Trace Analysis on Capillary Columns. Selected Practical Applications: Insecticides in Raw Butter Extract; Aroma Head Space from Liquors; Auto Exhaust Gas

Trace analysis on capillary columns becomes feasible provided appropriate injection techniques without stream splitting are used. To demonstrate potentialities and limitations of the methods, we investigated practical applications, the conditions of which were as dissimilar as possible. Insecticides in dairy products can be estimated by direct analysis of the raw petrol ether extract, without previous purification by column chromatography. 2-4 µl of extract are injected without splitting on a short inlet capillary fitted in a separate injection bloc. The inlet capillary is then connected to the capillary column mounted in the column oven with electron capture detector. Analysis is started by rapid heating to a constant temperature or by temperature programming resp. Head space analysis is another case in which trace components are important. Whereas several workers reported trapping of head space vapors in capillaries at low temperatures, we emphasize avoiding candensation, e.g. of water vapor, in the capillary. All sampling is done, therefore, near the original temperature of the head space material, i.e. at room temperature. In the case of coqnac aroma analysis in which most of the water and ethanol vapor are vented through the inlet capillary, the influences of most sampling variables—gas volume, length of inlet capillary—are studied. In the analysis of auto exhaust gas, again, bypassing of water is an important detail. In addition to hydrocarbons originating directly from the fuel as investigated by several authors, we found many combustion and conversion products, primarily naphthaline derivatives and phenol

Separation Efficiency Versus Column Length. An Experimental Study With Capillary Columns

The columns of different length used for studying the relation between HETP and column length are supposed to exhibit identical characteristics per meter. In the laboratory this condition cannot be rigorously fulfilled. The best approximation probably consists in starting the work with a relatively long capillary column followed by running shorter parts obtained by progressive cutting of the original column. Based on this procedure a marked increase of HETP with increasing column length is observe

Splitless Injection on Capillary Columns, Part II. Conditions and Limits, Practical Realization

Our procedure of direct splitless injection on capillary columns is based on the choice of column temperature for injection. Under appropriate conditions a marked concentration effect is observed, i.e. the eluted band is more concentrated than the injected one. The dependence of this effect on column temperature, injection time, sample size, and other variables has been studied experimentally. A solvent bypassing technique has been developed which allows the performance of trace analysis on capillary column

Splitless Injection on Capillary Columns, Part I. The Basic Technique; Steroid Analysis as an Example

A very simple procedure for splitless injection on capillary columns is discussed. In contrast to more sophisticated devices recently developed for the same purpose, the method described requires no additional equipment. The advantages of the method which broadens the use of capillary columns are discussed. Steroid analysis serves as an example of the application

New Liquid Phases for the Gas Chromatographic Separation of Strong Bases on Capillary Columns

The current practice of pretreating the solid support with free alkali to increase separation efficiency for basic compounds proved to be unsuitable for capillary columns. Instead of this, homogenous organic materials of high base strength are required. We found polyethylene imine (PEI) and polypropylene imine (PPI) to be very efficient as liquid phases of capillary columns for the separation of bases. The preparation of polymers is mentioned. Silanization or acetylation of the free hydroxyl groups of carbowax-type substrate makes them more suitable for use as liquid phases in capillary column

Early results in the treatment of proximal humeral fractures with a polyaxial locking plate

Objectives: We report early results using a second generation locking plate, non-contact bridging plate (NCB PH®, Zimmer Inc. Warsaw, IN, USA), for the treatment of proximal humeral fractures. The NCB PH® combines conventional plating technique with polyaxial screw placement and angular stability. Design: Prospective case series. Setting: A single level-1 trauma center. Patients: A total of 50 patients with proximal humeral fractures were treated from May 2004 to December 2005. Intervention: Surgery was performed in open technique in all cases. Main outcome measures: Implant-related complications, clinical parameters (duration of surgery, range of motion, Constant-Murley Score, subjective patient satisfaction, complications) and radiographic evaluation [union, implant loosening, implant-related complications and avascular necrosis (AVN) of the humeral head] at 6, 12 and 24weeks. Results: All fractures available to follow-up (48 of 50) went to union within the follow-up period of 6months. One patient was lost to follow-up, one patient died of a cause unrelated to the trauma, four patients developed AVN with cutout, one patient had implant loosening, three patients experienced cutout and one patient had an axillary nerve lesion (onset unknown). The average age- and gender-related Constant Score (n=35) was 76. Conclusions: The NCB PH® combines conventional plating technique with polyaxial screw placement and angular stability. Although the complication rate was 19%, with a reoperation rate of 12%, the early results show that the NCB PH® is a safe implant for the treatment of proximal humeral fracture

Roughness and multiscaling of planar crack fronts

We consider numerically the roughness of a planar crack front within the long-range elastic string model, with a tunable disorder correlation length $\xi$. The problem is shown to have two important length scales, $\xi$ and the Larkin length $L_c$. Multiscaling of the crack front is observed for scales below $\xi$, provided that the disorder is strong enough. The asymptotic scaling with a roughness exponent $\zeta \approx 0.39$ is recovered for scales larger than both $\xi$ and $L_c$. If $L_c > \xi$, these regimes are separated by a third regime characterized by the Larkin exponent $\zeta_L \approx 0.5$. We discuss the experimental implications of our results.Comment: 8 pages, two figure

Management of mydriasis and pain in cataract and intraocular lens surgery: review of current medications and future directions

The maintenance of mydriasis and the control of postoperative pain and inflammation are critical to the safety and success of cataract and intraocular lens replacement surgery. Appropriate mydriasis is usually achieved by topical and/or intracameral administration of anticholinergic agents, sympathomimetic agents, or both, with the most commonly used being cyclopentolate, tropicamide, and phenylephrine. Ocular inflammation is common after cataract surgery. Topical steroids and nonsteroidal anti-inflammatory drugs are widely used because they have been proved effective to control postsurgical inflammation and decrease pain. Topical nonsteroidal anti-inflammatory drugs have also been shown to help maintain dilation. However, use of multiple preoperative drops for pupil dilation, inflammation, and pain control have been shown to be time consuming, resulting in delays to the operating room, and they cause dissatisfaction among perioperative personnel; their use can also be associated with systemic side effects. Therefore, ophthalmologists have been in search of new options to streamline this process. This article will review the current medications commonly used for intraoperative mydriasis, as well as pain and inflammation control. In addition, a new combination of ketorolac, an anti-inflammatory agent, and phenylephrine, a mydriatic agent has recently been designed to maintain intraoperative mydriasis and to reduce postoperative pain and irritation from intraocular lens replacement surgery. Two Phase III clinical trials evaluating this combination have demonstrated statistically significant differences when compared to placebo in maintaining intraoperative mydriasis (P<0.00001) and in reducing pain in the early postoperative period (P=0.0002). This medication may be of benefit for use in cataract and lens replacement surgery in the near future

Fracture Roughness Scaling: a case study on planar cracks

Using a multi-resolution technique, we analyze large in-plane fracture fronts moving slowly between two sintered Plexiglas plates. We find that the roughness of the front exhibits two distinct regimes separated by a crossover length scale $\delta^*$. Below $\delta^*$, we observe a multi-affine regime and the measured roughness exponent $\zeta_{\parallel}^{-} = 0.60\pm 0.05$ is in agreement with the coalescence model. Above $\delta^*$, the fronts are mono-affine, characterized by a roughness exponent $\zeta_{\parallel}^{+} = 0.35\pm0.05$, consistent with the fluctuating line model. We relate the crossover length scale to fluctuations in fracture toughness and the stress intensity factor