9.4 Sensitivity

< lppb in routine analysis.

9.5 Detailed Procedures

9.5.1 Procedure 1: Tropolone extraction/cgc/aed or cgc/ms

Materials

• Chemicals

• organotin standards, Janssen Chimica and Aldrich

• hexane, p.a.

• methanol, p.a.

• Grignard reagent,

methylmagnesium bromide, 3.0M solution in diethyl ether, Aldrich pentylmagnesium bromide, 2.0M solution in diethyl ether, Aldrich

• ammonium chloride, p.a.

• hydrochloric acid, p.a., min. 37%

• tropolone, 98%, Janssen Chimica

• Solutions

• standard solution of organotin compounds in methanol (25mg/l)

• 0.05% tropolone in hexane

• 20% aqueous ammonium chloride solution

• Tools

• 10 \i\ syringes

• plastipak 5 ml syringes with microlance needles

• reaction tubes

• diverse pipettes

• 500 ml separation funnel

• diverse glassware

• rotavapor

• Instrumentation

• capillary GC with atomic emission detection

• capillary GC with mass spectroscopic detection

• splitless or cool on-column injection

• non-polar capillary column

Organotin compounds9 189

Phenoxy acid herbicides and bentazone

10.1 Introduction

Phenoxy acids are selective agricultural herbicides whose water solubility and high toxicological risk necessitate monitoring of ground and drinking water for their presence. For the analysis of these compounds, high performance liquid chromatography (HPLC) with UV diode-array detection or capillary gas chroma­tography with mass spectroscopic detection (CGC/MS) of the derivatized compounds may be used.

10.2 Compounds

	Compound	R^1	R^2	R^3	R^4
R^2	1. MCPA	—CH2-COOH	-CH2	—a	—H (EC)
R^3-/y~O-R^1	ZMecopropMCPP —CH-COOH CH3		-CH2	—a	—H
	3. MCPB	—CH2-CH2-CH2-COOH	-CH2	—a	—H
^R	4. 2.4-D	—CH2-COOH	—a	—a	—H (EC)
	5. Dichlorprop "У 4-ПР	— CH-COOH 1	—a	—a	—H (EC)
		CH3
	6. 2.4-DB	—CH2-CH2-CH2-COOH	—a	—a	—H
[EC): European Community Priority Pollutant List	7.2.4.5-T 8. Fenoprop 2.4>TP	—CH2-COOH — CH-COOH	—a —a	—a —a	—a (EC) —a
a OCH3 Br ^ \— COOH HO—/^	У-CN (^	о V^N-CH^C"^3 °V^N	OCH,CO	OH	CN A.
a Br		H			OH
9. Dicamba 10. Bromoxynil 11. Bentazone (EC) 12. Tridopyr				13.	Ioxinyl

Phenoxy acid herbicides and bentazone 10

209

10.3 General Procedure

The analytes are isolated by liquid-liquid or solid phase extraction (SPE). The phenoxy acids are analysed directly by high pressure liquid chromatography with UV diode-array detection or after methylation by capillary gas chromato­graphy with mass spectroscopic detection (CGC/MS) in the ion monitoring mode.