supply of different parameters standard with traceability certificate for district water testing laboratory p . h . e . division ratlam , chloride standard solution traceable to srm from nist nacl in h2o 1000mg/l with traceability certificate 500 ml pack . , calcium standard solution traceable to srm from nist ca ( no3 ) 2 in hno3 0 . 5 mol/l 1000 mg/l with traceability certificate 500 ml pack . , alkalinity standard rm 1000mg/l as na2co3 certified reference standard with traceability certificate 1000 ml pack . , ph buffer standard for ph 4 . 0 traceable to srm from nist with traceability certificate minimum one year validity on date of supply . 475ml . pack , ph buffer standard for ph 7 . 0traceable to srm from nist with traceability certificate minimum one year validity on date of supply 475ml . pack , ph buffer standard for ph 9 . 0 traceable to srm from nist with traceability certificateminimum one year validity on date of supply475ml . pack