This guide describes quality assurance protocols for the determination of the anions and cations in atmospheric wet deposition which include the minimum recommended requirements for the preparation of calibration standards and suggested procedures for validating laboratory measurement results. Specimens to be used in all tests shall consist of reagent grade chemicals, water, and standard solutions. Common techniques for chemical analysis include automated colorimetry; ion chromatography, flame atomic absorption spectrophotometry, electrometry, and inductively coupled plasma spectrometry. Analytical precision and bias determinations shall be done for evaluation of the reference materials. Samples for reanalysis may be selected from the evaluation of control charts and the calculation of ion and conductivity percent differences.

1.1 This guide describes quality assurance (QA) protocols for the determination of the anions and cations in Atmospheric Wet Deposition (AWD) shown in Table 1.

Automated Colorimetry

Ion Chromatography

NH₄⁺

Cl^–, NO₃ ^–, SO₄^2–, NH₄⁺, Ca²⁺, Mg²⁺, Na⁺, K⁺

Flame Atomic Absorption Spectrophotometry

Electrometric

Na⁺, K⁺, Ca²⁺ , Mg²⁺

pH, specific conductance

Inductively Coupled Plasma Spectrometry

Na⁺, K⁺, Ca²⁺, Mg²⁺

1.2 Included in this guide are minimum recommended requirements for the preparation of calibration standards and suggested procedures for validating laboratory measurement results.

1.3 This guide describes minimum requirements for the frequency of analysis of quality assurance samples and recommends procedures for the evaluation of quality assurance data.

1.4 The guide's recommendations are based upon expected anion and cation concentrations in AWD (1) ² and Appendix X1.

1.5 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.

1.6 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.