Accurate mass and nuclear magnetic resonance identification of bisphenolic can coating migrants and their interference with liquid chromatography/tandem mass spectrometric analysis of bisphenol A

Abstract

Two unknown compounds were previously determined to be potential interferences in liquid chromatography/tandem mass spectrometry (LC/MS/MS) analysis of bisphenol A (BPA) in canned infant formula. Both yielded two identical MS/MS transitions to BPA. The identities of the unknowns were investigated using accurate mass LC/MS, LC/MS/MS, and elemental formula and structures proposed. Exact identities were confirmed through purification or synthesis followed by (1)H and (13)C nuclear magnetic resonance (NMR) experiments, as well as comparisons of one unknown with commercial standards. Comparisons of negative ion electrospray ionization (ESI) MS/MS and accurate mass spectra suggested both unknowns to be structurally identical (to BPA and each other). Positive ion ESI spectra confirmed both were larger molecules, suggesting that in the negative mode they likely fragmented to the deprotonated BPA ion in the source [corrected]. Elemental composition of positive ion accurate mass spectra and NMR analysis concluded the unknowns were oxidized forms of the known epoxy can coating monomer, bisphenol A diglycidyl ether (BADGE). One of the unknowns, 2,2-[bis-4-(2,3-dihydroxypropoxy)phenyl]propane, commonly known as BADGE*2H(2)O, is widely reported as an epoxy-phenolic can coating migrant, but has not been suggested to interfere with the MS/MS analysis of BPA. The other unknown, 2-[4-(2,3-dihydroxypropoxy)phenyl]-2-[4'-hydroxyphenyl]propane, or the oxidized form of bisphenol A monoglycidyl ether (BAMGE*H(2)O), has not been previously reported in food or packaging.

Concentration of Bisphenol A in Highly Consumed Canned Foods on the U.S. Market

“…The alternate chromatographic conditions, described above, shortened the BPA retention time and changed the elution order of BPA and known comigrants. 31 Such changes were consistent with the retention and elution profiles previously reported by Petersen et al 32 for bisphenol A diglycidyl ether derivatives. All of the BPA concentrations determined with the Luna C8(2) chromatographic conditions were comparable, within the 95% confidence limit, to those reported using the standard method.…”

“…All of the BPA concentrations determined with the Luna C8(2) chromatographic conditions were comparable, within the 95% confidence limit, to those reported using the standard method. On the basis of the results from the confirmatory quantification method, it is clear that the BPA concentrations reported (Table 3) are not affected by the previously identified comigrating epoxy derivatives 31 and unlikely that they are affected by other coeluting interference.…”

Screening for Bisphenol Chemicals: A Strategy Based on Dansyl Chloride Derivatizatio n Coupled with In-Source Fragmentation by High-Resolution Mass Spectrometry

“…Due to the electronegative properties of phenols, the model BPs were inefficiently ionized under the positive ESI mode. 25 The presence of sulfonyl group in BPS resulted in higher polarity (Table S1) may enhance sensitivity than other nonsulfone bisphenols under positive ESI mode, thus making it the only detectable bisphenol at a concentration of 200 ng/mL. By contrast, DnsCl derivatization could introduce dimethylaminonaphthalene moieties into the phenolic hydroxyl groups and increase the hydrophobicity and protonation, therefore greatly increasing the sensitivity of derivatized BPs by positive ESI ionization via monoprotonation.…”

“…For example, the limits of detection (LODs, defined as an instrumental response three times the standard deviation of the noise) of DnsCl-derivatized BPS (d-BPS), BPB (d-BPB), and BPBP (d-TBBPS) were determined to be 0.03, 0.001, and 0.03 ng/mL (at pH = 2.8 for mobile phase A), approximately 6, 60000, and 700 times lower than their optimal LODs without derivatization (0.17, 63, 22 ng/mL), respectively (Table S3). Due to the electronegative properties of phenols, the model BPs were inefficiently ionized under the positive ESI mode . The presence of sulfonyl group in BPS resulted in higher polarity (Table S1) may enhance sensitivity than other nonsulfone bisphenols under positive ESI mode, thus making it the only detectable bisphenol at a concentration of 200 ng/mL.…”

Cladosporioles A and B, Two New Indole Derivatives from the Deep‐Sea‐Derived Fungus Cladosporium cladosporioides 170056

“…By comparison of the NMR, MS, and OR data with the references, 14 known compounds were identified as cyclo[Trp‐Gly] (3), [10] cyclo(Trp‐Ana) (4), [11] cyclo‐(Trp‐Ser) (5), [12] glioperazine C (6), [13] cyclo(Ala‐Tyr) (7), indazole (8), [14] 2‐(4‐hydroxyphenyl)‐2‐oxoethanol (9), [15] 2,2‐[bis‐4‐(2,3‐dihydroxypropoxy)phenyl]propane (10), [16] 2‐[4‐(2,3‐dihydroxypropoxy)phenyl]‐2‐[4′‐hydroxyphenyl]propane (11), furan‐2,5‐diyldimethanol (12), [17] 2,3‐butanediol (13), [18] ergosterol (14), [19] 10‐hydroxy‐cis‐12‐octadecenoic acid (15), [20] and oleic acid (16) [21] …”