Artifact Peaks Due to Minor Decomposition of Sample Diluent DMSO in Head Space-GC Analysis: Mass Spectrometric Investigation Using Deuterated DMSO and Quadrupole Time-of-Flight Mass Detection

<p><b>Rationale: </b>Head space gas chromatography (HS-GC) has become a widely used analytical technique for residual solvents determination in drug substances and drug products. During our method development of residual solvents by HS-GC for certain drug substances, four unknown peaks were observed when dimethyl sulfoxide (DMSO) was employed as sample diluent.</p><p><b>Methods:</b> Use of other sample diluents replacing DMSO did not show these unknown peaks in the HS-GC analysis. HS-GC-MS was then utilized to investigate these peaks. As part of the investigation, DMSO-<i>d₆</i> was used to trace the origins of these unknown peaks to DMSO. A stress study of methanethiol and formic acid was carried out to provide further evidence that <i>S</i>-methyl methanethioate was one of the unknown peaks observed during the original HS-GC analysis.<b></b></p><p><b>Results:</b> The four unknown peaks have been identified as methanethiol, dimethylsulfide, <i>S</i>-methyl methanethioate, and dimethyldisulfide, respectively, and it has been demonstrated that the four peaks are clearly related to DMSO through the use of its deuterated counterpart. Plausible formation mechanisms of these species are proposed.</p><p><b>Conclusions:</b> The occurrence of the peaks is due to minor degradation of DMSO, facilitated by certain drug substances as analytes of the analysis. These peaks are artifacts, rather than genuine impurities of the drug substances. These artifact peaks could widely occur in HS-GC analysis, when DMSO is used as sample diluent.</p>

Artifact Peaks Due to Minor Decomposition of Sample Diluent DMSO in Head Space-GC Analysis: Mass Spectrometric Investigation Using Deuterated DMSO and Quadrupole Time-of-Flight Mass Detection

<p><b>Rationale: </b>Head space gas chromatography (HS-GC) has become a widely used analytical technique for residual solvents determination in drug substances and drug products. During our method development of residual solvents by HS-GC for certain drug substances, four unknown peaks were observed when dimethyl sulfoxide (DMSO) was employed as sample diluent.</p><p><b>Methods:</b> Use of other sample diluents replacing DMSO did not show these unknown peaks in the HS-GC analysis. HS-GC-MS was then utilized to investigate these peaks. As part of the investigation, DMSO-<i>d₆</i> was used to trace the origins of these unknown peaks to DMSO. A stress study of methanethiol and formic acid was carried out to provide further evidence that <i>S</i>-methyl methanethioate was one of the unknown peaks observed during the original HS-GC analysis.<b></b></p><p><b>Results:</b> The four unknown peaks have been identified as methanethiol, dimethylsulfide, <i>S</i>-methyl methanethioate, and dimethyldisulfide, respectively, and it has been demonstrated that the four peaks are clearly related to DMSO through the use of its deuterated counterpart. Plausible formation mechanisms of these species are proposed.</p><p><b>Conclusions:</b> The occurrence of the peaks is due to minor degradation of DMSO, facilitated by certain drug substances as analytes of the analysis. These peaks are artifacts, rather than genuine impurities of the drug substances. These artifact peaks could widely occur in HS-GC analysis, when DMSO is used as sample diluent.</p>

Derivatized volatile organic compound characterization of Friulano wine from Collio (Italy–Slovenia) by HS-SPME-GC-MS and discrimination from other varieties by chemometrics

PurposeMethods to assess the authenticity and traceability of wines have been extensively studied as enhancers of food quality, allowing producers to obtain market recognition and premium prices. Among analytical techniques, the volatilome profile attained by gas chromatography coupled with mass spectrometry is acquiring more and more attention by the scientific community, together with the use of chemometricsDesign/methodology/approachThe volatilome profile of three varieties of blanc wines from the Collio area (namely Ribolla Gialla, Malvasia and Friulano) between Italy and Slovenia, was determined by head space-solid phase micro extraction-gas chromatography-mass spectrometry, enhancing the carbonyl compounds identification with O-(2, 3, 4, 5, 6-pentafluorobenzyl)-hydroxylamine with the aim of identifying the autochthonous Friulano variety.FindingsA two-step chemometric approach based on an unsupervised technique (PCA) followed by a supervised one (PLS-DA) allowed to identify possible markers for discriminating the Friulano Collio variety from the others, in particular two chemical classes were identified by PCA (ketones and long chain esters). PLS-DA showed 87% accuracy in classification. A correct classification (i.e. non-Friulano Collio) of a group of wines obtained from the same grape variety but produced in an extra-Collio area was obtained as well. The results confirmed the benefits of using a derivatization step prior to volatile organic compounds analysis.Research limitations/implicationsAmong methods to assess the authenticity and traceability of wines, volatilome profile of wines determined by head space-solid phase micro extraction-gas chromatography-mass spectrometry, enhanced by the carbonyl compound identifications with O-(2, 3, 4, 5, 6-pentafluorobenzyl)-hydroxylamine, may have a key role in conjunction with chemometrics and, in particular with principal component analysis and partial least square discriminant analysis.Practical implicationsAmong methods to assess the authenticity and traceability of Friulano wine, volatilome profile of wines determined by head space-solid phase micro extraction-gas chromatography-mass spectrometry, enhanced by the carbonyl compound identifications with O-(2, 3, 4, 5, 6-Pentafluorobenzyl)Hydroxylamine hydrochloride, may have a key role in conjunction with chemometrics.Originality/valueFew works investigated both wine traceability with a volatilome enhancer and chemometrics of the Friulano wine variety obtaining such an improvement in this wine variety discrimination.

Desenvolvimento e caracterização do perfil de compostos voláteis de casquinha de sorvete produzida com farinha da casca e amêndoa de manga Tommy Atkins

O objetivo do estudo foi analisar os compostos voláteis presentes na farinha de casca e amêndoa de manga Tommy Atkins e em casquinha de sorvete elaborada com esta farinha. Na elaboração da casquinha substituiu-se 41% da farinha de trigo da receita tradicional pela farinha de coprodutos de manga. Os compostos voláteis foram analisados por meio da microextração em fase sólida no modo head space combinada com cromatografia gasosa e espectrometria de massas. Foram identificados 29 compostos voláteis na farinha produzida com coprodutos de manga, sendo constituídos principalmente de terpenos (89,7%), dos quais 22 (75,9%) permaneceram na casquinha de sorvete. A distribuição percentual dos compostos na casquinha de sorvete apresentou-se de forma distinta à da farinha, com diminuição das classes dos aldeídos e sesquiterpenos e aumento dos monoterpenos. Conclui-se que dos 29 compostos voláteis presentes na farinha elaborada com coprodutos de manga, a maioria (n=22) permaneceu na casquinha de sorvete, mesmo empregando-se elevadas temperaturas no processo de produção, fazendo com que o produto desenvolvido apresente sabor e aroma característico de manga