Expression of Analytical Results

1.0 OBJECTIVE

1.1 To define a procedure for Expression of Analytical Results.

2.0 SCOPE

2.1 This procedure is applicable for the Expression of Analytical Results.

3.0 RESPONSIBILITY

3.1 QC-Microbiologist

3.2 QC- Chemist

3.3 QC- Head

4.0 ACCOUNTABILITY

4.1 In Charge – Quality Assurance

5.0 PROCEDURE

5.1 A result can be reported as a percentage, part per thousand (ppt), part per million (ppm), part per billion (ppb), etc..  Solutes can be solids , liquids, or gases. The concentration can be expressed as weight solute per weight sample (w/w), weight solute per volume solution (w/v), or volume solute per volume solution (v/v).

5.2 For Solid Solutes

% (w/w) = [weight solute (g)/weight sample (g)] x 100

ppt (w/w) = [weight solute (g)/weight sample (g)] x 1000

ppm (w/w) = [weight solute (g)/weight sample (g)] x 10⁶

ppb (w/w) = [weight solute (g)/weight sample (g)] x 10⁹

A ppm can be represented by several terms like the one above, (mg solute/kg sample), ( g solute/10⁶g sample), etc..

5.3 If the solute is dissolved in solution we have

% (w/v) = [weight solute (g)/volume sample (mL)] x 100

ppt (w/v) = [weight solute (g)/volume sample (mL)] x 1000

ppm (w/v) = [weight solute (g)/volume sample (mL)] x 10⁶

ppb (w/v) = [weight solute (g)/volume sample (mL)] x 10⁹

Also a ppm can be expressed as above or as (g solute/10⁶ mL solution), (mg solute/L solution), or (mg/mL), etc..

5.4 For Liquid Solutes

% (v/v) = [volume solute (mL)/volume sample (mL)] x 100

ppt (v/v) = [volume solute (mL)/volume sample (mL)] x 1000

ppm (v/v) = [volume solute (mL)/volume sample (mL)] x 10⁶

ppb (v/v) = [volume solute (mL)/volume sample (mL)] x 10⁹

A ppm can be expressed as above or as (mL/L), (mL/10³ L), etc..

6.0 ANNEXURES

Nil