By Anonymous on Tuesday, May 11, 2004 - 09:20 am:
Our lab purchasing the oxygenate calibration std from SQS(spectrum quality standards inc) for D4815 system.
Mixure 1(mass%)
Methanol = 14.22%
T-Buthanol=7.12%
IPA=2.37%
DME=5%
ISO/XYL=Balance
The internal standard(DME)weight is 5%. My question is what should be the sample weight? Is all add up equal to 100 V% or 105 V%.
Awaiting for your reply
Thanks
By Anonymous on Wednesday, May 12, 2004 - 07:20 am:
A percentage over 100% really doesn't have much physical meaning, especially if the numbers being summed are accurate to the second decimal place. The total of the analytes and the internal standard should sum up to 100%.
By Les on Wednesday, May 19, 2004 - 10:52 am:
I prepare samples to approx 50 ml in a volumetric with 25 mL of a weighed sample of gasoline and weigh 3 ml of DME. Bring the total to 50 ml using toluene. The DME mass % is approx 5%. The technicians need to enter the mass in grams. The DME weight is about 2.5 grams. I use 2.5 grams for the purchased standards to fit our system.