Shenzhen JXD Technology Co., Ltd. in order to investigate the characteristic odor components of courier bags in depth. The volatile odor components of the courier bags were obtained by liquid-liquid extraction and separated and identified by gas chromatography-mass spectrometry (GC-MS).
The results showed that more than 30 substances were identified from the courier bags by liquid-liquid extraction, among which the highest relative mass fractions were alcohols and other compounds; 2-(octadecyloxy)-ethanol, tributyl acetyl citrate, 1-chloro-heptadecyl, 2-hexadecanol, 2-bromooctadecane, and tert-hexadecanethiol all had higher relative mass fractions, which may have a have a critical influence.
Courier bags are widely used in the logistics industry with the advantages of low price, light volume, large volume and convenient storage. In the production of express packaging bags, plasticizers, synthetic resins, heat stabilizers, coloring agents, fillers and flame retardants are added.
Plasticizers, stabilizers, synthetic resins and other components make express packaging bags have better stability and ductility, etc., but also gives the express packaging bags unique smell. However, there is less research on the volatile odor components of express packaging bags.
Liquid-liquid extraction method is a gentle and comprehensive extraction of volatile components in an intricate matrix of compounds, which allows the extract to have the original natural and real odor of the sample, especially suitable for the identification and analysis of volatile substances in more complex industrial products such as express packaging bags.
In order to clarify the volatile odor characteristic components of the courier bags, this experiment uses liquid-liquid extraction method combined with gas chromatography ⁃mass spectrometry (GC⁃MS) technology for the separation and identification of its odor characteristic components, in order to provide a theoretical basis for the industrial production and use of courier bags.
1 Sample preparation
Referring to the method of Sun Ying et al, take 10 cm×10 cm courier bags, quickly place them in a 500 mL round bottom flask, add 100 mL of organic solvent (dichloromethane) and the courier bags, mix and filter out the solvent, separate the bags from the organic solvent, collect the organic solvent, then continue to add 100 mL of the same organic solvent, repeat the above operation 3 times, and finally combine all the obtained The organic extracts were combined and re-evaporated; enriched and concentrated to 6 mL by rotary evaporator, nitrogen blowing to about 0.5 mL to obtain aromatic dark yellow transparent liquid, sealed and stored in refrigerator under refrigeration, to be analyzed by GC⁃MS on-line.
2 Results and Discussion
The volatile odor components were extracted from the courier bag samples by liquid-liquid extraction and analyzed by GC⁃MS, and the corresponding total ion flow chromatograms are shown in Figure 1, and the GC⁃MS identification results are shown in Table 1, where RI represents the retention index. The results showed that 30 volatile flavor components were extracted and identified from the courier bags by liquid-liquid extraction, including 10 alcohols, 5 acids, 3 esters, 2 ketones, 1 phenol, and 9 others; their contents were, in descending order, alcohols (25.16 %), others (21.60 %), esters (6.93 %), acids ( 2.42 %), ketones (1.49 %) and phenolic compounds (0.31 %).
2.1 Alcohol compounds
Complete courier bags do not have obvious irritating odor, the general courier bag odor mainly from the volatile compounds. In this study, 10 alcohol compounds were extracted and identified from the courier bag samples. Among them, birch alcohol is a lupine type pentacyclic triterpenoid composed of six isoprene, a white crystalline powder with molecular weight of 442.72 and melting point of 252-253 ℃, soluble in ethanol, ether, chloroform and benzene, slightly soluble in cold water, petroleum ether and other organic solvents; in 1788, Lowit first reported the substance in birch bark and isolated it; meanwhile, birch 3⁃Methoxybutanol can be used as high boiling point solvent, on the one hand, it can be used as nitrocellulose paint, epoxy resin paint, brake fluid viscosity adjuster, printing ink solvent, cutting oil and dyestuff, pigment, pesticide, vinyl chloride On the other hand, it can also be used as an intermediate of pharmaceuticals and medicines. In addition, the acetate produced from it is also an excellent high boiling point
2.2 Acid compounds
Five kinds of acid volatile compounds were identified in the express packaging bags. Among them, ricinoleic acid is used in the preparation of surfactants, plasticizers, lubricant additives, also used in the preparation of sebacic acid, heptanoic acid, etc.; its role is mainly to weaken the secondary bonds between resin molecules, increase the mobility of resin molecular bonds, reduce the crystallinity of resin molecules, increase the plasticity of resin molecules, making them more flexible and easy to process.
Ricinoleic acid is widely used in food packaging, cosmetics, medical equipment and environmental water; Pawar et al. found that the addition of 2 g/(only-d) ricinoleic acid to castor oil had no effect on milk yield, milk composition and blood biochemical characteristics of cows, however, it increased the content of unsaturated fatty acids and polyunsaturated fatty acids and decreased the content of saturated fatty acids in milk fat, but this did not have any This did not have any adverse effect on the health status of the cows. Erucic acid has few direct uses and is mainly used as an intermediate in fine chemicals to make various surfactants, lubricants, plasticizers, emulsifiers, softeners, water repellents, decontaminants, etc..
Erucic acid is present in high amounts in rapeseed oil or mustard oil made from rapeseed and in the seeds of several other cruciferous plants. Oleic acid, together with other fatty acids, exists as glycerides in all animal and vegetable fats and oils; in animal fats, oleic acid accounts for about 40 to 50 % of the fatty acids (mass fraction, same below); its content in vegetable oils varies widely, and can be as high as 83 % in tea oil, 54 % in peanut oil, and only 5 to 6 % in coconut oil; in addition, oleic acid is a co-product in the production of stearic acid, industrial stearic acid and industrial oleic acid actually contain other fatty acids; used to produce stearic acid and oleic acid grease raw materials, industry generally according to the mixed grease formula, such as molten beef fat 30 %, molten pig fat 10 %, bone fat 40 % and cottonseed oil 20 %; grease by refining, hydrolysis of the mixed fatty acids obtained, saturated acid and unsaturated acid melting point differences.
The yield of stearic acid and oleic acid is mainly determined by the formulation of oleic ester, in general, 30 %~50 % oleic acid and 50 %~70 % stearic acid can be obtained by cold pressing; hydrolysis of animal and vegetable fats and emulsions at 105 ℃, purification with stearic acid, removal of stearic acid by primary pressing, separation of crude oleic acid, dehydration, distillation, freezing, then secondary pressing, removal of soft stearic acid, and finally refined by dehydration to obtain finished products The same process of making stearic acid from oleic acid also co-produces oleic acid.
2.3 Ester compounds
Express packaging bag ester volatile compounds in the highest relative mass fraction is acetyl tributyl citrate, acetyl tributyl citrate as a plasticizer can improve the flexibility and impact resistance of polylactic acid polymer; the lowest relative mass fraction is acetate, which is also known as acetate products, widely used in recent years as solvents, plasticizers, surfactants and polymer monomers. The domestic coating industry is gradually stopping the use of solvents with high VOCs, such as methyl ethyl ketone and methyl isobutyl ketone, according to environmental requirements, while acetate is an environmentally friendly solvent.
Ethyl acetate mainly refers to ethyl acetate and butyl acetate; among them, ethyl acetate has excellent solvency ability and can be used as fast-drying solvent, and it is gradually replacing some low-grade solvents as an excellent solvent with high development potential; ethyl acetate is divided into 85 %, 88 %, 99 % and 99.5 % by purity, and the purity of general grade is 99 %; ethyl acetate is mainly used as a solvent for paints (paints and enamels), inks and Ethyl acetate is mainly used as an active solvent in coatings (paints and enamels), inks and adhesives formulations, and as a process solvent in pharmaceutical and organic chemical synthesis.
Also, ethyl acetate has many applications in the food industry as a flavoring agent and process extractant because it is a natural compound present in many fruits; butyl acetate has four isomers, but only n-butyl acetate and isobutyl acetate are the most useful in industry; the main use of butyl acetate is as a solvent for paints.
Because of its good fluidity and anti-scratch ability, it can be used in film coating resins, such as cellulose nitrate, cellulose butyl acetate, polystyrene and methyl methacrylate resin; it is also widely used as solvent for manufacturing artificial leather, textiles and plastics, extractant for oil and medicine and component of fragrance and synthetic flavor; in addition, it can be used as dehydrating agent, and it can form ternary azeotrope with water.
2.4 Phenolic compounds
Only one phenolic compound was identified in the sample, namely 2,4⁃di-tert-butylphenol. It is brownish yellow solid, freezing point 56.5 ℃, boiling point 263.5 ℃, 152-157 ℃ (3.3 kPa), relative density 0.907 (i.e. its density at 60 ℃ is 0.907 of the density of water at 4 ℃), soluble in methanol and ether, very slightly soluble in water; it is an important intermediate of fine chemicals, used in the manufacture of natural rubber and synthetic rubber antioxidants, plastic antioxidants, fuel Stabilizer, UV absorber, phenolic resin, adhesive and pesticide, dye intermediates, etc.
2.5 Other compounds
Other types of volatile compounds also play a vital role in the formation of the unique odor of express packaging bags. Trichloroethane common isomers are 1,1,1⁃trichloroethane (CH3CCl3) and 1,1,2⁃trichloroethane (CH2ClCHCl2) 2, colorless non-flammable liquid, is an intermediate in chemical synthesis, with solvent properties but not often applied; express bags in the 1,1,2⁃trichloroethane content is low, not exceeding national standards, but still need to draw the attention of manufacturers. Digitalis toxin is a toxic substance, the product is the same as digoxin (isohydroxyl digitalis toxin), can strengthen myocardial contraction, slow down the heart rate and inhibit conduction, characterized by slow onset of action and long-lasting, suitable for long-term use in patients with chronic cardiac insufficiency.
Dodecyl succinic anhydride, also known as dodecyl succinic anhydride, has a molecular weight of 266.38 and two types of straight-chain type (LDDSA) and branched-chain type (BDDSA); LDDSA is used as an epoxy resin curing agent with a long duration of application, low irritation and better performance of cured products. It is a light yellow transparent oily viscous liquid with relative density of 1.002, used as toughness curing agent for epoxy resin adhesive, the reference dosage is 120~150 parts; it is easy to mix with epoxy resin, the applicable period is 3~4 d, the curing condition is 100 ℃, 2 h+150 ℃, 2 h or 85 ℃, 2 h+150 ℃, 20 h, the cured product has certain toughness, the heat deformation temperature of 66 to 78 ℃.
Due to poor heat and chemical resistance, DDSA can be mixed with other acid anhydride. Oleic acid amide can be used as antistatic agent, mold release agent, slip agent, dispersant, lubricant, anti-caking additive and printing ink additive, etc. When preparing low density polyethylene film, oleic acid amide is added as chemical additives and plastic ink modifier.
(1) A total of 30 volatile components were identified in the courier bags in this study by Shenzhen JXD Technology Co., Ltd, among which the highest relative mass fractions were mainly alcohols and other compounds; 2⁃(octadecyloxy)⁃ethanol, tributyl acetyl citrate, 1⁃chloro- hesperidin, 2⁃hexadecanol, 2⁃bromooctadecane, and tert-hexadecanethiol all had higher relative mass fractions, which may have a critical influence on the formation of special odor of courier bags.
(2) The liquid-liquid extraction method is suitable for the gentle and comprehensive extraction of volatile components from complex sample matrices, and is especially suitable for the identification and analysis of volatile compounds in complex samples such as courier bags.