Standard Methods: 3500-Al B: Aluminum by Eriochrome Cyanine R Method

Summary
Analytes
Revisions
Data and Sites

Official Method Name

3500-Al B. Eriochrome Cyanine R 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

With Eriochrome cyanine R dye, dilute aluminum solutions buffered to a pH of 6.0 produce a red to pink complex that exhibits maximum absorption at 535 nm. The intensity of the developed color is influenced by the aluminum concentration, reaction time, temperature, pH, alkalinity, and concentration of other ions in the sample. To compensate for color and turbidity, the aluminum in one portion of sample is complexed with EDTA to provide a blank.

Scope and Application

The Eriochrome cyanine R colorimetric method provides a means for estimating aluminum with simple instrumentation.

Applicable Concentration Range

20 - 300 ug Al/L

Interferences

Negative errors are caused by both fluoride and polyphosphates. Orthophosphate in concentrations under 10 mg/L does not interfere. Procedures are given in the method for the removal of intereference from fluoride and polyposphates. The interference caused by even small amounts of alkalinity is removed by acidifying the sample just beyond the neutralization point of methyl orange. Sulfate does not interfere up to a concentration of 2000 mg/L.

Quality Control Requirements

See Section 3020 Quality Assurance/Quality Control.

Sample Handling

Collect samples in clean, acid-rinsed bottles, preferably plastic, and examine them as soon as possible after collection. If only soluble aluminum is to be determined, filter a portion of sample through a 0.45-um membrane filter; discard first 50 mL of filtrate and use succeeding filtrate for the determination. Do not use filter paper, absorbent cotton, or glass wool for filtering any solution that is to be tested for aluminum, because they will remove most of the soluble aluminum.

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
Aluminum(7429-90-5) Al Aluminium Aluminum Aluminum (fume or dust) Aluminum powder	6.000 ug/L	2Rel. Error (ML)	34.40 % RSD (ML)			520.00 ug/L

Precision Descriptor Notes:	A synthetic sample containing 520 ug Al/L and no interference in distilled water was analyzed by the Eriochrome cyanine R method in 27 laboratories. Relative standard deviation was 34.4% and relative error 1.7%. A second synthetic sample containing 50 ug Al/L, 500 ug Ba/L, and 5 ug Be/L in distilled water was analyzed in 35 laboratories. Relative standard deviation was 38.5% and relative error 22.0%. A third synthetic sample containing 500 ug Al/L, 50 ug Cd/L, 110 ug Cr/L, 1000 ug Cu/L, 300 ug Fe/L, 70 ug Pb/L, 50 ug Mn/L, 150 ug Ag/L, and 650 ug Zn/L in distilled water was analyzed in 26 laboratories. Relative standard deviation was 28.8% and relative error 6.2%. A fourth synthetic sample containing 540 ug Al/L and 2.5 mg polyphosphate/L in distilled water was analyzed in 16 laboratories that hydrolyzed the sample in the prescribed manner. Relative standard deviation was 44.3% and relative error 1.3%. In 12 laboratories that applied no corrective measures, the relative standard deviation was 49.2% and the relative error 8.9%. A fifth synthetic sample containing 480 ug Al/L and 750 ug F/L in distilled water was analyzed in 16 laboratories that relied on the curve to correct for the fluoride content. Relative standard deviation was 25.5% and relative error 2.3%. The 17 laboratories that added fluoride to the aluminum standards showed a relative standard deviation of 22.5% and a relative error of 7.1%. The precision reported in NEMI was obtained from the first study with no interferencees (520 ug Al/L).
Detection Level Note:	The minimum aluminum concentration detectable by this method in the absence of fluorides and complex phosphates is approximately 6 ug/L.

Precision Descriptor Notes:

A synthetic sample containing 520 ug Al/L and no interference in distilled water was analyzed by the Eriochrome cyanine R method in 27 laboratories. Relative standard deviation was 34.4% and relative error 1.7%. A second synthetic sample containing 50 ug Al/L, 500 ug Ba/L, and 5 ug Be/L in distilled water was analyzed in 35 laboratories. Relative standard deviation was 38.5% and relative error 22.0%. A third synthetic sample containing 500 ug Al/L, 50 ug Cd/L, 110 ug Cr/L, 1000 ug Cu/L, 300 ug Fe/L, 70 ug Pb/L, 50 ug Mn/L, 150 ug Ag/L, and 650 ug Zn/L in distilled water was analyzed in 26 laboratories. Relative standard deviation was 28.8% and relative error 6.2%. A fourth synthetic sample containing 540 ug Al/L and 2.5 mg polyphosphate/L in distilled water was analyzed in 16 laboratories that hydrolyzed the sample in the prescribed manner. Relative standard deviation was 44.3% and relative error 1.3%. In 12 laboratories that applied no corrective measures, the relative standard deviation was 49.2% and the relative error 8.9%. A fifth synthetic sample containing 480 ug Al/L and 750 ug F/L in distilled water was analyzed in 16 laboratories that relied on the curve to correct for the fluoride content. Relative standard deviation was 25.5% and relative error 2.3%. The 17 laboratories that added fluoride to the aluminum standards showed a relative standard deviation of 22.5% and a relative error of 7.1%. The precision reported in NEMI was obtained from the first study with no interferencees (520 ug Al/L).

Detection Level Note:

The minimum aluminum concentration detectable by this method in the absence of fluorides and complex phosphates is approximately 6 ug/L.

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

The Water Quality Portal contains sample results from sites that use this method.

Download WQP data

Select data:

Sites only
Sample results only

File format:

Comma-separated
Tab-separated
MS Excel 2007+

Sites where this method was used

Loading Sites ...

Standard Methods: 3500-Al B: Aluminum by Eriochrome Cyanine R Method

WHO WE ARE

LEGAL