Internal Standards for Quantitative Analysis of Chemical Warfare Agents by the GC/MS Method: Nerve Agents

Table 10

Evaluation of multilaboratory comparison results, showing the determination of several CWAs using the GC/method with the internal standard procedure.

Compound		Tabun	Sarin	Soman	VX agent	Edemo
Known concentration (mg/L)		7.5	9.9	15.0	18.7	23.5
Total number of results		16	24	18	20	20
Accurate/inaccurate results obtained on the system	7890A/5975C	6/0	9/0	8/0	6/0	8/0
	Intuvo 9000/5977B	10/0	8/1	6/0	8/1	6/0
	EM 640	0/0	6/0	4/0	4/1	6/0
Total number of accurate results		16	23	18	18	20
Average determined multilaboratory concentration (mg/L)		7.2	9.7	14.3	19.7	24.8
Relative difference of known and determined concentration (%)		−4.0	−2.0	−4.7	+5.3	+5.5
Relative standard deviation between laboratories (%)		10.0	14.1	9.7	13.3	14.4