HPLC-ESI

Dugo, P. et al.. Characterization of the anthocyanin fraction of Sicilian blood orange juice by micro-HPLC-ESI/MS, J. Agric. Food Chem., 51, 1173, 2003. 

Wu, X. and Prior, R.L., Systematic identification and characterization of anthocyanins by HPLC-ESI-MS/MS in common foods in the United States fruits and berries, J. Agric. Food Chem., 53, 2589, 2005. 

In another example, a multiresidue method using HPLC/ESI-MS was developed to determine six imidazolinone herbicides in five different soil types. Good recoveries (80-120%) and adequate sensitivity at the 2.0 ngg level were obtained for the compounds investigated. In the method, a 50-g soil sample was extracted for 1 h in 0.5N NaOH solution. A portion of the extract was acidified, to precipitate the humic acids, and the supernatant was then loaded on to a preconditioned trifunctional Cig SPE cartridge and eluted with ethyl acetate. Further cleanup was achieved using a tandem strong anion-exchange (SAX)-SCX SPE combination. Analytes were eluted... 

Table 6 List of ions monitored for imidazolinone herbicides using in-source CID (HPLC/ESI-MS)...

Chiron et al. used HPLC/ESI-MS in the negative mode for the determination of acidic herbicides in environmental waters. The acidic herbicides investigated were benazolin, bentazone, 2,4-dichlorophenoxyacetic acid (2,4-D), 4-chloro-... 

Figure 5 Determination of 1 ng g of imazethapyr in soil HPLC/ESI-MS/MS with SIM of the ion transition m/z 290 86...

In this study, HPLC/fluorescence was compared with HPLC/ESI-MS and HPLC/ESI-MS/MS. A summary of the procedure is described as follows. The sample was prepared using the method of Luke et al.f and the sample was then cleaned up using a 1-g aminopropyl SPE cartridge. The sample was loaded on to the... 

Table 8 Ion transition data for 12 iV-methyl carbamate insecticides (HPLC/ESI-MS/MS)...

For APCI (if matrix effects become a problem in ESI), the mobile phase consisted of (A) 9 1 methanol-water containing 50 mM ammonium acetate and (B) water containing 50 mM ammonium acetate-methanol (9 1). The gradient was held at 50% A-50% B for 10 min and was then changed to 90% A-10% B in 22 min (held for 3 min). The HPLC column was a Zorbax RX-C8, 4.6-mm i.d. x 250 mm, 5 pm particle size, with a flow rate of l.OmLmin and a 50-pL injection. Table 8 shows the ion transitions (parent to product ions) that were monitored for HPLC/ESI-MS/MS. For single-stage HPLC/ESI-MS, Table 9 shows the ions that were monitored. 

In this study, the preliminary findings showed that the HPLC/fluorescence data were in agreement for all 12 carbamates with HPLC/ESI-MS/MS for most of the nine fruits and vegetables at the 1.0 ng g fortification level. The recoveries were generally within 70-120% however, at the 1.0 ng g level in each commodity, HPLC/ESI-MS (single-stage MS) had difficulty with interferences for three out of the 12 carbamate pesticides (aldicarb sulfoxide, aldicarb sulfone, and 3-hydroxycarbofuran), which made quantification impossible for these three compounds. 

Figure HPLC/ESI-MSofgrapefruitjuice fortified with l.OngmL ofS-hydroxycarbofiiran (top) and grapefruit juice control (bottom). Ion monitored [M + NH4] ion at m z 238...

G.C. Mattem, C.I. Nuessle, D.L. Green, W.M. Leimkuehler, J.D. Philpot, RJ. Ness, and K.S. Billesbach, Accelerated field residue analysis of tebuconazole using Soxtec extraction and HPLC/electrospray tandem mass spectrometry (HPLC/ESI-MS-MS), Presented at the Midwest Regional Meeting of the American Chemical Society, Osage Beach, MO, October 29, 1997. 

High performance liquid chromatography (HPLC) ESI, APCI, APPI Separation of polar, ionic, nonvolatile, high molecular weight and thermally labile analytes... 

Statistical evaluation of HPLC UV MS[19] and CE UV MS[20] methods proves that MS detection of anthraquinone dyes is more sensitive than UV, especially in the case of chromatographic analysis of laccaic acids (almost 20 times) and purpurin (almost 40 times). However, detection limits of HPLC ESI MS determination of alizarin and purpurin (0.03 gg ml ) are about 20 times lower than those of CE ESI MS (0.52 0.58 gg ml x). 

HPLC ESI MS is also a useful tool in the analysis of non-anthraquinone red dyestuffs. The use of this technique allows the identification of carthamin as the main colour component of safflower.[34] Ten species of the genus Alkanna are extracted with hexane, and dissolved in water-methanol solution after evaporation. [47] Ammonium formate buffer (pH 3.0) was used as the mobile phase modifier. In the preparations, alkannin and many hydroxynaphthoquinones (alkannin derivatives) were identified by comparison of retention times, as mass spectra (in the NI mode) for all compounds consisted only of quasi-molecular peaks. 

Figure 13.5 Product ion spectra of curcuminoids (Nl HPLC ESI MS/MS). Product ion labels correspond to fragments depicted in Figure 13.6 (a) bisdemethoxycurcumin (b) demethox ycurcumin (c) curcumin. Reproduced from H. Jiang, A. Somogyl, N.E. Jacobsen, B.N. Timmermann and D.R. Gang. Rapid Commun. Mass Spectrom., 20, 1001 1012 (2006). By permission of John Wiley Sons, Ltd...

Fig. 2.6.3. Mixed-mode HPLC-ESI-MS summed ion chromatogram of a sediment extract (32-36 cm depth core slice) showing resolution of NPEOs and NPs. Numbered peaks correspond to NPEOs and [13CeJNPEOs with the indicated number of ethoxy groups (0 = NP, [13C6]NP 1 = NPEOi, [13C6]NPEOi, etc.). Peaks A and B are the internal standards, re-NP and re-NPE03, respectively. (Note the discontinuity at retention time 25.8 min, corresponding to the shift in MS polarity from positive to negative ion mode.)...

The more polar components have been characterised by FTICR—MS and HPLC-ESI-MS, and include excess PEG [CH30(E0)nH and HO(EO) Hl starting materials, confirmation of which was obtained by comparison with commercial standards [29]. ESI—MS, FTICR—MS and H NMR data analysis also indicated the presence of the Si—O—C byproduct 3, abbreviated to MDOH-0-(E0)ra-CH2CH=CH2, shown in Fig. 2.8.7. The formation of 3 can occur through side reactions of the... 

Determination of two esterquats used as substitution products of DTDMAC, such as diethylester dimethylammonium chloride (DEED-MAC) and diesterquaternary (DEQ) (Fig. 4.2.8) in sewage water samples was carried out by the same ion-pair extraction procedure for the analysis of DTDMAC reported elsewhere [103,111] followed by microbore HPLC-ESI-MS analysis [116] and quantification employing commercial blends. 

Because of the advantageous dietary effects of flavonoids they have been vigorously investigated in food and food products. The objectives of these measurements were the separation and quantitation of well-known flavonoids in foods and the identification of new flavonoids. An HPLC-ESI MS method has been developed for the isolation and identification of new quercetin derivatives in the leaves of Eruca sativa (Mill). Fresh leaves (500g) were homogenized with 1 200 ml of methanol-water (7 3, v/v), the suspension was macerated for 24h at ambient temperature, then it was filtered, concentrated to 50 ml and diluted with water to 500 ml. The extract was applied to an Amberlite XAD-2 column (75 X 8cm i.d.) and was washed subsequently with 11 of water and 11 of diethyl ether. The glucoside fraction was eluted with 1.51 of methanol and the eluate was concentrated in vacuum and liophilized. 

It was stated that this combined technique (HPLC-DAD, HPLC-ESI-MS, GC-MS) allows the safe identification of flavonol aglycones and glycosides and can be used for the analysis of these compounds in berries [161]. 

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