Ultrasound Water Bath Research Articles

Effects of ultrasonic and microwave treatment on color, quality and drying characteristics of rice

This study explores the influence of various ultrasound treatment parameters and microwave drying parameters on the quality and drying characteristics of rice. The rice was treated in an ultrasound water bath (200W) for 30 min, 40 min, and 50 min, followed by microwave drying (210W) for 10 min. The influence of ultrasound treatment time on the moisture content variation of rice was found to be significant through correlation analysis. The time required for the 50-min ultrasound treatment to reach the safe moisture level (15 %) was approximately 20 % shorter than the time required for the 30-min ultrasound treatment. Due to the combined ultrasound-microwave treatment, changes occur in the constituents of rice (Starch gelatinization, Maillard reaction, etc.), and the variations in rice quality can be reflected by the changes in CIE Lab color parameters. The differences in characteristic peaks of Fourier Transform Infrared Spectroscopy (FTIR) can reflect the variations in flavor and aroma of rice, as well as the significant disruption of the ordered structure of starch molecules. Additionally, response surface experiments based on Box-Behnken design were conducted to obtain the optimal conditions for ultrasound-microwave combined treatment (240W, 46min, 3min). Moreover, ultrasound-microwave combined treatment leads to a significant reduction in rice hardness and an increase in elasticity.

Evaluation of the Effect of Various Cementation Protocols Used for 10% Zirconia-Reinforced Lithium Glass Ceramic Veneer on Shear Bond Strength to Resin Cement (An In Vitro Study)

Bonding failure between ceramic restoration and cement dramatically influences the success of resin-bonded ceramic restoration. This study evaluates the influence of various fitting surface treatments of 10% zirconia-reinforced lithium glass ceramic (ZLS) on its shear bonding strength to resin cement. Sixty blocks sized 8 × 8 × 2 mm3 were cut from a ZLS. All specimens were fired for 10 min and separated into six groups according to surface treatment: GI (Without treatment), GII (10% HF acid, Ultra Sound water bath US, and silane coupling agent S), GIII (HF, US, S, and bonding without light cure B1), GIV (HF, US, 37% phosphoric acid PA, US, S, B1), GV (HF, US, S, and bonding with light curing B2), VI (HF, US, PA, US, S, and B2). The treated specimens were cemented to a resin cement cylinder of 3.5 mm in diameter and 2 mm in height (Variolink, Esthetic. Neutral). A universal test machine was used to test the shear bond strength (SBS) and SEM for failure mode. The result indicated that applying a bonding agent on the prepared surface of ZLS without curing before cementation significantly increases the shear bond strength and affects the failure mode. In contrast, the application of PA does not influence bond strength.

Food-Package-Processing relationships in emerging technologies: Ultrasound effects on polyamide multilayer packaging in contact with different food simulants

In this study, the effect of ultrasound processing on the properties of two packages widely used in food products was evaluated: polyamide (PA) and polyethylene (PE) multilayer packaging. Packages composed of PE/PA/PE (Film A) and PE/PA/PE/PA/PE (Film B) were filled with aqueous and fatty food simulants and treated in an ultrasound water bath (frequency 25 kHz, volumetric power of 9.74 W/L, temperature of 25 °C, and time of 30 and 60 min). Materials were evaluated in term of structure and performance properties. Ultrasound did not or induced small changes in chemical groups, crystallinity, melting temperature, and tensile strength of the films. Film A showed a reduction in heat sealing tensile strength of 25% in the machine direction and 22% in the transverse direction. Film B showed a 20% increase of water vapor transmission rate after ultrasound processing. Although ultrasound had little impact on the properties of the evaluated materials, these modifications do not compromise the use of these packages for applications in ultrasound-processed foods. Therefore, the results indicate that ultrasound can be used as a food processing technology in multilayer PA and PE packaging.

Factors influencing the cleaning of plant samples with ultrasonic technology

Effective cleaning of biological samples is a critical step in environmental studies. However, the literature lacks standardized cleaning procedures and protocols and there is little information about how even the most basic conditions may affect cleaning efficiency. Here, leaves of different species were first exposed to the soil naturally containing mercury particles and then washed in an ultrasound water bath under the following conditions: newly cleaned/reused beakers, water temperature, sample immersion/free-floating, sample quantity, and the number of washing cycles. Additionally, the effects of sample pubescence on cleaning efficacy were also assessed. Results indicated that the best cleaning efficacy was recorded when samples were placed in cold water under forced immersion and beakers were cleaned between washing cycles. At least two of these three conditions were needed for adequate washing. The results also indicated that, for the glabrous leaves, a cumulative leaf surface area of ≤10,000 mm2 was efficiently cleaned after 3–5 washing cycles, while as pubescence increased, 9–11 cycles were needed and often the sample quantity had to be reduced (<5,000 mm2). Our experiments reveal that cleaning can be optimized by applying easy procedures and according to individual sample typology, resulting in faster and more effective cleaning. Novelty statement The cleaning of samples is a frequent stage in the analytical processes of phytoremediation studies. This work provides new and valuable information to optimize the cleaning of plant samples by simply applying ultrasonic technology and distilled water. In fact, we have tested the influence of some factors never taken into account previously.

Effect of Ultrasound Treatment on Barrier Changes of Polymers before and after Exposure to Food Simulants.

In this study, we investigated the impact of ultrasound treatment on barrier properties of linear low-density polyethylene (LLDPE) and acrylic/poly(vinylidene chloride) polypropylene (PPAcPVDC)-coated pouches intended for food packaging before and after exposure to food simulants. Packaging pouches were filled with two food simulants, namely ethanol (10% (v/v)) and acetic acid (3% (w/v)), in order to simulate food–packaging interaction and possible compound migration from packaging materials. Samples were subjected to an ultrasound water bath treatment for 5 min, 15 min, and 30 min at 60 °C (±2 °C) and with an amplitude of 100% as an equivalent to the heat-treatment conditions combined with an ultrasound effect. Furthermore, the effect of temperature on the polymer barrier (water vapour and oxygen permeability) properties was tested at 20 °C, 40 °C, and 60 °C. Results showed that PPAcPVDC possessed better properties of water vapour permeability and oxygen permeability properties to LLDPE. Statistical analyses showed a significant (p < 0.001) impact of ultrasound treatment on the overall migration value, regardless of the food simulant used.

Instrumental characterization of merino wool fibers dyed with Cinnamomum camphora waste/fallen leaves extract: An efficient waste management alternative

The present study describes the use of Cinnamomum camphora waste/fallen leaves as an eco-friendly natural colorant for developing colorful and antibacterial wool fibers in view of growing environmental pollution and increasing needs for biomedical textiles in healthcare sector. Extraction of the natural colorant from C. camphora reddish colored/middle-aged waste/fallen leaves was carried out via simple water bath and ultrasound water bath extraction methods. While optimizing the colorant extraction in an aqueous solvent, ultrasound water bath provided enhanced extraction efficiency at pH 3, temperature of 70 °C, an initial dose level of 1.0 gm/50 ml of H2O, time of 80 min, and ultrasonic frequency of 80 kHz. Phytochemical analysis of extracted dye was successfully carried out using simple qualitative experimental analysis. The extracted colorants from C. camphora waste leaves were used to dye merino wool fibers through exhaustion dyeing technique. The optimal dyeing conditions, dye performances, and the ultrasonic effects were reported effectively. Build-up properties and fastness characteristics were studied in the presence and absence of mordants under corresponding ISO standards. Increasing ethanol concentration, increased discoloration properties of dyed wool fiber. Dyeing kinetics and dyeing rates under both simple water bath and ultrasound water bath conditions were compared. The structural and thermal changes in the dyed fibers under both conditions were analyzed using FT-IR, TG, and SEM analysis. An adequate amount of C. camphora leaves extract on wool fiber exhibited good antibacterial behaviors with high durability to increasing number of washing cycles. Premordanting with Cu2+, Fe2+, and Al3+ salts had a slightly negative effect on the antibacterial activity of dyed wool fibers but showed enhanced durability. Camphor waste leaves will prove great potential for industrial application as a source of natural colorant, as well as a value-adding application (biomedical textile) in addition to its normal usage.

Combined application of electrolysed water and ultrasound to improve the sanitation of knives in the meat industry

SummaryThis study investigated the effect of the combination of basic electrolysed water (BEW) and slightly acid electrolysed water (SAEW) with ultrasound (US) for cleaning and sanitation of the knives used in slaughtering processes. The knives were sonicated in a US bath using two modes of operation (normal and sweep) in two steps: (i) 5 min with BEW and (ii) 10 min with SAEW at 35 °C. The microbiological counts and the possible changes in the physical structure of the knives were evaluated. The association BEW + SAEW + US, in the sweep mode, provided lower mesophilic, enterobacterial, Staphylococcus aureus and yeast counts when compared to the values recommended by the international legislation. In addition, these conditions removed all organic residues from the knife blades and promoted the highest migration rate of the residues to the US water bath (12.35 mg/L·min), without modifications in the knife blades. Thus, cleaning and sanitation of knives was feasible with the association of BEW + SAEW + US, which could be a useful alternative for the meat industry.

Use of Aronia melanocarpa Fruit Dye Combined with Silver Nanoparticles to Dye Fabrics and Leather and Assessment of Its Antibacterial Potential Against Skin Bacteria

The core purpose of this study was to extract natural dye from Aronia melanocarpa (black chokeberry) powder (BCP) via soxhlet extraction or ultrasound water bath using acidified ethanol (A. EtOH) as the extraction solvent. After optimization of the dye extraction conditions, high color intensity was achieved at pH 4, temperature of 80 °C, 40 and 90 ml of A. EtOH, 2 g of BCP, time of 80 and 90 min, ultrasonic output power of 75 W or 6 extraction cycles for ultrasonic water bath and soxhlet extraction, respectively. The extracted red natural dye (BCP) was used alone or together with commercial silver nanoparticles (C-AgNPs) to dye cotton, silk, and leather in an eco-friendly approach without using any external chemicals with augmented antibacterial activity. Rotary vacuum dyeing yielded excellent dyeing and the optimal conditions for high color strength (K/S) values were pH 4, 120 min at 80 °C for cotton and silk and 90 min at 60 °C for leather. Morphologies of dyed cotton, silk, and leather and the anchoring of C-AgNPs with elemental compositions were investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS). The dry and wet rubbing fastness values for dye alone and dye with nanoparticles were grade 4–5 and 4, respectively.

Comparison of Ultrasound and Conventional Technique for Removal of Methyl Orange by Luffa Cylindrica Fibers

The aim of this study is to investigate the effect of ultrasound propagation on the adsorption of methyl orange by Luffa cylindrica. Kinetics of adsorption was studied at 30 and 50 $${^{\circ }}\hbox {C}$$ . Adsorption isotherms were investigated at three different medium temperatures (30, 40 and 50 $${^{\circ }}\hbox {C}$$ ) for ultrasound and shaking water baths. The obtained adsorption isotherms were modeled by Freundlich, Temkin, Dubinin–Radushkevich and Chakraborty and Sun isotherm models. Diffusion coefficients of the methyl orange were found as $$8.65 \times 10^{-15}$$ and $$1.43\times 10^{-14} \hbox {m}^{2}/\hbox {s}$$ for shaking and $$6.38\times 10^{-14}$$ and $$9.94\times 10^{-13} \hbox {m}^{2}/\hbox {s}$$ for ultrasound water bath at medium temperatures of 30 and 50 $${^{\circ }}\hbox {C}$$ , respectively.

Extraction of natural colorant from purple sweet potato and dyeing of fabrics with silver nanoparticles for augmented antibacterial activity against skin pathogens

The main objective of this study was to extract natural colorant from purple sweet potato powder (PSPP) via a water bath and ultrasound water bath using acidified ethanol (A. EtOH) as the extraction solvent. When optimizing the colorant extraction conditions of the solvents, acidified ethanol with ultrasound yielded a high extraction capacity and color intensity at pH2, temperature of 80°C, 20mL of A. EtOH, 1.5g of PSPP, time of 45min, and ultrasonic output power of 75W. Subsequently, the colorant was extracted using the optimized conditions for dyeing of textiles (leather, silk, and cotton). This natural colorant extraction technique can avoid serious environmental pollution during the extraction and is an alternative to synthetic dyes, using less solvent and simplified abstraction procedures. The extracted purple sweet potato natural colorant (PSPC) was used to dye leather, silk, and cotton fabrics in an eco-friendly approach with augmented antibacterial activity by in situ synthesis of silver nanoparticles (AgNPs) and dyeing. The optimal dyeing conditions for higher color strength (K/S) values were pH2 and 70°C for 45min. The colorimetric parameters L∗, a∗, b∗, C, and H were measured to determine the depth of the color. The Fourier transform infrared spectroscopy (FTIR) spectra of undyed control, dyed with PSPC and dyed with blend of PSPC and AgNPs treated leather, silk and cotton fabric were investigated to study the interaction among fiber type, nanoparticles, and dye. The structural morphology of leather and silk and cotton fabrics and the anchoring of AgNPs with elemental compositions were investigated by scanning electron microscopy-energy-dispersive X-ray spectroscopy (SEM-EDS). The dry and wet rubbing fastness for dye alone and dye with nanoparticles were grade 4–5 and 4, respectively. Thus, the results of the present study clearly suggest that in situ synthesis of AgNPs along with dyeing should be considered in the development of antimicrobial textile finishes.

Application of ultrasound-assisted emulsification microextraction based on applying low-density organic solvent for the determination of organochlorine pesticides in water samples

In this study, a polyethylene Pasteur pipette-based ultrasound-assisted emulsification microextraction (USAEME) applying low-density organic solvent was successfully developed for the extraction of trace levels of organochlorine pesticides (OCPs) in water samples and followed by gas chromatography–mass spectrometry (GC–MS) analysis. In this approach, a polyethylene Pasteur squeeze-type pipette was employed as a convenient extraction device and ultrasound radiation was applied to accelerate the emulsification of low-density organic solvent in aqueous solutions to enhance the microextraction efficiency of OCPs in water samples. Thirty microliters of extraction solvent (isooctane), of lower density than water, were injected into the aqueous sample solution held in the pipette. The latter was then immersed in an ultrasound water bath to form an emulsion. After 30s extraction, phase separation was achieved by centrifugation. The upper layer (isooctane) was collected and analyzed by GC–MS. No disperser solvent was required in this procedure. Significantly, fast analysis and high extraction efficiency were achieved. Another feature of the procedure was the use of the pipette as the extraction device, which permitted less dense than water organic solvent to be used as extraction solvent. This method broadens the applicability of USAEME to a wider range of solvent. Additionally, carry-over problems were avoided with the use of the disposable pipette. Parameters affecting the efficiency of polyethylene Pasteur pipette-based USAEME, such as the extraction solvent, extraction solvent volume, extraction and centrifugation time, ionic strength and extraction temperature were investigated. Under the optimum conditions, the proposed method provided good enrichment factors (EFs) in the range of 128 and 328, with relative standard deviations (RSDs) ranging from 2.7% to 12.4%. The limits of detection were in the range of 0.8 and 10ng/L depending on the analytes. The linearities were between 0.01 and 50μg/L for hexachlorobenzene, dieldrin, endrin and o,p′-DDD, 0.05–25μg/L for heptachlor, and 0.005–50μg/L for p,p′-DDE. Finally, the polyethylene Pasteur pipette-based USAEME was successfully used for the fast determination of OCPs in river and tap water samples. The proposed method provides a simple, convenient, rapid, sensitive, cost-effective, and environmentally friendly process for the determination of OCPs in water samples.

Low-density solvent based ultrasound-assisted emulsification microextraction and on-column derivatization combined with gas chromatography–mass spectrometry for the determination of carbamate pesticides in environmental water samples

A fast and efficient method for the determination of trace level of carbamate pesticides using a lower-density-than-water solvent for ultrasound-assisted emulsification microextraction coupled to on-column derivatization and analysis by GC–MS has been developed and studied. In this approach, a soft plastic Pasteur pipette was employed as a convenient extraction device. Fifty microliters of extraction solvent, of lower density than water, was injected into the sample solution held in the pipette. The latter was immediately immersed in an ultrasound water bath to form an emulsion. After 2min extraction, the emulsion was fractionated into two layers by centrifugation. The upper layer (organic extract) could be collected conveniently by squeezing the bulb of the pipette, now held upside down, to move it into the narrow stem of the device, facilitating its retrieval for analysis. The extract was then combined with trimethylphenylammonium hydroxide and directly injected into a gas chromatography–mass spectrometry (GC–MS) system for on-column derivatization and analysis. The on-column derivatization provided an added convenience (since a separate step was not necessary). Parameters affecting the derivatization and extraction were investigated. Under the most favorable conditions, the method demonstrated high extraction efficiency with low limits of detection of between 0.01 and 0.1μg/L, good linearity in the range of 0.05–50μg/L, to 0.5–100μg/L, and good repeatability (RSD below 9.2%, n=5). The proposed method was evaluated by determining carbamate pesticides in river water samples.

Application of fast ultrasound water-bath assisted enzymatic hydrolysis – High performance liquid chromatography–inductively coupled plasma-mass spectrometry procedures for arsenic speciation in seafood materials

Enzymatic hydrolysis of seafood materials for isolating arsenic species (As(III), As(V), DMA and AsB) has been successfully performed by assisting the procedure with ultrasound energy (35 kHz) supplied by an ultrasound water-bath. The use of pepsin, as a proteolytic enzyme, under optimized operating conditions (pH 3.0, temperature 40 °C, enzyme to sample ratio of 0.3) led to an efficient assistance of the enzymatic process in a short period of time (from 4.0 to 30 min). The enzymatic extract was then subjected to a clean-up procedure based on ENVI-Carb™ solid phase extraction (SPE). An optimized anion exchange high performance liquid chromatography (HPLC) coupled to inductively coupled plasma-mass spectrometry (ICP-MS) permitted the fast separation (less than 15 min) of six different arsenic species (arsenite, As(III); arsenate, As(V); dimethylarsinic acid, DMA; and arsenobetaine, AsB; as well as monomethylarsonic acid, MMA; and arsenocholine, AsC) in a single run. Relative standard deviations ( n = 11) of the over-all procedure were 7% for AsB and DMA, 11% for As(III) and 9% for MMA. HPLC–ICP-MS determinations were performed using aqueous calibrations covering arsenic concentrations of 0, 5, 10, 25, 100 and 200 μg L −1 (expressed as arsenic) for As(III), As(V), MMA, DMA and AsC; and 0, 125, 250, 500, 750, 1000 and 2000 μg L −1 (expressed as arsenic) for AsB. Germanium (5 μg L −1) was used as an internal standard. Analytical recoveries from the anion exchange column varied from 96 to 105% (enzymatic digests spiked with low target concentrations), from 97 to 104% (enzymatic digests spiked with intermediate target concentrations), and from 98 to 103% (enzymatic digests spiked with high target concentrations). The developed method was successfully applied to two certified reference materials (CRMs), DORM-2 and BCR 627, which offer certified AsB and DMA contents, and also to different seafood samples (mollusks, white fish and cold water fish). Good agreement between certified and found AsB concentrations was achieved when analyzing both CRMs; and also, between certified and found DMA concentrations in BCR 627. In addition, the sum of the different arsenic species concentrations found in most of the analyzed samples was statistically similar to the assessed total arsenic concentrations after a total sample matrix decomposition treatment.

On-line gel permeation chromatography–attenuated total reflectance–Fourier transform infrared determination of lecithin and soybean oil in dietary supplements

Gel permeation chromatography (GPC) with attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectrometry detection has been proposed for the simultaneous determination of lecithin and soybean oil in dietary supplements. The method involves the extraction of analytes with dichloromethane in an ultrasound water bath and the injection of 2 ml of centrifuged and filtered extracts into the system integrated by two Envirogel GPC columns (19 mm × 150 mm, 19 mm × 300 mm) coupled on-line. Dichloromethane was used as mobile phase. A method has been developed to select the most appropriated wavenumber to be used for the determination of each considered compound from the calculation of a factor which maximizes the analyte signal minimizing the interferent contributions, being selected the detection wavenumbers of 1034 and 1138 cm −1 for lecithin and soybean oil, respectively in the first order derivative ATR-FTIR spectra. The method provides limits of detection of 2 and 4 mg ml −1 for lecithin and soybean oil and repeatability values, measured as relative standard deviation, of 2.5% and 3.4% being extended the linear range till 100 mg ml −1 for lecithin and up to 50 mg ml −1 for soybean oil. Accurate results were found for 10 synthetic samples and 7 commercial dietary supplement preparations.

Cold vapour atomic fluorescence determination of mercury in milk by slurry sampling using multicommutation

A highly sensitive mechanized method has been developed for the determination of mercury in milk by atomic fluorescence spectrometry (AFS). Samples were sonicated for 10 min in an ultrasound water bath in the presence of 8% (v/v) aqua regia, 2% (v/v) antifoam A and 1% (m/v) hydroxilamine hydrochloride, and after that, they were treated with 8 mmol l −1 KBr and 1.6 mmol l −1 KBrO 3 in an hydrochloric medium. Atomic fluorescence measurements were made by multicommutation, which provides a fast alternative in quality control analysis, due to the easy treatment of a large number of samples (approximately 70 h −1), and is an environmentally friendly procedure, which involves a waste generation of only 94.5 ml h −1 as compared with the 605 ml h −1 obtained by using continuous AFS measurements. The limit of detection found was 0.011 ng g −1 Hg in the original sample. The method provided a relative standard deviation of 3.4% for five independent analysis of a sample containing 0.30 ng g −1 Hg. To validate the accuracy of the method, a certified reference material NIST-1459 (non-fat milk powder) containing 0.3±0.2 ng g −1 Hg was analysed and a value of 0.27±0.06 ng g −1 Hg was found. A comparison made between data found by the developed procedure and those obtained by microwave-assisted digestion and continuous AFS measurements evidenced a good comparability between these two strategies. Results obtained for commercially available milk samples varied between 0.09 and 0.61 ng g −1 Hg depending on the type of sample and its origin. The confluence of the analytical waste with a 6 mol l −1 NaOH allowed us to reduce the waste generation in a working session from 1 l to 5 g solid residue with a matrix of Fe(OH) 3 which contributes to the deactivation of traces of heavy metals presents in the samples that does not form volatile hydrides.

Determination of As, Sb, Se, Te and Bi in milk by slurry sampling hydride generation atomic fluorescence spectrometry

A simple and fast analytical procedure has been developed for the determination of As, Sb, Se, Te and Bi in milk samples by hydride generation atomic fluorescence spectrometry (HG-AFS). Samples were treated with aqua regia for 10min in an ultrasound water bath and pre-reduced with KBr for total Se and Te determination or with KI and ascorbic acid for total As and Sb, the determination of Bi being possible in all with or without pre-reduction. Slurries of samples, in the presence of antifoam A, were treated with NaBH4 in HCl medium to obtain the corresponding hydrides, and AFS measurements were processed in front of external calibrations prepared and measured in the same way as samples. Results obtained by the developed procedure compare well with those found after microwave-assisted complete digestion of samples. The proposed method is simple and fast, and only 1ml of milk is needed. The values obtained for detection limit are 2.5, 1.6, 3, 6 and 7ngl−1 for As, Sb, Se, Te and Bi respectively in the diluted samples, with average relative standard deviation values of 3.8, 3.1, 1.9, 6.4 and 1.2% for three independent analysis of a series of commercially available samples of different origin. Data found in Spanish market samples varied from 3.2±0.3 to 11.3±0.2ngg−1 As, from 3.1±0.2 to 11.6±0.4ngg−1 Sb, from 10.7±0.5 to 25.5±0.4ngg−1 Se, from 0.9±0.2 to 9.4±0.6ngg−1 Te and from 11.5±0.1 to 27.7±0.4ngg−1 Bi.

Sonication effect on cellular material in sedimentation and gravitational field flow fractionation

Sonication procedures are generally used prior to field flow fractionation (FFF) separation in order to produce suspensions without aggregates. Yeast cells manufactured in active dry wine yeast (ADWY) were placed in an ultrasound water bath in order to disrupt possible clumps and to obtain a single-cell suspension to be used in optimal conditions during fermentation processes. In order to determine whether this sample preparation procedure meets absolute needs, different yeast samples before and after sonication were analysed by two field flow fractionation techniques. It is shown that 2 min of sonication in the sample preparation process is sufficient to obtain an optimal dispersion of the yeast cells, that is, without critical percentage of aggregates. To demonstrate this effect, photographs of the yeast cell suspensions were performed with non-sonicated and sonicated yeast sample dispersion. The resulting data are compared with the elution profiles obtained from the two different FFF techniques. It is demonstrated that fractogram profiles prove the effectiveness of sonication methodologies.

Diagnosis of fetal skeletal dysplasias with ultrasound

In 1977 we reported the in utero diagnosis of a skeletal dysplasia, chondroectodermal dysplasia. Since then we have used ultrasound to examine 66 pregnant women who were at risk for fetal skeletal dysplasia. In an effort to establish a normal curve for long bone length, the femurs and, in some cases, humeri, of 57 normal second-trimester fetuses were measured by real-time ultrasound. In addition, femur and humerus measurements were obtained in 50 abortuses by means of ultrasound in a waterbath and were compared with blindly obtained extemal measurements of the same long bones. Mean in vivo ultrasound measurements of fetal femur and humerus were consistently less than mean ultrasound waterbath measurements by 16%. External measurements of the femur and humerus of abortuses were in concordance with water-bath ultrasound measurements in the same abortuses until 18 weeks, after which the means progrssively diverged to a difference of 17% at 25 weeks, with the ultrasound measurements being smaller. Based on the above in vivo normative ultrasound data, a positive diagnosis was made in five of seven second-trimester fetuses at risk for a skeletal dysplasia (camptomelic dysplasia, two fetuses with Roberts syndrome, diastrophic dysplasia, and thrombocytopenia with absent radii syndrome). In two others (chondroectodermal dysplasia and osteogenesis imperfecta) long bone measurements were diminished, but not outside 95% confidence levels, and the diagnosis was based on fetoscopy findings and identification of a femoral fracture. All other fetuses were normal at birth following negative ultrasound evaluation. The study demonstrates the feasibility of diagnosing various skeletal dysplasias with ultrasound. Further study will be required before the accuracy of diagnosis in all dysplasias can be fully assessed.