ENVIRONMENTAL ANALYSIS I. Solid Phase Extraction example - triazines

Example: Atrazine Atrazine Structure

Atrazine from Water Apolar Retention Column: C18, 1g / 6mL 1. Sample pre-treatment: none 2. Solvation: 10mL MeOH 3. Equilibration: 10mL water 4: Sample: 500mL aqueous 5: Wash: 10mL water; dry: 30min 6: Elution: 2 x 4 mL acetone

Atrazine from Corn Oil Polar Retention Column: DIOL, 500mg / 6mL 1. 2mL oil  dilute w. 18mL of nC6 2. Solvation: 6mL nC6 3. Equilibration: none 4. Sample: 20mL (diluted) 5. Wash: 2mL nC6 6. Elution: 1mL methanol

Atrazine from Soybeans Cation-Exchange Mechanism Column: SCX, 500mg / 6mL 1. 5g sample + 10mL ACN  homogenize, filter; dilute 5mL filtrate w. 20mL 1% AcOH 2. Solvation: 3mL methanol 3. Equilibration: 6mL 1% AcOH 4. Sample: 25mL (diluted) 5. Wash: 1mL of 1% AcOH and 1ml of ACN 6. Elution: 2mL of 1:1 ACN - 0.1M K 2 HPO 4

ISOLUTE Triazine Traditionally, problems have been reported in achieving high, reproducible recoveries of triazine herbicides, when extracting from water samples. This is particularly true for the polar metabolites desethyl and desisopropyl atrazine (see figure) due to their reduced non-polar functionality. IST have introduced a column specifically for triazine analysis, which is QC tested in house to ensure good recoveries of the polar metabolites.

Triazine Structures

Extraction of Triazines from Water Samples Extraction of the triazines from river water was performed using IST’s large volume extraction cap. This is designed for direct loading of the sample from collection vessel to SPE column, and can be used in the field.  To Vacuum Loosened cap

SPE of Triazines ColumnISOLUTE ® Triazine 1g / 6ml SolvationMethanol (2 x 5 ml) EquilibrationWater (2 x 5 ml) SampleRiver water (500 ml) spiked with application10 ng / ml of 4 triazines InterferenceWater (10 ml) elutionDry 30 mins at -20“ Hg vacuum Analyte elution2 x 1.5 ml ethyl acetate Evaporate to dryness and reconstitute with 500  l acetonitrile

HPLC Chromatogram HPLC column: Kromasil CN, 15cm x 4.6mm x 5  m Mobile phase: 15% acetonitrile, 85% Trichloroacetic acid (0.05%) pH 3. Flow rate 1 ml / min. 5  l injected.  254nm.

ResultsResults Analyte % Recovery (w. depth filter) Desethyl atrazine94(100) Desisopropyl atrazine85(86) Simazine80(94) Propazine91(94) N.B. The river water sample contained 0.4mg/L suspended solids. Use of the depth filter improved recovery, reproducibility and flow characteristics.