Salinity Intrusion and Seasonal Water Quality Variations in the Tidal ...

Onceback in the laboratory, where reagents had in advance been prepared and the
instruments calibrated, the analyses were carried out immediately, except for total iron,
hardness and chloride, which were done in the afternoon.
2.8 Laboratory quality control checks
The validity ofany monitoring programme depends on the quality ofmonitoring data.
To ensure the quality ofdata the following Quality Control aspects were ensured. To
prevent any deviation in analytical procedures a document on standard operating
procedure (SOP) was compiled. All the members of the team were trained in the
procedures laid down in the SOP.
• Familiarity with the quality assurance plan required ofall the analyses
• Pre cleaning of sample containers with material specific to the
preservation ofthat fraction
• Use ofAPHA recommended sample preservatives whenever analyses got
delayed
• Adherence to APHA recommended sample holding times
• Maintenance of samples in the safe custody of the crew until after the
analyses
• Documentation ofall reagent preparation
• Routine calibration ofall analytical instruments
• Precision criteria applied to duplicate samples
• Accuracy criteria applied to spiked samples
• Monitoring ofreagent blanks and slopes ofstandard curves
• Specified corrective action
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