SPE—HPLC法同时测定浓缩苹果汁中四螨嗪等4种农药的残留量

建立固相萃取-反相高效液相色谱-双波长检测法同时测定浓缩苹果汁中除虫脲、灭幼脲、烯唑醇、四螨嗪4种农药的残留量。浓缩苹果汁样品用35%的乙醇稀释,ENVITM-18固相萃取柱浓缩净化,乙醇洗脱,分析时用C18色谱柱分离,以V(乙腈)∶V(水)=70∶30为流动相,选择250 nm和270 nm双波长检测。该方法在0.02~5 mg/L范围内4种农药的线性关系良好(r≥0.9999),最低检出限均为0.002 mg/kg(S/N=5),加标回收率为85.8%~108.5%,相对标准偏差1.8%~4.7%。     

超高效液相色谱-串联质谱法测定浓缩苹果汁中61种农药残留量

建立了浓缩苹果汁中61种农药残留量的超高效液相色谱-串联质谱检测方法。样品经Na2HPO4缓冲液稀释、Na OH溶液调节p H后用乙腈提取,N-丙基乙二胺(PSA)固相萃取柱净化,采用ACQUITY UPLC HSS T3色谱柱分离,甲醇-0.1%甲酸溶液梯度洗脱,多反应监测(MRM)模式测定,外标法定量。61种农药在0.01~0.5 mg/L浓度范围内线性关系良好,相关系数均大于0.98,检出限在0.23×10-3~2.9×10-3mg/kg范围内。在浓缩苹果汁中分别添加0.01,0.02,0.05 mg/kg 3个浓度水平,进行加标回收率实验,平均回收率均在77.5%~103.5%范围内,相对标准偏差均低于15%,方法的灵敏度、准确性、重现性均符合农药残留检测的要求。     

液相色谱-串联质谱法快速筛查测定浓缩果蔬汁中的156种农药残留

建立了浓缩果蔬汁中156种农药多残留的液相色谱-电喷雾串联质谱(LC-ESI-MS/MS)测定方法。样品用1%醋酸乙腈溶液萃取,经Waters Sep-Pak Vac固相萃取柱净化,乙腈-甲苯(体积比为3∶1)洗脱,旋转蒸发浓缩,用乙腈-水（体积比为3∶2）溶解,以Agilent ZORBAX SB-C18色谱柱分离,以电喷雾电离串联质谱在正离子多反应监测(MRM)模式下进行测定。对156种农药在5种浓缩果蔬汁(橙汁、苹果汁、葡萄汁、白菜汁、胡萝卜汁)中两个添加水平下的回收率进行了测定,回收率范围为57.2%～122.7%,相对标准偏差范围为0.9%～19.8%。方法的检出限(S/N=3)和定量限(S/N=10)范围分别为0.10～56.77 μg/kg和0.33～189.23 μg/kg。该方法样品前处理简单、快速、分析时间短,灵敏度、准确度和精密度均符合农药多残留检测技术的要求,适用于苹果汁、橙汁、葡萄汁、白菜汁、胡萝卜汁等浓缩果蔬汁中156种农药多残留的快速筛查测定。     

UPLC法测定浓缩苹果汁中阿维菌素残留量

建立了超高效液相色谱法(UPLC)测定浓缩苹果汁阿维菌素残留的方法。样品经C18固相萃取柱(250×4.6μmi.d.,5 mm)净化分离,以V(乙腈)∶V(水)=80∶20为流动相,245 nm波长检测,流速0.3 mL/min。结果表明:本法测定的阿维菌素在4 min内可以完全分离,线性范围为0.01~200 mg/L,R2=0.9997,当添加量为0.05、0.5、1.0 mg/kg时,回收率为99.5%~108.1%,RSD为0.30%~1.1%,测定下限为0.005 mg/kg。方法可用于浓缩苹果阿维菌素残留量测定。     

超高效液相色谱-串联质谱法同时测定浓缩苹果汁中的4种链格孢霉毒素

建立了浓缩苹果汁中链格孢霉素、链格孢酚、腾毒素、链格孢酚甲醚4种毒素残留量的固相萃取-超高效液相色谱-串联质谱检测方法。样品用水稀释后,用PS DVB固相萃取柱净化,外标法定量。测定时用BEH C18色谱柱(50 mm×2.1 mm, 1.7 μm)分离,乙腈和水梯度洗脱,质谱测定采用多反应监测(MRM)模式。4种链格孢霉毒素的测定低限在1.0～5.0 μg/L范围内,加标回收率为77.8%～117.2%,相对标准偏差均低于9.7%。该方法灵敏、稳定、可靠,可用于浓缩苹果汁样品中4种链格孢霉毒素的检测和确证。     

高效液相色谱测定浓缩苹果汁展青霉素的残留量

报道采用高效液相色谱(HPLC)法分析浓缩苹果汁中展青霉素的含量。果汁样品先经纯水稀释,再用乙酸乙酯提取,通过净化、浓缩,用甲醇/水(1∶1,V/V)定容后,进行HPLC检测。色谱柱为资生堂MG-ⅡC18柱,采用等度洗脱,流动相为甲醇、水、乙酸-乙酸钠盐缓冲液(pH=4.6);采用可变波长检测器(VWD)在276 nm波长检测。展青霉素在0.02~1.0μg/mL范围内与其峰面积呈良好的线性关系,其相关系数(R2)为0.9965。果汁样品中不同水平标准加入回收率在69.82±1.64%~87.54±3.61%范围;展青霉素在样品中残留量检测的定量限为50μg/L。     

3%吩嗪-1-羧酸水悬浮剂的高效液相色谱分析

确定一种简单、快速地检测3%吩嗪-1-羧酸悬浮剂中吩嗪-1-羧酸含量的高效液相色谱分析方法,以便准确检测农药、食物和环境中吩嗪-1-羧酸的含量,评价农药和食物是否合格。样品经溶解、稀释、过滤,采用C18反相色谱柱和紫外可见检测器,以乙腈-冰乙酸-水为流动相,检测波长250 nm,用外标法对悬浮剂有效成分进行定性和定量分析。该方法条件下,吩嗪-1-羧酸在0.005~8.0 mg/L时其峰面积与进样质量浓度有良好的线性关系,相关系数R2为0.9999,最小检出量为0.05 ng,最低检测浓度为0.005 mg/L,吩嗪-1-羧酸在样品中的加标回收率为103%~105.2%,日内精密度(RSD)为0%~3.4%,日间精密度(RSD)为0.1%~7.2%。方法适用于测定3%吩嗪-1-羧酸悬浮剂有效成分含量及残留。     

高效液相色谱法测定番茄酱中辛硫磷残留

建立了高效液相色谱(HPLC)法测定番茄酱中辛硫磷残留量的方法。番茄酱样品经乙腈提取盐析,弗罗里硅土固相萃取小柱净化,样液浓缩过滤膜后用乙腈溶解定容。采用C18色谱柱,流动相为体积比4∶1的乙腈∶0.15%甲酸水溶液,检测波长285nm,外标法定量。结果表明:在0.01～1mg/kg范围内辛硫磷的线性关系良好(r=0.9999)。方法检出限为0.01mg/kg,平均回收率为86.1%～102.7%,相对标准偏差为2.0%～6.5%。该法简便、快速、灵敏、准确,各项技术指标均满足农药残留检测的要求。     

农产品中多种农药残留的气相色谱-质谱联用法测定

建立了同时检测大白菜、苹果、大豆和豆沙中211种农药残留的气相色谱-质谱联用法。农药经乙腈-水溶液匀质提取,C18固相萃取柱净化和PSA固相萃取柱净化,洗脱液浓缩后用丙酮-正己烷(1∶1)溶解,经HP-5MS石英毛细管柱分离后,用气相色谱-质谱联用仪采用选择离子扫描方式测定,外标法定量。结果表明211种农药在0.05~0.5 mg/L范围内线性关系良好,相关系数为0.975~0.998,其定量下限为0.002~0.020 mg/kg。在0.1 mg/kg加标水平下,211种农药在大白菜、苹果、大豆和豆沙中的平均回收率为67%~117%,相对标准偏差为1.1%~23.8%。该方法操作简单、净化效果好、灵敏度高,适用于蔬菜、水果等农产品中多种农药残留的测定。     

QuEChERS-UPLC-MS/MS法检测苹果中5种农药残留

建立了QuEChERS-超高效液相色谱-串联质谱(QuEChERS-UPLC-MS/MS)检测苹果中5种农药残留的分析方法。样品采用QuEChERS进行前处理,乙腈提取,经PSA、纳米氧化锆(Nano-ZrO₂)和多壁碳纳米管(MWCNTs)组合净化,结合UPLC-MS/MS检测,外标法定量。结果表明,在0.005~0.5 mg/L的浓度范围内5种农药在苹果基质中的线性关系良好,R²≥0.9950;在0.05,0.5和5 mg/kg的添加水平下5种农药的平均回收率在78.1%~117.5%之间,相对标准偏差(RSDs)在1.8%~9.1%之间;定量限(LOQ)为0.1~2μg/kg。该方法适用于苹果中5种农药残留检测。     

Optimization of clean-up procedure for patulin determination in apple juice and apple purees by liquid chromatography

Patulin (PAT) is a mycotoxin produced in fruits, mainly in apples, by several fungal species that can be carried into industrial apple juice by-products during factory processing. An analytical method for determination of PAT in apple juice and another one for determination of this compound in apple purees and apple compotes by liquid chromatography are proposed in the present paper. These methods have better precision and sensitivity than previously reported methods and focus mainly on extraction and clean-up. To accomplish analytical methods with higher accuracy, lower limits of detection and simpler procedures for application in quality control of the goods, different extraction and clean-up procedures for PAT were comparatively studied. PAT recoveries in apple juice spiked with 1.0 mg PAT/kg varied between 52.3% and 81.0%. The highest PAT recovery in apple puree spiked with 0.1 mg PAT/kg was 82.9%. Addition of NaH₂PO₄ during the extraction phase here reported for the first time has the advantage of keeping the pH slightly acidic, thus avoiding PAT degradation.     

Computational analysis of atpB gene promoter from different Pakistani apple varieties

Apple is the fourth most important fruit crop grown in temperate areas of the world belongs to the family Rosaceae. In the present study, the promoter (∼1000 bp) region of atpB gene was used to evaluate the genetic diversity and phylogeny of six local apple varieties. atpB gene is one of the large chloroplastic region which encodes β-subunit of ATP synthase and previously it had been used largely in phylogenetic studies. During the present study, atpB promoter was amplified, sequenced and analyzed using various bioinformatics tools including Place Signal Scan, MEGA6 and BLASTn. During the phylogenetic analysis, obtained phylogram divided the studied varieties into two clusters revealing the monophyletic origin of studied apple varieties. Pairwise distance revealed moderate genetic diversity that ranges from 0.047–0.170 with an average of 0.101. While identifying different cis-acting elements present in the atpB promoter region, results exhibited the occurrence of 56 common and 20 unique cis-regulatory elements among studied varieties. The identified cis-acting regulatory elements were mapped as well. It was observed that Kala Kulu has the highest unique features with reference to the availability of cis-acting elements. Moreover, the possible functions of all regulatory elements present on the promoter sequence of atpB gene were predicted based on already reported information regarding their in vivo role.     

Proteomic fingerprinting of apple fruit,juice, and cider via combinatorial peptide ligand libraries and MS analysis

Combinatorial peptide ligand libraries coupled to MS was applied to extensively map the proteome of apple fruit, and to detect its presence in commercial apple juice and cider to evaluate their authenticity and genuineness. Using the Uniprot_Malus database, 96 proteins were detected in apples, among which 30 proteins were specifically captured via combinatorial peptide ligand libraries. Next, three proteins, previously recognized in fruits, were found in apple juice, which were involved in cellular metabolism of fruit maturation and in allergenic reactions. On the other hand, only one Malus allergen was identified in cider beads eluate, demonstrating that the industrial processes did not prevent any negative effects in sensitive subjects. Thus, the present study not only increases the knowledge of the apple proteome but also offers a reliable analytical method to assess quality and genuineness of commercial products, which could be also used to inform consumers about the presence of allergens.     

Rapid reversed-phase liquid chromatographic determination of patulin in apple juice

A rapid, simple and economical method using a limited amount of organic solvent is described for the determination of patulin in apple juice. The sample was extracted with ethyl acetate and the extract was cleaned up by extraction with sodium carbonate solution. Patulin was then determined by reversed-phase liquid chromatography using a MicroPak C₁₈ column and a variable-wavelength UV-Vis detector set at 276 nm. Patulin and 5-hydroxymethylfurfural were completely resolved by using water- acetonitrile (99:1, v/v) as the mobile phase at a flow-rate of 1.0 ml/min. The detection limit was <5 μg/1 and the recovery was 98%.     

High-performance liquid chromatographic determination of furfural and hydroxymethylfurfural in apple juices and concentrates

Summary A rapid and sensitive method for determining 2-furaldehyde (FUR) and 5-hydroxymethyl-2-furaldehyde (HMF) in apple juices and juice concentrates has been developed. The method for FUR and HMF involves the solid-liquid extraction of the juice by using a C-18 cartridge prior to reversed-phase separation with detection at 280 nm. The mobile phase was acetonitrile-water (8/92, v/v) at a flow rate of 1.0 ml/min. Recoveries from apple juices and juice concentrates spiked at different levels ranged from 94.1 to 104.0 (FUR) and 94.5 to 100.5 (HMF). The quantification limit for both, FUR and HMF, was 5 ppb.     

Stereoselective synthesis of 10,14-dimethyloctadec-1-ene, 5,9-dimethyloctadecane, and 5,9-dimethylheptadecane, the sex pheromones of female apple leafminer

The stereoselective synthesis of (10R,14R)-10,14-dimethyloctadec-1-ene (1), (5R,9R)-5,9-dimethyloctadecane (2), and (5R,9R)-5,9-dimethylheptadecane (3) the sex pheromone components of female apple leafminer was accomplished by reductive elimination tosyl and isonitrile groups of dialkylated tosylmethyl isonitrile. The key steps involved were dialkylation of TosMIC with 1-iodo 2-methyl alkanes, which were derived from Evan's alkylation of chiral auxiliary and subsequent reduction.     

Application of HPLC to characterization and control of individual acids in apple extracts and ciders

Summary Three HPLC methods have been tested in order to compare their separation of apple and cider organic acids. Optimum results for simultaneous determination of malic, citric, quinic, succinic, lactic and shikimic acids have been obtained using an RP-18 column with phosphate buffer as the mobile phase.This method was applied to organic acids monitoring during the ripening of apples and throughout the fermentation process. After filtration and degasification the organic acids in the sample were separated, and quantified by using a diode array detector.Recovery studies show good results for all solutes (88%–106%). The coefficients of variation show excellent precision (5%).     

Quantitative determination of formic acid in apple juices by H NMR spectrometry

A quantitative determination method of formic acid in apple juices is proposed by means of the proton nuclear magnetic resonance (¹H NMR) technique. Formic acid gives a singlet signal at the 8.2-8.4 ppm interval of the spectrum, and its area is used to determine the concentration of the acid. 1,3,5-Benzenetricarboxylic acid is added to the juice as an internal standard. Since the chemical shift of both species varies with the pH, ascorbic acid is also added to adjust it at 2.74 and to avoid the overlapping of the signals. Recoveries between 95 and 109% are obtained when the standard addition method is applied to the juices of five different cider apple varieties. The coefficient of variation obtained is 3.9% for intra-day repeatability (n = 5), and 4.6% for inter-day repeatability (n = 10). The limit of detection is 1.49 mg/l, calculated from “3S_y/x + intercept”. The described method is direct and no previous derivatization is needed.