Surfactant Sensitized Calix[4]arenes Fluorescence Quenching Method for Speciation of Cr(VI)/Cr(III) in Water Samples

Table 3

Analysis of certified reference materials (mean ± S.D., 𝑛=3).

Sample	Certified value (µg mL^−1)			Found (µg mL^−1)			Total Cr recovery (%)
	Cr(VI)	Cr(III)	Total Cr	Cr(VI)	Cr(III)^a	Total Cr
GSBZ50027-94	0.40±0.01	—	—	0.42±0.01	ND	0.42±0.01	105.0
GBW(E)080642	—	—	100.00±5.00	24.80±1.30	73.24±3.04	98.04±3.04	98.0

ND: not detected; ^athe concentration of Cr(III) was calculated by subtracting of Cr(VI ) from the total chromium.