Investigation of the formation of furfural compounds in apple products treated with pasteurization and high pressure processing.

The thermal treatment carried out in the processing of apple products is very likely to induce Maillard reaction to produce furfurals, which have raised toxicological concerns. This study aimed to elucidate the formation of furfural compounds in apple products treated with pasteurization and high pressure processing (HPP). The method for simultaneous determination of five furfural compounds including 5-hydroxymethyl-2-furfural (5-HMF), furfural (F), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (HDMF), 2-acetylfuran (FMC), and 5-Methyl-2-furfural (MF) using high performance liquid chromatography equipped with diode array detector (HPLC-DAD) was successfully developed and validated. All five furfurals exhibited an increasing trend after the pasteurization treatment of apple clear juice, cloudy juice, and puree. 5-HMF, F, FMC, and MF were increased significantly during the precooking of apple puree. Whereas there was no significant change in the furfurals formation after apple products treated with high pressure processing (HPP) with 300 MPa and 15 min. Based on the variation of the fructose, glucose and sucrose detected in apple products after thermal treatment, it revealed that the saccharides and thermal treatment have great effect on the furfural compounds formation. The commercial fruit juice samples with different treatments and fruit puree samples treated with pasteurization were also analyzed. Five furfurals were detected more frequently in the fruit juice samples treated with pasteurization or ultra-high temperature instantaneous sterilization (UHT) than those treated with HPP. 5-HMF and FMC were detected in all fruit puree samples treated with pasteurization, followed by F, MF, and HDMF with the detection rate of 79.31 %, 72.41 %, and 51.72 %. The results could provide a reference for risk assessment of furfural compounds and dietary guidance of fruit products for human, especially for infants and young children. Moreover, moderate HPP treatment with 300 MPa and 15 min would be a worthwhile alternative processing technology in the fruit juice and puree production to reduce the formation of furfural compounds.

A commercially viable solution process to control long-chain branching in polyethylene.

In polyolefins, long-chain branching is introduced through an energy-intensive, high-pressure radical process to form low-density polyethylene (LDPE). In the current work, we demonstrated a ladder-like polyethylene architecture through solution polymerization of ethylene and less than 1 mole % of α,ω-dienes, using a dual-chain catalyst. The ladder-branching mechanism requires catalysts with two growing polymer chains on the same metal center, thus enchaining the diene without the requirement of a steady-state concentration of pendant vinyl groups. Molecular weight distributions lacking a high-molecular weight tail, distinctive Mark-Houwink signatures, nuclear magnetic resonance characterization, and shear and extensional rheology consistent with highly branched polyethylene architectures are described. This approach represents an industrially viable solution-polymerization process capable of producing controlled long-chain branched polyethylene with rheological properties comparable to those of LDPE or its blends with linear low-density polyethylene (LLDPE).

Separation and determination of triadimefon and its metabolites triadimenol enantiomers in fruit puree by supercritical fluid chromatography.

A method was established for the separation and determination of triadimefon and its metabolite triadimenol enantiomer residues in major complementary fruit puree for infants and young children (banana puree, pineapple puree, and grape puree) by supercritical fluid chromatography. After the samples were extracted with acetonitrile and purified with a solid phase extraction cartridge, Acquity Trefoil CEL2 chiral chromatographic column was adopted for separation, and gradient elution was conducted at the flow rate of 1.0 ml/min under the mobile phase of supercritical carbon dioxide - 0.5% ammonia methanol, the detection wavelength was 220 nm and quantification was conducted with the external standard method. The limits of quantitation of triadimefon and triadimenol enantiomers were both 0.05 mg/kg, the linear ranges were 0.5-50 mg/L, and the linear correlation coefficients were greater than 0.9993. The recoveries in the spiked samples at 0.05, 0.2, and 3.0 mg/kg were from 80.1 to 106%, and the relative standard deviation reached 3.3-7.6%. The method is efficient, rapid, reproducible, and environmentally friendly, enabling accurate analysis of pesticide enantiomers, which can detect the enantiomer residues of triadimefon and its metabolite triadimenol in major complementary fruit puree for infants and young children.

Determination of sugars and sugar alcohols in infant formula by high performance liquid chromatography with evaporative light-scattering detector.

A method was established for the simultaneous determination of five sugars (fructose, glucose, sucrose, lactose, maltose) and five sugar alcohols (erythritol, xylitol, sorbitol, mannitol, maltitol) in infant formula by high performance liquid chromatography-evaporative light scattering detector. After the samples were extracted with acetonitrile-water solution, precipitated by acetic acid, and purified with solid phase extraction cartridge, ALLChrom Rocksil Carbohydrate ES column was adopted for separation, and isocratic elution was conducted at the flow rate of 1.0 mL/min with acetonitrile-0.04 % ammonia solution as the mobile phase. The analytes were detected by an evaporative light-scattering detector, and quantified by external standard method. The linear ranges of the 10 components were 0.04-4.0 g/L with the correlation coefficients greater than 0.999, and the limits of quantification (S/N = 10) of the method were 0.08-0.4 g/100 g. The relative standard deviation of the lactose parallel samples reached 1.29 %, and the recoveries of the other 9 components ranged from 80.4 % to 99.4 % with the relative standard deviation of 2.8 %-7.1 %. The method performs well in sensitivity and separation, which is suitable for the simultaneous quantitative determination of sugars and sugar alcohols in infant formula.

Research method of rapid determination of chiral pesticide fenpropathrin enantiomers in fruit and vegetable puree by supercritical fluid chromatography.

A method is first established for the separation and determination of fenpropathrin enantiomer residues in apple puree, strawberry puree, and tomato puree considered a supplementary food for infants by supercritical fluid chromatography. After the sample was extracted with acetonitrile and cleaned up by a solid-phase extraction column, then it was separated by a CHIRALPAK AD-3 chiral column with gradient elution at a flow rate of 1.5 mL/min using methanol and supercritical carbon dioxide as the mobile phase, detected by ultraviolet detector at 230 nm wavelength and quantified with the external standard method. The limits of quantification of the two fenpropathrin enantiomers were both 0.2 mg/kg, the linear ranges were 1.0-20.0 mg/L with linear correlation coefficients greater than 0.9992, the recoveries in the spiked samples at 0.2, 0.4 and 2.0 mg/kg were from 80.6 to 105%, and the relative standard deviation reached 2.6-7.7%. This method has the advantages of convenient operation, good resolution, and environmental protection, which can satisfy the requirement of determination for fenpropathrin enantiomer residues in fruit and vegetable puree as supplementary food for infants.

The heart as a target for deltamethrin toxicity: Inhibition of Nrf2/HO-1 pathway induces oxidative stress and results in inflammation and apoptosis.

As a synthetic pyrethroid pesticide, deltamethrin (DLM) is widely employed in veterinary medicine and farming, and DLM-triggered oxidative stress largely causes serious harm to the organism. It is well-known that nuclear factor erythroid-2-related factor 2/heme oxygenase-1 (Nrf2/HO-1), a pivotal endogenous anti-oxidative pathway, acts on inhibiting oxidative stress-induced cell injury under the activated state. The purpose of this research was to observe the impact and molecular mechanism of DLM on inflammation and apoptosis in quail cardiomyocytes based on the Nrf2/HO-1 signaling route. In this research, quails were established as a cardiac injury model through gastric infusion of various doses of DLM (0, 15, 30, and 45 mg/kg b. w.) for 12 weeks. Our results showed that DLM could induced cardiomyocyte injury in a dose-dependent manner though weakening antioxidant defense via down-regulating Nrf2 and its downstream protein HO-1. Furthermore, DLM stimulation induced apoptosis in quail heart by decreasing the protein expressions of B-cell lymphoma-extra large and B-cell lymphoma gene 2 (Bcl-2), as well as increasing P53, caspase 3, and Bcl-2-associated X protein levels. Meanwhile, relative levels of nuclear factor-kappa B and interleukin-1ß in quail hearts were up-regulated under DLM intervention progressively. Collectively, our study demonstrates that chronic exposure to DLM can induce quail cardiomyocyte inflammation and apoptosis by mediating Nrf2/HO-1 signaling pathway-related oxidative stress.

[Separation and determination of clenbuterol enantiomers by ultra-performance convergence chromatography].

Clenbuterol enantiomers differ greatly in their bioactivities. By optimizing the conditions for chromatographic separation and method validation, ultra-performance convergence chromatography (UPC2) was adopted to separate the enantiomers of clenbuterol. Standard solutions of (+)-clenbuterol and (-)-clenbuterol were stored at -18 ℃ for 1, 3, 5, 7, 14, 30, and 60 d, and then, their stability was monitored. The impacts of different chromatographic columns, cosolvents, system backpressure, and chromatographic column temperature on the separation of the two enantiomers were investigated. Acquity Trefoil AMY1 (150 mm×3.0 mm, 2.5 µm) was used for separation, and CO2-0.5% (v/v) ammonium acetate was used as the mobile phase. Gradient elution at a flow rate of 2.0 mL/min was adopted. The detection wavelength was set to 241 nm, and the injection volume was set to 10 µL. The backpressure was set to 13.8 MPa, and the column temperature was maintained at 40 ℃. The two enantiomers showed good linear relationships in the range of 1.0 to 20.0 mg/L with correlation coefficients greater than 0.9997. The limits of detection (LODs, S/N=3) of (+)-clenbuterol and (-)-clenbuterol were both 0.5 mg/L. The relative standard deviation (RSD, n=6) for the peak area of the 10.0 mg/L mixed standard working solution with six replicate injections ranged from 0.65% to 0.76%. The effectiveness and practicability of this method were demonstrated by using it to detect standard clenbuterol racemate. The (+)-clenbuterol and (-)-clenbuterol contents were 5.6 mg/L and 5.5 mg/L, respectively, in the standard clenbuterol racemates, as determined by the external standard method of quantification. The detection results suggested that the content ratio of (+)-clenbuterol and (-)-clenbuterol was close to 1.02∶1.00, which is consistent with the literature data. The established method has the advantages of rapid analysis, good separation effect, and low consumption of organic solvents, and it is suitable for the separation of clenbuterol enantiomers. This method can also provide technical support for the separation of other chiral drugs, analysis of the effects of chiral drugs, and assessment of product quality.

Analytical research on the separation and residue of chiral pesticide triadimenol in fruit and vegetable puree.

In this paper, a method for the separation of triadimenol stereoisomers using ultra-performance convergence chromatography and an analytical method for the determination of triadimenol stereoisomer residues in pumpkin puree, apple puree, and tomato puree as a supplement for infants are established. Test samples were extracted with acetonitrile and successively purified with graphitized carbon black and Florisil column. Afterward, Acquity Trefoil AMY1 column was adopted for chiral separation of chromatographic column, and gradient elute was carried out with supercritical carbon dioxide-methanol as the mobile phase and with external standard method for quantitation. Results showed that the linearly dependent coefficient of the four kinds of triadimenol stereoisomers within 1.0 and 50 mg/L was greater than 0.9997, and the limit of quantitation of the four kinds of triadimenol stereoisomers was 0.05 mg/kg. Recovery experiment was carried out within 0.05 and 1.0 mg/kg scope, the recoveries were 81.0-107％, and the relative standard deviation was 2.3-7.6%. This method implemented the separation of triadimenol stereoisomers and its residue test in pumpkin puree, apple puree, and tomato puree as a supplement for infants, and it can provide reliable technical support for the analysis of pesticide residue and assessment of product quality.

Characterization of Polymer Molecular Weight Distribution by NMR Diffusometry: Experimental Criteria and Findings.

NMR diffusometry finds useful applications in characterizing molecular weight (M) and molecular weight distribution (MWD) for polymers due to its unique advantages in generic detection, chemical selectivity, and quantitation. Here, we present a fundamental study to explore how the condition of diffusion measurement impacts the determined MWD. We use the critical dilute concentration Cdilute* to explicitly delineate the boundary of the sufficiently dilute condition, below which chain interactions have a negligible impact on polymer diffusion. We present solid evidence to validate the postulated theory that links Cdilute* to molecular weight, polydispersity, and chain conformation. Quantitative analysis reveals the consequence of violating the sufficiently dilute condition with M/MWD characterization. These findings provide useful guidance for M/MWD characterization by NMR diffusion and help to rationalize the data disparity that exists in the literature. The results further provide new insights into the interplay between chain conformations and diffusion for globular structure, such as proteins, and provide a different approach toward characterizing polymer architecture and molecular weight.

[Simultaneous determination of 16 flavonoids and ferulic acid in honey by solid phase extraction and high performance liquid chromatography-tandem mass spectrometry].

Flavonoids are polyphenol compounds that are widely distributed in honey; they play an important role in its antioxidant activity and aid in distinguishing various species of honey. An analytical method based on solid phase extraction and high performance liquid chromatography with tandem mass spectrometry (SPE-HPLC-MS/MS) for the simultaneous determination of rutin, myricetin, morin, quercetin, naringenin, hesperetin, luteolin, genistein, kaempferol, isorhamnetin, apigenin, pinocembrin, wogonin, chrysin, galangin, genkwanin, and ferulic acid in honey was developed and validated. The honey samples were diluted with HCl solution (pH 2) and cleaned up on a C18 column by solid phase extraction; the methanol eluent was filtered through a nylon membrane and analyzed by LC-MS/MS on an ODS-3 column (150 mm×4.6 mm, 3 µm). Quantitative detection was performed by LC-MS/MS in the multiple reaction monitoring (MRM) mode under negative electrospray ionization (ESI-) conditions. The external standard method was used for quantitation. The method validation data were obtained. The calibration standard curve solutions were prepared by honey matrix-matching; the linear range was 0-200 µg/kg, with correlation coefficients of the calibration standard curves greater than 0.997. The limits of quantification (LOQs) of this method were 20 µg/kg. The recoveries were in the range of 64.5%-113%, and the relative standard deviations were 1.4%-14.5% at three spiked levels (20, 40, and 100 µg/kg). The developed method is convenient, rapid, and effective, and it is suitable for the determination and confirmation of flavonoids in honey samples.

[Rapid screening of sibutramine and five derivatives in health food by high performance liquid chromatography-quadrupole/electrostatic orbitrap high-resolution mass spectrometry].

A rapid screening method was developed to determine sibutramine and five derivatives in health food by high performance liquid chromatography-quadrupole/electrostatic orbitrap high-resolution mass spectrometry (HPLC-Q/Orbitrap HRMS). The sample was extracted with methanol via ultrasonic-assisted extraction coupled with high-speed centrifugation. Separation was performed on a Hypersil Gold column (100 mm×2.1 mm, 3 µm) by gradient elution with methanol/water (containing 0.15%(v/v) formic acid) as the mobile phase. The positive full mass scan/date-dependent MS2 (Full MS/dd-MS2) mode was used during MS detection, and quantification was achieved by resolution of the precursor mass. The analytes in the sample were separated, and accurate mass and MS2 fragment ions were simultaneously attained within 8 min. The results indicated that the obtained mass accuracy errors of the six analytes were less than 1×10-6. Good linearities were obtained in the range of 0.5-20.0 µg/L, and all correlation coefficients were higher than 0.999. The limits of quantification were 25 µg/kg and the recoveries were in the range of 93.5%-103.5% with relative standard deviations of 1.5%-7.7%. This simple-pretreatment, rapid, accurate, high-sensitivity, and high-selectivity method can be used in the rapid screening and quantitative analysis of sibutramine and its derivatives in health food.

Matrix-Induced Sugaring-Out: A Simple and Rapid Sample Preparation Method for the Determination of Neonicotinoid Pesticides in Honey.

In the present work, we developed a simple and rapid sample preparation method for the determination of neonicotinoid pesticides in honey based on the matrix-induced sugaring-out. Since there is a high concentration of sugars in the honey matrix, the honey samples were mixed directly with acetonitrile (ACN)-water mixture to trigger the phase separation. Analytes were extracted into the upper ACN phase without additional phase separation agents and injected into the HPLC system for the analysis. Parameters of this matrix-induced sugaring-out method were systematically investigated. The optimal protocol involves 2 g honey mixed with 4 mL ACN-water mixture (v/v, 60:40). In addition, this simple sample preparation method was compared with two other ACN-water-based homogenous liquid-liquid extraction methods, including salting-out assisted liquid-liquid extraction and subzero-temperature assisted liquid-liquid extraction. The present method was fully validated, the obtained limits of detection (LODs) and limits of quantification (LOQs) were from 21 to 27 and 70 to 90 µg/kg, respectively. Average recoveries at three spiked levels were in the range of 91.49% to 97.73%. Precision expressed as relative standard deviations (RSDs) in the inter-day and intra-day analysis were all lower than 5%. Finally, the developed method was applied for the analysis of eight honey samples, results showed that none of the target neonicotinoid residues were detected.

[Chiral separation of six triazole pesticide enantiomers by ultra-performance convergence chromatography and residue determination in cucumber].

The separation of six triazole pesticide enantiomers (TPEs) by ultra-performance convergence chromatography (UPC2) was attempted, and residue analytical methods for these TPEs in cucumber were established. The triazole pesticides were triadimefon, triadimenol, hexaconazole, tebuconazole, bitertanol, and myclobutanil. The sample was extracted with acetonitrile and cleaned up using graphitized carbon black (GCB), a Florisil-phase extraction column, and the QuEChERS method. The treated extract was separated on an Acquity Terifoil AMY1 chromatographic column, with gradient elution using a mixture of supercritical CO2 and methanol or ethanol-isopropanol as the mobile phase. The residues of the six TPEs were quantified by the external standard method. The limits of quantitation (S/N>10) of these TPEs in cucumber were 0.1 mg/kg. The recoveries of the TPEs in cucumber at three spiked levels of 0.1, 0.2, and 0.5 mg/kg ranged from 65.1% to 116% with relative standard deviations (RSDs) of 1.0%-9.6%. The developed method facilitated the enantioseparation of the six TPEs and the accurate estimation of their residues in the cucumber matrix. This method is expected to play an important role in the production and utilization of chiral pesticides, as well as the establishment of relevant laws and regulations.

Simultaneous determination of ten neonicotinoid insecticides and two metabolites in honey and Royal-jelly by solid-phase extraction and liquid chromatography-tandem mass spectrometry.

An analytical method based on liquid chromatography-tandem mass spectrometry (LC-MS/MS) method was developed for the first simultaneous determination of ten neonicotinoid insecticides (pymetrozine, dinotefuran, nitenpyram, thiamethoxam, flonicamid, imidacloprid, clothianidin, imidaclothiz, acetamiprid, thiacloprid) and two metabolites (4-trifluoromethylnicotinamide and N-desmethylacetamiprid) in honey and royal-jelly. The quantitative detection was performed by LC-MS/MS on multiple reaction monitoring (MRM) mode under positive-ion electrospray ionization. The isotope dilution internal standard method or external standard method was used for quantitation analysis. The limits of quantification (LOQs), calculated as 10 times the standard deviation, were 0.25-5.0 µg kg-1 for ten neonicotinoid insecticides and two metabolites. The average recoveries were in the range of 72.8-106.5%, with relative standard deviations (RSDs) below 13.8%, measured at three concentration levels. The developed method exhibits a high sensitivity and suitable for the simultaneous determination of neonicotinoid insecticides and metabolites in honey and royal-jelly.

Quantitative adiabatic-refocused INEPT (QA-RINEPT) as a tool for fast and reliable characterization of polyols.

13 C nuclear magnetic resonance (NMR) is a powerful tool for the detailed characterization and structure elucidation of polymeric samples. The low natural abundance and sensitivity of the 13 C isotope, however, lead to very long acquisition time, therefore limiting the use of such technique. We report here the implementation of a quantitative method, quantitative adiabatic-refocused insensitive nuclei enhanced by polarization transfer (QA-RINEPT), for the characterization of polyol samples. The method, based on the well-known insensitive nuclei enhanced by polarization transfer sequence, allows the boost in sensitivity of the carbon resonances without sacrificing the quantitative aspects of the analysis. This is achieved controlling the polarization transfer mechanism and introducing a response factor to calculate precisely the sensitivity gain of the different carbon signals. Compared with the standard single pulse quantitative experiment, the QA-RINEPT method produces up to 4.7× signals enhancement per unit of time. An in-depth statistical analysis was conducted to confirm the reliability of the QA-RINEPT method. We show that there is excellent agreement between the new and old 13 C-NMR methods for the quantitative determination of several important polyol properties such as the comonomer and initiator content as well as the ratio of primary and secondary hydroxyl groups.

Controlling Proton Delivery through Catalyst Structural Dynamics.

The fastest synthetic molecular catalysts for H2 production and oxidation emulate components of the active site of hydrogenases. The critical role of controlled structural dynamics is recognized for many enzymes, including hydrogenases, but is largely neglected in designing synthetic catalysts. Our results demonstrate the impact of controlling structural dynamics on H2 production rates for [Ni(PPh2 NC6H4R2 )2 ]2+ catalysts (R=n-hexyl, n-decyl, n-tetradecyl, n-octadecyl, phenyl, or cyclohexyl). The turnover frequencies correlate inversely with the rates of chair-boat ring inversion of the ligand, since this dynamic process governs protonation at either catalytically productive or non-productive sites. These results demonstrate that the dynamic processes involved in proton delivery can be controlled through modification of the outer coordination sphere, in a manner similar to the role of the protein architecture in many enzymes. As a design parameter, controlling structural dynamics can increase H2 production rates by three orders of magnitude with a minimal increase in overpotential.

Generic applications of (13) C-detected NMR diffusion to formulated systems with suppression of thermal convection induced by proton decoupling.

Fast and effective structural/compositional analysis on formulated systems represents one of the major challenges encountered in analytical science. (13) C-detected diffusion represents a promising tool to tackle the aforementioned challenges, particularly in industry. Toward exploring the generic applications of (13) C-detected diffusion, thermal convection induced by (1) H decoupling has been identified as a key factor that resulted in significantly reduced resolution in the diffusion dimension. Optimization of experimental parameters and utilization of double-stimulated echo-based pulse sequence both can effectively suppress the thermal convection caused by the (1) H decoupling, the success of which allows robust and generic applications of (13) C-detected diffusion to systems from mixtures of small molecules, polymer blends, and copolymers to actual complex formulated systems. The method is particularly powerful in differentiating small molecules from polymers, polymer blends from copolymers, and end-group analysis. Copyright © 2016 John Wiley & Sons, Ltd.

[Simultaneous determination of ethephon, thidiazuron, diuroN residues in cotton by using high performance liquid chromatography-tandem mass spectrometry].

A method for the determination of ethephon, thidiazuron and diuron in cotton samples has been developed by high performance liquid chromatography-tandem mass spectrometry (HPLC-MS/MS). The sample was extracted with methanol-water. The separation was carried out on a C8 column (150 mm x 4.6 mm, 5 microm) with methanol-water (6:4, v/v) as mobile phase at a flow rate of 0.4 mL/min, and the injection volume was 20 microL. Then the sample solution was analyzed by HPLC-MS/MS in negative ion mode with multiple reaction monitoring (MRM). There were one precursor/two product ion transitions for each pesticide. The results showed that the working curves were linear in the range of 0-10 microg/L for ethephon and thidiazuron, and 0-1 microg/L for diuron. The correlation coefficients (r) were all over 0. 999. The limits of quantitation (LOQ) of ethephon, diuron were 40 microg/kg, that of thidiazuron was 4 microg/kg. The average recoveries varied from 89.4% to 100.2% with the relative standard deviations (RSDs) of 5.7%-11.5% at three spiked levels (LOQ, 2LOQ and 4LOQ). The method is simple, rapid and accurate, and can meet the requirements of the domestic and international legislation. The method adapts to confirm the residues of ethephon, thidiazuron and diuron pesticides in cotton samples.

Enzyme design from the bottom up: an active nickel electrocatalyst with a structured peptide outer coordination sphere.

Catalytic, peptide-containing metal complexes with a well-defined peptide structure have the potential to enhance molecular catalysts through an enzyme-like outer coordination sphere. Here, we report the synthesis and characterization of an active, peptide-based metal complex built upon the well-characterized hydrogen production catalyst [Ni(P(Ph)2N(Ph))2](2+) (P(Ph)2N(Ph)=1,3,6-triphenyl-1-aza-3,6-diphosphacycloheptane). The incorporated peptide maintains its ß-hairpin structure when appended to the metal core, and the electrocatalytic activity of the peptide-based metal complex (≈100,000 s(-1)) is enhanced compared to the parent complex ([Ni(P(Ph)2N(APPA))2](2+); ≈50,500 s(-1)). The combination of an active molecular catalyst with a structured peptide provides a scaffold that permits the incorporation of features of an enzyme-like outer-coordination sphere necessary to create molecular electrocatalysts with enhanced functionality.

Research on the design of an optical information storage sensing system using a diffractive optical element.

This paper introduces a compact optical information storage sensing system. Applications of this system include longitudinal surface plasmon resonance detection of gold nanorods with a single femtosecond laser in three-dimensional space as well as data storage. A diffractive optical element (DOE) is applied in the system to separate the recording-reading beam from the servo beam. This allows us to apply a single laser and one objective lens in a single optical path for the servo beam and the recording-reading beam. The optical system has a linear region of 8 λ, which is compatible with current DVD servo modules. The wavefront error of the optical system is below 0.03 λ(rms). The minimum grating period of the DOE is 13.4 µm, and the depth of the DOE is 1.2 µm, which makes fabrication of it possible. The DOE is also designed to conveniently control the layer-selection process, as there is a linear correlation between the displacement of the DOE and the layer-selection distance. The displacement of DOE is in the range of 0-6.045 mm when the thickness of the layer-selection is 0.3 mm. Experiments were performed and the results have been verified.