Parameters

After CPE

Before CPE

Amount of ethanol

0.2

---

pH

3.5

3.5

Optimum [aluminon]

1.5 × 10^-4

3.0 × 10^-4

Reaction time (min)

5.0

20

Stirring time (min)

5.0

----

λ_max (nm)

538

518

Working range (mg/ml)

7.5 - 220

5000 - 235000

Ringbom range (ng/ml)

25 - 205

7500 - 200000

Molar absorptivity (L/mol.cm)

1.92 × 10⁷

1.65 × 10⁴

Sandell sensitivity (ng/cm²)

0.0033

0.45

Regression equation ^a

Slope

3.02

0.0027

Intercept

0.005

- 0.009

Correlation coefficient (r)

0.99926

0.9965

RSD ^a (%)

1.75

3.90

Detection limits (ng/ml)

2.20

1500

Quantification limits (ng/ml)

7.40

4950

Preconcentration factor

500

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Improvement factor

1165

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