A revised method for determination of dialkylphosphate levels in human urine by solid-phase extraction and liquid chromatography with tandem mass spectrometry: application to human urine samples from Japanese children

Table 4 Storage stability of urinary DAPs

Condition	Concentration (μg/L urine)	%RSD
Condition	Concentration (μg/L urine)	DMP	DMTP	DEP	DETP
Urine sample
Stored at 4 °C	2		111	94	112
	20	93	101	102	93
	200	99
Stored at 37 °C	2		106	109	108
	20	97	104	104	102
	200	100
After four times freeze–thaw cycles	2		97	94	96
	20	95	100	104	103
	200	111
Prepared sample
Stored at 4 °C for 1 day	5	93	97	96	95
Stored at 4 °C for 5 days	5	90	109	104	102

ISSN: 1347-4715