Standard Methods: 3500-Zn B: Zinc by Zincon Method

Summary
Analytes
Revisions
Data and Sites

Official Method Name

3500-Zn B. Zincon Method

Current Revision

Standard Methods Online

Media

WATER

Instrumentation

Spectroscopy (Colorimetry; Photometry)

Method Subcategory

Inorganic

Method Source

Standard Methods

Citation

Standard Methods Online - Standard Methods for the Examination of Water and Wastewater

Brief Method Summary

Zinc forms a blue complex with 2-carboxy-2'-hydroxy-5'-sulfoformazyl benzene (zincon) in a solution buffered to pH 9.0. Cyanide is added to complex zinc and heavy metals. Cyclohexanone is added to free zinc selectively from its cyanide complex so that it can be complexed with zincon to form a blue color. Sodium ascorbate reduces manganese interference. The developed color is stable except in the presence of copper.

Scope and Application

The zincon method, suitable for analysis of both potable and polluted waters, may be used if instrunemtation for other methods is not available.

Applicable Concentration Range

0.25-7.0 mg Zn/L (can be extended, per method)

Interferences

The following species interfere to varying degrees: cadmium(II), aluminum(III), manganese(III), iron(II &III), chromium(III), nickel(II), copper(II), cobalt(II), and chromate. A table in the method lists the concentrations at which these species interfere.

Quality Control Requirements

See Section 3020 Quality Assurance/Quality Control.

Sample Handling

Plastic or glass containers. Add HNO3 to pH <2.

Maximum Holding Time

6 months (See Section 1060)

Relative Cost

Less than $50

Sample Preparation Methods

This method has 1 analyte associated with it.

Analyte	Detection Level	Bias	Precision	Pct False Positive	Pct False Negative	Spiking Level
Zinc(7440-66-6) Zinc Zinc (fume or dust) Zinc and Compounds Zn	0.020 mg/L	0Rel. Error (ML)	0.96 % RSD (SL)			650.00 mg/L

Precision Descriptor Notes:	A synthetic sample containing 650 ug Zn/L, 500 ug Al/L, 50 ug Cd/L, 110 ug Cr/L, 470 ug Cu/L, 300 ug Fe/L, 70 ug Pb/L, 120 ug Mn/L, and 150 ug Ag/L in doubly demineralized water was analyzed in a single laboratory. A series of 10 replicates gave a relative standard deviation of 0.96% and a relative error of 0.15%. A wastewater sample from an industry in Standard Industrial Classification (SIC) No. 3333, primary smelting and refining of zinc, was analyzed by 10 different persons. The mean zinc concentration was 3.36 mg Zn/L and the relative standard deviation was 1.7%. The relative error compared to results from an atomic absorption analysis of the same sample was -1.0%. The precision reported in NEMI was obtained from the single laboratory study of 650 ug Zn/L.
Detection Level Note:	Minimum detectable concentration is 0.02 mg Zn/L.

Precision Descriptor Notes:

A synthetic sample containing 650 ug Zn/L, 500 ug Al/L, 50 ug Cd/L, 110 ug Cr/L, 470 ug Cu/L, 300 ug Fe/L, 70 ug Pb/L, 120 ug Mn/L, and 150 ug Ag/L in doubly demineralized water was analyzed in a single laboratory. A series of 10 replicates gave a relative standard deviation of 0.96% and a relative error of 0.15%.

A wastewater sample from an industry in Standard Industrial Classification (SIC) No. 3333, primary smelting and refining of zinc, was analyzed by 10 different persons. The mean zinc concentration was 3.36 mg Zn/L and the relative standard deviation was 1.7%. The relative error compared to results from an atomic absorption analysis of the same sample was -1.0%.

The precision reported in NEMI was obtained from the single laboratory study of 650 ug Zn/L.

Detection Level Note:

Minimum detectable concentration is 0.02 mg Zn/L.

Revision	PDF/Link
Standard Methods Online
As Method 3500-Zn F in Standard Methods 18th Edition (1992)
As Method 3500-Zn F in Standard Methods 19th Edition (1995)
Standard Methods 18th, 19th, 20th ed.

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Standard Methods: 3500-Zn B: Zinc by Zincon Method

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