What is the holding time for Lachat reagents and standards?

Document ID

Document ID TE6622

Version

Version 2.0

Status

Status Published

Published Date

Published Date 27/05/2017
Question
What is the holding time for Lachat reagents and standards?
Summary
Holding time for solutions prepared following Lachat methods.
 
Answer
Many Lachat methods will specify how long a solution is good for within the preparation instructions.  When they are not specified one can consider the following general guidelines.
 
  • Organic chemical dissolved in water:  1 day
  • Inorganic salt in water (KCl, NaOH, CuSO4) :  1 month
  • Inorganic salts containing nutrients (KNO3, (NH4)2SO4):  2 days
  • Stock Standards (>1ppm):  1 week
  • Working Standards (<1ppm): 1 day