General Administration of Quality Supervision, Inspection and Quarantine of the People’s Republic of China Standardization Administration of the People’s Republic of China

Foreword

The national standard was drafted according to the provisions specified in GB/T 1.1-2009.

This standard replaced GB/T 19464-2004 Alkylpolyglycosides from the implementation date. It was issued on 22 Dec. 2014, and implemented on 1 June, 2015.

In comparison with GB/T 19464-2004, the significant changes of this national standard are as follows:

— The requirement for alkylpolyglycosides products category has been added.

— The technical indexes of alkylpolyglycosides used for cosmetics have been added, and the corresponding analytical methods have been specified.

— The index of sulfated ash has been modified.

— The viscosity index and its determination temperature of C12～14alkylpolyglycosides have been modified.

— The test methods for determination of polymerization degree and total free fatty alcohols content of alkylpolyglycosides have been modified.

— The determination method for pH of alkylpolyglycosides has been modified, and the pH range of the products has been extended.

The national standard was proposed by China National Light Industry Council.

The national standard is under the jurisdiction of National Technical Committee 272 on Surfactant and Detergent of Standardization Administration of China (SAC/TC 272).

The national standard was drafted by Shanghai Fine Chemical Co., Ltd., Nanjing Jinling Petrochemical Research Institute Co., Ltd., Shenzhen Changyuan Jiacai Co., Ltd., Infinitus (China) Company Ltd., Zhejiang Zanyu Technology Co., Ltd., Yangzhou Chenhua Sci-tech Group Co., Ltd., Productivity Promotion Center of Surfactants & Detergents.

The main drafters of the standard are Feng Yu, Wang Fengshou, Zhou Yucheng, He Jianghuai, Dong Wantian, Deng Wei, Huang Yaru, Yu Zizhou, Huoshuwen, Li Yong and Hao Qiaolin.

The previous standard replaced GB/T 19464-2004.

Scope

The national standard specifies categories, technical requirements, test methods, inspecting rules, marks,packaging, transport, storage and shelf life of alkylpolyglycosides (hereafter referred to as APG) products.

The national standard is applicable to industrial APG products prepared by direct glycosidation process and trans-glycosidation process, which could be applied in many fields such as washing products, personal care,pesticide emulsifier and textile, functioned as detergent,emulsifier, penetrant, foaming agent and so on.

The national standard is not applicable to any formulated products or APG used mainly as emulsifier such as C16～18APG.

Normative references

The following referenced documents are indispensable for the application of this document. For dated references,only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.

GB/T 6682 Water for analytical laboratory use—Specification and test methods;

GB/T 3143 Color determination method of liquid chemicals—Hazen unit — Platinum-cobalt scale;

GB/T 8170 Rules of rounding off for numerical values &expression and judgement of limiting values;

GB/T 9722 Chemical reagent—General rules for the gas chromatography;

GB/T 15357 Surface active agents and detergents—Determination of viscosity and flow properties of liquid products using a rotational viscometer;

Health Supervision Order No. 1 [2007] Hygienic standard for cosmetics.

Product name, category, and general formula

APG products can be divided into two categories based on the manufacturing process, namely direct glycosidation products and trans-glycosidation products.Direct glycosidation products are prepared by the direct glycosidation reaction of long chain fatty alcohol and glucose without producing short chain glycosides during reaction process. Trans-glycosidation products are prepared through two steps. First, glucose react with short chain alcohols (e.g. butanol) to form short chain glycosides; then, short chain glycosides react with long chain fatty alcohols through trans-glycosidation reaction to synthesize the target APG. Two steps can be done successively or simultaneously. The APG products obtained by trans-glycosidation process contain a proportion of short chain APG as byproducts.

The general formula of APG molecule is as follows (R is C8～18, n = 1～10. Trans-glycosidation products contain short chain APG, where R is C2, C3or C4. Direct products don’t contain short chain APG).

Table 1. Physico-chemical indexes of APG

Technical requirements

Physico-chemical indexes

Physico-chemical indexes of APG shall conform to specifications in Table 1.

APG used for cosmetics

APG used for cosmetics shall meet the requirements of provisions specified in Hygienic standard for cosmetics to ensure that the products shall not do harm to human health when used under normal, reasonable and foreseeable conditions.

APG used for cosmetics shall conform to specifications in both Table 1 and Table 2.

Table 2. Additional indexes of APG used for cosmetics

Test methods

Unless otherwise specified, during the analysis, use only reagents of recognized analytical grade and only distilled water or deionized water or water of equivalent purity.

Appearance and odor

Visual inspection.

Color

1) Principle

APG test solution is prepared with isopropanol and water mixed solvent, which is transparent at pH = 7.Determine the color by visual colorimetry of standard Pt-Co scale, and the Hazen value of the Pt-Co scale which is the nearest to the product is considered to be the value of color.

2) Apparatus

Ordinary laboratory apparatus and

Spectrophotometer, wavelength range 380 nm to 800 nm;

Nessler tube, of capacity 50 mL.

3) Reagents

Isopropanol, 40% (V/V) aqueous solution, dilute 40 mL of isopropanol with water to 100 mL and mix.Nitric acid,1 mol / L solution, dilute 65 mL of nitric acid with water to 1,000 mL and mix.

4) Preparation of standard color solution

Prepare series of Pt-Co standard color solution with different Hazen values in accordance with GB/T 3143.

5) Preparation of test solution

Weigh, to the nearest 0.1 g, 30 g of the test sample, add 45 mL of 40% (V/V) isopropanol aqueous solution with a graduated cylinder, stir to dissolve. Insert pH electrode into the test solution, and add 1 mol / L nitric acid solution dropwise while stirring to adjust the pH to 6.8 ～7.0. Take 50 mL of the test solution in a colorimetric tube.Observe straight down from the top of the colorimetric tube, and compare with standard color solution in the same volume. The Hazen value of the standard color solution which is the nearest to the test solution is considered to be the value of color.

Solid content

1) Principle

Determine the solid content by the percentage of residual mass, after drying at 105℃ ± 2℃ for 4 h, to the total mass, of the test sample.

2) Apparatus

Ordinary laboratory apparatus and

Weighing bottle, Φ50 mm × 30 mm, with cover;Oven, capable of being controlled at 105℃ ± 2℃;Glass desiccator, Φ240 mm, containing allochroic silicagel.

3) Procedure

Weigh, to the nearest 0.001 g, about 1 g of the test sample in a weighing bottle, of which constant-weight has been obtained. For sample in paste form, heat to melt first and mix well before sampling. Dry the weighing bottle in the oven at 105℃ ± 2℃ for 4 h, and cool it in the desiccator for 30 min. Cover it and weigh, to the nearest 0.001 g.

4) Calculation

The solid content w(S), expressed as a percentage by mass, is given by the formula (1)

Where,

m1is the mass, in grams, of the residue after drying;

m0is the mass, in grams, of the test sample;

Calculate the arithmetic average of the parallel determination results, keep one decimal place, as the result.

Precision—The maximum difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 1%(95% confidence intervals).

pH

1) Principle

Prepare 20% (m / m) test solution with isopropanol and water mixed solvent. Determine the pH at 25℃.

2) ApparatusIsopropanol;

pH-meter, meets the requirements of precision;

pH composite electrode, or glass electrode and calomel / potassium chloride reference electrode;Beaker, of capacity 150 mL;

One-mark volumetric flask, of capacity 100 mL;

Thermometer, measuring range 0℃ to 100℃;Thermostat.

Procedure

1) Test conditions

During the determination, the temperature of the test solution, standard buffer solution and the water for washing should be controlled at 25℃ ± 1℃. The pH-meter shall be calibrated according to the instructions.

2) Determination

Weigh, to the nearest 0.1 g, 20.0 g of the test sample.Dissolve with 68.0 g of CO2-free distilled water, followed by 12.0 g of isopropanol for completely dissolving. Insert the electrode into the test solution, of which the temperature has been controlled at 25℃ ± 1℃. Record the reading when it stabilizes for 1 min.

The same test sample shall be determined twice parallelly, with results rounded to 0.1 pH. Calculate the arithmetic average of the parallel determination results,keep one decimal place, as the result.

Precision—The absolute difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 0.1 pH(95 % confidence intervals).

Sulfated ash

1) Principle

Heat, at 850℃, in the presence of sulfuric acid, the residue of test portion which has been pre-carbonized,and weigh the sulfated ash obtained.

2) Apparatus

Ordinary laboratory apparatus and

Crucible, in porcelain, of capacity 50 mL to 100 mL;Furnace, capable of being controlled at 850℃ ± 25℃;Desiccator, containing allochroic silicagel;Crucible tongs;

Electric stove, 1 kW to 2 kW.

3) Reagents

Concentrated sulfuric acid.

Procedure

1) Test portion

Heat the crucible in the furnace at 850℃ ± 25℃ for 30 min. Allow to cool in air for 1 to 2 min, then cool it in a desiccator for 45 min, and weigh, to the nearest 0.001 g.Repeat the operation above till the weight is constant.Weigh, to the nearest 0.001 g, 10 g of test sample in the crucible.

2) Carbonization

Place the crucible on the electric stove, and heat slowly.The moisture in test portion evaporates, producing foam gradually. Adjust the temperature of electric stove to avoid foam spill. For test portion which produces too much foam during heating, addition, in batches, of test sample to the crucible is recommended until the specified weight is obtained. When most of the foam disappears, increase the temperature to carbonize the test portion sufficiently.Allow it to cool when no smoke coming out of the crucible. Add 2.0 mL of sulfuric acid dropwise to wet the carbide. Continue heating until no white smoke coming out.

3) Calcination

Heat the crucible in the furnace at 850℃ ± 25℃ for 4 h. Allow to cool in air for 1 to 2 min, then cool it in a desiccator for 45 min, and weigh to the nearest 0.001 g.Repeat the calcination till the difference between two weights less than 2 mg.

4) Calculation

The sulfated ash content w(C), expressed as a percentage by mass, is given by the formula (2).

Where,

m1is the mass, in grams, of the residue in crucible;

m0is the mass, in grams, of the test portion.

Note — For the sample (m) of which the solid content(S) is not 50%, the mass of test portion m0shall be corrected by the following formula m0=[m (Weight) × S (%)(Solid Content)] / 50%.

Calculate the arithmetic average of the parallel deter-mination results, keep one decimal place, as the result.

Precision—The maximum difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 10%(95% confidence intervals).

Free fatty alcohols

Determined in accordance with annex A.

Short chain APG

Determined in accordance with annex B.

Average polymerization degree of APG

Determined in accordance with annex B.

Viscosity

Determined in accordance with GB/T 15357.

Total bacterial count

In accordance with Hygienic standard for cosmetics.

Pb

In accordance with Hygienic standard for cosmetics.

As

In accordance with Hygienic standard for cosmetics.

Hg

In accordance with Hygienic standard for cosmetics.

Inspection rules

Inspection

1) Routine inspection

Routine inspection items shall include appearance,odor, color, solid content, pH and free fatty alcohols specified in chapter 4.

2) Type inspection

Type inspection items shall cover all the items specified in chapter 4. It should also be conducted in the following cases.

Once every three months under regular production；

Any change or unusual state in production processes,manufacturing equipment, raw materials, or catalysts, and any change in production management(including personnel quality) that may affect the quality and properties of the products；

Resume production after long-time shutdown；

Big differences between the results of routine inspection and the latest type inspection；

Request of quality supervision organizations or end users.

Batch and sampling

APG products shall be delivered in batch with acceptance sampling. The products with the same type,specification, batch number form a consignment lot.

The products can leave the factory only if they’ve been deemed qualified as specified in the standard and the Certificate of Analysis has been issued by the quality control department of the factory. The consignee shall complete acceptance inspection within a month after the arrival of goods based on the Certificate of Analysis.Conduct acceptance sampling if necessary.

1) Sampling

Determine the sample size according to the batch quantity in Table 3, and sample randomly from batch.

As APG products with long carbon chain easily crystallize when stored in the environment below 35℃, it is necessary to mix the sample thoroughly and maintain homogeneous before sampling.

Table 3. Batch quantity and sample size Unit — barrel

During sampling, use a dry and clean sampling tube with the diameter approximately 15 mm or other sampling devices to take same quantity of sample at 2/3 depth of each sample barrel. The total quantity of the sample shall not be less than 1.0 kg. Divide the sample taken into two parts, one for inspection and the other kept in reserve.

Decision rules and reinspection

The inspection results shall be rounded off according to GB/T 8170 to meet the technical requirements.Determine whether the product is qualified or not against the limit value of specified requirements.

Reinspection shall be done in cases of unqualified item found in the results. Resampling from a double sample size is necessary, and test of unqualified item shall be conducted. The batch can be deemed qualified as the reinspection results conform to the national standard.Otherwise, unqualified.

Arbitration

If finding that the products quality does not conform to the standard, the consignee shall negotiate with the producer within one month after the arrival of goods.If an agreement can’t be reached due to the differences between inspection results, both sides shall sample. The total quantity of the sample shall not be less than 1.5 kg.Mix the sample carefully and thoroughly, divide into 3 parts in 3 clean and dry sample bottles, seal and label.The label shall list product name, specification, batch number, manufacturer, sampling date and operator.Each side holds one. The third one is for arbitration inspection. The sample can be stored in the dark for a month. The result of the arbitration inspection is the final.

Marks, packaging, transport, storage and shelf life

Marks

The label on the packaging barrel shall be legible and straight, declaring:

Product name, trademark, specification, grade and standard code;

Batch number, production date, shelf life (or expiry date);

Name, address, zip code and contact number of manufacturer;

Net weight and gross weight;

Warnings (Avoid water and damp, handle with care,etc.).

Packaging

APG shall be packed with plastic or plastic-lined metal container, which has clean surface, enough strength and no corrosion. Leave appropriate gaps when filling the products into the container. Seal well to prevent water intake. The net weight shall conform to the nominal mass.

Transport

The products shall be loaded and unloaded with the seal side uppermost. Avoid sunlight and rain.

Storage

APG product is aqueous solution, which shall be stored in a well-ventilated storehouse with ambient temperature not below 0℃ and not higher than 45℃.Avoid rain and sun exposure.

Shelf life

Under the packaging, transport and storage conditions specified, the shelf life shall not be less than 12 months from the production date. Declare the category and content of preservatives if added.

Annex A

(Normative)

Determination of Total Free Fatty Alcohols Content—Gas Chromatography

A.1 Principle

The total free fatty alcohols in APG products are separated from products by extraction method and quantitatively determined by gas chromatography.

A.2 Reagents

Unless otherwise specified, during the analysis, use only reagents of recognized analytical grade and only distilled water or deionized water or water of equivalent purity.

A.2.1 Fatty alcohols standard, C8OH, C10OH, C11OH, C12OH,C14OH, C16OH, C18OH, etc., GC grade

A.2.2 Dichloromethane

A.2.3 Ethanol, anhydrous

A.2.4 Diatomite, CP grade, dried at 105℃ ± 2℃ for 2 h before use

A.2.5 Petroleum ether, boiling range 30℃ to 60℃

A.2.6 Dichloromethane-petroleum ether, add 7 mL of dichloromethane (A.2.2) in 100 mL of petroleum ether(A.2.5) and mix

A.2.7 Carrier gas, Nitrogen, purity 99.99 %

A.2.8 Auxiliary gas, Hydrogen, purity 99.99%Air, supplied by cylinder or oil-free gas compressor.

A.3 Apparatus

A.3.1 Gas chromatography, equipped with flame ionization detector (FID), temperature programming controller and data processor.

Packed column, stainless steel or glass, 2.0 m long,internal diameter 2 to 4 mm. Stationary phase Chromsorb WHP, particle size between 0.120 mm and 0.180 mm,coated with 2% OV-101 stationary liquid. Aging for 5 to 10 h before use. Or capillary column or equivalent.

A.3.2 Syringe, 5 μL or 10 mL

A.3.3 Volumetric flask, of capacity 5 mL.

A.3.4 Pipette, of capacity 1 mL.

A.3.5 Glass column, Ф 18 mm, 400 mm long, fitted with glass wool at the bottom.

A.3.6 Thermostat water bath

A.4 GC operating conditions

The following conditions are typical for packed column recommended in A.3.1. Conditions for other columns are similar and appropriate modification is recommendatory.

A.4.1 Carrier gas, Nitrogen, flow rate 30 mL / min

A.4.2 Hydrogen, flow rate 45 mL / min

A.4.3 Air, flow rate 450 mL / min

A.4.4 Injection temperature 300℃

A.4.5 Detector temperature 300℃

A.4.6 Column temperature, initial temperature 100℃,initial time 1 min, rate 5℃ / min, final temerature 250℃,final time 2 min.

A.5 Determination of calibration factor

Accurately and respectively weigh, to the nearest 0.0002 g, about 0.2 g of n-undecanol internal standard(A.2.1) and other fatty alcohol standard (A.2.1), and dissolve in 5 mL of dichloromethane (A.2.2). Inject proper volume of solution and analyze.

The calibration factor of the fatty alcohol with carbon chain length i, against n-undecanol internal standard, is given by formula (A.1)

Where,

ASis the peak area of internal standard;

msis the mass, in grams, of internal standard;

Aiis the peak area of component i;

miis the mass, in grams, of component i.

The determination method of the calibration factor of other fatty alcohol standard against n-undecanol is the same as above.

A.6 Sample pretreatment and GC determination

Accurately weigh, to the nearest 0.0002 g, about 0.1 g of n-undecanol internal standard, and dissolve in anhydrous ethanol (A.2.3). Transfer the solution to a 5 mL volumetric flask. Rinse and dilute to the mark with anhydrous ethanol. This is the internal standard solution.

Weigh, to the nearest 0.001 g, about 2 g of homogeneous APG sample in a 50 mL beaker. Add 0.5 mL of internal standard solution and 0.5 mL of anhydrous ethanol respectively. When the sample is dissolved, add 5 g of dried diatomite (A.2.4), stir thoroughly to make the diatomite absorb sample solution completely and become half-dry powder. Then introduce into the glass column(A.3.5). Collect the eluate with a 50 mL beaker. Pass 50 mL of dichloromethane - petroleum ether (A.2.6) through the column at a flow rate of 1 mL / min. Evaporate the eluate to 1 to 2 mL on a water bath (A.3.6) at 70℃. Inject proper amount of concentrate and analyze. Calculate the free fatty alcohol content by internal standard method.

A.7 Method of calculation

The fatty alcohol content with carbon chain length i by internal standard method w (Xi), expressed as a percentage by mass, is given by formula (A.2)

where,

Aiis the peak area of fatty alcohol with carbon chain length i;

fs,iis the calibration factor of the fatty alcohol with carbon chain length i, against n-undecanol internal standard;

msis the mass, in grams, of internal standard;

ASis the peak area of n-undecanol internal standard;

m is the mass, in grams, of the test portion.

The total fatty alcohols content w (X), expressed as a percentage by mass, is given by formula (A.3)

Where,

Xiis fatty alcohol content with carbon chain length i,in a percentage by mass;

Calculate the arithmetic average of the parallel determination results, keep one decimal place, as the result.

Precision—The maximum difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 5 %(95% confidence intervals).

Annex B

(Normative)

Determination of Short Chain APG Content and The Average Polymerization Degree - Gas Chromatography

B.1 General

B.2.1 Main components of APG

The APG product is composed of the following homologs: alkyl mono-glycoside, alkyl bi-glucoside, alkyl tri-glucoside, alkyl tetra-glycoside, alkyl penta-glycoside and little alkyl poly-glycoside with higher polymerization degree. All alkyls above mean the long chain alkyls with carbon chain length longer than 8. The APG synthesized by trans-glycosidation process contains, except the components above, about 5 to 15 % short chain APG, such as butyl glycoside, propyl glycoside, etc. Moreover, APG also contains little free fatty alcohols and monosaccharide or oligosaccharide.

B.1.2 Principle

Sample was separated via chromatography column after silanization. Each component flows out according to the boiling points in the order fatty alcohols, short chain APG such as butyl glycoside or propyl glycoside, long chain alkyl mono-glycoside, long chain alkyl bi-glycoside,long chain alkyl tri-glycoside, till the long chain alkyl penta-glycoside. Qualitative analysis of chromatographic peaks can be done by comparison with standard peak or sample peaks of known compositions. During quantitative analysis, calculate the low carbon APG residue content by internal standard method, and long chain APG content by area normalization method, thus, the polymerization degree of product was obtained. For the APG product synthesized from direct glycosidation process without short chain APG residues, the polymerization degree can be directly calculated by area normalization method without the internal standard.

B.2 Reagents

Unless otherwise specified, during the analysis, use only reagents of recognized analytical grade and only distilled water or deionized water or water of equivalent purity.

B.2.1 Trichloromethane

B.2.2 Pyridine, shake with molecular sieve (dried at 550 ℃for 2 h) and keep for 24 h before use

B.2.3 Trimethylchlorosilane (TMCS), for GC

B.2.4 Hexamethyldisilazane (HMDS) (tailing-suppressing reagent for GC, Q GHSA 754-94)

B.2.5 Standard samples: n-docosane standard (GC grade),short chain mono-glycoside with known carbon chain length

B.2.6 Carrier gas, Nitrogen, purity 99.99%

B.2.7 Auxiliary gas, Hydrogen, purity 99.99%; Air, supplied by cylinder or oil-free gas compressor

B.3 Apparatus

B.3.1 Gas chromatography, equipped with flame ionization detector (FID) and temperature programming controller.

B.3.2 Chromatography column, packed column, stainless steel or glass, 0.5 m long, internal diameter 2 mm to 4 mm. Stationary phase, Chromsorb W AW DMCS or 405 silanization white carrier, particle size between 0.120 mm and 0.180 mm, coated with 3% Dexil-300 stationary liquid. Aging for 5 h to 10 h before use. Or capillary column or equivalent.

B.3.3 Recorder or printer

B.3.4 Data processor

B.3.5 Syringe, 5 μL or 10 μL

B.3.6 Volumetric flasks, of capacity 5 and 10 mL

B.3.7 Pipette, of capacity 1 mL

B.3.8 Test tube with stopper, of capacity 1 mL

B.4 GC operating conditions

The following conditions are appropriate for the packed column recommended in B.3.2. Conditions for other columns are similar and appropriate modification is recommendatory.

B.4.1 Injection temperature 350℃

B.4.2 Column temperature, initial temperature 80℃,initial time 2.0 min, rate 8.0℃ / min, final temperature 340℃, final time 15 min.

B.4.3 Carrier gas, flow rate 50 mL / min

B.4.4 Hydrogen, flow rate 45 mL / min

B.4.5 Air, flow rate 450 mL / min

B.4.6 Detector temperature 350℃

B.5 Determination of calibration factor

B.5.1 GC performance tuning

Adjust each parameter of the apparatus according to the conditions above, if necessary, GB/T 9722 or injection of standard samples can be employed to adjust the GC performance to conform to the standard.

B.5.2 Determination of calibration factor

Accurately and respectively weigh, to the nearest 0.0002 g, about 0.15 to 0.2 g of n-docosane internal standard (B.2.5)and short chain mono-glycoside standard (B.2.5), and dissolve in 5 mL of pyridine (B.2.2). Transfer 0.3 mL of the solution into a 1 mL test tube with stopper, and add 0.1 mL of TMCS (B.2.3) and 0.2 mL of HMDS (B.2.4). Shake for 30 s vigorously, then stand for 5 min. Inject proper volume of clear solution and analyze.

The calibration factor of low carbon APG, against n-docosane internal standard, is given by formula (B.1)

Where,

ASis the peak area of internal standard;

msis the mass, in grams, of internal standard;

Aiis the peak area of short chain mono-glycoside;

miis the mass, in grams, of short chain mono-glycoside(correction by purity necessary if less than 100%).

B.6 Preparation and silanization of test portion

B.6.1 Preparation of internal standard solution

Accurately weigh, to the nearest 0.0002 g, about 0.2 g of n-docosane internal standard (B.2.5), and dissolve in trichloromethane (B.2.1). Transfer the solution to a 5 ml volumetric flask (B.3.6), wash and dilute to the mark with trichloromethane. The solution contains about 0.04 g n-docosane internal standard per milliliter.

B.6.2 Test portion

B.6.2.1 Liquid sample

Weigh about 2 g of homogenized sample on a watch glass with diameter not less than 100 mm. Spread the sample out evenly, and heat on a boiling water bath until the water completely evaporated, with the sample becoming hard. Place in an oven at 105℃ for 1 h. Allow to cool in a desiccator for 30 min. Weigh, to the nearest 0.001 g. 1 g of dried sample in a 5 mL volumetric flask. Add 3 to 4 mL pyridine (B.2.2). When the solid test portion is dissolved completely, dilute to the mark with pyridine. The solution contains about 0.2 g sample per milliliter.

B.6.2.2 Sample in paste form

Before sampling, heat the sample on a water bath or in an oven at about 50℃ until the precipitate disappears completely. Stir the sample to mix it thoroughly, and allow to cool to ambient temperature. Weigh about 2 g of the sample, and follow the procedure in B.6.2.1.

B.6.3 Silanization of test portion

Pipette 0.3 mL of test solution (B.6.2.1) in a 1 mL test tube with stopper. Then add 0.1 mL of internal standard solution (B.6.1), 0.1 mL of TMCS (B.2.3), and 0.2 mL of HMDS (B.2.4). Shake for 30 s vigorously, then stand for 5 min.

B.7 GC determination

B.7.1 Chromatography determination

Inject the clear solution (B.6.3) and analyze.

B.7.2 Qualitative determination

Qualitatively analyze the chromatographic peak with the APG sample of known compositions as the standard sample. Or determine the chromatographic peak of mono-glycoside with the alkyl mono-glycoside standard sample with known carbon chain length. The subsequent peaks are alkyl bi-glycoside, alkyl tri-glycoside, alkyl tetraglycoside, alkyl penta-glycoside, etc.

A typical gas chromatogram of APG is shown in Figure B.1.

Figure B.1. Gas chromatogram of C12, C14 APG(Trans-glycosidation products)

B.8 Calculation

B.8.1 Short chain APG (such as butyl glycoside) content

The short chain APG (such as butyl glycoside) content wiby internal standard method, expressed as a percentage by mass, is given by formula (B.2)

Where,

Aiis the peak area of short chain APG (such as butyl glycoside);

fs,iis the calibration factor of the short chain APG (such as butyl glycoside), against n-docosane internal standard;

msis the mass, in grams, of internal standard;

ASis the peak area of n-docosane internal standard;

m is the mass, in grams, of the dried test portion.

Calculate the arithmetic average of the parallel determination results, keep the integer, as the result.

Precision—The maximum difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 5%(95% confidence intervals).

B.8.2 Determination of average polymerization degree

The long chain APG content w (D) by area normalization method, expressed as a percentage by mass, mono-glycoside for example, is given by formula (B.3)

Where,

Aiis the peak area of long chain alkyl mono-glycoside;

A is the total peak area of long chain APG (not counting the peak area of solvent, internal standard,alcohol residues, short chain APG).

Determination of other APG content is the same as above.

The average polymerization degree of APG w (Dp), is given by formula (B.4)

Where,

w (D1) is the alkyl mono-glycoside content, in a percentage by mass;

w (D2) is the alkyl bi-glycoside content, in a percentage by mass;

w (D3) is the alkyl tri-glycoside content, in a percentage by mass;

w (D4) is the alkyl tetra-glycoside content, in a percentage by mass;

w (D5) is the alkyl penta-glycoside content, in a percentage by mass.

Calculate the arithmetic average of the parallel determination results, keep one decimal place, as the result.

Precision—The maximum difference found between the results of two determinations carried out simultaneously or in rapid succession on the same sample, by the same analyst using the same apparatus, shall not exceed 5% (95%confidence intervals).

1 - Chromatographic peak of n-dodecanol

2 - Chromatographic peak of n-tetradecanol

3 - A group of butyl glycoside peaks

4 - Chromatographic peak of n-docosane internal standard

5 - A group of alkyl (C12, C14) mono-glycoside chromatographic peaks

6 - A group of alkyl (C12, C14) bi-glycoside chromatographic peaks

7 - A group of alkyl (C12, C14) tri-glycoside chromatographic peaks

8 - A group of alkyl (C12, C14) tetra-glycoside chromatographic peaks

9 - Chromatographic peak of alkyl (C12, C14) pentaglycoside