离子色谱-质谱联用测定牛奶中的高氯酸盐、溴酸盐和碘离子

以离子色谱-质谱联用同时测定了不同品牌牛奶中的高氯酸盐、溴酸盐和碘离子。以高容量、强亲水性IonPac AS20(2 mm)为分析柱,EGC在线产生KOH为淋洗液,串联质谱检测。ESIMS/MS以多元反应监测(MRM)模式分别监控高氯酸盐的m/z100.8/84.9、98.8/82.9离子对,溴酸盐的m/z126.8/110.9、126.8/95.0离子对和碘离子的m/z126.8/127.0离子对,并分别对高氯酸盐、溴酸盐和碘离子以m/z98.8/82.9、126.8/110.9和126.8/127.0离子对的峰面积进行定量。该方法对高氯酸盐、溴酸盐和碘离子的检出限(S/N=3)分别为0.02、0.1和0.5μg/L,线性相关系数分别是0.999(0.05~50μg/L)、0.999(0.5~100μg/L)、0.998(1~1 000μg/L)。高氯酸盐和碘离子的样品加标回收率分别在102%~108%之间和86%~114%之间。     

液相色谱-串联质谱法测定生活饮用水中4种卤代乙酸的含量

提出了液相色谱-串联质谱法测定生活饮用水中二氯乙酸、三氯乙酸、一碘乙酸和二碘乙酸等4种卤代乙酸含量的方法。取0.5 mL过滤后的水样,与0.5 mL乙腈混合。以Torus DEA色谱柱为固定相,以体积比10∶90的含1.0 mmol·L^-1乙酸铵的2.0%(体积分数)氨水溶液-乙腈混合液为流动相进行等度洗脱。分离后的4种目标物经电喷雾离子源负离子模式扫描,采用多反应监测模式进行检测,外标法定量。结果显示：4种卤代乙酸的质量浓度在5～100μg·L^-1内与定量离子峰面积呈线性关系,检出限(3S/N)为0.3～3.0μg·L^-1;对自来水水样进行3个浓度水平的加标回收试验,回收率为70.1%～114%,测定值的相对标准偏差为(n=6)为0.90%～5.8%;方法用于10份末梢水分析,其中一碘乙酸、二碘乙酸和三氯乙酸均未检出,有8份样品检出二氯乙酸,检出量为2.0～4.4μg·L^-1。     

快速溶剂萃取-离子色谱-质谱法测定人体血液、尿液中的氟乙酸

建立了快速溶剂萃取-离子色谱-质谱法测定人体血液、尿液中氟乙酸的方法。以去离子水为萃取溶剂，使用快速溶剂萃取仪处理血液和尿液样品，取上清液依次经超滤管和0.22μm水相针式滤膜净化，稀释50倍后进样检测。采用Ion Pac AS20离子色谱柱以15.0 mmol/L的KOH溶液为淋洗液进行等度淋洗，流出液通过抑制器后进入三重四极杆质谱，在负离子、多反应监测模式下检测，外标法定量。结果表明，氟乙酸在0.5～500.0μg/L范围内线性关系良好(r>0.999),检出限和定量限分别为0.14、0.47μg/L。氟乙酸在血液和尿液中的回收率分别为93.4%～95.8%、96.2%～98.4%,日内精密度分别为0.8%～1.6%、0.2%～1.0%,日间精密度分别为2.3%～3.8%、3.9%～6.9%。进一步考察发现该方法在血液、尿液中的基质效应较弱，分别为-7.4%、-3.0%。该法无需衍生化处理，简便高效，灵敏度高，重复性好，适用于人体血液、尿液中氟乙酸的快速检测。     

气相色谱法检测月饼中的脱氢乙酸

应用硫酸锌试剂沉淀月饼样品中的蛋白,乙醚提取样品中的脱氢乙酸,建立了Rtx-5弱极性毛细管柱-气相色谱分离检测月饼中的脱氢乙酸的方法。经方法验证,方法的检出限为0.24μg/mL,定量下限为0.32μg/mL,在0.0～0.5 mg/mL浓度范围内脱氢乙酸的浓度与色谱峰面积呈良好线性关系,相关系数r2=0.999 5,加标回收率在87.9%～94.4%之间,测定结果的相对标准偏差为2.5%(n=12)。该方法样品处理简单,适合月饼中脱氢乙酸的定量分析检测。     

离子色谱法同时测定蛋白胨中氯离子、硫酸根离子、碘离子

建立离子色谱法测定蛋白胨中氯离子、硫酸根离子、碘离子3种阴离子的含量。采用氢氧化钾淋洗液发生器产生的KOH溶液为流动相,进行梯度淋洗,流量为1.0 mL/min。氯离子、硫酸根离子的质量浓度分别在0.5～200μg/mL范围内与色谱峰面积呈良好的线性关系,碘离子的质量浓度在0.75～50μg/mL范围内与色谱峰面积呈良好的线性,线性相关系数均不小于0.999,检出限分别为0.003,0.01,0.22μg/mL。样品加标回收率为92.94%～96.59%,测定结果的相对标准偏差为2.42%～5.70%(n=9)。该方法灵敏、高效,可用于蛋白胨中氯离子、硫酸根离子、碘离子的快速准确测定。     

离子色谱-电感耦合等离子体质谱同步分离测定环境水中砷、铬、溴、碘的10种形态

建立了离子色谱-电感耦合等离子体质谱(IC-ICP-MS)联用技术，用于测定环境水中亚砷酸根、砷酸根、一甲基砷(MMA)、二甲基砷(DMA)、三价铬、铬酸根、溴离子、溴酸根离子、碘离子、碘酸根离子。使用Hamilton PRP-X100阴离子交换色谱柱，在流速1.4 mL/min、5%甲醇-40 mmol/L NH₄NO₃流动相(pH=8.6)等度洗脱条件下，20 min内实现了砷、铬、溴、碘4种元素10种形态的分离检测。10种元素形态检出限在0.1～2μg/L之间，定量限在0.5～6μg/L之间，平均加标回收率在75.4%～104.7%之间，相对标准偏差(RSD,n=3)在0.91%～4.96%之间。该方法可以用于环境水样中砷、铬、溴、碘4种元素10种形态的常规分析检测。     

UHPLC-MS/MS法测定耕地周围地表水中5种除草剂含量

实验研究建立了超高压液相色谱-三重四级杆串联质谱法测定耕地周围地表水中2,4-二氯苯氧乙酸、灭草松、草铵膦、α-萘乙酸、马来酰肼除草剂含量的分析方法。随机采集耕地周围地表水样品,预处理后,取上述水样500 mL,调节酸度为中性,取HLB固相萃取柱,活化完毕后,设定程序,将上述水样以12 mL·min^-1的流量过柱,最后用16 mL甲醇洗脱,收集洗脱液;洗脱液于氮吹至近干,加甲醇1 mL定容,涡旋混匀,质谱分析采用多反应监测模式,定性、定量检测。2,4-二氯苯氧乙酸、灭草松、草铵膦、α-萘乙酸、马来酰肼质量浓度在0.004～4.0μg·mL^-1范围内呈良好的线性关系,检测限分别为0.21μg·L^-1、0.23μg·L^-1、0.14μg·L^-1、0.25μg·L^-1、0.15μg·L^-1;三水平回收率范围在85.4%～96.6%;2,4-二氯苯氧乙酸、灭草松、草铵膦、α-萘乙酸、马来酰肼重复性RSD分别为3.4%,4.0%,3.2%,2....     

离子色谱法同时测定饮用水中5种消毒剂副产物

建立了离子色谱电导检测大体积进样同时测定饮用水中5种消毒剂副产物(亚氯酸盐、溴酸盐、氯酸盐、二氯乙酸和三氯乙酸)的方法.选用大容量IonPac AS19阴离子交换分析柱,以KOH溶液梯度淋洗,流速为1.0 mL/min,可在33 min内一次进样同时分析上述5种消毒剂副产物和7种常见阴离子.亚氯酸盐、溴酸盐、氯酸盐、二氯乙酸和三氯乙酸的检出限分别为0.43、0.68、0.78、1.04和1.53μg/L(500 μL进样),线性相关系数r＞0.9995.运用该法测定了自来水中5种消毒剂副产物,并对样品加标回收,回收率在97.6%～105.6%之间.对影响分离和测定的因素,如温度、共存非测定离子、相邻离子间等进行了研究.     

离子色谱法测定水中的高氯酸盐

采用离子色谱法测定了饮用水中痕量的高氯酸盐,以30mmol／LNaOH为淋洗液,1mL／min流量,1000μL进样,在25min内可完成测定高氯酸盐;利用加热浓缩的方法对水样进行前处理,浓缩10倍后进样。结果表明,该法回收率为87．9％,检测限为0．10μg/L,具有实际应用价值。     

抑制型电导检测法测定饮用水中的碘离子

采用ASRS - ULTRAⅡ4mm阴离子抑制器,将待测水样在IonPac AS 16型阴离子柱上,以55 mmol/LKOH淋洗液等度洗脱,流速为1.0 mL/min,用ICS - 3000型离子色谱仪通过电导检测水样中痕量碘离子含量.碘离子分离效果较好,其浓度在0～40 μg/L范围内与色谱峰面积具有良好的线性,相...     

Determination of ascorbic acid, dehydroascorbic acid, and isoascorbic acid in blood

Summary High-performance liquid chromatography with UV-detection at 254 nm was used for determining ascorbic acid, dehydroascorbic acid, and isoascorbic acid in plasma and erythrocytes obtained from healthy volunteers and from patients with coronary infarct, acute lymphatic leukemia (ALL), and acute myeloic leukemia (AML). Deproteinisation was done by a simple ultrafiltration technique. Dehydroascorbic acid (DHA) was determined after reduction to ascorbic acid with dithiothreitol. The separation system chosen allows the search for the stereoisomer isoascorbic acid. To exclude interfering substances which could coelute with ascorbic or isoascorbic acid, several other compounds present in plasma were investigated including e.g. the aromatic amino acids, glutathione, cysteine, and uric acid. The results reveal a drastic decrease in total vitamin C concentration in plasma and erythrocytes with a concomitant increase in rel. DHA concentration in patients with AML. In ALL patients, both the total vitamin C and rel. DHA concentrations were increased.

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Bestimmung von Ascorbinsäure, Dehydroascorbinsäure und Isoascorbinsäure in Blut

Zusammenfassung High-performance-liquid-Chromatographie mit UV-Nachweis bei 254 nm wurde zur Bestimmung von Ascorbinsäure, Dehydroascorbinsäure und Isoascorbinsäure in Plasma und Erythrocyten von gesunden Probanden und von Patienten mit Herzinfarkt, akuter lymphatischer Leukämie (ALL) und akuter myeloischer Leukämie (AML) benutzt. Deproteinisierung erfolgte mittels einer einfachen Ultrafiltrationstechnik. Dehydroascorbinsäure wurde nach Reduktion mit Dithiothreitol als Ascorbinsäure bestimmt. Die benutzte Methode erlaubt auch die Bestimmung des Stereoisomers Isoascorbinsäure. Der mögliche Einfluß von im Plasma vorkommenden Substanzen auf die Bestimmung des Vitamin C wurde untersucht. Die Ergebnisse zeigen eine drastische Abnahme der Gesamt-Vitamin C-Konzentration in Plasma und Erythrocyten mit einer parallelen Zunahme der relativen DHA-Konzentration in AML-Patienten. In ALL-Patienten sind sowohl die Gesamt-Vitamin C- als auch die relative DHA-Konzentrationen erhöht.

     

Raman spectra of glycolic acid,l-lactic acid and d,l-lactic acid oligomers

Polymerization of glycolic acid, l- and d,l-lactic acid was followed by Raman spectroscopy in aqueous solution at different concentrations, in viscous and solid states. The Raman spectra of some oligomers obtained by progressive polycondensation of α-hydroxycarboxylic acid aqueous solutions were investigated in the 200–18 cm⁻¹ region. Vibrational analysis revealed the characteristic peaks of ester groups that appeared in the repeat unit of the polymeric chain during the polymerization reaction, and those of the monomers which disappeared. In particular, the ν(CC) stretching vibrations occur in the 800–1000 cm⁻¹ range, which is easily accessible because of the weak diffusion of water. Moreover, spectral monitoring of the semicrystalline sample of poly(glycolic acid) oligomers showed Raman peaks associated with the vibrations of the polymer in the amorphous and semicrystalline states.     

Simultaneous and direct determination of oxalic acid, tartaric acid, malic acid, vitamin C, citric acid, and succinic acid in Fructus mume by reversed-phase high-performance liquid chromatography

A method for the simultaneous separation and direct determination of oxalic acid (OA), tartaric acid (TA), malic acid (MA), vitamin C (VC), citric acid (CA), and succinic acid (SA) in Fructus mume using reversed-phase high-performance liquid chromatography with a UV detector in an acidic medium is presented in this study. In the experiment, the optimization of chromatographic conditions (i.e., the pH and flow rate of the mobile phase, the absorption wavelength, and temperature of column) that affect the separation degree and peak shape of organic acids has been obtained. The linear ranges are found to be 0.05-4.7 microg for OA (r = 0.9999), 0.11-10.5 microg for TA (r = 0.9999), 0.114-11.4 microg for MA (r = 0.9999), 0.033-3.30 microg for VC (r = 0.9999), 0.155-15.5 microg for CA (r = 0.9998), and 0.194-19.4 microg for SA (r = 0.9996). For OA, TA, MA, VC, CA, and SA, the even recovery (n = 3) of six effective components are 100.9%, 99.97%, 101.2%, 102.1%, 101.1%, and 100.7%, respectively, and the largest relative standard deviation (n = 11) for the six components is less than 1.7%. The detection limits are 0.01 microg for OA, TA, and VC; 0.05 microg for MA; 0.03 microg for CA; and 0.1 microg for SA. In a single chromatographic run, OA, TA, MA, VC, CA, and SA can be determined in less than 7 min. The method can be used for the purpose of routine analysis and the quality control of a botanic (Fructus mume) containing these effective components.     

Fragmentation of the deprotonated ions of peptides containing cysteine, cysteine sulfinic acid, cysteine sulfonic acid, aspartic acid, and glutamic acid

We examined the fragmentation of the electrospray-produced [M-H]- and [M-2H]2- ions of a number of peptides containing two acidic amino acid residues, one being aspartic acid (Asp) or glutamic acid (Glu), and the other being cysteine sulfinic acid [C(SO2H)] or cysteine sulfonic acid [C(SO3H)], on an ion-trap mass spectrometer. We observed facile neutral losses of H2S and H2SO2 from the side chains of cysteine and C(SO2H), respectively, whereas the corresponding elimination of H2SO3 from the side chain of C(SO3H) was undetectable for most peptides that we investigated. In addition, the collisional activation of the [M-H]- ions of the C(SO2H)-containing peptides resulted in the cleavage of the amide bond on the C-terminal side of the C(SO2H) residue. Moreover, collisional activation of the [M-2H]2- ions of the above Asp-containing peptides led to the cleavage of the backbone N-Calpha bond of the Asp residue to give cn and/or its complementary [zn-H2O] ions. Similar cleavage also occurred for the singly deprotonated ions of the otherwise identical peptides with a C-terminal amide functionality, but not for the [M-H]- ions of same peptides with a free C-terminal carboxylic acid. Furthermore, ab initio calculation results for model cleavage reactions are consistent with the selective cleavage of the backbone N-Calpha bond in the Asp residue.     

Density,viscosity, and surface tension of binary liquid systems: Ethanoic acid,propanoic acid,and butanoic acid with nitrobenzene

Density, viscosity, and surface tension of three binary liquid systems: ethanoic acid+nitrobenzene, propanoic acid+nitrobenzene, and butanoic acid+nitrobenzene have been determined at 25, 35, and 45°C, over the whole composition range. The excess molar volumes, viscosities, Gibbs energies for the activation of flow, and surface tension were evaluated and fitted to a Redlich-Kister type of equation. The Grunberg-Nissan parameter d was also calculated. Binary viscosity data were fitted to the models of McAllister, Heric, Krishnan, and Laddha, Auslander, and Teja and Rice. Surface tension data were fitted to the models of Zihao and Jufu, Rice, and Teja, and an empirical two-constant model.     

Surface treatment of LLDPE and LDPE blends by nitric acid,sulfuric acid,and chromic acid etching

Surface treatment of linear low density polyethylene and low density polyethylene blends is investigated herein using nitric acid, sulfuric acid, and chromic acid. These chemical treatments not only make the surface rough but also introduce polar groups. A new method, “sulfonic groups index” (SI) is employed to quantify the newly generated polar groups in the wavenumber of 1,250–840 cm⁻¹ in the Fourier transform infrared spectra. The SI values effectively indicate that the most polar groups are incorporated into the chromic acid-etched samples among the three inorganic acids, which is also confirmed by scanning electron microscopy and roughness tests. Besides, annealing treatment can enhance the crystallinity X _c of all etched samples which plays a predominant role in the increase of roughness within 2 h. As etching time increases, chain scission and destruction of amorphous parts happen and roughness increases a lot for chromic acid-treated samples, but for sulfuric acid- and nitric acid-treated samples, the destruction of amorphous parts may not happen so that the roughness has not many changes.     

Solubilities of l-glutamic acid, 3-nitrobenzoic acid,p-toluic acid,calcium-l-lactate,calcium gluconate,magnesium-dl-aspartate,and magnesium-l-lactate in water

Solubilities of l -glutamic acid, 3-nitrobenzoic acid, p -toluic acid, calcium-l -lactate, calcium gluconate, magnesium- dl -aspartate, and magnesium- l -lactate in water were determined in the temperature range 278 K to 343 K. The apparent molar enthalpies of solution at T =  298.15 K as derived from these solubilities areΔ_solH_m (l -glutamic acid,m_sat =  0.0565 mol · kg ^− 1)  =  30.2 kJ · mol ^− 1,Δ_solH_m (3-nitrobenzoic acid, m =  0.0188 mol · kg ^− 1)  =  28.1 kJ · mol ^− 1, Δ_solH_m( p - toluic acid, m =  0.00267 mol · kg ^− 1)  =  23.9 kJ · mol ^− 1,Δ_solH_m (calcium- l -lactate tetrahydrate,m =  0.2902 mol · kg ^− 1)  =  25.8 kJ · mol ^− 1,Δ_solH_m (calcium gluconate, m =  0.0806 mol · kg ^− 1)  =  22.1 kJ · mol ^− 1, Δ_solH_m(magnesium-dl -aspartate tetrahydrate, m =  0.1469 mol · kg ^− 1)  =  11.5 kJ · mol ^− 1, andΔ_solH_m (magnesium- l -lactate trihydrate,m =  0.3462 mol · kg ^− 1)  =  3.81 kJ · mol ^− 1.     

Simultaneous determination of chlorogenic acid, caffeic acid, ferulic acid, protocatechuic acid and protocatechuic aldehyde in Chinese herbal preparation by RP-HPLC

In the present study, a reversed phase high performance liquid chromatographic (RP-HPLC) method was established for simultaneous determination of chlorogenic acid, caffeic acid, ferulic acid, protocatechuic acid and protocatechuic aldehyde in a Chinese herbal preparation (Fufang-Pugongying-Mixture). The separation was performed on a Hypersil ODS-2 column by isocratic elution with methanol and 0.2 M acetate buffer (pH 3.6) (15 : 85, v/v) as the mobile phase at the flow-rate of 1.0 ml/min with operating temperature of 30 degrees C, and detection wavelength of 300 nm. A good linear regression relationship between peak-areas and concentrations was obtained over the range of 2-200 microg/ml for the five marker compounds mentioned above. The spike recoveries were within 96.72-104.07%. The variation coefficient (CV) values of the precision were in the range of 0.89-4.50%. Moreover the developed method has reference value for quantitative analysis of Taraxacum, Lonicera and Angelica.