Direct aqueous injection

This technique, although widely used, and indeed necessarily used for very polar solvents, is rarely used for the analysis of VOCs in soils due to the extensive 

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Trihalomethanes. Wherever chlorine is used as a disinfectant in drinking-water treatment, trihalomethanes (THMs) generaUy are present in the finished water. The THMs usuaUy formed are trichloromethane (chloroform), bromodichloromethane, dibromochloromethane, and tribromomethane (bromoform). There are four main techniques for the analysis of THMs headspace, Hquid— Hquid extraction (Ue), adsorption—elution (purge—trap), and direct aqueous injection. The final step in each technique involves separation by gas—Hquid chromatography with a 2 mm ID coUed glass column containing 10 wt % squalene on chromosorb-W-AW (149—177 p.m (80—100 mesh)) with detection generaUy by electron capture. 

The method for chloroacetanilide soil metabolites in water determines concentrations of ethanesulfonic acid (ESA) and oxanilic acid (OXA) metabolites of alachlor, acetochlor, and metolachlor in surface water and groundwater samples by direct aqueous injection LC/MS/MS. After injection, compounds are separated by reversed-phase HPLC and introduced into the mass spectrometer with a TurboIonSpray atmospheric pressure ionization (API) interface. Using direct aqueous injection without prior SPE and/or concentration minimizes losses and greatly simplifies the analytical procedure. Standard addition experiments can be used to check for matrix effects. With multiple-reaction monitoring in the negative electrospray ionization mode, LC/MS/MS provides superior specificity and sensitivity compared with conventional liquid chromatography/mass spectrometry (LC/MS) or liquid chromatography/ultraviolet detection (LC/UV), and the need for a confirmatory method is eliminated. In summary,... 

The direct aqueous injection and LC/MS/MS muiti-residue method determines aiachior, acetochior, metoiachior and their soii metaboiites in water sampies. The accuracy of the anaiyticai method is estimated based on the recovery of known concentrations of each metaboiite fortified into controi water sampies that are then carried through the anaiyticai procedure. The method was vaiidated over the range 0.25-20 qg kg for aii components and is presented in Section 7. 

This analytical method determines levels of major oxanilate and sulfonate soil metabolites of acetochlor, alachlor, and metolachlor in groundwater and surface water. The method consists of analysis of environmental samples by direct aqueous injection reversed-phase LC/MS/MS. 

Water samples, received from the respective groundwater trials, are analyzed by direct aqueous injection (DAI) by LC/ESI-MS/MS. A 1-mL volume of the water is pipetted into a 1.8-mL autosampler vial. The internal standard solution is added (200 qL) and mixed. The vials are capped and analyzed by LC/ESI-MS/MS using the selected reaction monitoring (SRM) mode. 

Hcxanc can be determined in biological fluids and tissues and breath using a variety of analytical methods. Representative methods are summarized in Table 6-1. Most methods utilize gas chromatographic (GC) techniques for determination of -hexane. The three methods used for preparation of biological fluids and tissues for analysis are solvent extraction, direct aqueous injection, and headspace extraction. Breath samples are usually collected on adsorbent traps or in sampling bags or canisters prior to analysis by GC. 

Injection HPLC with Post Direct Aqueous Injection HPLC... 

Fujii T. 1977. Direct aqueous injection gas chromatography-mass spectrometry for analysis of organohalides in water at concentrations below the parts per billion level. J Chromatogr 139 297-302. 

Determination of Glyphosphate in Drinking Water by Direct-Aqueous Injection HPLC, Post-Column Derivatization, and Eluorescence Detection... 

Analysis of Bis(2-chloroethyl) Ether and Hydrolysis Products by Direct Aqueous Injection GC/Fourier Transform... 

Potter, T.L. Analysis of petroleum-contaminated water by GC/FID with direct aqueous injection, Groundwater Monitor. Remed, 16(2) 157-162, 1996. 

Detection limit of acrylonitrile by direct aqueous injection was 2300 J.g/L. This value believed to be a glassware contaminant. 

The exact concentrations of some of the volatile solvents in the wastewater were determined using direct aqueous injection of 2 m1 aliquots onto a 2 m x 0.32 cm ID stainless steel column packed with 0.4% Carbowax 1500 on Carbopak C (Supelco, Inc.) and analyzed by GC/MS. 

Analysis of aqueous solutions of the polar compounds (DCP, TCP, CA, and DCB) at concentrations of 1-10 ppm was easily accomplished by direct aqueous injection liquid chromatography. The Hamilton PRP-1 reverse-phase column gave a better resolution of these compounds than the conventional reverse-phase columns. Acetonitrile/water mixtures have been found to be as effective as the buffered mobile phases recommended by the manufacturer (28). Analyses of the nonpolar compounds (BHC and DEHP) at concentrations of 25-100 ppb were achieved by XAD resin adsorption-desorption, concentration, and GC techniques. 

The Supelcowax 10 column has the ability to accept water injections. Direct aqueous injections of the 10-ppm standard water mix were performed to verify... 

Figure 2. GC-MS chromatogram of direct aqueous injection of the standard mixture.

Trimesic acid Diazomethane derivatization, GC-FID capillary Direct aqueous injection, HPLC (paired ion) Diazomethane derivatization, HPLC... 

The use of LC also has increased in use in recent years, driven by greater sensitivities of the detectors. Traditional ultraviolet (UV) and photo diode-array detectors were frequently employed in triazine analysis, but advances in source designs have provided efficient coupling of MS with LC. The advantage of LC is the ability to analyze polar metabolites not amenable to analysis using GC. Recent progress in LC/MS/MS instrumentation has enabled the direct aqueous injection (DAI) of a water sample without prior cleanup. 

Fuhrman, J.D. and J.M. Allan (2003). Determination of acetanilide degradates in ground and surface waters by direct aqueous injection LC/MS/MS. ACS Symposium Series. 850 256-272. 

Huang, S-B., T.J. Mayer, R.A. Yokley, and Rolando Perez (2006). Direct aqueous Injection LC-ESI/MS/MS analysis of water for atrazine, simazine, and their chlorotriazine metabolites. J. Agric. Food Chem., 54(3) 713-719. 

Munch, J.W. 1995. EPA, Method 531.1—Measurement of V-methylcarbamoyloximes and /V-mclhyl-carbamates in water by direct aqueous injection HPLC with post column derivatization, Revision 3.1. Washington, DC. 

Extractant phase None Direct aqueous injection (DAI) Static headspace with gas syringe (SHS) Dynamic headspace/ purge trap (P T)... 

Wolska, L., C. Olszewska, M. Turska, et al. 1998. Volatile and semivolatile organo-halogen trace analysis in surface water by direct aqueous injection GC-ECD. Chemosphere 37 2645-2651. 

T etrachloroethy lene - - Direct aqueous injection - 0.06pM [96]... 

Votalite fatty acids - Flame ionisation Sample steam distilled, then direct aqueous injection into GLC, recovery 97.6-99% [600]... 

Calibration is carried out using standard calibration curves. The simplicity, repeatability, and low cost of the method have allowed its use for routine determination of trihalomethanes in tap water. SOME has also been compared with solid phase microextraction (SPME), purge and trap (P T), and direct aqueous injection (DAI) [10]. This technique offers accuracy comparable with that obtained using P T and DAI. With respect to conventional LEE, the SDME method is more accurate. In contrast to DAI and P T, it requires no special equipment. SDME has been used for extraction of chlorophenols [II], pesticides [12, 13], warfare agents [14], and butanone derivatives [15], and for control of food products [16]. The low costs of the SDME method (typical GC syringe and 2-3 pL of solvent), simplicity, and short extraction time (approximately 15 min) make it particularly suitable for preliminary analyses of organic pollutants in water samples. It can also be an effective alternative to SPME, as it does not require the use of expensive instrumentation. 

Zwank L., Schmidt T., Haderlein S., and Berg M. (2002) Simultaneous determination of fuel oxygenates and BTEX using direct aqueous injection gas chromatography mass spectrometry (DAI/GC/MS). Environ. Sci. Technol. 36(9), 2054-2059. 

Despite the potential for direct aqueous injection of water samples into reverse phase systems, there are very few cases where this is possible due to the low detection levels normally required for environmental analysis. Using direct aqueous injection and coulometric electrochemical detection, the analysis of phenol and chlorophenols and 2-mercaptobenzothiazole have been achieved at trace levels (methods with limits of detection for phenol 0.034 ngp and 0.8 pgl for mercaptobenzothiazole have been achieved). There is a potential for the use of direct aqueous injection for the analysis of phenol in effluents using fluorescence detection which would be expected to detect down to low mg T. Direct aqueous injection has been used in an automated system similar to that shown in Figure 11.1. The trace enrichment cartridge was replaced by a large sample loop (50 pi) and a coulometric electrochemical detector used instead of the UV detector. 

The flow diagram in Figure 10.4 is intended as a guide and is the way the author would normally approach a new HPLC analysis. Reversed-phase chromatography is assumed and this will mean evaporation of solvent and dissolution in mobile phase if using the hquid-liquid extraction path. No mention has been made of direct aqueous injection as the times that this technique can be employed in environmental analysis are few indeed. It can be seen that the author s choice of detector is fluorescence then electrochemical then UV. 

R.A. Baker, "Phenolic Analyses by Direct Aqueous Injection Gas Chromatography , Journal of the American Waterworks Association, v. 58, 1966, p. 751-60. 

Fig.4. Direct aqueous injection, 1/itof test mixture (Table D.Oparating conditions temperature 30° 3 min, 8°/min to 120, hydrogen carrier gas 50 cm/sec (100 °C), chart speed 1 cm/min...

It is particular concern in the analysis of aqueous samples, because the solvent effects involved during the direct aqueous injection (DAI) allow the direct analysis of levels ()ig l) of trihalomethanes and related compounds in water, using well deactivated thick film columns and E(D detection [19, 20 ]. 

A Hewlett Packard 5880-A gas chromatograph equipped with a flame ionization detector, a 5880-A series level four computerized data system and a DB-5 (30 m x 0.25 mm I.D.) fused silica capillary column (J W Scientific, Folsom, CA) were used. Puree was centrifuged at 10,000 x g and the supernatant was injected onto the column (direct aqueous injection). Ultrafiltered juice was injected directly with no sample preparation. Sample size in all cases was 5uL split 15 1 with helium as the carrier gas at a flow rate of 1 ml/min. The oven temperature was held at 60°C for the initial seven minutes of the injection time. It was then increased to 200°C at a rate of 5°C/min and was held there for twenty five minutes. Total volatiles were obtained by summation of integrated peak areas on the chromatograms. Percent areas of each peak were also calculated. 

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