PROBLEMS AND SOLUTIONS IN

MEASURING EXCHANGEABLE

Ca, Mg AND K IN SOIL SAMPLES

Paulina DróVdV

Laboratory of Forest Environment Chemistry

Forest Research Institute

Poland

Meeting of the Heads of the Laboratories, 19-20 September 2013 Zadar, Croatia

Problem

�Short stability of plasma

Solution

�Barium chloride for rinsing

(f.e. between samples) instead

of water

�Manual determination instead

of sequence automation

(autosampler) to make sample

flush time shorter and

eliminate water rinsing

water BaCl2

ICP �OES iCAP 6000 series Thermo Scientific

Problem

�Short stability of

calibration

Solution

�Check and control

calibration (f.e. after 10

samples)

- quality control check (QC)

- blank

- blind sample

�Recalibrate QC failed lines

(after recalibration repeat

samples from last QC

checked)

Purity of barium chloride !

Quality Control Check after calibrationQuality Control Check after calibration

Quality Control Check before and after RecalibrationQuality Control Check before and after Recalibration

Ca Ca -- Calibration CurveCalibration Curve

K, Mg K, Mg -- Calibration CurveCalibration Curve

Subarray plotsSubarray plots

DilutionDilution

HighStd

Ca 100 ppm

K, Mg 10 ppm

ConclusionConclusion

Measuring exchangeable Ca, Mg and K in soil samples

� Use barium chloride for rinsing and dilution

� It’s better to use manual determination

� Check and control calibration curve ( R > 0,999) – quality control check,

blank, blind sample, reference materials

� Recalibrate