Comparison of solidification of floating drop and homogenous liquid–liquid microextractions for the extraction of two plasticizers from the water kept in PET‐bottles

Two approaches based on solidification of floating drop microextraction (SFDME) and homogenous liquid–liquid microextraction (HLLE) were compared for the extraction and preconcentration of di‐(2‐ethylhexyl) phthalate (DEHP) and di‐(2‐ethylhexyl) adipate (DEHA) from the mineral water samples. In SFDME, a floated drop of the mixture of acetophenone/1‐undecanol (1:8) was exposed on the surface of the aqueous solution and extraction was permitted to occur. In HLLE, a homogenous ternary solvent system was used by water/methanol/chloroform and the phase separation phenomenon occurred by salt addition. Under the optimal conditions, the LODs for the two target plasticizers (DEHA and DEHP), obtained by SFDME–GC‐FID and HLLE–GC‐FID, were ranged from 0.03 to 0.01 μg/L and 0.02 to 0.01 μg/L, respectively. HLLE provided higher preconcentration factors (472.5‐ and 551.2‐fold) within the shorter extraction time as well as better RSDs (4.5–6.9%). While, in SFDME, high preconcentration factors in the range of 162–198 and good RSDs in the range of 5.2–9.6% were obtained. Both methods were applied for the analysis of two plasticizers in different water samples and two target plasticizers were found in the bottled mineral water after the expiring time and the boiling water was exposed to a polyethylene vial.     

Determination of phthalates and adipate in bottled water by headspace solid-phase microextraction and gas chromatography/mass spectrometry

The performance of three fibres for the headspace solid-phase microextraction (SPME) of di-2-ethylhexyl adipate (DEHA) and eight phthalates in water was investigated systematically under different extraction conditions. Good responses on the 65 microm polydimethylsiloxane/divinylbenzene (PDMS/DVB) SPME fibre were observed for DEHA and all phthalates. The polydimethylsiloxane (PDMS) SPME fibre had very poor responses for the lighter and slightly polar phthalates, dimethyl phthalate (DMP) and diethyl phthalate (DEP), while the divinylbenzene/carboxen/polydimethylsiloxane (DVB/CAR/PDMS) SPME fibre had very poor responses for the heavier and non-polar adipate and phthalates. The salt (NaCl) was found to increase the partitioning of DMP, DEP, diisobutyl phthalate (DiBP), di-n-butyl phthalate, and benzyl butyl phthalate (BBP) from water into the headspace, while partitioning of heavier adipate and phthalates from water into headspace was suppressed when the concentration of NaCl was above 10%. The automated headspace SPME methods were developed and validated under two different salting conditions (30% NaCl for DMP, DEP and BBP, and 10% for DEHA, DiBP, DBP, di-n-hexyl phthalate (DHP), di-2-ethylhexyl phthalate (DEHP), and di-n-octyl phthalate (DOP)). Linearity with R(2) values better than 0.9949 was observed for DEHA and eight phthalates over the range from 0.1 to 20 microg L(-1). Method detection limits ranged from 0.003 microg L(-1) for DOP to 0.085 microg L(-1) for BBP. Good repeatability was observed for DEHA and most phthalates with relative standard deviation (RSD) values less than 10%. The methods were used to analyse bottled water samples for DEHA and eight phthalates. DMP, DHP, BBP, DEHA and DOP were not detected in any samples. Concentrations of the other phthalates were low (around sub-ppb) except for DBP in the water from a polycarbonate bottle at 1.72 microg L(-1).     

Performance evaluation of new plasticizers for stretch PVC films

Six stretch PVC films have been formulated to have Shore A hardness of approx. 80 and nominal thickness of 15 μm with the aim of evaluating the performance of plasticizers from renewable and non-renewable sources for stretch PVC films intended to be employed as packaging. The reference film was produced with DEHA and ESBO, while the other films were produced with conventional plasticizers (ATBC and Polyadipate), new plasticizers from renewable sources (Mixture of glycerin acetates and Acetic acid esters of mono- and diglycerides of fatty acids) or a plasticizer employed in toy and childcare applications (DEHT) as a third plasticizer. The films were evaluated as to their physical and mechanical properties (durometer hardness, tensile strength and elongation), IR spectroscopy and light transmission. The several plasticizers influenced the mechanical properties of the PVC films to different degrees. All films will probably show adequate performance when used in packaging applications. Nevertheless, the vegetable oil-based plasticizers showed better mechanical performance than the other plasticizers when compared to DEHA.     

高效液相色谱-串联质谱法测定葡萄中的吡效隆和赤霉素

采用高效液相色谱-串联质谱法（HPLC-MS/MS）建立了葡萄果实中吡效隆（CPPU）和赤霉素（GA3）两种植物生长调节剂残留量的定性定量分析方法。样品用0.5%甲酸水溶液和乙腈（体积比4:1）混合溶剂提取,经Strata-X固相萃取净化,使用Agilent SB-C18 色谱柱（50mm×2.1mm,1.8μm）,以0.5%甲酸水溶液-乙腈为流动相,流量0.3mL/min,采用电喷雾离子化源（ESI）多反应监测（MRM）模式下HPLC-MS/MS检测。在最佳检测条件下,得到吡效隆和赤霉素在2.0～100.0μg/L检测范围内线性关系良好,相关系数大于0.999;检出限(LOD)分别为0.3μg/L、0.5μg/L,定量限(LOQ)分别为1.0μg/L、2.0μg/L,回收率和精密度均能达到要求,表明该法准确,可用于葡萄中吡效隆和赤霉素残留量测定。     

Combining stir bar sorptive extraction and MEKC for the determination of polynuclear aromatic hydrocarbons in environmental and biological matrices

In this work, stir bar sorptive extraction and liquid desorption was combined with MEKC and diode-array detection (SBSE-LD-MEKC-DAD) for the determination of polynuclear aromatic hydrocarbons (PAHs) in aqueous medium, using biphenyl, fluorene, anthracene, phenanthrene, fluoranthene and pyrene as model compounds. MEKC-DAD conditions and parameters affecting SBSE-LD efficiency are fully discussed. Assays performed on aqueous samples spiked at trace levels, yielded recoveries ranging from 55.5 +/- 6.1% (pyrene) to 70.7 +/- 7.1% (anthracene), under optimized experimental conditions. The methodology proved to be nearly described by the octanol-water partition coefficients (K(PDMS/W) approximately K(O/W)). The analytical performance showed good precision (<12.0%), suitable detection limits (2-11 microg/L) and convenient linear dynamic ranges (r(2)>0.99) from 5 to 25 microg/L for anthracene and 25 to 125 microg/L for the remaining compounds. The application of the proposed methodology to environmental water, sediments and fish bile matrices demonstrated good selectivity and accuracy. SBSE-LD combined with MEKC-DAD was shown to be an easy, reliable and robustness methodology, as well as a good analytical alternative to monitor environmental priority pollutants.     

Determination of closantel residues in milk and animal tissues by HPLC with fluorescence detection and SPE with oasis MAX cartridges

A liquid chromatographic method for the determination of closantel residues in milk and tissues is developed and validated. An acetonitrile-acetone solution (80:20, v/v) is used for the extraction of closantel residues from milk and animal tissues, and the extract is purified by solid-phase extraction with Oasis MAX cartridges and a mixture of formic acid-acetonitrile (5:95, v/v) as the elution solution. A C(18) bonded silica column is used for chromatographic separation. The mobile phase consists of acetonitrile-water (85:15, v/v) containing 0.05% triethylamine at pH 2.5, adjusted with phosphoric acid with the flow-rate set at 1.0 mL/min. Using the fluorescence emission of closantel at lambda(ex) = 335 nm and lambda(ex) = 510 nm, the calibration curve is linear, with a correlation coefficient of 0.9999 over the concentration range of 10-5000 microg/kg for the tissue sample and 10-5000 microg/L for the milk sample. The detection limit (s/n = 3) is 3 microg/kg for tissue sample and 3 microg/L for milk sample. The intra- and inter-day repeatabilities are between 3.35-7.66% and 4.04-8.67%, respectively. The proposed method enables the quantitative determination of closantel residues at levels as low as 10 microg/kg in animal tissue samples and 10 microg/L in milk samples.     

高效液相色谱-串联质谱法测定化妆品中的欧前胡素和异欧前胡素

建立了化妆品中欧前胡素和异欧前胡素的高效液相色谱-串联质谱(HPLC-MS/MS)测定与确证方法。样品经甲醇提取,以C18柱为分离柱,10 mmol/L乙酸铵/甲醇溶液-5 mmol/L乙酸铵水溶液(80:20, v/v)为流动相分离,采用电喷雾串联四极杆质谱进行检测。欧前胡素和异欧前胡素在0.25～20 μg/L内线性良好(相关系数大于0.999);方法定量限(LOQ)为0.50 mg/kg。在0.50～10.0 mg/kg内,欧前胡素和异欧前胡素的回收率范围分别为82.2%～105%和80.0%～103%,相对标准偏差分别为2.7%～4.9%和1.8%～4.6%。该方法能够满足化妆品中欧前胡素和异欧前胡素检测的需要。     

Cloud point extraction and simultaneous determination of zirconium and hafnium using ICP-OES

In the present study a simple versatile separation method using cloud point procedure for extraction of trace levels of zirconium and hafnium is proposed. The extraction of analytes from aqueous samples was performed in the presence of quinalizarine as chelating agent and Triton X-114 as a non-ionic surfactant. After phase separation, the surfactant-rich phase was diluted with 30% (v/v) propanol solution containing 1 mol l(-1) HNO3. Then, the enriched analytes in the surfactant-rich phase were determined by inductively coupled plasma-optical emission spectrometry (ICP-OES). The different variables affecting the complexation and extraction conditions were optimized. Under the optimum conditions (i.e. 3.4 x 10(-5) mol l(-1) quinalizarine, 0.1% (w/v) Triton X-114, 55 degrees C equilibrium temperature) the calibration graphs were linear in the range of 0.5-1000 mug l(-1) with detection limits (DLs) of 0.26 and 0.31 microg l(-1) for Zr and Hf, respectively. Under the presence of foreign ions no significant interference was observed. The precision (%RSD) for 8 replicate determinations at 200 microg l(-1) of Zr and Hf was better than 2.9% and the enrichment factors were obtained as 38.9 and 35.8 for Zr and Hf, respectively. Finally, the proposed method was successfully utilized for the determination of these cations in water and alloy samples.     

Multielement determination of cadmium and lead in urine by simultaneous electrothermal atomic absorption spectrometry with an end-capped graphite tube.

A method for the multielement determination of cadmium and lead in urine is proposed by simultaneous electrothermal atomic absorption spectrometry (SIMAAS) with an end-capped transversely heated graphite atomizer (EC-THGA). The best conditions for cadmium and lead determination were obtained in the presence of NH4H2PO4 as a chemical modifier, using 500 degrees C and 1800 degrees C as the pyrolysis and atomization temperatures, respectively. Urine samples were diluted 1 + 4 directly in autosampler cups with a mixture of 0.125% (w/v) Triton X-100 + 2.5% (v/v) HNO3 + 0.31% (w/v) NH4H2PO4. The optimized heating program was carried out in 57 s, and the instrument calibration was done with aqueous reference solutions. The use of EC-THGA increased the sensitivity of cadmium and lead by 14% and 25%, respectively. The detection limits (n = 20, 3delta) were 0.03 microg L(-1) (0.36 pg) for cadmium and 0.57 microg L(-1) (6.8 pg) for lead. The performance of EC-THGA was acceptable up to 500 heating cycles. The reliability of the entire procedure was checked with the analysis of a lyophilized urine certified reference material. The found concentrations were in agreement with the recommended values (95% confidence level).     

Determination of folic acid in tablets by microemulsion electrokinetic chromatography

A microemulsion electrokinetic chromatography (MEEKC) method has been developed and validated for the determination of folic acid, a water-soluble vitamin, in a commercial tablet formulation. The analysis was performed using a microemulsion containing 0.5% (w/w) ethyl acetate, 1.2% (w/w) butan-1-ol, 0.6% (w/w) sodium dodecyl sulfate, 15% (v/v) 2-propanol and 82.7% (w/w) 10 mmol L(-1) sodium tetraborate aqueous buffer at pH 9.2. Direct UV detection at 214nm led to an adequate sensitivity without interference from sample excipients. For quantitative purposes, niacin was used as internal standard. Acceptable precision (<1.2% relative standard deviation (R.S.D.)), linearity (r = 0.9992; range from 160.0 to 240.0 microg/mL), sensitivity (limit of detection (LOD) = 2.98 microg/mL; limit of quantification (LOQ) = 9.05 microg/mL) and recovery (99.8 +/- 1.8% at three concentration levels) were obtained. Based on the performance characteristics, the proposed methodology was found suitable for the determination of folic acid in tablet formulations.     

高效液相色谱法同时测定化妆品中的7种磺胺及甲硝唑和氯霉素

建立了化妆品中7种磺胺(磺胺醋酰、磺胺吡啶、磺胺甲基嘧啶、磺胺二甲嘧啶、磺胺甲氧嘧啶、磺胺间甲氧嘧啶、磺胺甲基异唑)和甲硝唑及氯霉素的高效液相色谱测定方法。样品经0.1%甲酸水溶液-乙腈(体积比为8∶2)混合液超声提取后进行液相色谱分析。方法的定量检测限为3～80 μg/g,7种磺胺在20～200 μg/mL时,甲硝唑及氯霉素在40～400 μg/mL时方法的线性关系良好(r≥0.9993)。加标回收率为83.8%～105.3%(7种磺胺的添加水平为50 μg/mL和150 μg/mL,甲硝唑及氯霉素的添加水平为100 μg/mL和300 μg/mL),其相对标准偏差均小于5%。     

Determination of aromatic amines in environmental water samples using solid-phase extraction modified with sodium dodecyl sulphate and micellar liquid chromatography

Extraction and determination of seven aromatic amines in environmental water samples were performed with solid-phase extraction (SPE) and micellar liquid chromatography (MLC) using experimental design. Extraction of aromatic amines was carried out with a C₁₈ cartridge modified with sodium dodecyl sulphate (SDS). The washing solution and elution solvent for extraction of aromatic amines were aqueous solution containing 5% (v/v) acetonitrile and 5% (v/v) acetone and 3 mL methanol, respectively. The chemometrics approach was applied for the separation optimisation of these compounds using MLC. Different mobile phase compositions were used for modelling based on retention times to obtain the best separation using central composite design. The optimum mobile phase composition for separation and determination of analytes in water samples was 69 mM SDS, 9% v/v 1-propanol and pH = 6.4. Recoveries were between 84.8–93.5% with relative standard deviation (RSD) less than 5.8% (n = 5). Limits of detection and linear range were 1–4.5 and 3.1–125.0 µg/L, respectively. The proposed method was applied to determine the aromatic amines in real samples (river and well waters). Amount of 4-nitroaniline and 3-nitroaniline in river water sample were 2.15 and 1.91 µg/L, respectively.     

Rapid determination of cyclamate in foods by solid-phase extraction and capillary electrophoresis

A method for the determination of cyclamate in food was developed using solid-phase extraction (SPE) and capillary electrophoresis (CE) with indirect ultraviolet (UV) detection. A 5-10 g sample in 0.1 mol/L hydrochloric acid was homogenized and made up to a volume of 50 mL with 0.1 mol/L hydrochloric acid. After the sample was centrifuged, 25 mL of supernatant was loaded into an Oasis HLB SPE cartridge. The cartridge was washed with 2 mL of demineralized water followed by 2 mL of 50% aqueous methanol, and cyclamate was eluted with 4.5 mL of 50% aqueous methanol. The eluate was added to a solution of sodium propionate (internal standard) for CE analysis. The cyclamate in the eluate was electrophoresed on a fused-silica capillary using 1 mmol/L hexadecyltrimethylammonium bromide and 10 mmol/L potassium sorbate as a running buffer. Detection and reference wavelengths of cyclamate determined with a UV detector were 300 and 254 nm, respectively. The calibration curves for cyclamate showed good linearity in the range of 2-1000 microg/mL and the limits of detection in beverage, fruit in syrup, jam, pickles and confectionary are sample dependent and ranged from 5-10 microg/g. The recovery of cyclamate added at a level of 200 microg/g to various kinds of foods was 93.3-108.3% and the relative standard deviation was less than 4.9% (n=3). A number of commercial samples were analyzed using the proposed method. Cyclamate was detected in one waume, two pickles, and two sunflower seeds. The quantitative values determined with CE correlated to those from high-performance liquid chromatography (HPLC) (the detected values of cyclamate in a sunflower seed measured by CE and HPLC were 3.40 g/kg and 3.51 g/kg, respectively). This analytical method for cyclamate using CE is especially suitable for use in the field.     

超高效液相色谱-电喷雾三重四极杆质谱法测定中药中马兜铃酸A和B的含量

利用超高效液相色谱-电喷雾三重四极杆质谱仪建立了中药中马兜铃酸A和B的定性定量分析方法。选取柴胡、生甘草、桔梗、龙胆泻肝丸、消胖丸、减肥茶等14种代表性样品,用甲醇-水(70:30, v/v)溶液加热回流提取,经Oasis MAX固相萃取柱富集净化后,在Eclipse RP HD C18反相柱(150 mm×2.1 mm, 1.8 μm)上进行分离;流动相为5 mmol/L乙酸铵水溶液(pH 7.5)-乙腈(75:25, v/v)。采用电喷雾离子源正离子模式(ESI+)和多反应监测模式(MRM)进行质谱分析。马兜铃酸A和B的线性范围分别为0.5～200 μg/L和1～200 μg/L,相关系数(r2)均大于0.995;检出限(LODs)分别为5 μg/kg和7.5 μg/kg;定量限(LOQs)分别为12.5 μg/kg和25 μg/kg。在100 μg/kg和500 μg/kg添加水平下,马兜铃酸A和B的回收率(n=6)范围分别为60.3%～96.4%和61.3%～94.7%,相对标准偏差均不大于10.2%。该方法灵敏度高,重复性好,操作简便,适用于中药材、饮片及中成药中马兜铃酸A和B的痕量检测。     

Multielement electrothermal atomic absorption spectrometry: A study on direct and simultaneous determination of chromium and manganese in urine

A study was carried out on the direct determination of Cr and Mn in urine using simultaneous atomic absorption spectrometry (SIMAAS). The heating program conditions, the absorbance signal profiles, the influence of different chemical modifiers, and the urine sample volume delivery into the tube were optimized to perform the calibration with aqueous solutions. Among several chemical modifiers tested, the best recovery and repeatability results were obtained for 3 microg Mg(NO3)2. On using this modifier, the pyrolysis and atomization temperatures for simultaneous determination of Cr and Mn were 1,300 degrees C and 2,500 degrees C, respectively. Urine samples were diluted (1+1) with 2.0% (v/v) HNO3 + 0.05% (w/v) Triton X-100 prepared in high purity water. A 20-microL aliquot of analytical solution and 10 microL of chemical modifier solution were delivered to the graphite tube. The characteristic masses were 7.8 pg for Cr (RSD=4.0%) and 4.6 pg for Mn (RSD=2.6%). The limits of detection were 0.08 microg L(-1) (n=20, 3s) for Cr and 0.16 microg L(-1) (n=20, 3s) for Mn. Recovery studies for 1.0 or 2.5 microg L(-1) of Cr and Mn added to different urine samples showed acceptable results for Cr (100%, RSD=14%) and Mn (88%, RSD=5.6%).     

Determination of glyoxal and methylglyoxal in environmental and biological matrices by stir bar sorptive extraction with in-situ derivatization

Stir bar sorptive extraction with in-situ derivatization using 2,3-diaminonaphthalene (DAN) followed by liquid desorption and high performance liquid chromatography with diode array detection (SBSE(DAN)in-situ-LD-HPLC-DAD) was developed for the determination of glyoxal (Gly) and methylglyoxal (MGly) in environmental and biological matrices. DAN proved very good specificity as in-situ derivatising agent for Gly and MGly in aqueous media, allowing the formation of adducts with remarkable sensitivity, selectivity and the absence of photodegradation. Assays performed on spiked (1.0 microg L(-1)) water samples, under convenient experimental conditions, yielded recoveries of 96.2+/-7.9% for Gly and 96.1+/-6.4% for MGly. The analytical performance showed good accuracy, suitable precision (<12.0%), low detection limits (15 ng L(-1) for Gly and 25 ng L(-1) for MGly adducts) and excellent linear dynamic ranges (r2>0.99) from 0.1 to 120.0 microg L(-1). By using the standard addition method, the application of the present method to tap and swimming-pool water, beer, yeast cells suspension and urine samples allowed very good performance at the trace level. The proposed methodology proved to be a feasible alternative for routine quality control analysis, showing to be easy to implement, reliable, sensitive and with a low sample volume requirement to monitor Gly and MGly in environmental and biological matrices.     

Extraction of formic and acetic acids from aqueous solution by dynamic headspace-needle trap extraction temperature and pH optimization

A combined method of dynamic headspace-needle trap sample preparation and gas chromatography for the determination of formic and acetic acids in aqueous solution was developed in this study. A needle extraction device coupled with a gas aspirating pump was intended to perform sampling and preconcentration of target compounds from aqueous sample before gas chromatographic analysis. The needle trap extraction (NTE) technique allows for the successful sampling of short chain fatty acids under dynamic conditions while keeping the headspace (HS) volume constant. Two important parameters, including extraction temperature and effect of acidification, have been optimized and evaluated using the needle trap device. The method detection limits for the compounds estimated were 87.2microg/L for acetic acid and 234.8microg/L for formic acid in spite of the low flame ionization detection response for formic acid and its low Henry's law constant in aqueous solution. Precision was determined based on the two real samples and ranged between 4.7 and 10.7%. The validated headspace-needle trap extraction method was also successfully applied to several environmental samples.     

Flow injection analysis with in-line solid phase extraction for the spectrophotometric determination of sulfonated and unsulfonated Quinoline Yellow in Cologne

An integrated solid-phase spectrophotometry/ FIA method is proposed for the determination of the synthetic colorant matter Quinoline Yellow (QYWS) in the presence of its unsulfonated derivative QYSS. The procedure is based on the retention and preconcentration of the low level QYSS on a C-18 silica gel minicolumn, followed by sequential measurement of its absorbance at lambda = 410 nm after its elution with methanol. The applicable concentration range, the detection limit and the relative standard deviation were the following: for QYWS, from 0.10 to 30.0 mg L(-1); 0.013 mg L(-1); and 0.6%; and for QYSS, between 10 and 1.000 microg L(-1); 2 microg L(-1); and 1.3%, respectively. The method was applied to the determination of small amounts of QYSS present in QYWS in Colognes. Percentages of recovery between 98% and 99% were obtained in all instances. The method was also satisfactorily applied to the determination of these compounds in samples of commercial Colognes comparing the results for QYWS with those offered by an HPLC reference method and also validating the results chemometrically.     

固相萃取-超高效液相色谱-电喷雾串联质谱法同时测定地表水中9种微囊藻毒素

建立了固相萃取-超高效液相色谱-电喷雾串联三重四极杆质谱(SPE-UPLC-ESI-MS/MS)联用技术分析水中9种微囊藻毒素的方法。样品经SPE提取和净化后,以Waters ACQUITY UPLCTM BEH C18色谱柱为分离柱,以含0.1%甲酸乙腈和含0.1%甲酸水作为流动相进行梯度洗脱,电喷雾离子源电离、正离子多反应监测模式质谱进行定性和定量分析。9种微囊藻毒素在0.1～50 μg/L或0.5～100 μg/L质量浓度范围内线性良好,相关系数为0.9990～0.9998,方法的检出限(以3倍信噪比计)为0.1～0.5 ng/L;高、中、低3个添加水平的回收率为75.8%～109%,相对标准偏差为0.49%～10.0%。结果表明,该方法灵敏、准确,检测范围广,分析速度快。应用该方法检测了杭州市两处水库水样中的微囊藻毒素,分别检出了3种和8种微囊藻毒素。     

Trace-level determination of benzidine and 3,3'-dichlorobenzidine in aqueous environmental samples by online solid-phase extraction and liquid chromatography with electrochemical detection

A simple, rapid, and reliable online methodology for the determination of benzidine and 3,3'-dichlorobenzidine (3,3'-DCB) in natural waters is proposed. The analytes are extracted and preconcentrated from aqueous samples in a small stainless steel precolumn packed with a polymeric PLRP-S phase. The precolumn is further online-analyzed by reversed-phase gradient-elution chromatography with a highly sensitive and selective coulometric detection at E = 700 mV. Recoveries greater than 90% and a relative standard deviation of approximately 5% are achieved with samples spiked at low micrograms-per-liter concentration levels. The detection limits of the method in fortified reagent water samples are 100 ng/L for benzidine and 50 ng/L for 3,3'-DCB.