7.1 Introduction

The anilines and nitroaromatics of interest comprise some 36 compounds, seven of which are included in the EC priority pollutants list (EC). The determination of halogen and alkyl-substituted anilines and nitroaromatics in drinking, surface and ground water may be performed after liquid-liquid or solid phase extraction (SPE) by capillary gas chromatography with either nitrogen phosphorus (CGC/NPD) or mass spectroscopic (CGC/MS) detection. Special care must be taken when the presence of aniline precursors is suspected; urea herbicides for example, can generate anilines by thermal degradation in the sampling system.

Anilines and nitroaromatics 7 163

7.2 Compounds

Aniline

4-Bromoaniline

2-Chloroaniline (EC)

3-Chloroaniline (EC)

4-Chloroaniline (EC)

3 -Chloro- 4 -fluoraniline

3 -Chloro- 4 -methoxyaniline

3. -Chloro- 4 -methylaniline

4. -Chloro- 2 -methylaniline 2,4-Dichloroaniline (EC) 2,5-Dichloroaniline (EC) 2,6-Dichloroaniline (EC) 3,4-Dichloroaniline (EC) 2,6 -Diethylaniline

2,6 -Dimethylaniline 2 -Ethyl- 6 -methylaniline

Nitrobenzene

2. -Nitrotoluene

3. -Nitrotoluene 4-Nitrotoluene

.,3 -Dinitrotoluene 2,4-Dinitrotoluene 2,6-Dinitrotoluene

3.4 -Dinitrotoluene

2 -Methyl- 3 -nitroaniline 2 -Methyl- 4 -nitroaniline 2 -Methyl- 5 -nitroaniline 2 -Methyl- 6 -nitroaniline

4. -Methyl- 3 -nitroaniline

5. -Methyl- 2 -nitroaniline 2,4,6 -Trinitrotoluene

.,2 -Dinitrobenzene

.,3 -Dinitrobenzene

.,4 -Dinitrobenzene

2 -Amino- 4,6 -dinitrotoluene 4 -Amino- 4,6 -dinitrotoluene

(EC) Included on the European Community Priority Pollutants list.

164

7 Anilines and nitroaromatios

7.3 General Procedure

Water is alkalized prior to solid phase extraction (pH9.0) or liquid-liquid extraction (pHll.O). Anilines and nitroaromatics are subsequently analysed by capillary gas chromatography/nitrogen phosphorus detection (CGC/NPD) or capillary gas chromatography/mass spectroscopy in single ion monitoring mode

(CGC/MS/SIM).

7.4 Sensitivity

0.025ppb for anilines. 0.050ppb for nitroaromatics.

7.5 Detailed Procedures

7.5.1 Procedure 1: Solid phase extraction/CGC/NPD or CGC/MS

Materials

• Chemicals

• aniline standards

• nitroaromatic standards

• ethyl acetate, nanograde

• heptadecanoic acid nitrile, internal standard

• octadecanoic acid nitrile, internal standard

• silica gel RP-C18

• sodium hydroxide, p.a.

• sodium chloride, p.a.

• water, HPLC-grade

• acetone, nanograde

• methanol, nanograde

Anilines and nitroaromatics7 165

Benzidines

8.1 Introduction

Benzidine and 3,3-dichlorobenzidine are poisonous, carcinogenic compounds formed as intermediates during the synthesis of dyes. Protective legislation limits their dispersal into the environment and both compounds are included on the EPA and EEC priority pollutants lists.

A quantitative analysis for water samples using HPLC with electrochemical detection is described.

8.2 Compounds

Compound names and structures are listed in Figure 8.1.

NH₂ Benzidine

33-Dichlorobenzidine

Figure 8.1: Chemical structures.

Benzidines 8

181

8.3 General Procedure

Water at neutral pH is extracted using chloroform. The benzidines are back-extracted with 1M sulphuric acid and after neutralization, re-extracted with chloroform. Analysis is done by HPLC with electrochemical detection.

8.4 Sensitivity

O.Olppb

8.5 Detailed Procedure

8.5.1 Liquid-liquid extraction/HPLC/EC (EPA 605)

Materials

• Chemicals

• benzidine, 3,3-dichlorobenzidine

• methanol, nanograde

• chloroform, nanograde

• acetic acid, p.a.

• sulphuric acid, p.a.

• sodium hydroxide, p.a.

• sodium acetate trihydrate

• sodium phosphate, tribasic decahydrate

• water, HPLC grade

• acetonitrile, HPLC grade

• Solutions

• 5M sodium hydroxide

• 1M sulphuric acid

• 0.4MNa₃PO₄.10H₂O

• 0.1M sodium acetate buffer : 5.8ml acetic acid and 13.6ml sodium acetate trihydrate in llitre HPLC water, Na₂EDTA made up to O.OOIM.

• Tools

• 21 and 250 та\ sepaxatvm ^wwweYs

• rotary evaporator

HPLC instrument (isocratic) with amperometric detector

an HPLC column that can resolve the compounds shown in Figure 8.1

182 8 Benzidines

Organotin Compounds