Fine positioning of a poloidal probe array

Multipoint detection is an essential requirement for investigating plasma turbulence which is a highly nonlinear phenomenon in space and time. We have fabricated an array of 64-channel poloidal probes surrounding the linear cylindrical plasma named LMD-U in order to study turbulence properties, particularly the nonlinear mode couplings, in the domain of poloidal wave number and frequency. However, misalignments of probe tips produce spurious modes, which do not exist in the real plasma, to distort the precise wave number measurements. The paper presents the description of the 64-channel poloidal probe array with means to adjust the probe positions, with discussion on the effects of the misalignments on the wave number measurements.

Effects of delta-opioid receptor stimulation and inhibition on hippocampal survival in a rat model of forebrain ischaemia

BACKGROUND

It has been reported that delta-opioid (DOP) receptor agonists may be neuroprotective in the central nervous system. However, the DOP agonist [d-Ala(2), d-Leu(5)]enkephalin (DADLE) does not produce neuroprotection in severe forebrain ischaemia. The aim of this study was to examine the effects of DADLE on hippocampal neurone survival against less severe forebrain ischaemia.

METHODS

Intraperitoneal injection of DADLE (0 or 16 mg kg(-1)) in male Sprague-Dawley rats was performed 30 min before ischaemia. Severe (10 min), moderate (8 min), or mild (6 min) forebrain ischaemia was produced by bilateral carotid occlusion combined with hypotension (35 mm Hg) under isoflurane (1.5%) anaesthesia. Naltrindole (10 mg kg(-1)) (DOP antagonist) was administered 30 min before DADLE in order to confirm DOP receptor activation in the neuroprotective efficacy of DADLE. Naltrindole alone was also administered 30 min before ischaemia to examine endogenous DOP agonism as a self-protecting mechanism against ischaemia. All animals were evaluated neurologically and histologically after a 1 week recovery period.

RESULTS

DADLE improved neurone survival in hippocampal CA3 and dentate gyrus (DG) sectors. CA1 neurones were not protected against moderate and mild ischaemia. Naltrindole abolished DADLE neuroprotection in the CA3 and DG after both moderate and mild ischaemia. Interestingly, regardless of co-administration of DADLE, naltrindole significantly worsened neuronal injury in the CA1 region after mild ischaemia.

CONCLUSIONS

These results suggest that DADLE provides limited neuroprotection to relatively ischaemia-resistant regions but not to selectively vulnerable regions. This was probably mediated by DOP stimulation. Pre-ischaemic treatment with a DOP antagonist, regardless of co-administration of DADLE, worsened neuronal damage at the selectively vulnerable regions only after mild forebrain ischaemia. These data suggest that DOP activation with endogenous DOP ligand may be involved in self-protecting ischaemia-sensitive regions of the brain.

Synthetic double-stranded RNA induces multiple genes related to inflammation through Toll-like receptor 3 depending on NF-kappaB and/or IRF-3 in airway epithelial cells

BACKGROUND

We hypothesized that synthetic double-stranded (ds)RNA may mimic viral infection and induce expression of genes related to inflammation in airway epithelial cells.

OBJECTIVE

We analysed what gene was up-regulated by synthetic dsRNA poly I : C and then focused this study on the role of Toll-like receptor 3 (TLR3), a receptor of dsRNA and its transcriptional pathway.

METHODS

Airway epithelial cell BEAS-2B and normal human bronchial epithelial cells were cultured in vitro. Expression of targets RNA and protein were analysed by PCR and ELISA. Localization of TLR3 expression in the cells was analysed with flow cytometry. To analyse the role of TLR3 and transcription factors, knockdown of these genes was performed with short interfering RNA (siRNA).

RESULTS

Real-time PCR revealed that poly I : C significantly increased the expression of mRNAs for chemokines IP-10, RANTES, LARC, MIP-1alpha, IL-8, GRO-alpha and ENA-78 and cytokines IL-1beta, GM-CSF, IL-6 and the cell adhesion molecule ICAM-1 in both cell types. Increases in protein levels were also observed. Expression of these genes was significantly inhibited in BEAS-2B cells in which TLR3 expression was knocked down. However, pre-treatment with anti-TLR3 mAb, which interferes with the function of TLR3 expressed on the cell surface, did not inhibit the genes expression and these data were concordant with the results that TLR3 was expressed inside airway epithelial cells. The study of siRNA for NF-kappaB and IRF3 showed that they transduce the signal of poly I : C, but their roles were different in each target gene.

CONCLUSION

TLR3 is expressed inside airway epithelial cells and transduces synthetic dsRNA signals. These signals may increase expression of inflammatory cytokines, chemokines and ICAM-1 through activation of transcription factors NF-kappaB and/or IRF3 in airway epithelial cells.

Role of interleukin-17F in chronic inflammatory and allergic lung disease

IL-17 family members belong to a distinct category of cytokines that coordinate local tissue inflammation by inducing the release of pro-inflammatory and neutrophil-mobilizing cytokines. The importance of the IL-17 family in inflammatory and autoimmune disease is becoming increasingly apparent. IL-17F is a recently discovered member of the IL-17 family that has a number of biological activities through induction of various cytokines, chemokines, and mediators. IL-17A, the founding member of the IL-17 family, and IL-17F are produced by several inflammatory cells, including activated T cells, in response to infectious and antigenic stimuli. Overexpression of IL-17A or IL-17F in the lungs results in induction of CXC chemokines and neutrophil recruitment. In a case-control study of 1125 unrelated Japanese subjects, a His161 to Arg161 (H161R) substitution in the third exon of the IL17F gene was shown to be associated with asthma and chronic obstructive pulmonary disease (COPD). Functionally, this variant failed to induce cytokines and chemokines, and interestingly, was able to antagonize the activity of wild-type IL-17F. These results provide an experimental basis for the observed genetic association with chronic inflammatory lung diseases, and also suggest the potential therapeutic utility of this antagonistic variant of IL-17F. Given that asthma and COPD are complex diseases involving a number of genetic and environmental factors, the genetic impact of IL-17F H161R with regard to the development of chronic airway inflammation likely varies among individuals with different genetic backgrounds and environmental exposures.

Stir-bar-sorptive extraction, with in-situ deconjugation, and thermal desorption with in-tube silylation, followed by gas chromatography-mass spectrometry for measurement of urinary 4-nonylphenol and 4-tert-octylphenol glucuronides

A novel method, stir-bar-sorptive extraction (SBSE), with in-situ deconjugation and thermal desorption (TD) with in-tube silylation, followed by gas chromatography-mass spectrometry (GC-MS), for determination of trace amounts of 4-nonylphenol glucuronide (NP-G) and 4-tert-octylphenol glucuronide (OP-G) in human urine, is described. The method involved correction by use of stable isotopically labeled internal standards 4-(1-methyl)octylphenol-d5 (NP-d) and deuterium 4-tert-octylphenol (OP-d). A human urine sample to which beta-glucuronidase had been added was extracted for 90 min at 37 degrees C using a stir bar coated with a 500-microm-thick layer of polydimethylsiloxane (PDMS). NP-G and OP-G were deconjugated, becoming free 4-nonylphenol (NP) and 4-tert-octylphenol (OP). The analytes were then extracted with the PDMS stir bar and the stir bar was subjected to TD with in-tube silylation; this was followed by GC-MS in selected-ion-monitoring (SIM) mode. To optimize the conditions for SBSE with in-situ deconjugation and to test recovery, NP-G and OP-G were synthesized by a biochemical technique in our laboratory. Average recoveries from human urine samples spiked with NP-G and OP-G were between 91.9 and 95.6% with correction using the added surrogate standards. Limits of detection were 0.11 ng mL-1 for NP and 0.01 ng mL-1 for OP. We also measured background levels of NP-G and OP-G in six urine samples from healthy volunteers. NP and OP were detected in the samples at concentrations of 0.62-1.95 ng mL-1 and <0.04-0.18 ng mL-1, respectively.

Significance of p27 as a predicting marker for medroxyprogesterone acetate therapy against endometrial endometrioid adenocarcinoma

We reported that p27 induced by medroxyprogesterone acetate (MPA) may be involved in the progestin-induced growth suppression of human endometrial adenocarcinoma cells. This study aimed at investigating whether p27 expression could be a predicting marker to evaluate the effectiveness of MPA therapy. The clinical responses of 15 patients with endometrial carcinoma treated with MPA were examined. p27 expression was evaluated by immunohistochemical staining. Percentage of positive nuclear staining was expressed as a strongly positive (SP) labeling index (LI). Before MPA treatment, SP LIs in the effective and noneffective groups were 22.6 +/- 14.3% and 9.1 +/- 9.2%. At 1-6 weeks in the MPA treatment, SP LIs increased in both groups and were significantly higher than those before the therapy. At 7-12 weeks, SP LIs in both groups decreased to the level of pretherapy. At 13-18 weeks, SP LIs in the effective group were 14.9 +/- 5.7%, whereas in the noneffective group, 1.1 +/- 2.0%. The former was significantly higher than the latter. p27 expression could predict the effectiveness of MPA treatment for endometrial carcinoma at an early stage of the 4-month period in MPA therapy and could be a useful predicting marker for MPA.

Effect of sterilization process on the formation of mono(2-ethylhexyl)phthalate from di(2-ethylhexyl)phthalate

The risk assessment of di(2-ethylhexyl)phthalate (DEHP) migrating from polyvinyl chloride (PVC) medical devices is an important issue. Many studies have been conducted to determine the level of DEHP migration. A recent report has indicated that DEHP in blood bags is hydrolyzed by esterase into mono(2-ethylhexyl)phthalate (MEHP). However, MEHP is thought to be even more toxic than the parent compound. Therefore, a method for the simultaneous determination of DEHP and MEHP was developed. The limits of quantification (LOQs) of DEHP and MEHP were 2.5 and 0.75 ng/ml, respectively. In this study, the effect of sterilization process on the levels of DEHP and MEHP migration was investigated. The level of migration of DEHP from gamma(gamma)-ray sterilized PVC sheet was low compared with that of the unsterilized control. By contrast, the level of MEHP migration from the gamma-ray sterilized PVC sheet was high compared with that of the unsterilized control. In addition, a high content of MEHP was found in the gamma-ray sterilized PVC sheet.

Liquid phase microextraction with in situ derivatization for measurement of bisphenol A in river water sample by gas chromatography-mass spectrometry

A new method that involves liquid phase microextraction (LPME) with in situ derivatization and gas chromatography-mass spectrometry (GC-MS) is described for the determination of trace amounts of bisphenol A (BPA) in river water samples. The LPME conditions, such as the type of extraction solvent and the extraction time, are investigated. Then, the extract is directly injected into GC-MS. The detection limit and the quantification limit of BPA in river water sample are 2 and 10pgml(-1) (ppt), respectively. The calibration curve for BPA is linear with a correlation coefficient of >0.999 in the range of 10-10,000pgml(-1). The average recoveries of BPA in river water samples spiked with 100 and 1000pgml(-1) BPA are 104.1 (RSD: 8.9%) and 98.3 (RSD: 3.2%), respectively, with correction using the added surrogate standard, bisphenol A-(13)C(12). This simple, accurate, sensitive and selective analytical method may be applicable to the determination of trace amounts of BPA in liquid samples.

Dual derivatization–stir bar sorptive extraction–thermal desorption–gas chromatography–mass spectrometry for determination of 17β-estradiol in water sample

A novel method for the trace analysis of 17beta-estradiol (E2) in river water sample was developed, which involved stir bar sorptive extraction (SBSE) with in situ acylation (first derivatization) and thermal desorption (TD) with quartz wool assisted (QWA) in tube silylation (second derivatization), followed by gas chromatography-mass spectrometry (GC-MS), and is called the "dual derivatization method." The optimum conditions for SBSE with in situ acylation, such as the volume of acetic acid anhydride and the extraction time, were investigated. In addition, the optimum conditions for TD with QWA in tube silylation, such as the volume of N,O-bis(trimethylsilyl)trifluoroacetamide (BSTFA) and the TD temperature and hold time, were investigated as well. The detection limit (S/N = 3) and the quantitation limit (S/N>10) of E2 in the river water sample were 0.5 and 2 pg ml(-1) (ppt), respectively, by the dual derivatization method. In addition, the detection limit was 0.1 pg ml(-1) by using dual derivatization method with multi-shot mode. The calibration curve for E2 was linear in the range of 0.002-10 ng ml(-1) with correlation coefficients >0.999. The average recoveries of E2 (n = 6) at the concentrations of 0.05 and 1.0 ng ml(-1) from the river water sample were 93.1 (RSD: 1.4%) and 98.4% (RSD: 0.8%), respectively, with correction using the added surrogate standard, 17beta-estradiol-(13)C(4). This simple, accurate, sensitive and selective analytical method may be applicable to the determination of trace amounts of E2 in water samples.

Clear cell adenocarcinoma of the endometrium is a biologically distinct entity from endometrioid adenocarcinoma

Clear cell adenocarcinoma (CCA) of the endometrium has a poor prognosis, although the biologic features of this rare tumor are not clear. In this study, we analyzed the expression of biologic markers relating to carcinogenesis, tumor growth, and progression. Thirteen cases of CCA were compared with cases of endometrioid adenocarcinoma (EMA) of the endometrium. Immunohistochemical staining for p53; Ki-67; cyclins A, D1, and E; E-cadherin; progesterone receptor (PR)-A and PR-B; P-glycoprotein; MLH1; and MSH2 was performed. Labeling indices of p53, Ki-67, and cyclins A, D1, and E in CCA were 46.4 +/- 24.3%, 52.1 +/- 20.5%, 37.9 +/- 21.4%, 12.3 +/- 27.9%, and 8.2 +/- 22.9%, respectively. E-cadherin was expressed in only 1 case (7.7%) of CCA, as compared to 39 cases (61.0%) of EMA. No CCAs were positive for PR-A and PR-B. P-glycoprotein was detected in seven cases (53.8%). Loss of either MLH1 or MSH2 expression occurred in eight cases (61.5%). High-level expression of p53, cyclin A, and P-glycoprotein, and low-level or no expression of cyclin E, E-cadherin, PR-A, and PR-B was observed in CCA compared with EMA. The mechanism of cell-cycle regulation in endometrial CCA is different from that in EMA and may influence its malignant potential. Endometrial CCA is a distinct entity from EMA.

Significance of p27 as a predicting marker for medroxyprogesterone acetate therapy against endometrial endometrioid adenocarcinoma

Watanabe J, Watanabe K, Jobo T, Kamata Y, Kawaguchi M, Imai M, Okayasu I, Kuramoto H. Significance of p27 as a predicting marker for medroxyprogesterone acetate therapy against endometrial endometrioid adenocarcinoma. Int J Gynecol Cancer 2006;16(Suppl. 1): 452–457.

We reported that p27 induced by medroxyprogesterone acetate (MPA) may be involved in the progestin-induced growth suppression of human endometrial adenocarcinoma cells. This study aimed at investigating whether p27 expression could be a predicting marker to evaluate the effectiveness of MPA therapy. The clinical responses of 15 patients with endometrial carcinoma treated with MPA were examined. p27 expression was evaluated by immunohistochemical staining. Percentage of positive nuclear staining was expressed as a strongly positive (SP) labeling index (LI). Before MPA treatment, SP LIs in the effective and noneffective groups were 22.6 ± 14.3% and 9.1 ± 9.2%. At 1–6 weeks in the MPA treatment, SP LIs increased in both groups and were significantly higher than those before the therapy. At 7–12 weeks, SP LIs in both groups decreased to the level of pretherapy. At 13–18 weeks, SP LIs in the effective group were 14.9 ± 5.7%, whereas in the noneffective group, 1.1 ± 2.0%. The former was significantly higher than the latter. p27 expression could predict the effectiveness of MPA treatment for endometrial carcinoma at an early stage of the 4-month period in MPA therapy and could be a useful predicting marker for MPA.

Medroxyprogesterone acetate stimulates cdk inhibitors, p21 and p27, in endometrial carcinoma cells transfected with progesterone receptor-B cDNA

PURPOSE OF INVESTIGATION

Progestin is reported to suppress the growth of endometrial carcinomas, although its precise mechanism of action is not clear. This study aimed to transfect progesterone receptor-B (PRB) cDNA into endometrial carcinoma cells and investigate the effect of medroxyprogesterone acetate (MPA) on cell growth, and p21 and p27 expression in the transfectant.

METHODS

Immunoblotting for p21 and p27 was performed at predetermined times after the administration of MPA.

RESULTS

PR expression was maximally induced in Ishikawa cells at 24 hrs after the transfection. At 1 x 10(-6) M, MPA suppressed the growth of the transfectant by 34% on day 6 and stimulated p21 accumulation at 48 to 72 hrs and p27 accumulation at 48 to 96 hrs after its administration. PRB cDNA was effectively transfected and in the transfectant MPA at 1 x 10(-6) M, the dosage suppressing growth, induced p21 and p27expression.

CONCLUSION

p21 and p27 may be related to progesterone-induced growth suppression in human endometrial adenocarcinoma.

Evaluation and analysis of exposure levels of di(2-ethylhexyl) phthalate from blood bags

BACKGROUND

The US FDA and The Ministry of Health, Labor and Welfare of Japan have indicated that the risk assessment of di(2-ethylhexyl) phthalate (DEHP) released from polyvinyl chloride (PVC) medical devices requires immediate attention. In particular, the analysis of the exposure to DEHP from blood bags is very important for medical treatment. However, human exposure to DEHP via blood transfusion remains poorly understood. We evaluated DEHP and mono(2-ethylhexyl) phthalate (MEHP) levels, migration patterns, and metabolism in blood products for the detailed assessment of exposure to DEHP.

METHODS

A method that is based on column-switching liquid chromatography-electrospray mass spectrometry (LC-MS) coupled with on-line extraction was used for the direct analysis of DEHP and MEHP in the blood products. From the Japanese Red Cross Society, 78 blood products (red blood cell concentrate: n=18, irradiated red blood cell concentrate: n=18, whole blood: n=18, blood platelet: n=18, and frozen plasma: n=6) were sampled in January 2003 for use in this study.

RESULTS

The detection levels of DEHP and MEHP ranged from 1.8 to 83.2 microg/ml and from 0.1 to 9.7 microg/ml, respectively. The levels of MEHP and DEHP in the blood products were increased with increasing storage time. In addition, whole blood products in PVC bags had the highest DEHP levels compared to the other blood products. Our results indicate that the maximum level of human exposure to DEHP released from blood bags is 0.7 mg/kg weight/time.

CONCLUSION

This first quantitative evidence may be useful for the risk assessment of DEHP released from blood bags.

Systematic analysis and overall toxicity evaluation of dioxins and hexachlorobenzene in human milk

A systematic method for analyzing dioxins (PCDDs, PCDFs and dioxin-like PCBs), hexachlorobenzene (HCB), heptachlor epoxide and beta-hexachlorocyclohexane (HCH) in human milk was developed to determine the residual amount of HCB in human milk and to evaluate the overall toxicity of both dioxins and HCB in human milk. The fractionation behavior of HCB on chromatography with silica gel, alumina, and activated carbon/silica gel, and the concentrated sulfuric acid decomposition method, which is widely used as a dioxin cleanup method, were studied in order to make the preprocessing operation for HCB measurement compatible with that for conventional dioxin measurement. HCB was found to be eluted in the 2% dichloromethane (DCM)/hexane 60 ml fraction from an alumina column. Heptachlor epoxide and a part of beta-HCH were eluted in the 10% DCM/hexane 50 ml fraction from a silica gel column, while the remaining beta-HCH was eluted in the 25% DCM/hexane 60 ml fraction from an activated carbon/silica gel column. Moreover, HCB showed significant correlation with dioxin congeners having high toxicity equivalence factors (TEFs). The results suggest that the exposure route to HCB and its accumulation behavior in the human body are similar to those of the dioxins.

Novel stir bar sorptive extraction methods for environmental and biomedical analysis

Stir bar sorptive extraction (SBSE) is sample preparation technique that involves the extraction and enrichment of organic compounds from a liquid sample. The technique is based on the principle of sorptive extraction. A large amount of extraction phase is coated on a stir bar. An analyte is extracted into the extraction phase, based on its octanol-water partitioning coefficient and the phase ratio. Recently, various methods involving SBSE were developed in order to further facilitate analysis and improve sensitivity. In this review, we focused on the novel methods that involve SBSE with in situ derivatization, SBSE with in situ de-conjugation, thermal desorption (TD) in the multi-shot mode and TD with in tube derivatization method. Those methods were applied successfully to the trace analysis of environmental and biological samples and extremely low detection limits were achieved.

High-throughput determination of mono- and di(2-ethylhexyl)phthalate migration from PVC tubing to drugs using liquid chromatography-tandem mass spectrometry

The risk assessment of di(2-ethylhexyl) phthalate (DEHP) that migrated from polyvinyl chloride (PVC) medical devices is an important issue for hospitalized patients. Many studies have been conducted to determine the level of DEHP migration. A recent report has indicated that DEHP in blood bags was hydrolyzed by esterase to mono(2-ethylhexyl) phthalate (MEHP). Therefore, a method for the simultaneous determination of DEHP and MEHP was developed. The migration of DEHP and MEHP from PVC tubing to drugs was examined. Although we detected MEHP in the drugs, we found no enzymatic activity involved in the migration process. Some reports have indicated that hydrolysis may have occurred during sterilization by autoclaving. However, we did not perform any heat treatment. It is speculated that the MEHP migrated directly from the PVC tubing. The simultaneous determination of DEHP and MEHP is required for risk assessment, as MEHP may be even more toxic than the parent compound.

Overexpression of tumour necrosis factor-alpha-converting enzyme in psoriasis

BACKGROUND

Tumour necrosis factor (TNF)-alpha-converting enzyme (TACE) is a metalloproteinase-disintegrin that releases soluble TNF-alpha from cells by cleaving within the extracellular domain of membrane-bound pro-TNF-alpha. It was proposed that TNF-alpha is involved in the pathogenesis of psoriasis, and it is therefore suggested that TACE has important roles in psoriasis. However, it is unclear whether TACE is expressed in psoriatic tissue.

OBJECTIVES

To clarify whether TACE is expressed in psoriatic lesions and whether expression levels of TACE mRNA are increased in lesional compared with nonlesional psoriatic skin.

METHODS

Skin biopsies were obtained from patients with psoriasis. We examined the expression of TACE in psoriatic tissues using a novel real-time quantitative reverse transcriptase-polymerase chain reaction method and immunohistochemical analysis.

RESULTS

There was a significant rise in the level of TACE mRNA expression in lesional psoriatic skin compared with nonlesional skin in all patients. There was a statistically significant rise in the level of TACE mRNA expression in lesional psoriatic skin compared with nonlesional skin (mean +/- SD TACE/glyceraldehyde-3-phosphate dehydrogenase ratio 0.031 +/- 0.012 vs. 0.009 +/- 0.002, P < 0.05). In lesional psoriatic skin, immunostaining with anti-TACE antibody was present throughout all layers of the epidermis. TACE immunostaining was found in the cytoplasm of keratinocytes. There was staining associated with blood vessels in the papillary dermis and perivascular inflammatory cells. In particular, mast cells showed strong staining. They contained numerous granules that were stained for TACE in the cytoplasm.

CONCLUSIONS

The findings of the present study suggest that elevation of TACE mRNA in psoriatic lesions is due to many cells, particularly mast cells, that function in lesional psoriatic skin as an important source of TNF-alpha and other cytokines.

Stir bar sorptive extraction with in situ de-conjugation and thermal desorption gas chromatography-mass spectrometry for measurement of 4-nonylphenol glucuronide in human urine sample

4-Nonylphenol glucuronide (NP-G) in human urine samples was analyzed using stir bar sorptive extraction (SBSE) with in situ de-conjugation by beta-glucuronidase and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS). Distilled water (1 ml), 1.0 M ammonium acetate solution (100 microl) and beta-glucuronidase (10,000 units ml(-1), 10 microl) were added to human urine sample (1 ml), and extraction was commenced for 90 min at 37 degrees C while stirring at 250 rpm with a stir bar coated with a 500-microm-thick polydimethylsiloxane (PDMS) layer. Then, the stir bar was subjected to TD-GC-MS in the selected ion monitoring (SIM) mode. The calibration curve was made by SBSE method using 4-nonylphenol (NP) as the standard solution. The method showed good linearity and the correlation coefficients were 0.999 over the concentration range of 5-500 nM. Moreover, to optimize the conditions for SBSE with in situ de-conjugation and the recovery test, NP-G was synthesized by a biochemical technique in our laboratory. The limits of detection (S/N = 3) and quantitation (S/N > 10) for NP were 0.2 ng ml(-1) (1.0 nM) and 1.1 ng ml(-1) (5.0 nM), respectively. The average recoveries in the human urine samples (n = 6) spiked with NP-G at levels of 20 and 100 nM were 104.1 (R.S.D. 7.1%) and 100.6% (R.S.D. 9.2%), respectively, with correction using the added internal standard, 4-(1-methyl) octylphenol-d(5). The method enabled the precise determination of the standard and was applicable to the detection of trace amounts of NP-G in human urine samples.

Stir bar sorptive extraction with in situ derivatization and thermal desorption-gas chromatography–mass spectrometry for measurement of phenolic xenoestrogens in human urine samples

A high-sensitivity analytical method that uses stir bar sorptive extraction (SBSE) with in situ derivatization and thermal desorption (TD)-gas chromatography-mass spectrometry (GC-MS) for the simultaneous measurement of trace amounts of phenolic xenoestrogens (PXs), such as 2,4-dichlorophenol (DCP), 4-tert-butylphenol (BP), 4-tert-octylphenol (OP), 4-nonylphenol technical isomers (NP), pentachlorophenol (PCP) and bisphenol A (BPA), in human urine samples was developed. The urine sample (1 ml) was de-conjugated by adding beta-glucuronidase and sulfatase. Then, protein precipitation was performed by the addition of acetonitrile. After centrifugation, the supernatant was diluted with purified water and subjected to SBSE with in situ derivatization and TD-GC-MS. The detection limits of DCP, BP, OP, NP, PCP and BPA in the urine samples were 20, 10, 10, 50, 20 and 20 pg ml-1 (ppt), respectively. The calibration curves for PXs were linear and had correlation coefficients higher than 0.99. The average recoveries of those analytes in the urine samples were higher than 95% (RSD: <10%, n=6) with correction using the added surrogate standards. This simple, accurate, sensitive and selective method can be used in the determination of PXs in human urine samples.

Determination of 4-tert.-octylphenol and 4-nonylphenol in laboratory animal feed sample by stir bar sorptive extraction followed by liquid desorption and column-switching liquid chromatography-mass spectrometry with solid-phase extraction

A novel analytical method has been developed for the determination of 4-tert.-octylphenol (OP) and 4-nonylphenol (NP) in laboratory animal feed samples, which involves stir bar sorptive extraction (SBSE) followed by liquid desorption (LD) and column-switching liquid chromatography-mass spectrometry (CS-LC-MS) with solid-phase extraction (SPE). The method required correction by stable isotopically labeled surrogate standards, deuterium 4-tert.-octylphenol (OP-d) and [2H5] 4-(1-methyl)octylphenol (m-OP-d5). A feed sample was homogenized with methanol by ultrasonication. After centrifugation, the supernatant was subjected to extraction for 120 min at room temperature (25 degrees C) using a stir bar coated with polydimethylsiloxane. After the extraction, the analyte was desorbed from the stir bar by LD using acetonitrile. Then, the liquid sample was analyzed by CS-LC-MS with SPE. The average recoveries from laboratory feed samples spiked with OP and NP at 20 ng g(-1) were 99.5 and 103.8%, respectively, with correction using the added surrogate standards. The limits of quantification were 1 ng g(-1) for OP and 5 ng g(-1) for NP in feed sample. The measurement of OP and NP in commercial laboratory animal feed samples resulted in the detection of sub ng g(-1) NP