the calibration reading was taken. The barometric pressure was 
determined from either a mercury barometer or from a YSI 650 or 556 hand-held meter. 
139 
n 
