APCI river water

Crescenzi et al. developed a multi-residue method for pesticides including propanil in drinking water, river water and groundwater based on SPE and LC/MS detection. The recoveries of the pesticides by this method were >80%. Santos etal. developed an on-line SPE method followed by LC/PAD and LC/MS detection in a simultaneous method for anilides and two degradation products (4-chloro-2-methylphenol and 2,4-dichlorophenol) of acidic herbicides in estuarine water samples. To determine the major degradation product of propanil, 3,4-dichloroaniline, the positive ion mode is needed for atmospheric pressure chemical ionization mass spectrometry (APCI/MS) detection. The LOD of 3,4-dichloroaniline by APCI/MS was 0.1-0.02 ng mL for 50-mL water samples. 

Polymeric precolumns of styrene-divinylbenzene were used by Aguilar et al. to monitor pesticides in river water. Water samples (50 mL) were trace enriched on-line followed by analysis using LC combined with diode-array detection. LC atmospheric pressure chemical ionization (APCI) MS was used for confirmatory purposes. It was found that after the pesticides had been extracted from the water sample, they could be stored on the precartridges for up to 3 months without any detectable degradation. This work illustrates an advantage of SPE for water samples. Many pesticides which may not be stable when stored in water, even at low temperature, may be extracted and/or enriched on SPE media and stored under freezer conditions with no detectable degradation. This provides an excellent way to store samples for later analysis. 

Puig et al. [450] determined ng/1 levels of priority methyl-, nitro-, and chloro-phenols in river water samples by an automated on-line SPE technique, followed by liquid chromatography-mass spectrometry (LC-MS) using atmospheric pressure chemical ionization (APCI) and ion spray interfaces. 

In particular, the priority pollutant phenols (PPP), identified by EPA since the 1970s are widespread water pollutants that must receive the greatest attention due to their recognized toxicity. For the separation of eleven PPP, an ion-interaction reagent (HR) RP HPLC/UV method has been developed that allows limits of detection lower than 30 J,g in river waters, after LLE in dichlo-romethane and a 500-fold pre-concentration [82]. Through on-line SPE followed by both UV and electrochemical detection [83], 16 priority phenols have been determined in water samples with the LOD value for chlorophenols lower than 1 ng L [84]. LODs at ng L levels were obtained for all the PPPs in samples of river water, employing a relatively small volume of sample through an on-line SPE HPLC/MS method with an APCI source. 

C. Aguilar, 1. Ferrer, F. Borrull, R. M. Marce, D. Barcelo, Monitoring of pesticides in river water based on samples previously stored in polymeric cartridges followed by on-line SPE-LC-DAD and confirmation by APCI-MS, Anal. Chim Acta, 386 (1999) 237. 

D. Puig, I. Solgoner, M. Grasserbauer, D. Barcelb, Ppt level determination of priority methyl-, nitro- and chlorophenols in river water samples by automated on-line SPE-LC-MS using APCI and ESI interfaces. Anal. Chem., 69 (1997) 2756. 

In the environmental investigation on the stams of pollution [20], LCCPs with 40 and 70% chlorine in sediments were determined by APCI-negative using LC/MS. The detection limits of this method were based on the experimental values obtained in six recovery tests. The results indicated that LCCPs were accumulated in sediments of all sampling sites except the Ishikari River estuary. In the Ishikari River estuary, however, LCCPs were detected in river water but not in sediments, which was the reverse of the result of others. 

Besides TSP-spectra from organophosphorus and different groups of polar pesticides, APCI, ESI, FAB and PBI spectra were presented. CID allowed the identification of pesticide residues and the confirmation and quantification of these compounds by TSP at concentrations < 100 ng L [175]. Barcelo et al. [239] extracted river water and spiked seawater samples by Cig Empore disks to concentrate orga-nophosphoras pesticides prior to identification and quantification while Bagheri et al. [247] for the same purpose used on-line SPE for phosphorus pesticides and TSP-LC-MS. 

The degradation of pentachlorophenol (PCP) in natural waters was studied by LC-DAD and confirmed by APCI-LC-MS both after Lichrolut EN SPE. A half-life of PCP in ground water, in estuarine and river waters of < 2 h was reported... 

The analyses of environmental samples confirmed the ubiquitious presence of surfactants in surface and sea water as a result of the surfactants discharged with STP effluents. Analysis of River Elbe (Germany) water samples by GC-MS and APCl-LC-MS and MS/MS confirmed qualitatively the presence of nonpolar and polar organic pollutants of AEO, NPEO, CDEA and aromatic sulfonic acid type, respectively [226], After Cjg and/or SAX SPE anionic and non-ionic surfactants were qualitatively and quantitatively analysed in surface water samples by APCI-LC-MS in the negative or positive mode, respectively. Alkylphenol ethoxylates (APEOs) could be confirmed in river water at levels of 5.6 pg L [331]. 

Stability studies of SPE-adsorbed anihdes and N-substituted amines (bentazone, molinate and metolachlor) were performed by means of APCI-LC-MS. From river water samples containing the pesticides and their degradation products, the pesticides had been extracted prior to APCI-LC-MS [320]. The SPE adsorbed compounds were stored on SPE cartridges (styrene-divinylbenzene) for up to 3 months at ambient temperature, +A °C and -20 °C. After 3 month storage at -20 °C on the polymeric cartridges recoveries were > 90% [320]. 

River water samples were under research by APCI and ESI-LC-MS to analyse seven N-methylcarbamate pesticides quantitatively. The effects of varying APCI and ESI conditions were investigated, confirming that APCI resulted in less effective sensitivity [357]. 

The results of PAH analysis with different types of interfaces (e.g. ESI, APCI, PBI and TSP - were reported by Clench et al. reviewing the state of the art of various mass spectral techniques [28]. For more polar PAHs pneumatically assisted ESI-LC-MS was used to determine mixtures of hydroxy polycyclic aromatic hydrocarbons. The abundance of ions dependent on flow rates was shown. ESI inonization was found to be less sensitive compared to APCI ionisation [304]. PAH analysis with ESI-LC-MS combined with RP-LC with post-column addition of silver nitrate was applied for the determination of 10 PAHs in river water. PAHs resulted in [Mj and [M-i-Ag]. The detection limits of different PAHs in spiked samples ranged from 0.001 to 0.03 pg L [442]. 

A rather new technique is APPI, which has only been applied in two studies to determine PFOS [57] in river waters and FTOH and sulfonamido derivatives in biotic samples [58]. APPI is a very selective tool and, in stark contrast to ESI, is considered to be virtually imperceptible to matrix effects, which was confirmed in both studies. APCI and especially APPI are not recommended for metabolism studies of unknown compounds, since ionization is very delicate with these methods. Therefore, unknown compounds may not be discovered due to a lack of ionizability. ESI is the method of choice due to the wide range of ionizable compounds after LC separations. 

For confirmation of low concentrations of NPEO homologues in complex samples from the Elbe river, APCI—LC—MS—MS(+) was applied to record the substance-characteristic ion mass trace of m/z 291. The SPE isolates contained complex mixtures of different surfactants. The presence of NPEOs in these complex samples was confirmed by generating the precursor ion mass spectrum of m/z 291 applying MS— MS in the FIA-APCI(+) mode. This spectrum, showed in Fig. 2.6.5, presents the characteristic series of ions of NPEOs at m/z 458, 502,...,678, all equally spaced with A m/z 44 u. Besides the NPEOs, small amounts of impurities could be observed because of the very low concentrations of NPEOs in the water sample [25]. In the foam sample, the identity of NPEOs could be easily confirmed by APCI-FIA-MS-MS(+) because of their high concentrations in this matrix. The LC-... 

Surface water samples from Southeastern regions of France and from the St. Lawrence River in Canada were monitored by APCI-LC-MS and MS/MS in the positive mode. Diuron and isoproturon were confirmed by MS/MS. Results obtained by LC-MS and ion trap LC-MS/MS were found to be comparable [374]. A substance-specific robust APCI-LC-MS/MS method using short columns for trace analysis of phenylureas was elaborated and vaUdated. Despite the low quantity of sample applied (15 mL) detection limits of < 5 pg L in full-scan and < 750 ng L in SIM mode, respectively, could be achieved. Product ion spectra were obtained from [M-i-H] parent ions and by means of a pesticide MS/MS Hbrary... 

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