An evaluation of selected ion flow tube mass spectrometry for rapid instrumental determination of paper type, origin and sensory attributes

Abstract

As the food and pharmaceutical industries move toward more sustainable forms of packaging, paper is experiencing somewhat of a comeback as a packaging material. However, by its very nature paper is rich in volatiles—both with and without significant olfactory impact. Human sensory analysis has long been the benchmark for determining that a product is fit for consumer application. However, sensory analysis is limited in its application due to the high per‐sample cost. Selected ion flow tube mass spectrometry (SIFT‐MS) is an instrumental approach that has potential to rapidly screen paper samples for both sensory and chemical composition attributes in a single broad‐spectrum and sensitive analysis of volatiles. In this study, a combined approach utilizing SIFT‐MS sample analysis with multivariate statistical data processing is evaluated for its ability to distinguish between samples of different paper composition (in particular, virgin, recycled, or mixed fibres), mill of origin (manufacturing mill), sensory odour intensity rating, and sensory odour note. Paper samples from four mills were analysed using instrumental and sensory methods, together with one pulp sample. The key discriminating volatiles varied depending on the classification model but typically included hydrogen sulfide, ethanol, acetone, hexanal, dimethyl sulfide, and formaldehyde. The pulp sample generally exhibited significantly higher concentrations of volatiles—especially methanol and hydrogen sulfide. Because it was so different, it was eliminated from certain models—in particular, for determination of the mill of origin. Chemical analysis with multivariate statistical processing exhibited near‐perfect classification of the fibre type and the mill of origin. Evaluation of instrumental prediction of odour intensity rating and odour note used multivariate statistical analysis to correlate sensory and instrumental results. It was found that concentration data provided superior classification of odour intensity rating and odour note than did odour activity values (compound concentrations divided by their human odour detection thresholds [ODTs]). This result is tentatively attributed to significant uncertainties introduced by literature ODTs and the method's limit of quantitation being higher than the ODT for several compounds. When using SIFT‐MS concentration data—when coupled with multivariate statistical data processing—this preliminary study demonstrates potential for rapid, instrumental determination of the odour intensity rating and odour note traditionally determined using human sensory analysis.

Robust Automated SIFT-MS Quantitation of Volatile Compounds in Air Using a Multicomponent Gas Standard

“…However, exceptions occur where a product ion m/z falls on a reagent ion or its isotopologue, or at very common fragment ions (e.g., m/z 43 is very common with O 2 +• due to C 3 H 7 + and C 2 H 3 O + fragment formation). For some compounds, high ion signal ratios do not occur due to significant fragmentation or the presence of several abundant stable isotopes (e.g., 35 Cl and 37 Cl, 79 Br and 81 Br, and in some circumstances 32 S and 34 S), resulting in reduced sensitivity per product ion. On the positive side, such isotopic signatures confirm the presence of the element in the analyte and, when not subject to interference, can be averaged manually to improve the signal-to-noise ratio.…”

“…Consider, for example, chlorobenzene 17 which reacts with NO + and O 2 +• via simple charge transfer to form C 6 H 5 Cl + . Since the natural abundance of Cl stable isotopes is 75.5% 35 Cl to 24.5% 37 Cl, corresponding product ions are observed in SIFT-MS mass spectra. Similarly, all organic molecules have 13 C isotopologues that can represent substantial percentages of the ion signal.…”

“…The final example (Table S3) involves the reactions of hexanal with the H 3 O + and NO + reagent ions 36 measured in the context of a study of paper odor 37 (first replicate of sample 1). While the NO + reaction is simple (i.e., yields a single product that does not have noticeable secondary chemistry), two primary product ions are formed with H 3 O + .…”

Evaluation of Solvent Compatibilities for Headspace-SIFT-MS Analysis of Pharmaceutical Products

“…, and NO 3 − ) on the SIFT-MS instrument used in this study (Voice200ultra; Syft Technologies Limited, Christchurch, New Zealand) [21]. Rapid switching of reagent ions provides high specificity, because the multiple reaction mechanisms give independent measurements of each analyte, while the absence of chromatographic separation means that it is straightforward to analyze VOCs with diverse chemical functionalities in a single procedure [22,23]. Instrument detection limits in the part-per-trillion by volume (pptV) range are typically achieved for 1 s ion dwell times for direct analysis of air, with no preconcentration or drying required [24,25].…”

Adoption of SIFT-MS for VOC Pollution Monitoring in South Korea

“…A microwave discharge through air is used to generate the reagent ions, with up to eight available (H3O + , NO + , O2 +• , O −• , OH − , O2 −• , NO2 − , and NO3 − ) on commercial SIFT-MS instruments [18]. Rapid switching of reagent ions provides high specificity because the multiple reaction mechanisms give independent measurements of each analyte, while the elimination of chromatographic separation means that it is straightforward to analyze VOCs of diverse chemical functionalities in a single procedure [13,19,20]. Instrument detection limits in the part-per-trillion by volume (pptV) range are typically achieved for 1s ion dwell times for direct analysis of air with no preconcentration or drying required [21,22].…”