LimsPulse
AAS · Calibration procedure

Precision

Measures the same standard repeatedly and checks that the absorbance readings agree closely (low %RSD).

Photo of a AAS
Photo: Talos (German Wikipedia), CC BY-SA 3.0 (cropped), via Wikimedia Commons
PURPOSE

Why this is checked

Good precision shows the nebuliser, flame and lamp are stable. Poor precision means noisy results and unreliable calibration curves.

Frequency

Typically sensitivity is checked each day of use and the full calibration is done every 6 or 12 months, and after lamp, burner or major repair, as defined in your calibration SOP.

Learn how the AAS works
YOU WILL NEED

Standards & tools

  • Certified copper standard, e.g. 2.0 mg/L Cu
  • Blank of the same acid
BEFORE YOU START

Prerequisites

  • Instrument warmed up and optimised as for the sensitivity check
  • Flame stable for at least 10 minutes
PROCEDURE

Step by step

  1. 1Aspirate the blank and auto-zero.
  2. 2Aspirate the Cu standard continuously and record ten consecutive absorbance readings (or the number in your SOP).
  3. 3Calculate the mean, standard deviation and %RSD.
RECORD

Example observation table

ReadingAbsorbance
10.2152
20.2148
30.2161
40.2139
50.2155
60.2146
70.2158
80.2143
90.2150
100.2157
CALCULATION

How to calculate the result

%RSD = (Standard deviation ÷ Mean) × 100
  1. Mean absorbance = 0.2151
  2. Standard deviation = 0.00070
  3. %RSD = 0.00070 ÷ 0.2151 × 100 = 0.33%
Use the Mean, SD and %RSD calculator
ACCEPTANCE CRITERIA

Pass if

  • %RSD of absorbance typically not more than 1.0% for flame AAS (furnace limits are wider, e.g. ≤ 5%). Use the limit in your SOP or the manufacturer's specification.
IF IT FAILS

What to do

  • Check the nebuliser and capillary for partial blockage or air leaks.
  • Clean the burner slot; check the drain trap and gas pressure stability.
  • Allow longer lamp warm-up and repeat.
  • Label 'Out of calibration' if it still fails and call service.
MORE

Other AAS calibrations

In LimsPulse · Calibration Management

LimsPulse schedules this calibration, records the result against limits, and blocks the instrument everywhere if it fails or goes overdue.

See how